Emergence of Penicillin‐Nonsusceptible<i>Streptococcus pneumoniae</i>Clones Expressing Serotypes Not Present in the Antipneumococcal Conjugate Vaccine

Abstract

Penicillin-nonsusceptible pneumococcal clones of serotypes not related to those included in the 11-valent conjugate vaccines may derive from capsular transformation of vaccine-related serotypes. Of particular concern was the detection of serotype 11A variants of the successful international Spain9V-3 clone. This phenomenon, although seemingly rare at present, can have implications for the long-term effectiveness of the conjugate vaccines.