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.
In some settings, malnourished children, who are at increased vulnerability to infection and death, are less likely to be immunized.
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.
Key Evidence: A study of over 80,000 children in Kenya designed to understand the role of inadequate health systems on childhood survival beyond 59 months of age showed that a higher per capita density of heath facilities resulted in a 25% reduction in the risk of death. However, user fees for sick-child visits increased the risk of death by 30%.
A strong national immunization program can be leveraged during critical health emergencies to aid in outbreak response.
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.
Investments made in disease eradication contribute to health systems strengthening and health service delivery.
Key Evidence: The expertise and assets gained through efforts to eradicate polio at least partially explain the improvement between 2013 and 2015 in vaccination coverage of DPT3 in six out of ten “focus” countries of the Polio Eradication Endgame strategic plan. This includes substantial increases in vaccination rates in India, Nigeria, and Ethiopia, which, combined, reduced the number of children not fully vaccinated with DPT by 2 million in 2 years.
Key Evidence: Tens of millions of volunteers, social mobilizers, and health workers have participated in the Global Polio Eradication Initiative. The program contributes to efforts to deliver other health benefits, including health systems strengthening. Polio eradication legacy efforts include documenting and applying the lessons learned from polio eradication and transitioning the capacities, assets, and processes of polio to other key health priorities.
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.
Use of vaccines decreases the need to use health services and treatments, like antibiotics, to treat disease.
Key Evidence: Among 33,000 preschool children in the UK (who received at least one prescription of amoxicillin) there were ~15% fewer amoxicillin prescriptions given during the influenza season to children who had received the live attenuated influenza vaccine than among children who were not vaccinated. This suggests that flu vaccination may lead to a reduction in excess, inappropriate prescribing of antibiotics for influenza in children.
Key Evidence: Over a four-year period following the introduction of PCV-10 in Finland, purchases of antimicrobials that are recommended for the treatment of acute otitis media (middle-ear infection) for children born during these years fell by nearly 18%, compared to pre-vaccine years, and the rate of surgeries to place ear tubes for severe cases fell 15%. Although it is considered a mild disease, acute otitis media caused by pneumococcus is 1,000 times more common in young children than invasive pneumococcal disease, such as pneumonia or meningitis, and thus the public health impact of the vaccine in reducing otitis media cases and in saving health care costs is considerable.
Key Evidence: In a study of nearly 40,000 recipients of PCV7 and control subjects in northern California, there was a 5.4% reduction in the number of antibiotic prescriptions and a 12.6% reduction in the use of “second-line antibiotics” among children who received the pneumococcal conjugate vaccine. Between the time the first dose was administered and the age of 3.5 years, use of the vaccine prevented 35 antibiotic prescriptions per 100 fully vaccinated children.
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.
Vaccination is a cost effective approach to prevent illness in high risk populations and in fragile settings.
Key Evidence: Providing a birth dose of hepatitis B vaccine to all newborns (in addition to routine HepB immunization) was found to be a highly cost-effective means of preventing hepatitis B-related deaths in three refugee populations in Africa which are at extremely high risk of hepatitis B infection. Providing a birth dose only to newborns whose mothers test positive on a rapid diagnostic test was less cost-effective than vaccinating all newborns automatically. Thus, universal hepatitis B vaccination of newborns should remain a priority in refugee camps, despite competing humanitarian needs.
Key Evidence: Children living in the Yida refugee camp in South Sudan in 2013 were found to have an elevated rate of pneumonia infections likely due to malnutrition, overcrowding, and inadequate shelter. Using these data, the CDC estimated that the use of Hib and pneumococcal vaccines in children under 2 years of age in the camp would be cost-effective under all dosing scenarios evaluated. Medecines Sans Frontiers (MSF) provided medical services to this refugee camp and found delivery of these vaccines to be feasible and effective in this setting.
Key Evidence: In a study of different strategies for preventing hepatitis B infections in newborns in a Burmese refugee population with a high infection rate, administering hepatitis B immune globulin to newborns whose mothers test positive through a rapid diagnostic test — in addition to vaccinating all newborns with a birth dose — prevented twice as many infections in newborns than vaccination alone and was cost-effective (while the current strategy of providing immune globulin only after a confirmatory lab test was done was not). Thus, this strategy could be considered for similar marginalized or poor populations.
Key Evidence: A comprehensive review of the economics of cholera and cholera prevention concluded that vaccination using oral cholera vaccines can be cost-effective, especially when herd effects are taken into account and when vaccination is administered to populations and age groups with high incidence rates (e.g., children) and to areas with high cholera case fatality rates.
Key Evidence: A study using local epidemiological and economic data found that vaccinating children 1-14 years old in high-risk slum areas in Dhaka, Bangladesh using a locally-produced oral cholera vaccine provided through periodic campaigns would be a highly cost-effective means of controlling endemic cholera — reducing cholera incidence in the entire population by 45% over 10 years and costing US$440-635 per DALY averted. Vaccinating all persons aged one and above would reduce incidence much further (by 91%) but would be less cost-effective.
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.
Repeated episodes of diarrhea during infancy and early childhood increases the risk of altered long-term growth and development
Key Evidence: A pooled analysis of nine studies assessing the effects of diarrhea on stunting prior to the age of 24 months showed that the odds of stunting were significantly increased with each diarrheal episode. Each day of diarrhea prior to attaining 24 months of age also contributed to the risk of stunting. For each five episodes of diarrhea, the odds of stunting increased by 13%. In addition, once a child becomes stunted, only 6% of those stunted at 6 months of age recovered by 24 months of age.
Key Evidence: A review of gut infections and effects on physical growth and development found that for children living in impoverished areas of the world, episodes of diarrhea during the first two years of life not only negatively affected their physical growth, but could result in a 10 points lower IQ than average by age 7.
Research suggests that children in communities with low unemployment rates are more likely to be fully immunized than children in communities with higher unemployment rates
Key Evidence: The 2008 Nigerian Demographic Health Survey data suggest that children in communities with high unemployment were 1/3 as likely to be fully immunized than children in communities with a medium level of unemployment.