Health

The Power of a Single Dose: Evidence for a Single-Dose HPV Vaccine Schedule 

Posted on by Tory

HPV Vaccination: A Critical Cancer Prevention Tool 

Since 2006, vaccines have been available to protect against human papillomavirus (HPV), an extremely common infection that causes virtually all cases of cervical cancer – the fourth most common cancer in women globally – and is also a known cause of several other types of cancer that impact both men and women [1]. In most instances, the immune system can clear HPV without any need for treatment, but persistent infection with high-risk strains of HPV can lead to several types of cancer [2]. This leads to stark disparities in cancer burden for women living with HIV, whose compromised immune systems may not clear HPV infections as readily; these women are six times more likely to develop cervical cancer [3]. Geographical disparities in cervical cancer burden also persist. In 2020, more than 600,000 women around the world were diagnosed with cervical cancer, with up to 90% of new global cases occurring in low- and middle-income countries (LMICs) and the majority of cancer cases and deaths concentrated in sub-Saharan Africa, Central America, and Southeast Asia [2]. To address these inequities and reduce global disease burden, the World Health Organization (WHO) has committed to a global strategy to accelerate the elimination of cervical cancer as a public health problem. Along with screening and treatment, HPV vaccination is a key cornerstone of this strategy–by 2030, WHO aims to vaccinate 90% of girls against HPV by the age of 15 [4]. 

Although this is an ambitious goal, new evidence-based recommendations from WHO may contribute to increased HPV vaccination coverage, especially where it is needed most. WHO had previously recommended a two-dose schedule for HPV vaccines, but an off-label recommendation for a one-dose schedule was added in December 2022 based on recent efficacy data from single-dose trials [5]. The latest guidance recommends a one or two-dose schedule for girls aged 9–14 as well as those between 15–20-years old, with girls older than 21 and those who are immunocompromised or living with HIV recommended to receive a third dose. This change is expected to have important programmatic and financial implications for HPV vaccination programs, particularly in LMIC settings. Further, a single-dose schedule could be an important tool to improve health equity and reduce disparities in HPV-related cancers, protecting all girls everywhere against this preventable disease.  

Evidence for a Single-Dose HPV Schedule  

A number of rigorous studies have been conducted to determine the efficacy and immunogenicity of a single-dose regimen of HPV vaccines. Researchers have concluded that a single dose of HPV vaccine provides high levels of protection against high-risk strains of HPV, even several years after vaccination, and induces a robust immune response.  

  • In a randomized trial in Kenya (KEN SHE), a single-dose of HPV vaccine was found to be 97.5% effective in preventing cancer-causing strains of HPV among 15–20-year-old girls [6].  Researchers examined the efficacy of single-dose bivalent (a single shot that can protect against two strains of a virus) and nonavalent HPV vaccines (a single shot that can protect against nine strains of a virus) among 15–20-year-old girls. After 18 months of follow-up, both the bivalent and nonavalent vaccines demonstrated 97.5% vaccine efficacy against high-risk strains of HPV. Researchers subsequently published results demonstrating similar vaccine efficacy three years following vaccination: bivalent vaccine efficacy remained at 97.5% (95% CI 90.0–99.4%), while nonavalent vaccine efficacy was 98.8% (CI 91.3–99.8%) [7].  
  • In a Costa Rican study (CVT), a single dose of HPV vaccine was found to provide a similar level of protection (82.1%) against high-risk strains of HPV as two or three doses (83.8% and 80.2%, respectively), even 11 years following vaccination [8]. Researchers examined the dose-specific vaccine efficacy of the bivalent HPV vaccine among 18–25-year-old women and determined that vaccine efficacy against high-risk strains of HPV was high, regardless of the number of doses received. Protection persisted for approximately 11 years following initial vaccination. Vaccine efficacy was 80.2% (95% CI = 70.7% – 87.0%) for three doses, 83.8% (95% CI = 19.5% – 99.2%) for two doses, and 82.1% (95% CI = 40.2% to 97.0%) for a single dose, with no statistically significant differences in either vaccine efficacy or infection rates across the three groups.  
  • A cohort study in India (IARC India) found that the protection provided by a single dose of HPV vaccine was comparable to that provided by two or three doses, even 10 years after vaccination [9]. Researchers compared the vaccine efficacy of a single dose of quadrivalent HPV vaccine to two and three doses in protecting against high-risk HPV strains. After 10 years of following the cohort of women, there were no significant differences in the frequency of incident HPV infection among adolescent women who received one, two, or three doses of HPV vaccine. The vaccine efficacy of a single dose was found to be 95.4% (95% CI 85.0 – 99.0), which did not differ significantly from the efficacy of two or three doses.   
  • In Tanzania, a randomized trial among 9–14-year-old girls (DoRIS) found that two years after vaccination, a single dose of HPV vaccine produced a non-inferior immune response for a high-risk strain of HPV compared to two or three doses [10]. Researchers examined the immune response two years after vaccination with a single dose of HPV vaccine.  Compared to two or three doses, a single dose of either bivalent or nonavalent HPV vaccine produced non-inferior levels of antibodies against HPV 16. Although non-inferiority was not met for HPV 18 antibodies, at least 98% of girls who received a single dose of HPV vaccine were seropositive for these antibodies two years following vaccination.   

Moving to a Single Dose Schedule – Why it Matters  

Compared to many of the routine immunizations given to infants and adolescents, HPV vaccination presents unique programmatic, financial, and logistical challenges, many of which could potentially be addressed by the use of a single-dose vaccination schedule.  

Countries’ limited immunization budgets have put HPV vaccine introduction in direct competition with the introduction of several other life-saving vaccines, including pneumococcal conjugate vaccines and rotavirus vaccines [11]. Compared to a two-dose schedule, a single-dose schedule for HPV vaccines would significantly reduce procurement and delivery costs [11]. For example, an economic study in Tanzania estimated that compared to a two-dose HPV vaccination schedule, a single-dose schedule would reduce the cost per fully vaccinated girl by 51%, accounting for all financial costs including injection supplies, training, and outreach activities [12]. These cost savings could potentially stretch immunization budgets further, allowing countries to protect more girls against HPV and cervical cancer. Additional cost savings may be seen in reduced cold chain requirements, as fewer doses would require countries to purchase fewer refrigerators, for example [13]. 

Although countries are well-versed in delivering vaccines to children under 5, vaccines targeting older children are more difficult to integrate into existing immunization programs. A single dose of HPV vaccine could be delivered once per year during child health weeks or annual vaccination events, eliminating the need for follow-up and simplifying delivery to this hard-to-reach population [11].  

Additional Resources 

The resources below provide additional information about HPV vaccination and the evidence for a single-dose schedule. 

References

1. Sung H, Ferlay J, Siegel RL, et al. Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries. CA Cancer J Clin. 2021;71(3):209-249. doi:10.3322/caac.21660 
2. Cervical Cancer. World Health Organization. Updated 17 November 2023. Accessed 25 January 2024. https://www.who.int/news-room/fact-sheets/detail/cervical-cancer 
3. Stelzle D, Tanaka LF, Lee KK, et al. Estimates of the global burden of cervical cancer associated with HIV [published correction appears in Lancet Glob Health. 2021 Feb;9(2):e119]. Lancet Glob Health. 2021;9(2):e161-e169. doi:10.1016/S2214-109X(20)30459-9 
4. Global strategy to accelerate the elimination of cervical cancer as a public health problem. Geneva: World Health Organization; 2020 
5. World Health Organization. Human papillomavirus vaccines: WHO position paper (2022 update) Weekly Epidemiological Record. 16 Dec 2022, No 50, 97, 645-672. https://www.who.int/publications/i/item/who-wer9750-645-672 
6. Barnabas RV, Brown ER, Onono M, et al. Single-dose HPV vaccination efficacy among adolescent girls and young women in Kenya (the KEN SHE Study): study protocol for a randomized controlled trial. Trials. 2021;22(1):661. Published 2021 Sep 27. doi:10.1186/s13063-021-05608-8 
7. Barnabas RV, Brown ER, Onono MA, et al. Durability of single-dose HPV vaccination in young Kenyan women: randomized controlled trial 3-year results. Nat Med. 2023;29(12):3224-3232. doi:10.1038/s41591-023-02658-0 
8. Kreimer AR, Sampson JN, Porras C, et al. Evaluation of Durability of a Single Dose of the Bivalent HPV Vaccine: The CVT Trial. J Natl Cancer Inst. 2020;112(10):1038-1046. doi:10.1093/jnci/djaa011 
9. Basu P, Malvi SG, Joshi S, et al. Vaccine efficacy against persistent human papillomavirus (HPV) 16/18 infection at 10 years after one, two, and three doses of quadrivalent HPV vaccine in girls in India: a multicentre, prospective, cohort study [published correction appears in Lancet Oncol. 2022 Jan;23(1):e16]. Lancet Oncol. 2021;22(11):1518-1529. doi:10.1016/S1470-2045(21)00453-8 
10. Watson-Jones D, Changalucha J, Whitworth H, et al. Immunogenicity and safety of one-dose human papillomavirus vaccine compared with two or three doses in Tanzanian girls (DoRIS): an open-label, randomised, non-inferiority trial. Lancet Glob Health. 2022;10(10):e1473-e1484. doi:10.1016/S2214-109X(22)00309-6 
11. Gallagher KE, LaMontagne DS, Watson-Jones D. Status of HPV vaccine introduction and barriers to country uptake. Vaccine. 2018;36(32 Pt A):4761-4767. doi:10.1016/j.vaccine.2018.02.003 
12. Hsiao A, Struckmann V, Stephani V, et al. Costs of delivering human papillomavirus vaccination using a one- or two-dose strategy in Tanzania. Vaccine. 2023;41(2):372-379. doi:10.1016/j.vaccine.2022.11.032 
13. Gallagher KE, Kelly H, Cocks N, et al. Vaccine programme stakeholder perspectives on a hypothetical single-dose human papillomavirus (HPV) vaccine schedule in low and middle-income countries. Papillomavirus Res. 2018;6:33-40. doi:10.1016/j.pvr.2018.10.004 

A Warming World Means Vaccination is More Important Than Ever

Posted on by Tory

“The climate crisis threatens to undo the last fifty years of progress in development, global health, and poverty reduction, and to further widen existing health inequalities between and within populations.”1

With July 2023 confirmed as the hottest month on record2, the impacts of climate change are becoming impossible to ignore. In addition to rising temperatures, climate change is also responsible for increasingly frequent extreme weather events like intense storms, catastrophic floods, and record-breaking heat waves. A growing body of evidence suggests that the consequences of climate change pose a major threat not only to the planet, but also to human health.

Altogether, climate change is expected to cause around 250,000 excess deaths per year between 2030 and 2050 due to malnutrition, malaria, diarrhea, and heat stress alone1. In addition to the excess mortality that is directly attributable to natural disasters, the wide-ranging effects of climate change can also indirectly contribute to illness and death through several pathways. Warm, dry conditions trigger more frequent wildfires3, which in turn contribute to dangerous levels of air pollution4. The stress of living through an extreme weather event and the resulting loss of critical resources has been linked with poor mental health5. Furthermore, climate change is expected to increase the prevalence of several vaccine-preventable diseases, such as malaria, cholera, and typhoid, thanks to the expansion of mosquito habitats, scarcity of clean water, and disruptions to routine immunization, among others6.

No one is safe from the effects of climate change, but its impact reflects deep inequities. Already marginalized communities – particularly those in developing countries – will be disproportionately affected due to existing health disparities and insufficient health system infrastructure7. To minimize climate change-related health impacts, equitable access to vaccines must be a priority, especially for those who will be most affected in the years to come.

Rising Temperatures Increase Disease Transmission

In August 2023, global temperatures were approximately 1.5°C above preindustrial levels8. In addition to the illnesses and deaths caused directly by these dangerously high temperatures, such as those related to heat stroke9, collateral effects also include increased transmission of a number of vaccine-preventable diseases.

Warmer winters and hotter summers are expected to increase the evaporation of water sources, endangering the availability of safe, clean water and increasing the risk of diarrheal diseases10. This includes cholera, which has recently seen a global surge: The WHO reported 472,697 cases of cholera in 2022, nearly double the number reported in 202111. Rising temperatures reduce the availability of high-quality crops12, threatening food security and leading to dangerous malnutrition that weakens a child’s immune system and increases the risk of infectious disease.

Undernourished child cycle
Source: The Value of Immunization Compendium of Evidence – The vicious cycle of undernutrition and infectious disease: How does it work and what role do vaccines play?

An analysis of 14 countries in sub-Saharan Africa13 demonstrated that for every 1°C increase in average maximum temperature, the prevalence of diarrhea increased by about 1%. The reasons for this association are not entirely clear, but researchers point to the impact of heat on the growth and survival of diarrhea-causing bacteria, as well as the potential for heat-related changes in hygiene or food storage. This increase in disease burden may significantly impact vulnerable populations, especially young children, as diarrhea is currently the second most deadly infectious disease worldwide and kills over 480,000 children under 5 each year14. We already have the means to prevent rotavirus infection, the leading cause of diarrhea-related mortality among children around the world – a 2018 analysis estimated that if 100% of children globally had access to rotavirus vaccination, more than 83,000 child deaths could be prevented in a single year15 – yet millions of children around the world are still unprotected against this disease16. As global temperatures continue to rise, efforts to increase access to lifesaving rotavirus vaccines will remain critical.

Rising Temperatures graph

Temperature changes are also expected to impact transmission of vector-borne diseases, including malaria. About 80% of the world’s population lives in a region that is at risk of at least one vector-borne disease17, and this number could grow as temperatures continue to rise. The malaria parasite develops more quickly at higher temperatures, increasing the chance that a mosquito will survive long enough to transmit the disease18. Additionally, areas that are presently too cold for malaria transmission may warm up enough to allow malaria parasites to survive, exposing new populations to this deadly disease. One recent analysis estimated that around 1.4 billion additional people will be at risk of malaria and dengue in urban areas in Africa and southeast Asia due to changes in climate19. On the other hand, areas where malaria is currently being transmitted may become too warm, which could actually decrease incidence of the disease. Controlling malaria is already complex, but additional climate-related factors such as temperature, rainfall, and humidity may be important considerations for preventing outbreaks.

The Dangerous Consequences of Floods and Droughts

“Climate change is exacerbating both water scarcity and water-related hazards (such as floods and droughts), as rising temperatures disrupt precipitation patterns and the entire water cycle.”20

Between 2001–2018, nearly two-thirds of natural disasters were water-related21, and floods and droughts are only expected to become more intense and more frequent as climate change worsens. These events threaten the availability of safe drinking water and can increase transmission of enteric diseases. For example, both droughts and floods have been found to be significantly associated with cholera outbreaks in sub-Saharan Africa22; in this region, a cholera outbreak can be expected in 1 out of every 3 droughts. During a drought, communities searching for water can be forcibly displaced, often to overcrowded refugee camps with poor sanitation and limited access to cooking tools, increasing the risk of contamination and disease transmission.

Conversely, floodwater can overflow sewage systems and contaminate drinking water23. This contaminated water can also destroy WASH facilities, further putting communities at risk of disease transmission. Additionally, the heavy rainfall and stagnant water associated with flooding can create new mosquito habitats and increase breeding. In 2007, for example, areas in China impacted by flooding saw significantly higher numbers of cases of both malaria and diarrhea than non-flood-affected areas24. Lastly, floods and other disasters can seriously disrupt the delivery of health services, including vaccination25. Not only can flood water damage hospitals and health clinics, making it difficult or even impossible to provide routine immunization services, but it can also block roads, potentially leading to supply chain gaps that can impact the availability of vaccines and other critical medical supplies.

Infographic showing links between flooding, enteric disease, new mosquito habitats and damage to health facilities

Disproportionate Impact to Disadvantaged Populations

Every year, approximately 21.5 million people around the world26 are forced to leave their homes due to climate-related disasters like floods, storms, wildfires, and extreme temperatures, and this number is only expected to continue growing27. These individuals are often referred to as “climate refugees”, though this includes those internally displaced within their own countries as well as those pushed across borders to seek safety. Climate-related displacement disproportionately impacts those living in low-resource settings, who are less able to prepare for and withstand natural disasters. Even within low- and middle-income countries (LMICs), climate change is more likely to impact those who are already most deprived. According to an analysis in Pakistan, the regions with worse socioeconomic conditions are also the most vulnerable to climate change28. The same analysis also found that some regions which should be most exposed to climate change due to their precipitation and temperature patterns are actually less vulnerable, most likely because their populations have higher socioeconomic status and thus a higher capacity to adapt, suggesting that strengthening a community’s resilience is one potential solution to fight the impacts of climate change.

In addition to equity considerations, forced migration can also lead to increased risks of vaccine-preventable disease outbreaks. Disruption to health services, malnutrition, overcrowded settlements, and insufficient sanitation resources all contribute to infectious diseases, such as pneumonia and diarrhea, which are the leading causes of death during humanitarian emergencies29. Vaccination programs that target measles, S. pneumoniae, H. influenzae type-b, and rotavirus have already been recognized as critical tools for reducing the health impacts of complex humanitarian emergencies.

Mitigating the Impact of Climate Change with Vaccines

At this point, the impact of climate change is inevitable, but there are steps we can take to mitigate its effects on human health. We must strengthen efforts to increase access to vaccines for diseases that will become more prevalent as extreme weather events continue, prioritizing disadvantaged communities that will be hardest hit by climate-related disasters. Beyond vaccine introduction, we must work to make sure that adequate supplies are made available to those who need them most. For example, millions of doses of life-saving malaria vaccines30 are being rolled out in Africa over the next two years, but there is still significant work to be done to meet the global demand for these vaccines and to ensure that LMICs can afford them31. Similarly, the global supply of oral cholera vaccine (OCV) is currently unable to meet the needs of more and more frequent cholera outbreaks and must be allocated equitably32.

Over the last decade, enormous victories have been won in protecting children from preventable illnesses. As climate change has been recognized as a serious threat to public health, policymakers must take decisive action now to safeguard vulnerable populations from potentially catastrophic infectious diseases and counteract immunization backsliding.

Download as a PDF

Additional Reading

Will the Earth’s changing climate make TB spread faster? [Bhekisisa Centre for Health Journalism]

Children displaced in a changing climate: Preparing for a future that’s already underway [UNICEF]

Vaccines for a sustainable planet [Science Translational Medicine]

References

  1. World Health Organization. Climate change and health. Updated 30 October 2021. Accessed September 28, 2023. https://www.who.int/news-room/fact-sheets/detail/climate-change-and-health
  2. World Meteorological Organization. July 2023 confirmed as hottest month on record. 14 August 2023. https://public.wmo.int/en/media/news/july-2023-confirmed-hottest-month-record
  3. National Oceanic and Atmospheric Administration. Wildfire climate connection. Updated 24 July 2023. Accessed September 28, 2023. https://www.noaa.gov/noaa-wildfire/wildfire-climate-connection
  4. World Health Organization. Wildfires. Accessed September 28, 2023. https://www.who.int/health-topics/wildfires
  5. Cianconi P, Betro S, Janiri L. The Impact of Climate Change on Mental Health: A Systematic Descriptive Review. Frontiers in Psychiatry. Mar 6 2020;11(74). doi:10.3389/fpsyt.2020.00074
  6. Joi P. Five key links between climate change and health. VaccinesWork blog. 2023. https://www.gavi.org/vaccineswork/five-key-links-between-climate-change-and-health
  7. Byers E, Gidden M, Leclere D, et al. Global exposure and vulnerability to multi-sector development and climate change hotspots. Environmental Research Letters. 31 May 2018. doi:10.1088/1748-9326/aabf45
  8. World Meteorological Organization. Earth had hottest three-month period on record, with unprecedented sea surface temperatures and much extreme weather. 6 September 2023, 2023. https://public.wmo.int/en/media/press-release/earth-had-hottest-three-month-period-record-unprecedented-sea-surface
  9. World Health Organization. Heatwaves. Accessed September 28, 2023. https://www.who.int/health-topics/heatwaves
  10. International Federation of Red Cross and Red Crescent Societies, 2021. Climate Change Impacts on Health: Malawi Assessment. April 2021.
  11. World Health Organization. Weekly Epidemiological Record. Vol. 38. 2023:431-452. 22 September 2023.
  12. Zhao C, Liu B, Piao S, et al. Temperature increase reduces global yields of major crops in four independent estimates. Proceedings of the National Academy of Sciences. 2017;114(35):9326-9331. doi:10.1073/pnas.1701762114
  13. Bandyopadhyay S, Kanji S, Wang L. The impact of rainfall and temperature variation on diarrheal prevalence in Sub-Saharan Africa. Applied Geography. April 2012;33:63-72. doi:10.1016/j.apgeog.2011.07.017
  14. International Vaccine Access Center (IVAC), Johns Hopkins Bloomberg School of Public Health. (2022). Pneumonia and Diarrhea Progress Report 2022.
  15. Troeger C, Khalil IA, Rao PC, et al. (2018). Rotavirus vaccination and the global burden of rotavirus diarrhea among children younger than 5 years. JAMA Pediatrics. Oct 2018;172(10). doi: 10.1001/jamapediatrics.2018.1960
  16. International Vaccine Access Center (IVAC), Johns Hopkins Bloomberg School of Public Health. VIEW-hub. www.view-hub.org. Accessed 10/19/2023.
  17. Alonso P, Engels D, Reeder J. Renewed push to strengthen vector control globally. The Lancet. June 10 2017;389(10086):2270-2271. doi:10.1016/S0140-6736(17)31376-4
  18. Agyekum T, Botwe P, Arko-Mensah J, et al. A Systematic Review of the Effects of Temperature on Anopheles Mosquito Development and Survival: Implications for Malaria Control in a Future Warmer Climate. International Journal of Environmental Research and Public Health. 7 July 2021;18(14).doi:10.3390/ijerph18147255
  19. Colon-Gonzalez FJ, Sewe MO, Tompkins AM, et al. Projecting the risk of mosquito-borne diseases in a warmer and more populated world: a multi-model, multi-scenario intercomparison modelling study. The Lancet Planetary Health. July 2021;5(7):E404-E414. doi:10.1016/S2542-5196(21)00132-7
  20. United Nations. Water – at the center of the climate crisis. Accessed September 28, 2023. https://www.un.org/en/climatechange/science/climate-issues/water?gclid=CjwKCAjw3oqoBhAjEiwA_UaLtjFAZ_AFhkgP6lr0YAg7vlwTwZwUbsZa9T-pBajg0zu2QyOFKT8CpBoC3RIQAvD_BwE
  21. UNICEF. Water and the global climate crisis: 10 things you should know. Updated 2 March 2023. https://www.unicef.org/stories/water-and-climate-change-10-things-you-should-know
  22. Rieckmann A, Tamason CC, Gurley ES, et al. Exploring Droughts and Floods and Their Association with Cholera Outbreaks in Sub-Saharan Africa: A Register-Based Ecological Study from 1990 to 2010. The American Journal of Tropical Medicine and Hygiene. 2018;98(5):1269-1274. doi:10.4269/ajtmh.17-0778
  23. ten Veldhuis JAE, Clemens FHL, Sterk G, et al. Microbial risks associated with exposure to pathogens in contaminated urban flood water. Water Research. May 2010;44(9):2910-2918. doi:10.1016/j.watres.2010.02.009
  24. Gao L, Zhang Y, Ding G, et al. Identifying Flood-Related Infectious Diseases in Anhui Province, China: A Spatial and Temporal Analysis. The American Journal of Tropical Medicine and Hygiene. 2016;94(4):741-749. doi:10.4269/ajtmh.15-0338
  25. Pradhan NA, Najmi R, Fatmi Z. District health systems capacity to maintain healthcare service delivery in Pakistan during floods: A qualitative study. International Journal of Disaster Risk Reduction. August 2022;78. doi:10.1016/j.ijdrr.2022.103092
  26. UNHCR. Frequently asked questions on climate change and disaster displacement. Updated 6 November 2016. Accessed September 28, 2023. https://www.unhcr.org/uk/news/stories/frequently-asked-questions-climate-change-and-disaster-displacement
  27. Institute for Economics & Peace. Over one billion people at threat of being displaced by 2050 due to environmental change, conflict and civil unrest. September 9, 2020.
  28. Malik SM, Awan H, Khan N. Mapping vulnerability to climate change and its repercussions on human health in Pakistan. Globalization and Health. 2012;8(31). doi:10.1186/1744-8603-8-31
  29. Close RM, Pearson C, Cohn J. Vaccine-preventable disease and the under-utilization of immunizations in complex humanitarian emergencies. Vaccine. 2016;34(39):4649-4655. doi:10.1016/j.vaccine.2016.08.025
  30. World Health Organization. 18 million doses of first-ever malaria vaccine allocated to 12 African countries for 2023–2025: Gavi, WHO and UNICEF. 5 July 2023. https://www.who.int/news/item/05-07-2023-18-million-doses-of-first-ever-malaria-vaccine-allocated-to-12-african-countries-for-2023-2025–gavi–who-and-unicef
  31. Gavi, the Vaccine Alliance. Gavi outlines plans to build sustainable supply of malaria vaccines. 25 April 2023. https://www.gavi.org/news/media-room/gavi-outlines-plans-build-sustainable-supply-malaria-vaccines
  32. Gavi, the Vaccine Alliance. Global vaccine alliance outlines path to sustainable cholera vaccine supply. 22 May 2023. https://www.gavi.org/news/media-room/global-vaccine-alliance-outlines-path-sustainable-cholera-vaccine-supply

Why Rotavirus Vaccine Introduction in Nigeria is a Milestone for Child Health

Posted on by stacy

In August 2022, Nigeria became the most recent country to introduce the rotavirus vaccine into its national immunization program. The integration of the rotavirus vaccine into Nigeria’s routine immunization schedule is expected to help reduce at least 40% of morbidity and mortality associated with rotavirus infections amongst children.

Key Points

  • Nigeria’s recent introduction of rotavirus vaccine into its immunization schedule has the potential to save the lives of nearly 100,000 children under five over the next decade.
  • Immunization against rotavirus significantly reduces diarrhea-related hospitalizations and can relieve pressure on overburdened health systems.
  • Rotavirus vaccines provide a return on investment and protect families from potentially catastrophic medical expenses.
  • By preventing diarrheal disease and the malnutrition that may be associated with rotavirus infection, rotavirus vaccines can reduce the risk of stunting and promote healthy cognitive development.

Diarrheal diseases are one of the leading killers of children worldwide, claiming the lives of an estimated 484,000 children under five each year.1 Though many bacteria and viruses can cause diarrhea, rotavirus may be responsible for up to 38% of diarrhea-related hospitalizations in children under five in countries where the rotavirus vaccine has not yet been introduced2. The burden of rotavirus is concentrated in low- and middle-income countries, with a 2013 study reporting that nearly half of all global rotavirus deaths occurred in just four countries: India, Nigeria, Pakistan, and Democratic Republic of Congo3. Because rotavirus is so highly transmissible, preventing rotavirus infection with the use of rotavirus vaccines is more effective than treating symptoms after infection.

In August 2022, Nigeria became the most recent country to introduce the rotavirus vaccine into its national immunization program. This measure will protect millions of vulnerable children and significantly lower the global burden of rotavirus disease. “Nigeria’s rotavirus vaccine introduction has been a long-awaited event, making the inaugural rollout a milestone moment for Nigeria as well as the rest of the world united in efforts to reduce the mortality and morbidity of diarrheal diseases caused by rotavirus,” wrote ROTA Council Chair Mathu Santosham. “The implications of this launch event are tremendous.”

Due to the country’s high disease burden, introduction of the vaccine in Nigeria has the potential to avert a significant number of rotavirus hospitalizations and deaths. The mortality rate for rotavirus in children under five in Nigeria is estimated to be 136 per 100,000, accounting for 30% of all global rotavirus deaths in children under five4. Introducing the rotavirus vaccine into Nigeria’s national immunization program has the potential to protect 6.9 million children from this disease each year5, and it could potentially save the lives of nearly 100,000 children over the next decade6.

Relieving Pressure on Health Systems

Like other vaccines, evidence shows that rotavirus vaccines are highly effective in preventing severe illnesses that require children to be hospitalized. Reducing hospitalizations from preventable illnesses like rotavirus infection may be especially important for health system capacity at this time, as delivery of many health services in Nigeria has been disrupted by the COVID-19 pandemic7. Introducing rotavirus vaccine in Nigeria offers great potential to reduce the number of hospitalizations in children under five and alleviate pressure on an overburdened health system.

  • A 2018 study reported that 46% of children under 5 in Nigeria hospitalized for acute gastroenteritis tested positive for rotavirus8.
  • According to a review of 57 articles from 27 countries, hospitalizations due to rotavirus-related acute gastroenteritis (AGE) among children under 5 fell by a median of 67% in the first 10 years after the rotavirus vaccine was licensed9.
  • In Rwanda, hospital admissions due to rotavirus among children under five decreased up to 70% in the two years after the vaccine was introduced10.
  • In Botswana, gastroenteritis-related hospitalizations among children under five decreased by 23% in the two years following rotavirus vaccine introduction, with an even larger decline (43%) during the rotavirus season11.
  • A review of the vaccine’s impact in the United States found that in the first 11 years of its use, rotavirus hospitalizations declined by an average of 80% among children under five12. Rotavirus-related emergency visits declined by a median rate of 57%.

Rotavirus Vaccine is Cost-Effective & Reduces Financial Burdens on Families

Research shows that like other immunizations, the rotavirus vaccine is cost-effective and provides a positive return on investment for both governments and families.

  • In Nigeria, introduction of the rotavirus vaccine is estimated to save the government approximately US$28.5M in healthcare costs over a 10-year period13. These savings translate to a cost per DALY averted of US$116 (95% UI: $69-$169), just five percent of the country’s GDP per capita.
  • A meta-regression analysis of the cost-effectiveness of rotavirus vaccination across 195 countries found that it was cost-effective, particularly in LMICs with the highest disease burden14. Among countries eligible for Gavi support, the mean ICER was $255 per DALY averted (95% UI: $39–$918).
  • Studies from high-income settings have found that introduction of rotavirus vaccines can provide significant short-term returns on investment (ROI). For example, a series of studies in the United States estimated that once rotavirus vaccines were introduced, the average annual savings in direct healthcare costs from rotavirus and acute gastroenteritis were between US$121M and US$231M12. An economic evaluation of rotavirus vaccination in Italy determined that the cost of introducing the vaccine would be more than offset by savings from prevention of disease cases and hospitalizations within as early as two years15.
Economic Costs of Rotavirus Disease and Value of Vaccines

Families of those treated for diarrheal diseases face significant out-of-pocket expenditures, which can be especially burdensome for those already living in poverty. Many of these costs are considered catastrophic, meaning that they exceed 10 percent of the household’s monthly income. In addition to out-of-pocket medical costs for rotavirus-related illnesses, families who miss work to care for a sick child also face indirect costs due to lost wages. By reducing disease burden, the rotavirus vaccine protects vulnerable families from these catastrophic expenditures.

  • In Malaysia, families of those treated for acute gastroenteritis pay an average of US$101 in out-of-pocket costs16. These expenses disproportionately affect families in the lowest income quartile, representing 23% of their monthly household income, compared to less than 6% of monthly household income for families in the highest income quartile.
  • The average direct and indirect costs for rotavirus-related diseases among poor families in Bangladesh are US$105.2, including out-of-pocket expenditures for treatment, non-medical costs like transportation and lodging for caregivers, and the opportunity costs of lost wages17. This accounts for nearly one-third of their total monthly household income.
  • On average, families in Vietnam lose more than nine working days due to caring for a child with rotavirus18.

Reducing Rotavirus Infections Promotes Healthy Development

Enteric infections like rotavirus can have long-term effects on a child’s development. Diarrheal illnesses often lead to malnutrition, which can cause stunting and impact cognitive development—and which also makes children more susceptible to subsequent infections. Rotavirus vaccine can break this vicious cycle by preventing the malnutrition that accompanies diarrheal diseases to promote healthy growth and development. These vaccines are especially beneficial for children living in low-resource and marginalized communities who are more likely to experience undernutrition and stunting.

  • A pooled analysis of studies from five LMICs demonstrated the cumulative effects of repeat diarrheal episodes from 0–24 months20. For every five episodes of diarrhea that a child experiences, they are 13% more likely to be stunted at age two.
  • A study of children in Jamaica found that at age 11 or 12, children who had been stunted by age 2 performed significantly worse than non-stunted children on reading, spelling, and arithmetic tests, even when accounting for socio-economic factors21.
  • An analysis of 8,000 children in five LMICs estimated that children who were stunted by age 2 completed an average of approximately one year less of schooling22. They were also 16% more likely than non-stunted peers to have failed a grade.
  • Children with diarrhea have a greater risk of developing pneumonia or acute lower respiratory infections (ALRI). A study of children in Ghana estimated that more than 1 in 4 cases of ALRI were attributable to recent diarrheal illnesses, and therefore, preventing diarrheal illnesses would also prevent a large number of pneumonia cases23.
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Nigeria’s introduction of rotavirus vaccine is promising, with the potential to protect millions of children from diarrheal diseases caused by rotavirus. Track immunization coverage for rotavirus and other essential vaccines through VIEW-hub, IVAC’s interactive data visualization platform.

References

  1. International Vaccine Access Center (IVAC), Johns Hopkins Bloomberg School of Public Health. (2022). Pneumonia and Diarrhea Progress Report 2022.
  2. Lanata CF, Fischer-Walker CL, Olascoaga AC, et al. Global causes of diarrheal disease mortality in children <5 years of age: A systematic review. PLoS One. 2013;8(9):e72788. doi:10.1371/journal.pone.0072788
  3. Tate JE, Burton AH, Boschi-Pinto C, Parashar UD; World Health Organization–Coordinated Global Rotavirus Surveillance Network. Global, Regional, and National Estimates of Rotavirus Mortality in Children <5 Years of Age, 2000-2013. Clin Infect Dis. 2016;62 Suppl 2:S96-S105. doi:10.1093/cid/civ1013
  4. Global Burden of Disease Collaborative Network. Global Burden of Disease Study 2019 (GBD 2019) Results. Institute for Health Metrics and Evaluation (IHME) 2020; Available from: http://ghdx.healthdata.org/ gbd-results-tool.
  5. International Vaccine Access Center. VIEW- hub. [cited 2022 January]; Available from: http://view-hub.org/.
  6. Giwa, Omotayo. Nigeria Writes a New Chapter for Child Health with the Introduction of Rotavirus Vaccine. DefeatDD. Published August 22, 2022. Accessed November 17, 2022. https://www.defeatdd.org/blog/nigeria-writes-new-chapter-child-health-introduction-rotavirus-vaccine
  7. Shapira G, Ahmed T, Drouard SHP, et al. Disruptions in maternal and child health service utilization during COVID-19: analysis from eight sub-Saharan African countries. Health Policy Plan. 2021;36(7):1140-1151. doi:10.1093/heapol/czab064
  8. Tagbo BN, Mwenda JM, Eke CB, et al. Rotavirus diarrhoea hospitalizations among children under 5 years of age in Nigeria, 2011-2016. Vaccine. 2018;36(51):7759-7764. doi:10.1016/j.vaccine.2018.03.084
  9. Burnett E, Jonesteller CL, Tate JE, Yen C, Parashar UD. Global Impact of Rotavirus Vaccination on Childhood Hospitalizations and Mortality From Diarrhea. J Infect Dis. 2017;215(11):1666-1672. doi:10.1093/infdis/jix186
  10. Ngabo, F., Tate, J.E., Gatera, M., et al 2016. Effect of pentavalent rotavirus vaccine introduction on hospital admissions for diarrhea and rotavirus in children in Rwanda: a time-series analysis. Lancet Global Health. 4:e129-36.
  11. Enane LA, Gastanaduy PA, Goldfarb DM, et al. 2016. Impact of rotavirus vaccination on hospitalizations and deaths from childhood gastroenteritis in Botswana. Clinical Infectious Diseases. 2016(2).
  12. Pindyck T, Tate JE, Parashar UD 2018. A decade of experience with rotavirus vaccination in the United States – vaccine uptake, effectiveness, and impact. Expert Review of Vaccines. 17(7).
  13. Debellut, F., Clark, A., Pecenka, C., Tate, J., Baral, R., Sanderson, C., … & Atherly, D. 2019. Re-evaluating the potential impact and cost-effectiveness of rotavirus vaccination in 73 Gavi countries: a modelling study. The Lancet Global Health. 7(12).
  14. Janko MM, Joffe J, Michael D, et al. Cost-effectiveness of rotavirus vaccination in children under five years of age in 195 countries: A meta-regression analysis. Vaccine. 2022;40(28):3903-3917. doi:10.1016/j.vaccine.2022.05.042
  15. Carroll S, Rojas AJ, Glenngård AH, Marin C. Vaccination: short- to long-term benefits from investment. J Mark Access Health Policy. 2015;3:10.3402/jmahp.v3.27279. Published 2015 Aug 12. doi:10.3402/jmahp.v3.27279
  16. Loganathan, T., Lee, W.S., Lee, K.F., et al 2015. Household Catastrophic Healthcare Expenditure and Impoverishment Due to Rotavirus Gastroenteritis Requiring Hospitalization in Malaysia. PLOS One. 10(5).
  17. Ahmed S, Dorin F, Satter SM, et al. The economic burden of rotavirus hospitalization among children < 5 years of age in selected hospitals in Bangladesh. Vaccine. 2021;39(48):7082-7090. doi:10.1016/j.vaccine.2021.10.003
  18. Riewpaiboon A, Shin S, Le TP, et al. Cost of rotavirus diarrhea for programmatic evaluation of vaccination in Vietnam. BMC Public Health. 2016;16(1):777. Published 2016 Aug 11. doi:10.1186/s12889-016-3458-2
  19. Guerrant RL, DeBoer MD, Moore SR, Scharf RJ, Lima AA. The impoverished gut–a triple burden of diarrhoea, stunting and chronic disease. Nat Rev Gastroenterol Hepatol. 2013;10(4):220-229. doi:10.1038/nrgastro.2012.239
  20. Checkley, W., Buckley, G., Gilman, R.H., et al. 2008. Multi-country analysis of the effects of diarrhoea on childhood stunting. International Journal of Epidemiology. 37(4).
  21. Chang SM, Walker SP, Grantham-McGregor S, Powell CA. Early childhood stunting and later behaviour and school achievement. J Child Psychol Psychiatry. 2002;43(6):775-783. doi:10.1111/1469-7610.00088
  22. Martorell R, Horta BL, Adair LS, et al. Weight gain in the first two years of life is an important predictor of schooling outcomes in pooled analyses from five birth cohorts from low- and middle-income countries. J Nutr. 2010;140(2):348-354. doi:10.3945/jn.109.112300
  23. Schmidt WP, Cairncross S, Barreto ML, Clasen T, Genser B. Recent diarrhoeal illness and risk of lower respiratory infections in children under the age of 5 years. Int J Epidemiol. 2009;38(3):766-772. doi:10.1093/ije/dyp159

Vaccination: Helping children think, learn and thrive

Infographic describing Immunization, schooling and future prospects
Posted on by stacy

A selection of VoICE evidence in this issue

Berger JT, Villalobos ME, Clark AM et al. 2017. Cognitive development one year after infantile critical pertussis. Pediatric Critical Care Medicine. 19(2).

Lorntz, B., Soares, A.M., Moore, S.R., et al 2006. Early childhood diarrhea predicts impaired school performance. Pediatric Infectious Disease Journal. 25(6).

Krauss-Mars, A.H., and Lachman, P.I. 1992. Social factors associated with tuberculosis meningitis. South African Medical Journal. 81(1).

Niehaus, M.D., Moore, S.R., Patrick, P.D., et al 2002. Early childhood diarrhea is associated with diminished cognitive function 4 to 7 years later in children in a northeast Brazilian shantytown. American Journal of Tropical Medicine and Hygiene. 66(5).

Driessen J, Razzaque A, Walker D, et al. 2015. The effect of childhood measles vaccination on school enrolment in Matlab, Bangladesh. Applied Economics. 47(55).

Mina, M.J., Metcalf, C.J. de Swart, R.L., et al 2015. Long-term measles-induced immunomodulation increases overall childhood infectious disease mortality. Science. 348(6235).

Nandi A, Shet A, Behrman JR, et al. 2019. Anthropometric, cognitive, and schooling benefits of measles vaccination: Longitudinal cohort analysis in Ethiopia, India, and Vietnam. Vaccine. 37.

A healthy child is more likely to attend school, performs better in school and attends school for longer than a child who is often ill or has suffered permanent disabilities as a result of illness. In this Feature, VoICE explores how vaccine-preventable infections affect cognitive development and schooling, and highlights evidence of the effect vaccination can have in protecting a child’s neurologic development, educational prospects and ultimately, future productivity.

Key Messages

  1. Common childhood illnesses cause children to miss school. Immunized children miss less school.
  2. Recurring episodes of diarrhea in young childhood can delay a child from starting school and affect physical growth and normal cognitive development during childhood. Vaccine-preventable rotavirus is the most common cause of severe diarrhea.
  3. Immunization against measles can increase the number of years of schooling a child achieves and may also improve cognitive scores, compared to unimmunized children.
  4. Some vaccine-preventable infections carry the risk of long-term hearing, psychosocial and neurological disabilities that negatively impact a child’s social functioning and educational prospects.
  5. On average, globally, each additional year of schooling can increase a child’s future adult earnings by more than 12%.

Immunization protects our children’s future prospects

Most people think of vaccines as important for preventing specific diseases and infections during childhood, but may not realize the extent to which immunization can strengthen a child’s future prospects well into the school years and beyond. Growing evidence is illuminating the link between vaccination and improved cognitive functions, education, and ultimately, adult productivity. In essence, vaccination may help improve a child’s ability to learn, think and thrive in society as a result of educational attainment, cognitive reasoning and thinking skills.

Immunization, Schooling and future Prospects

Vaccine-preventable diseases, immunization and educational attainment

Vaccinated kids miss less school

The most obvious link between immunization and education is that preventing bouts of illness means kids miss fewer school days. A study of school absenteeism in the US found that nearly 50% of absences were due to illness. A second US study found that schools that offered flu vaccine to their students reduced the risk of any child getting the flu by 30%, regardless of vaccination status. Children vaccinated against the flu missed 1.5 fewer days of school per 100 school days compared to those who did not receive flu vaccine. Thirty years ago, Varicella infections (chickenpox) caused a child to miss nearly 9 days of school, not to mention work missed by parents taking care of a sick child. But the introduction of chickenpox vaccine in 1995 has drastically reduced infections, hospitalizations and deaths from this common infection, preventing more than 3.5 million cases each year in the US, according to the CDC.

Infections and schooling delays

Rotavirus is the most common cause of severe diarrhea in young children worldwide, and researchers in Brazil found that recurrent bouts of diarrhea affect school readiness and long-term educational attainment. In children living in a Brazilian shantytown, the greater the number of episodes of persistent diarrhea before age two, the more delayed a child was in terms of school readiness. Overall, each episode of diarrhea delayed a child’s starting school by 0.7 months. Likewise, 6-10 years later, increasing episodes of diarrhea before age two predicted delays in age-appropriate educational attainment. Some infections, such as tuberculosis meningitis, although rare, significantly increase the risk of major educational delays. From a study in Western Cape, South Africa, among children who were well enough to attend school after surviving tuberculosis meningitis, more than half had failed at least one school grade.

Measles vaccine can help increase extent of education received

Measles infection has a well-known prolonged negative impact on the immune system, increasing the risk of other illnesses for up to 3 years after recovering from measles. A 2019 analysis of survey data from school aged children in Ethiopia, India and Vietnam shows that children vaccinated against measles achieved 0.2-0.3 years of additional schooling compared to children who did not receive the measles vaccine. As depicted in the graphic below, note that this value is as high as 0.8 years of schooling by age 11-12. Similarly, data from a poor, largely rural South African community found that for every 6 children vaccinated against measles, one additional grade of school was achieved. In terms of initial enrollment in school, the phased introduction of measles in Bangladesh in the 1980’s resulted in boys being more than 7% more likely to be enrolled in school if they were vaccinated during the first year of life, compared to unvaccinated boys or those vaccinated later in childhood. This effect was not observed for girls, but may suggest that overall physical and cognitive health of children – as a result of their measles vaccination status – played a role in parent’s decisions to enroll their children in school.

Measles Vaccination Associated with Increased Schooling

Maternal vaccination can help a child’s education

In 1974, a randomized trial of tetanus vaccine was designed to determine how well maternal vaccination would protect infants born to mothers in Bangladesh from tetanus. The study showed a significantly reduced risk of tetanus infection and death among infants born to mothers who had received the vaccine. Notably, 20 years later, researchers found a clear pattern of increased educational attainment among children whose mothers received tetanus vaccine during pregnancy. Helping to explain this observation is the fact that up to 50% of children who survive neonatal tetanus may have long-term cognitive impairment as a result of the infection.

Vaccine-preventable diseases affect the ability to learn, think and function socially

Long-term impairments resulting from vaccine-preventable infections can reduce a child’s educational prospects in several ways. Not only may the impairment itself represent a barrier to learning and future productivity, as in the case of significant cognitive delays, but educational support for children affected by these and other impairments may be lacking or nonexistent. In many places around the world, educational systems and local school are stretched exceedingly thin and unable to provide specialized assistance to children with hearing, vision, developmental or other impairments.

Vaccine preventable infections in childhood can negatively affect a child's education

Hearing impairments

In the era before the introduction of pneumococcal conjugate vaccine (PCV) in the US, pneumococcus was the most common cause of serious and recurring ear infections in children. In comparison to life-threatening meningitis or severe pneumonia brought on by pneumococcal infection, an ear infection may seem trivial. But from the perspective of learning, ear infections can have serious consequences. Multiple ear infections in early childhood increase the risk of hearing loss, and that speech and language develops during the same time in which most children are at the greatest risk of ear infections. These factors help explain why children who spent more time with ear infections during early childhood had lower cognitive, speech, language development and even IQ than children who suffered less time with ear infections, according to a 1990 study in the US. More recently, a 2015 review of long-term impairments resulting from invasive meningococcal disease – which is relatively rare in the era of meningococcal vaccines – was significantly associated with permanent hearing loss in survivors.

Social and psychological impairments

Another set of challenges presented to survivors of vaccine-preventable diseases includes behavioral, social and psychological disorders. The invasive meningococcal disease review above highlighted evidence that children who survived invasive meningococcal infections were nearly 15% more likely to have a significant psychological disorder 3-5 years after the disease than children who did not have the disease, and two studies found a significant association between the disease and later development of Attention Deficit Hyperactivity Disorder (ADHD).

Vaccine-preventable brain and brain-related infections and long-term cognitive impairment

Vaccines can prevent several infectious causes of severe brain and brain-related infections such as meningitis or encephalitis. These types of infections are not only life-threatening but are highly associated with impaired thinking and learning after infection, sometimes for the rest of one’s life. Vaccines that prevent these infections thus help protect and preserve one’s future ability to learn, engage socially and thrive in society.Infection with Japanese encephalitis virus (JEV), which circulates almost exclusively in Asia, usually results in mild or undetectable symptoms. However, in those who develop encephalitis, a serious inflammation of the brain, 1 in 4 do not survive. Among those who do survive, up to 50% are left with permanent cognitive, psychological or neurological disabilities. An effective vaccine is available and the WHO recommends its inclusion in the national immunization schedules of heavily affected countries.Another life-threatening infection of the central nervous system is meningitis, which may have viral or bacterial causes. A large portion of the most severe meningitis infections were caused by three bacteria – pneumococcus, Hib and meningococcus – which are now largely vaccine-preventable. Pneumococcal, Hib and meningococcal infections have been responsible for the majority of meningitis deaths among children and for significant numbers of permanent cognitive disabilities, making their prevention high on the list of priorities for safeguarding a child’s future prospects. In The Gambia, 58% of children who survived pneumococcal meningitis had long lasting negative health outcomes. Half had major disabilities such as mental retardation, hearing loss, motor abnormalities, and seizures. A systematic literature review of studies across Africa found that 25% of children who survived pneumococcal or Hib meningitis had neuropsychological deficits.

The link between diarrhea, physical growth and cognition

Especially during early childhood, good nutrition and physical growth are needed for normal cognitive development. Diarrhea, especially severe or recurring diarrhea, limits the absorption of nutrients in the body, which can affect physical and cognitive development in the long-term. (See the VoICE Featured Issue on Nutrition, Growth and Development). Many rotavirus infections can be prevented through the use of existing vaccines. Prevention of diarrhea is another way to safeguard cognitive development, based on these sobering facts:

Some vaccines have been linked to improved learning and cognitive development

Some evidence in the last 10 years points to a positive link between vaccination in early childhood and a corresponding gain in cognitive and learning tests in later childhood. A small study from the Philippines found that children immunized with 6 basic vaccines scored better on three cognitive tests (verbal, mathematics and language) at age 11 compared to children who received none of these 6 vaccines. A 2019 analysis of survey data from India, Ethiopia and Vietnam found that children vaccinated against measles scored better on cognitive tests of language development, math and reading than children who did not receive measles vaccines.

Vaccination as an investment in future productivity

Reporting on the Philippine study of cognition and vaccination, David Bloom and colleagues at Harvard University note that improvements in a child’s health translate into better earning potential and productivity as an adult, and thus describe vaccination as “an investment in human capital”, highlighting several studies that support this idea. Educational attainment is an important part of the equation for reaping the rewards of such investments. A 2014 World Bank review of the returns to schooling worldwide found a significant positive relationship between additional years of schooling and future adult wage earnings. Not only were the returns from schooling greatest in low- and middle-income countries, but the highest returns to schooling came from the primary years of education – years in which the influence of early childhood illnesses is the strongest. On average across Africa, the report concludes that an additional year of schooling would yield a 12.4% increase in future adult earnings.A healthy child is more likely to attend school, performs better in school and attends school for longer than a child who is often ill or suffering permanent disabilities as a result of illness. The list of consequences from vaccine-preventable illnesses is long and frightening. Each threat erased from that list by vaccination is another hurdle removed from a child’s path to an education and a full and productive adulthood.

Commentary from the VoICE editors

The literature investigating the linkages between immunization, education and cognition represents a complex web of research areas spanning epidemiology, neuroscience, economics, education and demography. Studies specifically and quantitatively looking at the relationships between vaccines and education or cognition are relatively few, and some are older than the literature typically covered in VoICE. Although the positive link between immunization and educational attainment is generally accepted, the lack of new studies on this topic highlights the need for additional focus on this area of study. Although the complexity of these linkages makes quantifying the effect of immunization on education and future productivity difficult, all the literature reviewed in VoICE demonstrates a clear positive – and logical – relationship between immunization and improvements in thinking, social development, schooling and educational success.

The Unyielding Impact of Childhood Diarrhea

Infographic
Posted on by stacy

Despite tremendous global progress, diarrhea remains the second leading infectious cause of under-5 deaths, taking a child’s life almost every minute. Although diarrhea can seem like a common, simple childhood ailment in many places, a single episode of diarrhea can be serious, even deadly, and have severe economic implications for families and communities. Advocates play a critical role in ensuring evidence-based diarrhea prevention and control programs and policies are a top priority globally and in the countries where this disease is most prolific.

A selection of VoICE evidence in this issue

Chai, P.F., and Lee W. S. 2009. Out-of-pocket costs associated with rotavirus gastroenteritis requiring hospitalization in Malaysia. Vaccine. 27(5).

DeBoer, M.D., Chen, D., Burt, D.R. et al 2013. Early childhood diarrhea and cardiometabolic risk factors in adulthood: The Institute of Nutrition of Central America and Panama (INCAP) Nutritional Supplementation Longitudinal Study. Annals of Epidemiology. 23(6).

Loganathan, T., Lee, W.S., Lee, K.F., et al 2015. Household Catastrophic Healthcare Expenditure and Impoverishment Due to Rotavirus Gastroenteritis Requiring Hospitalization in Malaysia. PLOS One. 10(5).

Saha, S., Santosham, M., Hussain, M. et al. 2018. Rotavirus Vaccine will Improve Child Survival by More than Just Preventing Diarrhea: Evidence from Bangladesh. American Journal of Tropical Medicine and Hygiene. 98(2).

Riumallo-Herl, C., Chang, A.Y., Clark, S., et al. 2018. Poverty reduction and equity benefits of introducing or scaling up measles, rotavirus, and pneumococcal vaccines in low-income and middle-income countries: a modeling study. British Journal of Medicine Global Health. 3:e000612.

Burnett, E., Jonesteller, C. L., Tate, J. E., et al. 2017. Global impact of rotavirus vaccination on childhood hospitalizations and mortality from diarrhea.. The Journal of Infectious Diseases. 215(11).

Hendrix, N., Bar-Zeev, N., Atherly, D., et al 2017. The economic impact of childhood acute gastroenteritis on Malawian families and the healthcare system. BMJ open. 7(9).

Schlaudecker, E.P., Steinhoff, M.C. and Moore, S.R. 2011. Interactions of diarrhea, pneumonia, and malnutrition in childhood: recent evidence from developing countries. Current Opinion in Infectious Diseases. 24(5).

How preventing diarrhea can protect children, families, communities, and health systems

Despite tremendous global progress, diarrhea remains the second leading infectious cause of under-5 deaths, taking a child’s life almost every minute.[1],[2] Although diarrhea can seem like a common, simple childhood ailment, in many places a single episode of diarrhea can be serious, even deadly, and have severe economic implications for families and communities.

  • Repeated, prolonged diarrhea can have lasting – but sometimes overlooked – impacts on child health and development.
  • Treating diarrhea can be costly to families and health systems, and treatment costs can even push some families into poverty.
  • Rotavirus causes approximately one third of diarrhea deaths, and is only adequately preventable via vaccination – water, sanitation, and hygiene interventions that work to prevent other types of diarrhea don’t work to prevent rotavirus.
  • Cholera vaccination is used to stop endemic cholera and respond to cholera outbreaks, which are common in humanitarian emergency settings.

Advocates play a critical role in ensuring evidence-based diarrhea prevention and control programs and policies are a top priority globally and in the countries where the outcomes of diarrheal diseases are most devastating.

The burden of diarrhea globally

Each year, there are an estimated 1 billion episodes of diarrhea with approximately 500,000 deaths in children under five years of age.[1],[2] WHO estimates that children in low- and middle-income countries each have approximately three episodes of diarrhea a year.[3]  Although improvements have been made in our efforts to stop diarrhea deaths, we still have far too many episodes: since 1990, the number of diarrhea deaths has decreased by 65%, but the number of new diarrhea episodes has decreased by only 24%.[4] This burden is disproportionally concentrated in low- and middle-income countries, with over half of the diarrheal deaths occurring in sub-Saharan Africa – a low-resource setting where progress is slowest.[5]

The impact of diarrhea on children

Each episode of diarrhea deprives a child of nutrition necessary for growth and contributes to malnutrition, making these children more vulnerable to diarrhea yet less able to fight it.[3] After an episode of diarrhea, children grow less in length than children who did not have diarrhea.  When a child has repeated episodes of diarrhea, it can lead to chronic malnutrition and stunting, which in turn is associated with poor functional outcomes such as impaired cognitive development. Prolonged and frequent episodes of diarrhea in young children under the age of two affects them in later childhood and adolescence by leading to delays in school readiness and poor performance in school, as compared to their peers.

Episodes of diarrhea can exacerbate underlying undernutrition and can impair immunity hampering the ability to fight diseases such as pneumonia.[6] During diarrheal episodes, children can lose Vitamin A and zinc, which may predispose some children to pneumonia. In addition, children with more frequent episodes of diarrhea are more likely have chronic health issues later in life, like high blood pressure, which are taxing on both families and health systems.

Tools to defeat diarrhea

Aids to Help Protect and Prevent diarrhea disease and deaths

We have highly effective tools to fight diarrhea. Interventions to improve water, sanitation, and hygiene (WASH) have been successful in reducing the number of diarrhea cases.[7]  Exclusive breastfeeding for the first 6 months of life can protect infants from undernutrition and its associated vulnerability to diarrhea.[7] Inexpensive but effective treatments like oral rehydration salts (ORS) and zinc supplements work to stop diarrhea episodes from becoming severe and deadly. Yet, access to ORS and zinc is dismally low in many high-burden settings. In 6 of the 10 countries with the highest number of diarrhea deaths[7], national ORS coverage is below 40%.[8] In half of the 10 highest-burden countries[7], fewer than one in ten children have access to zinc supplements. In addition, we also see inequities in access to treatment. In at least half of the 10 highest-burden countries, ORS coverage was at least 10 percentage points lower in rural areas compared to urban areas, or in the poorest 20% of the population compared to the wealthiest 20%.[8]

Infographic

Vaccination is our strongest protection against vaccine-preventable causes of diarrhea

Two types of common diarrhea are vaccine preventable: rotavirus and cholera. Rotavirus vaccines are especially crucial in preventing a large proportion of diarrhea deaths and hospitalizations around the world. Cholera vaccination is critical in preventing outbreaks in high-risk settings.

 Rotavirus vaccination can prevent hospitalizations and death

Although WASH interventions have successfully reduced the global burden of diarrhea, one main cause of diarrhea mortality – rotavirus – is not prevented through WASH interventions.[9],[10] Rotavirus is associated with approximately one third of diarrhea deaths and can only be adequately prevented through vaccination.[2],[9]

Rotavirus is a leading cause of diarrhea in infants.[5] This highly contagious virus kills about 200,000 children under 5 each year and is responsible for almost 40% of all diarrhea hospitalizations each year.[2],[5] Although ORS can treat simple cases of rotavirus, many of the world’s poorest children don’t have access to ORS.[8] Rotavirus vaccines have proven highly effective and impactful in countries where they have been introduced. In Malawi, for example, there was a 35% decrease in all-cause diarrhea deaths following rotavirus vaccination.[11] Rotavirus hospitalizations in children under 1 year fell by 80% after vaccine introduction.[12] As of January 2019, 97 countries have introduced rotavirus vaccines into their national schedule.[13] 

Current Rotavirus Vaccine Introduction Status*

Map of Current Rotavirus Vaccine Introduction Status
*As of January 2019

Rotavirus vaccination can protect health systems and resources 

Although diarrhea treatment is relatively inexpensive, when we factor in the sheer burden of diarrhea, these treatments are costly to health systems and require substantial health worker capacity.  Although many cases of diarrhea can be treated in outpatient facilities with low-cost treatment, inpatient treatment of diarrhea can cost hospitals 25 times the cost of outpatient treatment, per patient.[14]

Treating diarrhea uses limited health systems resources, such as hospital beds, and consequently consumes the resources that can be used to treat other diseases – often diseases aren’t preventable. Therefore, direct and indirect benefits of rotavirus vaccination programs play a critical role in reducing the strain on health systems. One in four children who were taken to a large pediatric hospital in Bangladesh were refused admission to the hospital because all of the beds were occupied. Acute diarrhea was one of the most common reasons for being admitted to the hospital, showing children with acute diarrhea filled many of the available hospital beds. Over half of the acute diarrhea cases that were admitted were due to rotavirus, showing that vaccination could prevent children from both needing and utilizing essential hospital resources.

We’ve seen tremendous reductions in hospitalizations for rotavirus diarrhea and all-cause diarrhea following rotavirus vaccine introductions.[15] A review of rotavirus vaccine introductions found that, globally, all-cause diarrhea hospitalizations reduced by almost 40% in children under 5 in regions where the vaccine had been introduced. The continued use and scale up of rotavirus vaccines will alleviate pressure from over-burdened facilities, enabling health systems to be more responsive.

Rotavirus vaccination may protect families from being pushed into poverty due to treatment costs

Rotavirus vaccination programs can protect the most vulnerable families from medical impoverishment and catastrophic healthcare costs. When looking at all-cause diarrhea In Malawi, the costs associated with treating diarrhea pushed families into poverty, with treatment costs exceeding the monthly income for one in six families needing inpatient care and one in ten families needing outpatient care. Families can be pushed into poverty by the costs of hospitalizing a child with rotavirus for several days. In Malaysia, the inpatient costs of rotavirus treatment can cost families 25% of an average family’s monthly income. Direct and indirect treatment costs, such as medicine and transportation, caused almost 9 in 10 Malaysian families to spend more than 10% of their monthly household income on treating rotavirus.

Rotavirus vaccine introduction in 41 GAVI-eligible countries could avert 40% of catastrophic health costs – 900,000 cases – and 40% of medical impoverishment – 200,000 cases. In other words, with rotavirus vaccination programs, 900,000 families would not incur health costs that are higher than a substantial proportion of their income and 200,000 families not would fall below the poverty line due to treatment costs. If rotavirus vaccination programs were introduced or scaled up in Gavi-supported countries, $200 million in out-of-pocket health expenses attributable to severe rotavirus infections could be averted, meaning low-income families would have more disposable income and greater financial stability. With vaccines being one of the more equitable health interventions accessible to poor families, they are an important strategy to reduce the gap in health outcomes by household income as well as protect many families from being pushed into poverty. Inequitable access to treatment, not an uncommon event, only exacerbates the disproportionate risk of mortality in vulnerable children, again underscoring the importance of preventing diarrhea in the first place and protecting children from the vicious aftermath of diarrhea.

Rotavirus vaccination can protect communities

Rotavirus vaccines provide immunity for not only children directly vaccinated but also affords protection to their families and communities. This herd immunity magnifies the public health benefit of rotavirus vaccination by extending protection to those age groups in the population who are not directly receiving the vaccine but can contract and transmit the disease. This additional benefit is essential for a resilient pathogen like rotavirus, that can live on surfaces – and therefore transmit disease – for days. As a result of rotavirus immunized children in the community, rotavirus hospital admissions in unvaccinated children aged two to five years of age, who were not age-eligible to receive the vaccine at the time, were reduced by 41% to 92% in hospitals across the US, showing the profound value of herd immunity.

Baby receiving vaccine

Cholera vaccination can protect vulnerable groups

Cholera burden

Diarrhea caused by cholera can be rapidly fatal, with as many as 1 in every 5 cases of cholera advances to severe disease.[16] Cholera, often called a disease of poverty, can be endemic and epidemic in settings without strong water and sanitation systems, such as humanitarian emergency settings. Because settings where cholera is most rampant are often those with weak or overburdened health systems, diagnosing and recording cases is difficult; the global estimates of cholera cases each year – between 1.3 and 4 million cases – likely underestimate the true burden.[16]

Unlike many vaccine-preventable diseases, the global number of cholera cases has been steadily climbing for the past 10 years. Devastating cholera epidemics have impacted Yemen, Haiti, Somalia, the Democratic Republic of Congo, and South Sudan in recent years, and continue to be a threat in fragile settings.[17] In addition to the health impacts of cholera, previous outbreaks have led to significant economic losses to countries, caused by reduced revenue on trade and tourism, and continue to threaten countries.[16]

Cholera vaccination

 Cholera vaccination is a crucial, cost-effective tool to fight cholera, especially in fragile settings that lack sufficient water and sanitation. In 2013, global partners collaborated to form a stockpile of the oral cholera vaccine, managed by the Global Task Force on Cholera Control and funded by Gavi, the Vaccine Alliance.[16] The stockpile has been utilized for mass vaccination campaigns for prevention in humanitarian crises and for reactive response to outbreaks.[17]

An important – and beneficial – feature of cholera is that vaccinating a relatively small number of people can result in significant herd protection. Research from Bangladesh suggests that 70% vaccine coverage can stop cholera transmission, which greatly amplifies the impact of vaccine campaigns and investments.[18] Cholera vaccination is also a critical tool in managing outbreaks and protecting national and global health security.

Continuing – and strengthening – the fight against diarrheal diseases

Certain types of serious diarrhea can be both preventable and treatable, and a large proportion of child diarrhea deaths can be prevented through vaccination. We have the tools to defeat diarrhea, but these tools are only effective when backed by strong political and financial commitment. The global fight against childhood diarrhea has undoubtedly had a profound impact on child health and broader societal development. Yet, consistently low treatment coverage and constraints in vaccine supply highlight ongoing challenges. These challenges must be responded to with the resources and commitment necessary to pick up the pace of progress, so we can be stronger in the global fight against one of the most common causes of childhood illness and death.

[1] WHO and Maternal and Child Epidemiology Estimation Group, Estimates of child cause of death, diarrhoea 2018. Retrieved from: https://data.unicef.org/topic/child-health/diarrhoeal-disease/

[2] Institute for Health Metrics and Evaluation (2018). Global burden of disease, GBD Results tool. Retrieved from: http://ghdx.healthdata.org/gbd-results-tool

[3] World Health Organization (2017).  Diarrheal Disease. Retrieved from: http://www.who.int/en/news-room/fact-sheets/detail/diarrhoeal-disease

[4] Troeger, C., Colombara, D. V., Rao, P. C., Khalil, I. A., Brown, A., Brewer, T. G., … & Petri, W. A. (2018). Global disability-adjusted life-year estimates of long-term health burden and undernutrition attributable to diarrhoeal diseases in children younger than 5 years. The Lancet Global Health, 6(3), e255-e269.

[5] Tate, J. E., Burton, A. H., Boschi-Pinto, C., Parashar, U. D., World Health Organization–Coordinated Global Rotavirus Surveillance Network, Agocs, M., … & Ranjan Wijesinghe, P. (2016). Global, regional, and national estimates of rotavirus mortality in children< 5 years of age, 2000–2013. Clinical Infectious Diseases, 62(suppl_2), S96-S105.

[6] Ibrahim, M. K., Zambruni, M., Melby, C. L., & Melby, P. C. (2017). Impact of childhood malnutrition on host defense and infection. Clinical microbiology reviews, 30(4), 919-971.

[7] WHO/UNICEF (2013). Ending preventable child deaths from pneumonia and diarrhoea by 2025: The integrated Global Action Plan for Pneumonia and Diarrhoea (GAPPD). Retreieved from: https://www.who.int/maternal_child_adolescent/documents/global_action_plan_pneumonia_diarrhoea/en/

[8] International Vaccine Access Center (IVAC), Johns Hopkins Bloomberg School of Public Health. (2018). Pneumonia and Diarrhea Progress Report 2018.

[9] Lamberti, L. M., Ashraf, S., Walker, C. L. F., & Black, R. E. (2016). A systematic review of the effect of rotavirus vaccination on diarrhea outcomes among children younger than 5 years. The Pediatric infectious disease journal, 35(9), 992-998.

[10] Glass, R. I., Parashar, U., Patel, M., Gentsch, J., & Jiang, B. (2014). Rotavirus vaccines: successes and challenges. Journal of infection, 68, S9-S18.

[11] Bar-Zeev, N., King, C., Phiri, T., Beard, J., Mvula, H., Crampin, A. C., … & Costello, A. (2018). Impact of monovalent rotavirus vaccine on diarrhoea-associated post-neonatal infant mortality in rural communities in Malawi: a population-based birth cohort study. The Lancet Global Health, 6(9), e1036-e1044.

[12] Burnett, E., Jonesteller, C. L., Tate, J. E., et al. 2017. Global impact of rotavirus vaccination on childhood hospitalizations and mortality from diarrhea.. The Journal of Infectious Diseases. 215(11), 1666-1672..

[13] International Vaccine Access Center (2018). VIEW-hub: Vaccine Introduction and Epidemiology Window. Retreived from: http://view-hub.org. Accessed January 31, 2018.

[14] Sarker, A. R., Sultana, M., Mahumud, R. A., Ali, N., Huda, T. M., Haider, S., … & Morton, A. (2018). Economic costs of hospitalized diarrheal disease in Bangladesh: a societal perspective. Global health research and policy, 3(1), 1.

[15] Groome, M. J., Zell, E. R., Solomon, F., Nzenze, S., Parashar, U. D., Izu, A., & Madhi, S. A. (2016). Temporal association of rotavirus vaccine introduction and reduction in all-cause childhood diarrheal hospitalizations in South Africa. Clinical Infectious Diseases, 62(suppl_2), S188-S195.

[16] World Health Organization. (2017). Cholera vaccines: WHO position paper–August 2017. Weekly Epidemiological Record. 92(34), 477-498.

[17] Wierzba, T. F. (2018). Oral cholera vaccines and their impact on the global burden of disease. Human vaccines & immunotherapeutics, 1-8.

[18] Dimitrov, D. T., Troeger, C., Halloran, M. E., Longini, I. M., & Chao, D. L. (2014). Comparative effectiveness of different strategies of oral cholera vaccination in Bangladesh: a modeling study. PLoS neglected tropical diseases, 8(12), e3343.

Cancer and Immunization: More than meets the eye

Posted on by stacy

Evidence from several disciplines indicates that immunization has a broader role to play in lessening the impact of cancer than one might expect. While it may be obvious that the widespread and growing use of vaccines against Hepatitis B and human papilloma virus (HPV) is directly responsible for preventing a significant number of related cancers, immunization against a host of other diseases may indirectly help to prevent additional cancers while helping to protect the health of immune-compromised cancer patients considerably. Read on for a brief explanation of how vaccines can prevent cancer, protect cancer patients and more.

A selection of VoICE evidence in this issue

Andrus, J.K., Cochi, S.L., Cooper, L.Z., et al 2016. Combining global elimination of measles and rubella with strengthening of health systems in developing countries. Health Affairs. 35(2).

Ramakrishnan, M., Ulland, A.J., Steinhardt, L.C., et al 2009. Sequelae due to bacterial meningitis among African children: a systematic literature review. BMC Medicine. 7(47).

Goetghebuer, T., West, T.E., Wermenbol, V., et al 2000. Outcome of meningitis caused by Streptococcus pneumoniae and Haemophilus influenzae type b in children in The Gambia. Tropical Medicine and International Health. 5(3).

Mina, M.J., Metcalf, C.J. de Swart, R.L., et al 2015. Long-term measles-induced immunomodulation increases overall childhood infectious disease mortality. Science. 348(6235).

Coles, C.L., Rahmathullah, L., Kanungo, R., et al 2012. Pneumococcal carriage at age 2 months is associated with growth deficits at age 6 months among infants in South India. Journal of Nutrition. 142(6).

Gewa, C.A. and Yandell, N. 2011. Undernutrition among Kenyan children: contribution of child, maternal and household factors. Public Health Nutrition. 15(6).

The direct benefits of preventing cancer-causing infections

HepB and liver cancer

Introduced in 1982, the hepatitis B vaccine was the first widely available vaccine to directly prevent cancer. More than 1 billion doses of HepB vaccine have been delivered, resulting in a significant reduction in the chronic liver infection that leads to cirrhosis or cancer in roughly a quarter of adults. The risk of HepB infection begins at birth – and lasts throughout a person’s life – which is why HepB is the first vaccine most children receive, often within hours of coming in to the world. In fact, 80-90% of children who are infected with HepB during the first year of life will go on to develop chronic liver disease, dramatically increasing their cancer risk.

More from the World Health Organization

HPV and cancer

A leading cause of death among women, cervical cancer took the lives of more than a quarter of a million women in 2012, 85% of whom were from low- or middle-income countries. Cervical cancer is caused by human papillomavirus (HPV), a common infection that can lead to abnormal cell growth and high-mortality cancers. Just two of the more than 100 strains of HPV are responsible for 70% of cervical cancers and precancerous lesions. Each of the three available HPV vaccines has been proven effective in preventing infection with high-risk strains of HPV and could protect against other forms of cancer caused by the virus. The exceedingly high mortality rate for cervical cancer (1 in 2 women will succumb to the disease) is due largely to the lack of access to early detection and treatment for women in much of the world, and reinforces the urgency of prevention through vaccination.

More from the World Health Organization

Additional benefits

HepB, Hib and polio vaccines

Some intriguing new evidence suggests that vaccines against HepB, Hib and polio may indirectly help to prevent the development of childhood cancers. Some scientists have suggested that early and robust stimulation of a child’s immune system – such as that afforded by vaccination – could help the body recognize and neutralize early tumors, thus decreasing the risk of developing certain childhood cancers such as leukemia. A study from the state of Texas in the US tested this idea and found that children born in counties with high coverage of HepB, polio and Hib vaccine were 33-42% less likely to develop a specific kind of leukemia than children born in counties with low vaccine coverage. Although only a small number of studies have demonstrated this indirect benefit of immunization on childhood cancers thus far, it is an exciting new area we will be following closely.

Protecting cancer patients and survivors from other infections

Cancer and cancer treatments can severely diminish the body’s capacity to fight infection, putting cancer patients and survivors at significantly greater risk of vaccine-preventable diseases and death from secondary infections. For example, a study of adults in the US found that invasive pneumococcal disease was more than 20 times more likely to occur in cancer patients than in cancer-naïve people. In a large study that followed survivors of childhood and early adult cancers for more than 5 years, researchers found a significantly higher rate of infections than in the siblings of these patients. Cancer survivors in this study were also 4 times more likely to die of infectious causes than their siblings. Pneumonia, a potentially vaccine-preventable infection, carried some of the highest increased risk to cancer patients, even more than 5 years after cancer diagnosis.

Survivors of pediatric and young-adult cancers must also be concerned about developing other forms of cancer later in life, some of which may be preventable through use of the HPV vaccine. A large study in the US found that longterm cancer survivors – both men and women – appeared to have a significantly increased risk of developing HPV-associated cancers and malignancies later in life. For these reasons, it is critical that cancer patients and survivors be vaccinated, and sometimes re-vaccinated, to ensure the greatest possible protection from additional infection.

Herd immunity in the general population is also an important protective firewall for cancer patients [1] weakened by the disease who may not yet have been vaccinated. Immune-suppressive treatments commonly used to treat some forms of cancer may erase the immunity a patient had already built up through previous vaccination and leave the immune system too weak to tolerate immunization.

The economic benefits of cancer prevention are substantial

Preventing cancer has significant economic implications, and vaccines that help prevent cancer carry a significant return on investment in a variety of settings.

Hep B: Economic benefits

In terms of economic benefits, HepB vaccine carries a high economic return on investment, due in part to the sustained risk of infection across the lifespan. Health economists have estimated that during the decade 2011-2020, the use of this vaccine in the world’s poorest countries will have a return of over nine times its cost, thanks to the widespread use and high effectiveness of HepB Vaccine.

HPV: Health System and economic benefits

HPV vaccine is recommended to be given to girls in early adolescence (as opposed to most other childhood vaccines which are given during the first few years of life), which has resulted in some unique opportunities to expand delivery of other health services to this age group – even those not receiving the vaccine – and to form new collaborations between agencies that may help strengthen health programs overall.

Despite gradual uptake of HPV vaccine among the world’s poorest countries, health economists have estimated a 3-fold return on investment from the use of HPV vaccine in these countries during this decade (2011-2020). Averting the premature death of women through prevention of cervical and other HPV-related cancers increases overall productivity and would prevent destabilization of families and communities.

[1] High vaccine coverage in the general population significantly reduces the chance that an infectious agent is transmitted to others, significantly reducing the risk that an unvaccinated person will be exposed and infected. This phenomenon is called herd immunity.

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