Decline of rotavirus-coded hospitalizations in children under 5 years: A report from Japan where rotavirus vaccines are self-financed. Issue 19 (3rd May 2018)

• Record Type: Journal Article
• Authors: Kobayashi, Masayuki; Adachi, Noriaki; Miyazaki, Makoto; Tatsumi, Masatoshi
• Is Part Of: Vaccine. Volume 36:Issue 19(2018)
• Page Start: 2727
• Page End: 2732
• Publication Date: 2018-05-03
• Subjects: Rotavirus -- Rotavirus gastroenteritis -- Vaccine -- Hospitalization -- Children -- Reduction; AGE acute gastroenteritis -- CI confidence interval -- IASR Infectious Agent Surveillance Report -- IR incidence rate -- IRR incidence rate ratio -- mo month -- Ref reference category -- RV rotavirus -- RVGE rotavirus gastroenteritis; Vaccines -- Periodicals; 615.372
• DOI: 10.1016/j.vaccine.2017.10.033
• Languages: English
• ISSNs: 0264-410X

Abstract

Highlights: The largest-scale study assessed the impact of rotavirus vaccines in Japan. Rotavirus vaccines have been moderately covered without routine immunization. Rotavirus-coded hospitalization declined by 60–70% from 2009 to 2015. Results suggest indirect effect in older children least likely to be vaccinated. Abstract: Objectives: To estimate the trend in incidence of rotavirus gastroenteritis (RVGE) hospitalization among children aged <5 years in Japan during pre- and post-vaccine periods (2009–2011 and 2012–2015). Study design: This retrospective observational study used a health insurance claims database (constructed by Japan Medical Data Center Co., Ltd.). Rotavirus vaccine became commercially available in 2011. We analyzed data of all children aged <5 years between January 2009 and December 2015. We estimated the incidence rate (IR) of RVGE hospitalization per 1000 person-years from 2009 to 2015 and incidence rate ratio (IRR) of post-vaccine years compared with the averaged pre-vaccine years. IRs and IRRs were also estimated by age group. Primary analysis was limited to the rotavirus season (January to June) of each year. Results: The IR was 6.3–9.3 in pre-vaccine years, 2.3 in 2014, and 3.0 in 2015; the decline was estimated to be 71% in 2014 and 61% in 2015 (p < 0.01). By age group, reduction in hospitalizations began in 2013 among children <1 year old, followed by children aged 1 to <5 years in 2014. In the 2014 season, a 65% reduction in RVGE hospitalization was observed in children aged 36 to <60 months, although this age group was unlikely to be vaccinated. Conclusions: A substantial decline of RVGE hospitalization in 2014 and its persistence was observed among children aged <5 years in Japan after introduction of rotavirus vaccine, although not included in the national immunization program. Indirect effects of rotavirus vaccination were suggested in the 2014 season.