Efficacy and safety of a live attenuated influenza vaccine in Chinese healthy children aged 3-17 years in one study center of a randomized, double-blind, placebo-controlled phase 3 clinical trial, 2016/17 season.

ABSTRACT

BACKGROUND: No data on the safety and efficacy of a live attenuated influenza vaccine in China have ever been reported. METHODS: At a site of a phase 3 randomized, double-blind, placebo-controlled clinical trial in eastern China, eligible healthy children aged 3-17 years underwent randomization to receive live attenuated vaccine or placebo at a ratio of 11. The primary objective of the study was the prevention of laboratory-confirmed influenza illness during the surveillance period, starting on day 15 after vaccination. RESULTS: A total of 2000 participants were enrolled, with 998 receiving the vaccine and 1001 receiving placebo. Sixty-four cases of influenza-like illness were observed, of which, 44 were laboratory-confirmed (12 in vaccine group versus 32 in placebo group). Vaccine efficacy was 62.5% (95%CI 27.6-80.6) against all types of influenza and 63.3% (95%CI 27.5-81.5) against influenza H3N2 illness. 11 severe adverse events reported (7 in LAIV group versus 4 in placebo group) were all deemed to be non-vaccine-related. Adverse events occurred in 412 (41.3%) participants in the vaccine group versus 389 (38.9%; p = 0.274) participants in the placebo group. Significant increase incidence of fever was observed in participants in the vaccine group, especially in those aged 3-9 years. CONCLUSIONS: The live attenuated influenza vaccine showed good efficacy and safety among 3- to 17-year-olds children during the 2016-2017 season at a site in eastern China. Clinical Trial Registry Number NCT02964065.