Norio Sugaya1, Masayoshi Shinjoh2, Yuji Nakata3, Kenichiro Tsunematsu4, Yoshio Yamaguchi5, Osamu Komiyama6, Hiroki Takahashi7, Keiko Mitamura8, Atsushi Narabayashi9, Takao Takahashi2. 1. Department of Pediatrics, Keiyu Hospital, Yokohama, Kanagawa, Japan. Electronic address: sugaya-n@za2.so-net.ne.jp. 2. Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan. 3. Department of Pediatrics, Nippon Kokan Hospital, Kawasaki, Kanagawa, Japan. 4. Department of Pediatrics, Hino Municipal Hospital, Hino, Tokyo, Japan. 5. Department of Pediatrics, National Hospital Organization, Tochigi Medical Center, Utsunomiya, Tochigi, Japan. 6. Department of Pediatrics, National Hospital Organization, Tokyo Medical Center, Tokyo, Japan. 7. Department of Pediatrics, Tokyo Metropolitan Ohtsuka Hospital, Tokyo, Japan. 8. Department of Pediatrics, Eiju General Hospital, Tokyo, Japan. 9. Department of Pediatrics, Kawasaki Municipal Hospital, Kawasaki, Kanagawa, Japan.
Abstract
OBJECTIVES: We assessed the vaccine effectiveness (VE) of inactivated influenza vaccine (IIV) in children 6 months to 15 years of age in 2015/16 season. In addition, based on the data obtained during the three seasons from 2013 to 2016, we estimated the three-season VE in preventing influenza illness and hospitalization. METHODS: Our study was conducted according to a test-negative case-control design (TNCC) and as a case-control study based on influenza rapid diagnostic test results. RESULTS: During 2015/16 season, the quadrivalent IIV was first used in Japan. The adjusted VE in preventing influenza illness was 49% (95% confidence interval [CI]: 42-55%) against any type of influenza, 57% (95% CI: 50-63%) against influenza A and 34% (95% CI: 23-44%) against influenza B. The 3-season adjusted VE was 45% (95% CI: 41-49%) against influenza virus infection overall (N = 12,888), 51% (95% CI: 47-55%) against influenza A (N = 10,410), and 32% (95% CI: 24-38%) against influenza B (N = 9232). An analysis by age groups showed low or no significant VE in infants or adolescents. By contrast, VE was highest in the young group (1-5 years old) and declined with age thereafter. The 3-season adjusted VE in preventing hospitalization as determined in a case-control study was 52% (95% CI: 42-60%) for influenza A and 28% (95% CI: 4-46%) for influenza B, and by TNCC design, it was 54% (95% CI: 41-65%) for influenza A and 34% (95% CI: 6-54%) for influenza B. CONCLUSION: We demonstrated not only VE in preventing illness, but also VE in preventing hospitalization based on much larger numbers of children than previous studies.
OBJECTIVES: We assessed the vaccine effectiveness (VE) of inactivated influenza vaccine (IIV) in children 6 months to 15 years of age in 2015/16 season. In addition, based on the data obtained during the three seasons from 2013 to 2016, we estimated the three-season VE in preventing influenza illness and hospitalization. METHODS: Our study was conducted according to a test-negative case-control design (TNCC) and as a case-control study based on influenza rapid diagnostic test results. RESULTS: During 2015/16 season, the quadrivalent IIV was first used in Japan. The adjusted VE in preventing influenza illness was 49% (95% confidence interval [CI]: 42-55%) against any type of influenza, 57% (95% CI: 50-63%) against influenza A and 34% (95% CI: 23-44%) against influenza B. The 3-season adjusted VE was 45% (95% CI: 41-49%) against influenza virus infection overall (N = 12,888), 51% (95% CI: 47-55%) against influenza A (N = 10,410), and 32% (95% CI: 24-38%) against influenza B (N = 9232). An analysis by age groups showed low or no significant VE in infants or adolescents. By contrast, VE was highest in the young group (1-5 years old) and declined with age thereafter. The 3-season adjusted VE in preventing hospitalization as determined in a case-control study was 52% (95% CI: 42-60%) for influenza A and 28% (95% CI: 4-46%) for influenza B, and by TNCC design, it was 54% (95% CI: 41-65%) for influenza A and 34% (95% CI: 6-54%) for influenza B. CONCLUSION: We demonstrated not only VE in preventing illness, but also VE in preventing hospitalization based on much larger numbers of children than previous studies.
Authors: Huiying Chua; Shuo Feng; Joseph A Lewnard; Sheena G Sullivan; Christopher C Blyth; Marc Lipsitch; Benjamin J Cowling Journal: Epidemiology Date: 2020-01 Impact factor: 4.822