Conjugate Pneumococcal Vaccine Inducing Herd Immunity

The incidence of invasive pneumococcal disease among adults has declined markedly since the introduction of the pediatric pneumococcal conjugate vaccine.

The pneumococcal conjugate vaccine now given to infants reduces nasopharyngeal carriage of the included serotypes in immunized individuals, and studies performed shortly after its U.S. licensure in 2000 provided evidence that it was also inducing a herd effect (see Journal Watch Infectious Diseases May 23 2003). To determine the extent of this herd effect, researchers analyzed Active Bacterial Core Surveillance data on invasive pneumococcal disease (IPD) from 1998 through 2003 in individuals aged ≥50 years in eight U.S. regions.

The incidence of IPD declined significantly from 1998–1999 to 2002–2003 in all age groups studied: by 17% in individuals aged 50–64, by 29% in those 65–74, by 35% in those 75–84, and by 28% in those ≥85. The decrease…

Reviewing Author

Richard T. Ellison III, MD