VoICE : Search Immunization Evidence
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.
Key Evidence: An analysis of the impact of rotavirus vaccine in 25 countries found that the rates of vaccination in all countries were highest and risk mortality lowest in the top two wealth quintile’s coverage. Countries differed in the relative inequities in these two underlying variables. Cost per DALYs averted in substantially greater in the higher quintiles. In all countries, the greatest potential vaccine benefit was in the poorest quintiles; however, reduced vaccination coverage lowered the projected vaccine benefit.
Key Evidence: Children in the poorest 20% of households in Laos have a 4-5 times greater risk of dying from rotavirus than the richest 20%. Consequently, rotavirus vaccination was almost five times more cost-effective in the lowest income groups in the Central Region than in the richest households in the wealthier North region. Thus, rotavirus vaccination has a greater potential for health gains and greater cost-effectiveness among marginalized populations.
From the VoICE Editors: Note that these gains are dependent on improving vaccination coverage, access to health care and environmental health in these populations.
Key Evidence: A study looking at the impact of pneumococcal vaccine introduction and scaling up pneumonia treatment in Ethiopia found that 30-40% of all deaths averted by these interventions would be expected to occur in the poorest wealth quintile. The greatest resulting financial risk protection would also be concentrated among the bottom income quintile.
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.
Undernutrition is a significant risk factor for disease and death in young children, making vaccination especially critical for this population.
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.
Key Evidence: The presence of malnourishment correlates with the severity of cholera illness. Additional factors include the number of V. cholerae bacteria ingested, lack of immunity from prior exposure or vaccination, pregnancy, lack of breast-feeding, immunocompromised state, reduced ability to produce gastric acid, and having blood group O.
Sustaining immunization activities and preventing vaccine-preventable outbreaks during conflict can be achieved through preemptive preparedness measures and concerted programmatic and financial support from governments and partners.
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.
Immunizing populations during complex humanitarian emergencies can help protect populations who are especially vulnerable to malnutrition and its effects.
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.
Key Evidence: Malnutrition is a leading contributor to morbidity and mortality during humanitarian emergencies, and a cyclical relationship exists between malnutrition and infectious diseases. Universal immunization programs have been shown to improve the height and weight measurement markers associated with malnutrition.
Key Evidence: A study modeling the relationship between disease and poverty in Ethiopia found that among the top 20 causes of death in Ethiopia, diarrhea and lower respiratory infections (LRIs) are the top two drivers of medical impoverishment. It is estimated that in 2013, out-of-pocket direct medical costs for diarrheal disease drove an estimated 164,000 households below the poverty line (representing 47% of all the diarrhea cases), and LRIs led to an estimated 59,000 cases of poverty (17% of LRI cases). Of the top 10 health-associated drivers of poverty, four are at least partially vaccine-preventable (1. Diarrhea, 2. LRI, 4. TB. 10. Pertussis).
Key Evidence: Costs for treatment for rotavirus at a large urban hospital in Malaysia led one third of families to experience catastrophic health expenditures (CHC). When direct and indirect costs of treating rotavirus were considered, almost 9 in 10 families spent more than 10% of their monthly household income on treating rotavirus. In addition, 6% of families were pushed into poverty after paying for treatment.
Key Evidence: In a study modeling the economic impact of immunization in 41 low- and middle-income countries, the authors estimate that 24 million cases of medical impoverishment would be averted through the use of vaccines administered from 2016-2030. The largest proportion of poverty cases averted would occur in the poorest 40% of these populations, demonstrating that vaccination can provide financial risk protection to the most economically vulnerable.
The greatest cost savings from introducing new vaccines and increasing immunization coverage would occur in countries and regions with high disease burden and large populations.
Key Evidence: The first study of the cost-effectiveness of typhoid conjugate vaccines found that routinely immunizing infants at 9 months of age would actually save costs in 2 settings (Delhi, India and a rural area of Vietnam), due to high incidence or high hospitalization rates, and would be cost-effective in the study’s 3 other sites (in India and Kenya). Adding a one-time catch-up campaign for various older age groups would still save costs in the Delhi and Vietnam, and increase the cost-effectiveness in the others, making it economically justifiable.
From the VoICE Editors: The study incorporated herd effects into its model, looked only at the perspective of healthcare payers and assumed the use of a single dose vaccine at 1 international dollar.
Key Evidence: In a modeled analysis of the economic impact of vaccine use in the world’s 72 poorest countries, for countries included in the analyses from the African region, scaling up coverage of the Rotavirus (RVV) vaccine to 90% was projected to result in more than US$900 million in treatment costs averted.
The interruption of disease outbreaks through vaccination can yield a significant return on investment.
Key Evidence: Considering both the direct and indirect costs, researchers in the Netherlands estimated that the preventative immunization of Dutch healthcare workers (HCW) against pertussis (to reduce exposure and transmission contributing to outbreaks) results in a return on investment of 4 Euros to every 1 euro invested. This projection assumes an outbreak of pertussis once every 10 years.
Key Evidence: In a study of a 2003 outbreak of pertussis in the U.S., including 17 cases among healthcare workers, researchers estimated that vaccinating healthcare workers would result in a 2.4-fold return on investment for hospitals.
Vaccination programs such as those for Rotavirus have shown a significant short-term return on investment.
Key Evidence: A series of studies in the U.S. estimated that the average savings in direct healthcare costs from rotavirus and acute gastroenteritis were between $121 million and $231 million per year once rotavirus vaccines were introduced.
Key Evidence: Vaccinating children against rotavirus in Bangladesh would prevent more than 50,000 outpatient visits and 40,000 hospitalizations in children under five each year, and reduce treatment costs by US$5.8 million over 2 years — nearly all (96%) from fewer hospitalizations. Since this study didn’t take herd effects into account, the actual impact would likely be greater.
Key Evidence: In a UK cost-effectiveness analysis, which takes into account herd effect, the budget impact analysis demonstrated that the introduction of a rotavirus vaccine (RVV) program could pay back between 58-96% of the cost outlay for the program within the first 4 years.
Key Evidence: In an economic evaluation of vaccination against rotavirus conducted in Italy, it was shown that as early as the second year after rotavirus vaccine introduction, the vaccine cost would be more than offset by savings from prevention of disease cases and hospitalizations.
Children with malnutrition are at greater risk of death from vaccine-preventable diseases than are children with no significant signs of malnourishment.
Key Evidence: Findings of a systematic review evaluating the relationship between pneumonia and malnourishment found that severely malnourished children in developing countries had 2.5 to 15 times the risk of death. For children with moderate malnutrition, the risk of death ranged from 1.2 to 36.
Key Evidence: A study of children under 5 years of age in Dhaka, Bangladesh found that severely malnourished children were nearly 8 times more likely to suffer death from diarrhea than those who were not severely malnourished.
Significant evidence of geographic inequity in vaccine coverage exists within countries, within states, and between populations living in rural, peri-urban, and urban areas.
Key Evidence: In India, inequities in vaccination coverage exist between states, within states, and in urban vs. rural settings. Lower parental education resulted in lower coverage, girls had lower coverage than boys and infants born to families with a large number of children also had lower coverage than others. A direct relationship between household wealth and coverage was also found.
Key Evidence: Full immunization coverage, within the Democratic Republic of Congo, varies drastically by region. In the province with the lowest coverage, approximately 5% of children were fully immunized, while in the province with highest coverage, over 70% of children were fully immunized.
Key Evidence: Inequity in vaccination coverage in India was found between states, within states, and in urban vs. rural. Lower parental education resulted in lower coverage, girls had lower coverage than boys, and infants born to families with a large number of children also had lower coverage than others. A direct relationship between household wealth and coverage was also found.