Article in Japanese

Effects of widely used of 7-valent pneumococcal conjugate vaccine on serotypes of colonized Streptococcus pneumoniae in infants and young children with lower respiratory tract infections

Akiyoshi NARIAI, Touru UCHIMURA, Taichi KANETAKA, Kentarou IWASAWA, Yu FUJIWARA, Sayumi SUZUKI, Makiko OGAWA

The objective of this study was to evaluate the effects of widely used 7-valent pneumococcal conjugate vaccine (PCV7) on pneumococcal serotypes associated with nasopharyngeal (NP) colonization in children under 6 years old with lower respiratory tract infections. A two year free vaccination program was initiated in 2011 and its data were compared to that of 2010.
NP swabs were obtained from 598, 598 and 645 children in 2010, 2011 and 2012, respectively, of which 21.9%, 22.0% and 22.1%, and 61.4%, 32.6% and 16.3% were colonized with Streptococcus pneumoniae and PCV7 serotypes, respectively. The rates of recipients vaccinated increased from 0% in 2010 to 71.4% in 2012. PCV7 serotypes were detected in vaccinated children with rates of 17.0% and 15.2% in 2011 and 2012, respectively. Simultaneously, rates of PCV7 serotypes declined in unvaccinated children to 40.5% and 19.0% in 2011 and 2012, respectively. Thus, PCV7 serotypes declined dramatically during the two years after widespread use of PCV7, due to the direct effect of PCV7 in vaccinated children and the indirect effect in unvaccinated children.
On the other hand, although serotypes 1, 5 and 7F out of 6 additional serotypes, included in a 13-valent PCV, were not detected, the other serotypes, i. e. 3, 6A and 19A, were detected with rates of 19.7%, 12.6% and 15.0% in 2010, 2011 and 2012, respectively.

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Department of Pediatrics, Yokohama Minami Kyosai Hospital

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Received	December 4, 2013
Accepted	February 20, 2014

26 (2)：213─219,2014