Immunizing children against pneumonia also provides protection for unvaccinated people through herd immunity

A study of the 10-strain pneumococcal conjugate vaccine in rural Kenya demonstrated herd protection. Over a 4-year period following the introduction of the vaccine for infants, coupled with a “catch-up” campaign for all children 12-59 months of age, the incidence of invasive pneumococcal disease (IPD) caused by the strains in the vaccine fell by 100% in infants less than two months of age who were too young to be vaccinated. In adults (≥ 15 years old) the incidence of IPD fell by 81% and in 5-14 year olds the incidence fell by nearly 75%. The chances of unvaccinated persons becoming ill with any strain of the disease also fell significantly – by 87% in infants under two months old, by nearly half (47%) in 5-14 year olds, and by more than one-third (37%) in adults.