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.
Malnourished children are at greater risk of death from potentially vaccine-preventable diseases than children with no significant signs of malnourishment.
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.
A study of children under 5 years of age in Dhaka Bangladesh found that severely malnourished children were at a significantly increased risk (nearly 8x) of death from diarrhea than those who were not severely malnourished.
Families who access the health system for non-vaccine services are more likely to have fully immunized children. Non-vaccine related healthcare encounters serve as opportunities to vaccinate children.
A study of 14 geographically diverse countries with a DPT vaccination rate below 70%, evaluated missed vaccination opportunities. Researchers found that children – and their mothers – who were fully immunized were more likely to have received other health interventions. In Cote d’Ivoire, children of mothers who had four or more antenatal care (ANC) visits were 54% more likely to be fully immunized than children of mothers who had no ANC visits. Large differences in full immunization coverage were also found in children who received Vitamin A vs. children who didn’t (greatest difference of 41% was noted in the DRC) and in mothers who had access to a skilled birth attendance (36 % difference in Nigeria) and postnatal care (31% difference in Ethiopia), as compared to mothers without access to these services.
Sustaining immunization activities and preventing VPD (vaccine preventable disease) outbreaks during conflict can be achieved through preemptive preparedness measures and concerted programmatic and financial support from governments and partners.
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).
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.
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).
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 interruption of disease outbreaks through vaccination can yield a significant return on investment.
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.
Significant evidence of geographic inequity in vaccine coverage exists within countries, within states, and between populations living in rural, peri-urban, and urban areas.
A study in a population of urban poor in Delhi, India, which examined household and neighborhood-level determinants of childhood immunization, found that less than half of children between 1 and 3.5 years of age received complete immunization as recommended. This was significantly lower than the overall state-level average of 70% immunization coverage.
Inequity in vaccination coverage in India was found between states, within states, 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.
Immunizing populations during complex humanitarian emergencies can help protect populations who are especially vulnerable to malnutrition and its effects.
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.
An analysis of the impact of rotavirus vaccine in 25 gavi 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 is 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.
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.
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 vaccines especially critical for malnourished children
An analysis of undernutrition and mortality in young children found that among the principal causes of death, 60.7% of deaths as a result of diarrhea, 52.3% of deaths as a result of pneumonia, 44.8% of deaths as a result of measles, and 57.3% of deaths as a result of malaria are attributable to undernutrition.
Vaccination programs such as those for Rotavirus have shown a significant short-term return on investment.
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.
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.