HE SUCCESS OF THE INTRODUCtion in 2000 in the United States of routine infant vaccination with the licensed 7-valent pneumococcal conjugate vaccine (PCV-7) is based on direct protection against vaccine serotype pneumococcal disease among vaccinees but also on the observed and unexpectedly large and widespread reduction in invasive and respiratory (eg, pneumonia and otitis media) vaccine serotype pneumococcal disease in nonimmunized individuals (indirect effect or herd protection). 1-6 This herd effect has been attributed to reduced carriage of vaccine serotype pneumococci in vaccinated infants and subsequent transmission to (household) adult contacts and spread in the community. The resulting decreased circulation of the 7 serotypes and herd effects have contributed substantially to the public health benefit and costeffectiveness of PCV-7 programs. 7,8 Increasingly crowded infant vaccine schedules and less favorable cost

The serotype appeared to be independently associated with IPD severity in adults, which indicates that careful monitoring of IPD after implementation of conjugate vaccines is necessary.

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Vaccine-serotype disease decreased, but non–vaccine-serotype disease increased.