Article in Japanese

Impact of rotavirus vaccination in Minamiboso medical care zone, Japan

Mayumi IWAMA¹⁾, Hiroaki ITO¹⁾, Takahiro UEHARA¹⁾

The effectiveness of rotavirus (RV) vaccine in reducing moderate to severe rotavirus gastroenteritis (RVGE) was investigated by comparing between the pre-vaccine era (2008-2012) and post-vaccine era (2012-2016) in a retrospective survey. Children aged under 5 years and hospitalized in the Minamiboso medical care zone due to RVGE were enrolled into this study. Ninety RVGE patients with a median age of 19 months were hospitalized during the RV outbreak season of December to May between 2008 and 2016. Fifty eight percent of these children were under the age of 2. Two cases of benign convulsion with mild gastroenteritis were recognized in the pre-vaccine era, but none showed signs of severe central nervous system complication such as encephalitis/encephalopathy in either the pre-vaccine or post-vaccine era. All 23 RVGE cases admitted to hospital in the post-vaccine era had not been vaccinated. A significant reduction in the rate of hospitalization was due to RVGE being observed among children aged under 5 years from the pre-vaccine era; 2.4/1,000 person-years to post-vaccine era; 0.9 person-years (p <0.001). The vaccine coverage increases annually, and in 2015, it was estimated to have reached 69% among 0 year-olds. Despite the low vaccine coverage of 11% and 29% among 2-4 year-olds during the outbreak seasons of 2014/15 and 2015/16, respectively, the hospitalization rate declined by 84% (p=0.014) and 100% (p <0.001), respectively. The burden of RVGE and effectiveness of the RV vaccine in children aged under 5 years old were recognized in the Minamiboso medical care zone. This study also implied the indirect effect of the RV vaccine.

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1) Department of Pediatrics, Kameda Medical Center

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Received	February 13, 2017
Accepted	May 25, 2017

29 (3)：234─240,2017