Collateral Effects on Health

The Collateral Effects on Health sub-topic explores evidence where, through immunization, one disease is prevented and the incidence of other unrelated diseases or conditions also decrease as a result.

3 Key Concepts

Key Evidence: Seizures are the most common non-gastrointestinal symptom associated with rotavirus infection. Studies have found that rotavirus vaccination significantly reduced the risk of childhood seizures during the year following vaccination by approximately 20% for seizures requiring emergency care or hospitalization in the US and by 16-34% for childhood seizures requiring hospitalization in Spain.

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Key Evidence: Seizures are the most common non-gastrointestinal symptom associated with rotavirus infection. Studies have found that during the year following rotavirus vaccination the risk of childhood seizures were reduced by 18-21% for seizures requiring emergency care or hospitalization in the U.S. and by 16-34% for childhood seizures requiring hospitalization in Spain.

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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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