Fumihiko Hattori1, Hiroki Miura1, Ken Sugata1, Akiko Yoshikawa1, Masaru Ihira2, Yuichiro Yahata3, Hajime Kamiya3, Keiko Tanaka-Taya3, Tetsushi Yoshikawa4. 1. Department of Pediatrics, Fujita Health University School of Medicine, Toyoake, Aichi 470-1192, Japan. 2. Graduate School of Health Sciences, Fujita Health University, Toyoake, Aichi 470-1192, Japan. 3. Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Tokyo 162-8640, Japan. 4. Department of Pediatrics, Fujita Health University School of Medicine, Toyoake, Aichi 470-1192, Japan. Electronic address: tetsushi@fujita-hu.ac.jp.
Abstract
OBJECTIVE: Matched case control study was conducted to elucidate the effectiveness of the Oka/Biken vaccine immediately after implementation of the universal immunization program in Japan. METHODS: Cases were laboratory confirmed varicella patient under 15years of age diagnosed at 14 designated pediatric clinics between September 2015 and September 2016. Controls were selected from patients who visited the same practice for different reasons as the varicella case within 2weeks. Swab samples were collected from varicella suspected patients and molecular diagnostic assays were used to confirm varicella cases. Matched odds ratio were used to calculate vaccine effectiveness (VE). RESULTS: Varicella zoster virus DNA was detected in 183 (81.3%) of 225 suspected cases. One sample was excluded because it was positive for the Oka vaccine strain (182/225, 80.9%). Three hundred twenty-three control subjects were enrolled. The effectiveness of 1 dose of the Oka/Biken vaccine compared with no vaccine was 76.7% (95% confidence interval [CI]: 58.6-86.9%; P<0.001). The effectiveness of 2 doses of the Oka/Biken vaccine was 94.2% (95% CI: 85.7-97.6%; P<0.001). After adjusting for potential confounding effects, the adjusted VE of 1 and 2 doses of varicella vaccine were 76.9% (95% CI: 58.1-87.3%; P<0.001) and 94.7% (95% CI: 86.0-98.0%; P<0.001), respectively. CONCLUSIONS: VE of one dose of Oka/Biken varicella vaccine was insufficient to control varicella. Therefore, two doses of Oka/Biken varicella vaccine is significant for controlling varicella in Japan.
OBJECTIVE: Matched case control study was conducted to elucidate the effectiveness of the Oka/Biken vaccine immediately after implementation of the universal immunization program in Japan. METHODS: Cases were laboratory confirmed varicellapatient under 15years of age diagnosed at 14 designated pediatric clinics between September 2015 and September 2016. Controls were selected from patients who visited the same practice for different reasons as the varicella case within 2weeks. Swab samples were collected from varicella suspected patients and molecular diagnostic assays were used to confirm varicella cases. Matched odds ratio were used to calculate vaccine effectiveness (VE). RESULTS:Varicella zoster virus DNA was detected in 183 (81.3%) of 225 suspected cases. One sample was excluded because it was positive for the Oka vaccine strain (182/225, 80.9%). Three hundred twenty-three control subjects were enrolled. The effectiveness of 1 dose of the Oka/Biken vaccine compared with no vaccine was 76.7% (95% confidence interval [CI]: 58.6-86.9%; P<0.001). The effectiveness of 2 doses of the Oka/Biken vaccine was 94.2% (95% CI: 85.7-97.6%; P<0.001). After adjusting for potential confounding effects, the adjusted VE of 1 and 2 doses of varicella vaccine were 76.9% (95% CI: 58.1-87.3%; P<0.001) and 94.7% (95% CI: 86.0-98.0%; P<0.001), respectively. CONCLUSIONS: VE of one dose of Oka/Biken varicella vaccine was insufficient to control varicella. Therefore, two doses of Oka/Biken varicella vaccine is significant for controlling varicella in Japan.