Article in Japanese

Serotype replacement of invasive pneumococcal disease after introduction of pneumococcal conjugated vaccine at children's hospital in Japan

Kazuhiro UDA¹⁾, Yoshihiko MORIKAWA²⁾, Kenta ITO³⁾, Shintaro HIROTAKI³⁾, Mihoko ISOGAI³⁾, Saeko MORINO³⁾, Tomoyuki TAME⁴⁾, Kaoru GOTO⁴⁾, Sachiko NAITO⁵⁾, Naruhiko ISHIWADA⁶⁾, Yuho HORIKOSHI³⁾

Serotype replacement of invasive pneumococcal disease (IPD) was reported in the United States of America and Europe after introduction of the 7-valent pneumococcal conjugate vaccine (PCV7), which has been used widely since 2011 in Japan and supported with public funding. PCV7 was switched to the 13-valent pneumococcal conjugate vaccine (PCV13) in November 2013, and little is known about the impact of PCV7 on serotypes of IPD among Japanese children. This study aimed to evaluate changes in IPD serotypes after PCV7 introduction. It investigated cases of IPD at Tokyo Metropolitan Children's Medical Center between March 2010 and March 2014. Cases of Streptococcus pneumoniae isolated from sterile sites were included. Demographic data, IPD risk factors, history of vaccinations, clinical diagnosis, and serotypes were reviewed, and 45 IPD in total cases were identified. Clinical diagnoses included occult bacteremia (26 cases), pneumonia (12 cases), bacterial meningitis (4 cases), orbital cellulitis (2 cases), and cervical lymphadenitis (1 case). Children who received PCV7 vaccination developed IPD due to non-PCV7 serotypes. PCV7 and PCV13 strains were isolated from 33% (15/45) and 56% (25/45) of cases, respectively. The incidence of IPD from PCV7 strains has declined significantly from 2010 to 2014 (p<0.001). PCV7 effectively prevented IPD, due to the covering serotypes, but the increase in non-PCV7 and non-PCV13 serotypes is of concern. Serotype replacement associated with current PCV13 immunization should be evaluated.

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1) Department of General Pediatrics, Tokyo Metropolitan Children's Medical Center
2) Clinical Research Support Center, Tokyo Metropolitan Children's Medical Center
3) Division of Infectious Diseases, Department of Pediatrics, Tokyo Metropolitan Children's Medical Center
4) Department of Clinical Laboratory, Tokyo Metropolitan Children's Medical Center
5) Department of Pediatrics, Graduate School of Medicine, Chiba University
6) Medical Mycology Research Center, Chiba Uni

Key words
Received	December 2, 2014
Accepted	January 13, 2015

27 (1)：9─15,2015