Increase in the Prevalence of the Newly Discovered Pneumococcal Serotype 6C in the Nasopharynx after Introduction of Pneumococcal Conjugate Vaccine

Abstract

Among NP isolates, the prevalence of 6C isolates has increased and the prevalence of 6A isolates has decreased since the introduction of PCV7 in Massachusetts in 2000. The observed increase in serotype 6C prevalence may be explained by the induction by PCV7 of low amounts of functional anti-6C antibody, compared with anti-6A and anti-6B antibodies.