title: The impact of heptavalent pneumococcal conjugate vaccine on the incidence of childhood community-acquired pneumonia and bacteriologically confirmed pneumococcal pneumonia in Japan.
abstract: Heptavalent pneumococcal conjugate vaccine (PCV7) was introduced to Japan in 2010. We investigated the impact of PCV7 on childhood community-acquired pneumonia (CAP) and pneumococcal pneumonia (PP). Children aged <5 years living in Chiba city, Japan, who were admitted to hospitals were enrolled to estimate the incidence of CAP based on the mid-year population. PP was determined by the presence of Streptococcus pneumoniae in cultured blood and/or sputum samples of CAP patients. The incidence of CAP and S. pneumoniae isolated from PP patients was compared before (April 2008-March 2009) and after (April 2012-March 2013) the introduction of PCV7 immunization. The annual incidence of CAP was reduced [incidence rate ratio 0·81, 95% confidence interval (CI) 0·73-0·90]. When comparing post-vaccine with pre-vaccine periods, the odds ratio for PP incidence was 0·60 (95% CI 0·39-0·93, P = 0·024). PCV7-covered serotypes markedly decreased (66·6% in pre-vaccine vs. 15·6% in post-vaccine, P < 0·01), and serotypes 6C, 15A, 15C and 19A increased. Multidrug-resistant international clones in the pre-vaccine period (Spain6B-2/ST90, Taiwan19F-14/ST236) decreased, while Sweden15A-25/ST63 was the dominant clone in the post-vaccine period. A significant reduction in the incidence of both CAP hospitalizations and culture-confirmed PP of vaccine serotypes was observed at 2 years after PCV7 vaccination.
authors.affiliation: Department of Pediatrics,Chiba University Graduate School of Medicine,Chiba City,Japan.
authors.forename: S
authors.initials: S
authors.lastname: Naito
authors.affiliation: Department of Pediatrics,Chiba University Graduate School of Medicine,Chiba City,Japan.
authors.forename: J
authors.initials: J
authors.lastname: Tanaka
authors.affiliation: Clinical Research Centre,Chiba University Hospital,Chiba City,Japan.
authors.forename: K
authors.identifier: http://orcid.org/0000-0003-4529-9045
authors.initials: K
authors.lastname: Nagashima
authors.affiliation: Department of Bacteriology I,National Institute of Infectious Diseases,Tokyo,Japan.
authors.forename: B
authors.initials: B
authors.lastname: Chang
authors.affiliation: Department of Pediatrics,Chiba University Graduate School of Medicine,Chiba City,Japan.
authors.forename: H
authors.initials: H
authors.lastname: Hishiki
authors.affiliation: Department of Pediatrics,Chiba University Graduate School of Medicine,Chiba City,Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Takahashi
authors.affiliation: Department of Pediatrics,Chiba University Graduate School of Medicine,Chiba City,Japan.
authors.forename: J
authors.initials: J
authors.lastname: Oikawa
authors.affiliation: Department of Pediatrics,Chiba University Graduate School of Medicine,Chiba City,Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nagasawa
authors.affiliation: Department of Pediatrics,Chiba University Graduate School of Medicine,Chiba City,Japan.
authors.forename: N
authors.initials: N
authors.lastname: Shimojo
authors.affiliation: Department of Infectious Diseases,Medical Mycology Research Center,Chiba University,Chiba City,Japan.
authors.forename: N
authors.initials: N
authors.lastname: Ishiwada
mesh_terms: D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000382:microbiology / Q000517:prevention & control; D024881:Drug Resistance, Bacterial; D005260:Female; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006760:Hospitalization / Q000639:trends; D006801:Humans; D015994:Incidence; D007223:Infant; D007564:Japan; D008297:Male; D058885:Multilocus Sequence Typing; D011018:Pneumonia, Pneumococcal / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control*; D012189:Retrospective Studies; D065288:Serogroup; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000187:drug effects
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine
keywords: Antibiotic resistance; Streptococcus pneumoniae (pneumococcus); community-acquired pneumonia; immunization (vaccination); infectious disease epidemiology