Population snapshot of emergent Streptococcus pneumoniae serotype 19A in the United States, 2005.

Background: Serotype 19A invasive pneumococcal disease (IPD) increased annually in the United States after the introduction of the 7-valent conjugate vaccine (PCV7). To understand this increase, we characterized serotype 19A isolates recovered during 2005.

Methods: IPD cases during 1998-2005 were identified through population-based surveillance.