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Changes in prevalence of pneumococcal serotypes related to introduction of conjugate vaccines
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Since the introduction of the 7-valent pneumococcal vaccine, the prevalence of its serotypes has decreased, and addition of serotypes to the 13-valent pneumococcal vaccine could provide 39% coverage of isolates that still cause disease, according to recent study findings published in Emerging Infectious Diseases.
“The large number of pneumococcal serotypes and ability of this organism to switch capsules has made prevention of disease through vaccination challenging,” researchers wrote. “The recognition of new serotypes, 6C and 6D, in 2007 and 2009 brought the total number of known pneumococcal serotypes to 93. A large portion of isolates identified as serotype 6A in the past were likely 6C or 6D. Monitoring of pneumococcal serotypes causing disease provides insight into pathogenesis and guidance for vaccine composition.”
Sandra Richter
The study determined the serotype of pneumococci recovered from patients with invasive and noninvasive diseases from at least 43 US centers during 2008 to 2009 and 2010 to 2011 compared with pre-conjugate vaccine data (1999 to 2000) and post-conjugate vaccine data (2004 to 2005).
Researchers found that the prevalence of PCV7 (Prevnar 7, Pfizer) serotypes decreased from 64% of invasive and 50% of noninvasive isolates in 1999 to 2000 to 3.8% and 4.2%, respectively. With the introduction of PCV13 (Prevnar 13, Pfizer) in 2010, increases in serotype 19A stopped. The prevalence of serotypes related to PCV13 remained similar for 2008 to 2009 and 2010 to 2011.
“On the basis of this 2010 to 2011 surveillance data, PCV13 could provide coverage for 48% of [penicillin-nonsusceptible Streptococcus pneumoniae] and 39% of all isolates causing disease,” researchers wrote. “Continued monitoring of pneumococcal serotypes causing invasive disease will be crucial for assessing the full effect of PCV13.”
Disclosure: The study was funded by Forest Laboratories. See the study for a full list of disclosures.
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