VoICE Immunization Evidence: Collateral effects on health
Collateral Effects on Health
Administration of vaccines can also decrease childhood deaths from other causes, above and beyond the expected direct impact of the vaccine.
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.
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.
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.
Vaccination may indirectly help prevent certain childhood cancers by priming the body to recognize and destroy tumor cells.
Key Evidence: A study including thousands of children from the US state of Texas found that children born in counties with high coverage of HepB, Polio, and Hib vaccines were 33%, 37%, and 42% less likely to develop a specific type of leukemia than children in counties with lower coverage of each vaccine.