Herd immunity from pneumo vaccine

An article in the Journal of the American Medical Association finds a substantial herd immunity effect from the pneumo vaccine. Infections in children below 2 (that is, younger than the age at which vaccinations are usually given) have fallen by 60%.

Streptococcus pneumoniae causes invasive diseases such as meningitis, bacteremia, and pneumonia in children. A heptavalent pneumococcal conjugate vaccine (PCV7) was licensed in February 2000 and recommended for all children aged 2 to 23 months in the United States.1-2 Since PCV7 introduction, the rate of invasive pneumococcal disease (IPD) among US children younger than 2 years has decreased by at least 60%. Concurrently, rates of IPD in adults have decreased. These declines suggest that PCV7 vaccination of children aged 2 to 23 months has led to changes in pneumococcal carriage in both the target and nontarget populations.

Owen comments: Almost all cost-benefit analysis of vaccines - which overwhelmingly show that vaccines are a highly cost-effective and safe health intervention - ignore the "herd immunity" effects by which other (unvaccinated) members of the population benefit from the lower risk of infection as a result of the vaccination program. This herd immunity effect not only suggests that vaccination is even more cost effective than our analysis shows, it makes the case for front-loading vaccination programs.