A school-based flu vaccination program in California led to higher vaccination rates, fewer absences, and less flu transmission

A school-located influenza vaccination program implemented in 95 preschools and elementary schools in California was associated with increased influenza vaccination coverage, decreased school absences due to illness, and lower influenza transmission across the community. The 11% increase in flu vaccination in children enrolled in target schools was associated with fewer flu hospitalizations in the community, including 160 fewer influenza hospitalizations per 100,000 among people aged 65 and older.

A study in Germany found that vaccinating children against influenza reduces infections in the general population

A modelling simulation study in Germany found that routine influenza vaccination coverage of 55% in children of 6 months to 17 years indirectly reduces influenza infections by 26% in the general population through pronounced herd effects. The study authors conclude that targeting children in influenza vaccination campaigns may not only reduce their individual disease burden, but also that of non-vaccinated individuals.

Catch-up vaccination can protect unvaccinated individuals, reducing disease burden across communities

A study in rural Kenya, over a 4-year period following the introduction of the 10-strain pneumococcal conjugate vaccine for infants, that included a catch-up vaccination campaign for children 12-59 months of age, suggests that the catch-up vaccination for older birth cohorts may have been a key factor in protecting unvaccinated individuals and speeding up the reduction of the disease in the community. In contrast, a study in The Gambia, where no catch-up campaign took place, found no herd effects during the first three years following the introduction of PCV-13 for infants.

The Gambia study publication referenced can be found at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4909992/

Immunization against rotavirus reduced hospitalizations in both children and adults via herd protection

Several studies in the U.S. have shown that hospitalizations due to rotavirus fell sharply in children too old to be vaccinated as well as in adults after rotavirus vaccines were introduced, indicating herd protection. In one large study, rotavirus hospitalizations in 2008 — two years after the first vaccine was introduced — declined by 71% in 5-14 year old children and by 65% in 15-24 year olds compared to the pre-vaccine period.