The 2017/18 winter influenza season in Hong Kong began in early January 2018, with influenza B/Yamagata dominating. Researchers worked with private medical practitioners from our sentinel monitoring system to gather respiratory specimens and clinical data from patients with influenza-like illnesses in order to estimate influenza vaccine efficacy (VE) using the test-negative case-control approach. 

The total VE was determined to be 59.1% (95%CI 41.1 to 71.8%) against all influenza and 53.5% (95%CI 35.4 to 74.6%) against influenza B. In the 2017/18 winter influenza season, seasonal influenza vaccination offered moderate to good protection against laboratory-confirmed influenza illness at the primary care level in Hong Kong.