TITLE:
Impact of Seven Valent Pneumococcal Conjugate Vaccine on Nasopharyngeal Carriage in Young Children in Okinawa, Japan
AUTHORS:
Hideki Akeda, Bin Chang, Yoshihisa Nakamura, Hirotsune Hamabata, Kenji Ameku, Takaya Toma, Eiichi Tamanaha, Makoto Ohnishi
KEYWORDS:
Nasopharynx, Carriage, Pneumococcal Conjugate Vaccine, Japan, Young Children
JOURNAL NAME:
World Journal of Vaccines,
Vol.5 No.2,
April
16,
2015
ABSTRACT: In Japan, the heptavalent pneumococcal conjugate vaccine (PCV7) became available in February 2010 and was subsidized by the national funding system from May 2011 in Okinawa, after which it was incorporated into the national immunization practice (NIP) in April 2013 using a 3 + 1 schedule for all infants. We conducted an annual survey in 2012 to determine the effect of PCV7 on nasopharyngeal colonization by pneumococcal serotypes and to analyze the risk factors for colonization in infants. Nasopharyngeal swabs for pneumococcal isolation and serotyping were obtained from infant 2 to 22 months of age before and after PCV7 immunization among 4 clinics in Okinawa, Japan. Between January 2012 and December 2012, nasopharyngeal swabs for bacterial cultures were obtained among 782 infants aged 2 to 22 months old and demographic data was obtained among 725 participant infants. Among the 725 evaluable infants, 193 pneumococcal strains were detected in 180 infants for an overall nasopharyngeal carriage of 24.8%. The main capsular serotypes isolated were 6C (16.1%), 19A (12.4%) and 15B (9.8%). Carriage of PCV7 serotypes accounted for 21.8% (42/193). The result of multivariate data analysis showed the pneumococcal carriage rate of non-PCV7 serotypes was significantly (P