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.

Skin preparation for prevention of peripheral blood culture contamination in children

“…More than half of the positive blood cultures in the present study were deemed to be contaminated (103/171, 60.6%), similar to reports by Min 3,25 With the wider access to pneumococcal conjugate vaccine in children aged <5 years 26 and Hib vaccine, 27 it is likely that in the present cohort the rate of positive blood cultures was also decreased in the 2015-2017 period, as well as the rate of positive S. pneumoniae and Hib isolations. With more vaccines available, the proportion of contaminated cultures may increase.…”

Difference between Japanese Secondary and Tertiary Medical Facilities Regarding Changes in the Hospitalization of Children for Pneumonia after the Introduction of the Pneumococcal Conjugate Vaccine

“…As in previous studies (4,8,10,11), in the present study, the number of patients hospitalized for pneumonia in the secondary medical facility declined after the beginning of official financial support of PCV vaccination. In particular, the number of patients with pneumonia other than confirmed viral or mycoplasmal pneumonia was markedly reduced.…”

“…In Japan, the incidence of pneumococcal meningitis and bacteremia in children was markedly decreased after the introduction of PCV7 in 2010 (7). In addition, the reduction of community-acquired pneumonia and pneumococcal pneumonia in children aged < 5 years was also observed in Japan (8).…”

Pneumococcal vaccination reduces the risk of community‐acquired pneumonia in children

“…As previously described, the effectiveness of PCV7 against pneumonia ranges from 65% to 6.0% . In Chiba City, Japan, a population‐based study showed that the annual incidence rate ratio of CAP was 0.81, and the OR for pneumococcal pneumonia incidence was 0.60, when comparing post‐vaccine with pre‐vaccine periods . The effectiveness of PCV7 against invasive pneumococcal disease (IPD) has been shown by the rapid and large decrease in the number of IPD patients after its introduction into Japan and the USA .…”

“…found a PCV7‐associated reduction in pneumonia of 6.0%. In Japan, Naito et al . reported very recently that the annual incidence rate ratio of CAP was 0.81, when comparing the post‐vaccine with pre‐vaccine period.…”