Influenza vaccine showed a good preventive effect against influenza-associated hospitalization among elderly patients, during the 2016/17 season in Japan. Issue 11 (November 2018)

• Record Type: Journal Article
• Authors: Seki, Yuki; Onose, Akira; Murayama, Takaya; Koide, Chiaki; Sugaya, Norio
• Is Part Of: Journal of infection and chemotherapy. Volume 24:Issue 11(2018:Nov.)
• Page Start: 873
• Page End: 880
• Publication Date: 2018-11
• Subjects: Influenza -- Influenza vaccine -- Influenza vaccine effectiveness; Chemotherapy -- Periodicals; Infection -- Periodicals; Communicable diseases -- Chemotherapy -- Periodicals; 615.5805
• DOI: 10.1016/j.jiac.2018.07.013
• Languages: English
• ISSNs: 1341-321X

Abstract

Abstract: The 2016/17 influenza season in Japan was characterized by a predominance of influenza A (H3N2) activity; with H3N2 accounting for 85% of all detected influenza virus infections. We assessed the vaccine effectiveness (VE) of an inactivated quadrivalent influenza vaccine (IIV4) in adult patients, using a test-negative case-control design study based on the results of a rapid influenza diagnostic test (RIDT). Between November 2016 and March 2017, a total of 1048 adult patients were enrolled: including 363 RIDT positive for influenza A, 9 RIDT-positive for influenza B, and 676 RIDT-negative. During the 2016/17 season, the overall adjusted VE was 28.8% (95% confidence interval [CI]: 6.3–46%). The adjusted VE against influenza A was 27.4% (95%CI: 4.4–45%). The VE against influenza B could not be estimated because of the very low number of influenza B patients. Twenty-nine patients were hospitalized due to influenza-associated illness-during the present study, all of whom were infected with influenza A virus. The adjusted VE, determined using a case-control study, for preventing hospitalization for influenza A infection was 72.6% (95%CI: 30.7–89.1%). In addition, the VE for preventing hospitalization of influenza patients with comorbidities was 78.2% (95%CI: 41.1–92%). Our study showed that, during the 2016/17season, IIV4 was effective for preventing both the onset of influenza and influenza-associated hospitalization.