VoICE : Search Immunization Evidence

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The VoICE tool is a compendium of the many direct and downstream impacts of vaccine-preventable disease and immunization. The database contains summary explanations of the link between immunization and each impact, as well as sources of evidence for each link. You can browse the VoICE tool by topic, or use the filters to find results based on topic, disease or vaccine, location and published year.

51 Key Concepts, 39 Sources
Key Concept

Key Evidence: 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.

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Key Evidence: A small study from the Philippines, published in a Working Paper from Harvard University, 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.

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Key Concept

Key Evidence: An outreach strategy in Kenya to vaccinate children against measles in hard-to-reach areas (e.g., beyond 5 km from a vaccination post) would be highly cost-effective, despite the higher cost per child to reach these children. The estimated cost per DALY averted ranged from US$122 (if 50% of these children receive the first dose and one-half of them the second dose) to US$274 (if 100% receive the first dose) — considerably less than the country’s GDP per capita of US$1,865 used as the threshold of cost-effectiveness.

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Key Concept

Key Evidence: Antibody screening of asylum seekers arriving in Germany found that few subgroups, such as people from the same country, were sufficiently protected against measles, rubella, and varicella, and that the majority of adolescents and adults would benefit from immunizations. The serology screening results were used to target specific high-risk groups (for example, people from certain countries and age groups) for vaccination as a cost-savings measure, which proved successful in managing varicella outbreaks at refugee reception centers.

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Key Concept

Key Evidence: A 2015 study projected that the crippling of immunization programs resulting from the 2014 Ebola epidemic in Guinea, Liberia, and Sierra Leone could double the number of people at risk of a measles outbreak, and could cause up to 16,000 measles deaths, surpassing the number of deaths caused by Ebola itself.

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Key Concept

Key Evidence: Children in Tanzania living 5 km or greater distance from the nearest healthcare facility were less likely to be immunized than children living less than 5 km from facilities. Compared to children living close a health facility, children far from a health facility had almost three times the risk of missing out on BCG, 84% higher risk of missing the third dose of DTP, and 48% higher risk of missing the first dose of measles-containing vaccine. Of children who did receive BCG, those living more than 5 km from facilities were 26% more likely to received BCG vaccine late than children close to the facility.

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Key Concept

Key Evidence: In urban residents in the Democratic Republic of Congo, chronically malnourished children were less likely to have received two doses of measles-containing vaccine compared to healthy children.

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Key Concept

Key Evidence: It is estimated that under current vaccine coverage trends in 41 Gavi-eligible countries, enhanced Gavi funding would help to avoid out-of-pocket health expenditures in an amount that surpasses US$4.5 billion attributable to measles, US$168 million attributable to severe pneumococcal disease, and US$200 million attributable to severe rotavirus.

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Key Concept

Key Evidence: In 41 Gavi-eligible countries it is estimated that, in the absence of measles vaccination, the occurrence of Medical Impoverishment (MI) or households falling below the poverty line due to medical expenditures to manage measles disease would be 5.3 million. With current coverage rates, 700 thousand households would suffer MI. If Gavi support afforded enhanced coverage, the estimate of households suffering MI would decrease to 500 thousand.

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Key Concept

Key Evidence: In 41 Gavi-eligible countries, it is estimated that without any rotavirus vaccine (RVV) coverage, an estimated 2.2 million Catastrophic Health Costs (CHC) cases and 600,000 Medical Impoverishment (MI) cases would occur due to rotavirus gastroenteritis. Unfortunately these figures would not significantly decrease under the current immunization forecasts because very few countries have introduced the RVV. However, with the introduction of RVV the number of CHC cases would drop to 1.3 million and MI cases to 400,000, representing a 40% reduction.

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Key Concept

Key Evidence: A study of measles vaccine in Bangladesh found that children from the poorest quintile were more than twice as likely to die as those from the least quintile in the absence of measles vaccination. The difference in mortality between unvaccinated and vaccinated was statistically significant (p<0.10) and robust across alternative measures of socioeconomic status.

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Key Concept

Key Evidence: Children under 5 years of age bear the greatest burden of indirect conflict-associated mortality (indirect mortality results from disruption of health services including immunization, food insecurity, and high risk living conditions such as those found in refugee camps). The leading causes of child death in these circumstances include respiratory infections, diarrhea, measles, malaria, and malnutrition.

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Key Concept

Key Evidence: In a study of data from England & Wales, Denmark and the US, it was shown that measles infection suppresses the immune system for up to 3 years after infection, increasing the risk of death due to other childhood infections during that time. This means that prevention of measles significantly impacts overall health during critical childhood years.

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Key Concept

Key Evidence: In Tanzania, poverty was found to have a negative effect on receiving vaccines on time (at the recommended age). Children in the wealthiest quintile experienced 19% fewer delays for BCG vaccination, 23% fewer delays for the third dose of DTP vaccination, and 31% fewer delays for the first dose of measles-containing vaccine compared to children of the poorest quintile.

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Key Concept

Key Evidence: In a study of timely measles vaccination – – defined as vaccination within one month of the recommended age – – children living in Zheijiang province in China whose families immigrated from elsewhere in the country were 2.6 times more likely to receive the first measles dose late and nearly 3 times more likely to receive the second dose late than were children originally from the area.

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Key Evidence: Children in Shanghai, China whose families migrated from rural areas — now roughly 40% of the city’s total population — are half as likely as “local” children to receive the first dose of measles vaccine by 9 months of age and 42% less likely to receive the second measles dose by 24 months. The lower rates of timely first dose measles vaccination among rural migrants vs. local children — 78% vs. 89% – – are a key obstacle to measles elimination in China. This indicates a need to specifically target non-local children for vaccination, especially those living in primarily migrant communities.

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Key Concept

Key Evidence: A study in Kenya estimated that the failure to vaccinate the 21% of children considered hard-to-reach (living beyond a 5 km radius of a vaccination post) against measles would result — over 4 years — in more than 1,400 measles cases, 257 deaths, and cost nearly US$10 million, mainly in productivity losses from caretakers missing work.

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Key Concept

Key Evidence: An analysis conducted in areas of Ethiopia with high proportions of refugees found that high measles vaccination coverage was linked to lower rates of acute malnutrition (wasting) in children under five. For each percentage point increase in measles vaccination coverage, there was a 0.65% decrease in the rate of acute malnutrition in these areas.

From the VoICE Editors: The analysis was conducted on data from more than 150 nutrition surveys.

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Key Concept

Key Evidence: An analysis conducted in areas of Ethiopia with high proportions of refugees found that high measles vaccination coverage was linked to lower rates of acute malnutrition (wasting) in children under five. For each percentage point increase in measles vaccination coverage, there was a 0.65% decrease in the rate of acute malnutrition in these areas.

From the VoICE Editors: The analysis was conducted on data from more than 150 nutrition surveys.

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Key Concept

Key Evidence: A large measles outbreak in the Netherlands in 2013-14 resulted in 2700 cases of disease and cost an estimated US$4.7 million — or US$1,739 per case. Costs included outbreak response (including vaccination and enhanced surveillance), the cost of treatment (primarily hospitalizations), and the loss of productivity among caregivers ($365,000, less than 8% of total costs). Due to the likely under-reporting of the disease, the actual costs could be nearly 20% greater ($5.6 million).

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Key Evidence: The US state of Iowa incurred more than US$140,000 in direct costs of outbreak containment stemming from a single case of measles in an unvaccinated student infected overseas. Swift containment procedure limited the outbreak to 3 additional cases but included significant and costly steps including tracking down contacts of the infected student, establishing a measles information hotline, testing exposed medical staff for immunity, conducting measles vaccination clinics, and putting quarantines into effect.

From the VoICE editors: Although even small outbreaks of highly contagious diseases can be exceedingly costly to contain, the value of containment to society is very high. Traditional economic evaluations of outbreaks which include just the costs of illness to individuals should be expanded to include the costs and value of containing the outbreak required to protect society. 

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Key Concept

Key Evidence: Children of Bangladeshi mothers younger than 34 years were more than three times as likely to have incomplete vaccination compared to children of mothers older than 35 years.

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Key Evidence: Children who were born as the fourth or fifth child in their household were more than twice as likely to be incompletely vaccinated with BCG, measles vaccine, and pentavalent vaccine than those who were born as the second or third child in their household.

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Key Concept

Key Evidence: Children of unemployed mothers in Bangladesh were 1.5 times as likely to have incomplete vaccination status compared to children of employed mothers. Maternal unemployment was also significantly linked to delays in BCG and measles vaccinations.

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Key Concept

Key Evidence: During the conflict in Yemen, efforts spearheaded by WHO, with coordination among partners and effective use of resources, especially GAVI, resulted in continued high pentavalent vaccine coverage decreasing only 3% from 2010 to 2015. Yemen also remained polio-free through 2015 and smoothly introduced two new vaccines (MR and IPV).

Key Evidence: During the humanitarian crisis in the Syrian Arab Republic, the constant support from WHO, UNICEF, and local NGOs resulted in immunizations against VPDs reaching over 90% of children.

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Key Concept

Key Evidence: Efforts to eliminate measles — which has been called a public health “canary in the coalmine” since it’s a sign of weak health systems — can also serve to strengthen immunization programs as well as the broader health systems. These efforts include improving infection prevention and control practices in health care facilities, disease surveillance and outbreak detection systems, and countries’ ability to prepare for and respond to infectious disease outbreaks.

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Key Concept

Key Evidence: An analysis of the association between undernutrition and mortality in young children revealed that in 60% of deaths due to diarrhea, 52% of deaths due to pneumonia, 45% of deaths due to measles and 57% of deaths attributable to malaria, undernutrition was a contributing factor.

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Key Concept

Key Evidence: The detection of H1N1 influenza virus in Mexico in 2009, and subsequently throughout other countries in the Americas, benefited from the laboratory experience with measles and rubella in the region, leading to the rapid detection of and response to what eventually became a novel pandemic virus.

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Key Concept

Key Evidence: In a financial risk model analysis of 41 Gavi-eligible countries, the burden of Catastrophic Health Costs (CHC) and Medical Impoverishment (MI) would be greatest in the lowest income populations. With expanded vaccine coverage, the share of prevented cases of measles, pneumococcal disease, and rotavirus, in relation to the total number of cases prevented, would be larger in the lowest income populations thereby providing a larger financial risk protection (FRP) to these populations.

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Key Concept

Key Evidence: In 41 Gavi-eligible countries it is estimated that, in the absence of any measles vaccine use, approximately 18.9 million households would have Catastrophic Health Costs (CHC) attributable to measles. The number of CHC decreases to 3.4 million households in these countries if the current vaccine coverage forecasts is unchanged and decreases to 2.6 million cases if coverage was enhanced with Gavi support. Overall, optimizing vaccine coverage for measles can reduce by approximately 90% the incidence of CHC due to measles disease.

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Key Concept

Key Evidence: In a study of immunization in the Philippines, children vaccinated against 6 diseases performed significantly better on verbal reasoning, math, and language tests than those who were unvaccinated. (note: Researchers did not find an association with physical growth.)

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Key Concept

Key Evidence: A measles outbreak in the Federated States of Micronesia (FSM) in 2014, causing nearly 400 confirmed cases, cost nearly US$4 million (around US$10,000 per case), 88% of which was for a mass vaccination campaign, outbreak investigations, and other containment costs. While the U.S. government covered 2/3 of the costs, the economic burden to FSM — in labor and other costs of containing the outbreak, the direct costs of illness, and productivity losses — were the equivalent of the country’s entire education budget for one year.

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Key Concept

Key Evidence: For every 6 children vaccinated against measles in a poor, largely rural community in South Africa, one additional grade of schooling was achieved.

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Key Concept

Key Evidence: It is estimated that in 41 Gavi-eligible countries, approximately 6.6 million households would suffer Catastrophic Health Costs (CHC) in the absence of pneumococcal vaccine coverage. Due to the current absence of a pneumococcal immunization plan in many of these countries, the number of CHC cases would only decrease slightly to 6.4 million with current immunization programs. If pneumococcal vaccine programs would be implemented or expanded with Gavi support, the number of households experiencing CHC would decrease to 4.6 million – a decrease of approximately 30%.
Similarly, the estimates of medical impoverishment without vaccine coverage in this model showed that pneumococcal disease would cause 800,000 households to fall under the poverty line.

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Key Concept

Key Evidence: 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.

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Key Evidence: For every 6 children vaccinated against measles in a poor, largely rural community in South Africa, one additional grade of schooling was achieved.

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Key Evidence: A study of the staggered roll-out of measles vaccination in Matlab, Bangladesh, which started in the early 1980s, found that boys vaccinated before 12 months of age were 7.4% more likely to be enrolled in school than boys who were never vaccinated or vaccinated later in childhood, while measles vaccination had no effect on girls’ enrolment in school.

From the VoICE editors: This may suggest that poor health, resulting from complications of measles that can lead to deficits in physical and cognitive development, affected schooling decisions for boys in Bangladesh, but not for girls.

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Key Concept

Key Evidence: Researchers looking at vaccination coverage in 45 low- and middle-income countries found that maternal education is a strong predictor of vaccine coverage. Children of the least educated mothers are 55% less likely to have received measles containing vaccine and three doses of DTP vaccine than children of the most educated mothers.

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Key Concept

Key Evidence: A review of measles vaccination data found that female children experience substantially higher mortality risks from measles relative to male children and greater reductions in mortality with vaccination. In essence, vaccinating female children against measles provides them with the same survival chances as unvaccinated male children.

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Key Evidence: Across multiple studies reviewed, the effect of measles vaccine appears to be more beneficial to girls combating all-cause mortality when differences between vaccine effect in boys and girls was assessed.

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Key Concept

Key Evidence: A multiple-strategy community intervention program of the National Rural Health Mission (NRHM) in India, designed to reduce maternal and child health (MCH) inequalities was implemented between 2005 and 2012. The gender gap in immunization coverage swung from significantly favoring boys before the intervention to a slight advantage for girls by the end of the intervention. Specifically the coverage differentials changed as follows: for full immunization (5.7% to -0.6%), for BCG immunization (1.9 to -0.9 points), for oral polio vaccine (4% to 0%), and for measles vaccine (4.2% to 0.1%).

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Key Evidence: An impact evaluation for a women’s empowerment program in India found that the children of mothers who participated the empowerment program were significantly more likely to be vaccinated against DTP, measles, and tuberculosis than children of mothers not involved in the program. This study also found that the women’s empowerment program had positive spillover effects: In villages where the program occurred, children of mothers not in the program (non-participants) were 9 to 32% more likely to be immunized against measles than in villages where the program did not occur (controls). Overall, measles vaccine coverage was nearly 25% higher in the program villages compared to the control villages.

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Key Concept

Key Evidence: In an analysis of immunization coverage in 45 low- and lower-middle income Gavi-eligible countries, researchers found that overall, maternal and paternal education were two of the most significant drivers of coverage inequities in these countries. Pooling the data from all countries, the authors found that “children of the most educated mothers are 1.45 times more likely to have received DTP3 than children of the least educated mothers.” The same held true for measles vaccines with a 1.45-fold likelihood of vaccination in children of the most educated mothers.

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Key Concept

Key Evidence: A small hospital-based study in India found that 6 month old infants born to HIV-infected women were 11 times more likely to lack measles antibodies than 6 month olds not exposed to HIV whether or not the exposed infants were themselves infected with HIV. The lack of antibodies in most HIV-exposed infants — making them more vulnerable to measles — may be due to lower levels of measles antibodies in HIV-infected mothers or to poorer transfer of antibodies to the fetus across the placenta.

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Key Concept

Key Evidence: A study of Kenyan children under 5 years of age found that immunization with polio, BCG, DPT, and measles to be protective against stunting in young children (27% less likely to be stunted than unimmunized children under age 2 years). In addition, children with diarrhea and cough in the 2 weeks prior to the survey were 80-90% more likely to be underweight or to suffer from wasting.

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Key Evidence: An analysis of the association between undernutrition and mortality in young children revealed that in 60% of deaths due to diarrhea, 52% of deaths due to pneumonia, 45% of deaths due to measles and 57% of deaths attributable to malaria, undernutrition was a contributing factor.

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Key Concept

Key Evidence: A study of the impact of measles vaccine in Bangladesh found that unvaccinated children in the poorest quintile were more than twice as likely to die as those from the least poor quintile. In addition, vaccination reduced socioeconomic status-related mortality differentials

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Key Evidence: An analysis of the association between undernutrition and mortality in young children revealed that in 60% of deaths due to diarrhea, 52% of deaths due to pneumonia, 45% of deaths due to measles and 57% of deaths attributable to malaria, undernutrition was a contributing factor.

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Key Concept

Key Evidence: A study of the impact of measles vaccine in Bangladesh found that unvaccinated children in the poorest quintile were more than twice as likely to die as those from the least poor quintile. In addition, vaccination reduced socioeconomic status-related mortality differentials

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Key Concept

Key Evidence: A study of measles vaccine in Bangladesh found that children from the poorest quintile were more than twice as likely to die than those from the least quintile in the absence of measles vaccination. The difference in mortality between unvaccinated and vaccinated was statistically significant (p<0.10) and robust across alternative measures of socioeconomic status.

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Key Concept

Key Evidence: In Tanzania, poverty was found to have a negative effect on receiving vaccines on time (at the recommended age). Children in the wealthiest quintile experienced 19% fewer delays for BCG vaccination, 23% fewer delays for the third dose of DTP vaccination, and 31% fewer delays for the first dose of measles-containing vaccine compared to children of the poorest quintile.

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Key Concept

Key Evidence: Researchers investigating the causes of a measles outbreak in Burkina Faso that occurred despite a recent mass vaccination campaign found that migration to and from Cote d’Ivoire was a major risk factor for children. Unvaccinated children who developed measles were 8.5x more likely to have recently traveled to Cote d’Ivoire than unvaccinated children who had not traveled across the border. Children returning to Burkina Faso after a period of time in Cote d’Ivoire were less likely to have been vaccinated due to low routine coverage of measles vaccines in Cote d’Ivoire. Conversely, unvaccinated children from Burkina Faso who traveled to Cote d’Ivoire and returned were more likely to be exposed to measles and thus had a higher rate of disease than children who never visited Cote d’Ivoire.

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Key Evidence: The influx of Syrian refugees into Turkey as a result of the Syrian civil war has led to a re-emergence of several infectious diseases in Turkey, including vaccine-preventable diseases, such as measles (930 cases reported among refugees over 4 years), tuberculosis and hepatitis A.

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Key Evidence: The humanitarian emergency in Venezuela, and resulting collapse of its primary health care infrastructure, has caused measles and diphtheria to reemerge — disproportionately affecting indigenous populations — and to spread to neighboring countries. This sets the stage for the potential reemergence of polio. The re-establishment of measles as an endemic disease in Venezuela (with >5,500 confirmed cases) and its spread to neighboring countries threaten the measles-free status.

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Key Evidence: Large measles outbreaks occurred in Lebanon and Jordan, following an influx of Syrian refuges migrating to escape conflict. In Lebanon, the measles incidence increased 200-fold in one year following high migration. There were 2.1 measles cases per million population in Lebanon in 2012; this increased to 411 cases per million in 2013.

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Key Concept

Key Evidence: Conflict in the Eastern Mediterranean Region impacted health infrastructure and compromised the success of the region’s measles elimination goal. At the same time that rates of migration and displacement skyrocketed, the number of measles cases in the region doubled, from 10,072 cases in 2010 to 20,898 in 2015.  

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Key Concept

Key Evidence: In 2013 nearly all of the 175 cases of measles in the US could be traced back to international importations.

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Key Evidence: The humanitarian emergency in Venezuela, and resulting collapse of its primary health care infrastructure, has caused measles and diphtheria to reemerge — disproportionately affecting indigenous populations — and spread to neighboring countries. This sets the stage for the potential reemergence of polio. The re-establishment of measles as an endemic disease in Venezuela (with >5,500 confirmed cases) and its spread to neighboring countries threaten the measles-free status.

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Key Concept

Key Evidence: In a study of data from England & Wales, Denmark, and the US, it was shown that measles infection suppresses the immune system for up to 3 years after infection, increasing the risk of death due to other childhood infections during that time. This means that prevention of measles significantly impacts overall health during critical childhood years.

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Key Evidence: An analysis of children aged 12-59 months in rural India showed that children who were not vaccinated against measles vaccine in infancy had a three times higher likelihood of death, with unvaccinated children from lower caste households having the highest risk of mortality (odds ratio, 8.9). However, the results also revealed a nonspecific reducing effect of the vaccine on the overall child mortality in this region. This indicates that vaccination against measles can benefit the overall population, especially those in lower castes who have not received the vaccine in infancy. Thus, making them the group that would receive the highest benefit.

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Key Evidence: In a 2014 review of the non-specific effects of measles vaccines, among others, the WHO Strategic Advisory Group of Experts indicated that some studies of measles vaccine were suggestive (but not conclusive) of a beneficial effect of measles vaccine on overall mortality beyond the expected direct effect of the vaccine against measles. In particular, randomized control trials of children in Guinea- Bissau which looked at mortality up to the age of 9 months showed a low number of deaths post administration of the 3 doses of the measles vaccine over the study follow up period. Another trial in Nigeria also showed similar results.

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Key Concept

Key Evidence: Modeling of data from India’s National Family Health Survey-3 indicated that vaccinations against DPT, polio and measles were significant positive predictors of a child’s height, weight and hemoglobin concentration. This was ascertained post modeling of data obtained from over 25,000 children.

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Key Evidence: A study in Kenya revealed that immunization with polio, BCG, DPT and measles had protective effects with respect to stunting in children under 5 years of age. In children under the age of 2 years, immunized children were 27% less likely to experience stunting when compared to unimmunized children. Additionally, children who suffered from cough or diarrhea in the 2 weeks prior to the study showed an 80-90% higher probability of being underweight or experiencing wasting.

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Key Concept

Key Evidence: A study of Kenyan children under 5 years of age found that children with diarrhea and cough in the 2 weeks prior to the survey were 80-90% more likely to be underweight or to suffer from wasting.

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Key Concept

Key Evidence: Mothers infected with rubella virus during the first trimester of pregnancy can give birth to children with permanent disabilities such as intellectual impairment, autism, blindness, deafness, and cardiac defects. The infection is completely preventable if mothers are vaccinated before pregnancy.

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Key Concept

Key Evidence: In the Americas, a platform built to secure polio eradication has been expanded to help track, control, prevent, and monitor immunization impact for measles and rubella. In India, highly trained polio health workers have become the basis for a trained workforce working towards the elimination of measles and rubella and helping ensure India’s certification by WHO for having eliminated maternal and neonatal tetanus.

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Key Concept

Key Evidence: The American Academy of Pediatrics and the International Pediatric Association were included as partners in the measles and rubella elimination initiative, allowing for more direct collaboration around the interactions of primary health and immunization services and concerns.

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Key Concept

Key Evidence: The detection of H1N1 influenza virus in Mexico in 2009, and subsequently throughout other countries in the Americas, benefited from the laboratory experience with measles and rubella in the region, leading to the rapid detection of, and response to, what eventually became a novel pandemic virus.

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