In the U.S., before the advent of the pneumococcal conjugate vaccine, known as Prevnar, S. pneumoniae caused more than 7 million ear infections each year, half a million episodes of bacterial pneumonia, and life-threatening cases of meningitis and bacteremia. Prevnar is made up of material from the outer capsule of each of the seven pneumococcal strains most common in the U.S. This material triggers recipients' immune systems to produce so-called anticapsular antibodies specific to those strains. However, Prevnar doesn't work against many pneumococcal strains in the developing world, where pneumococcus kills nearly 1 million children annually, and it is expensive and difficult to manufacture, leading to chronic shortages. Moreover, in several studies, use of pneumococcal conjugate vaccines caused non-vaccine strains to become more common, raising concerns that Prevnar could eventually become ineffective even in the U.S. Of 90 known pneumococcal strains, Prevnar only covers seven.
Lipsitch and Malley first conducted epidemiologic studies in unvaccinated toddlers in the U.S., Israel, and Finland. As they reported in January in the online journal PLoS Medicine, the incidence of invasive disease from almost all pneumococcal strains fell by nearly half between 1 and 2 years of age. Yet, anti-ca
Contact: Susan Craig or Rachel Pugh
Children's Hospital Boston