Seasonal influenza vaccine effectiveness at primary care level, Hong Kong SAR, 2017/2018 winter

ABSTRACT

The 2017/18 winter influenza season in Hong Kong started in early January 2018, predominated by influenza B/Yamagata. We collaborated with private medical practitioners of our sentinel surveillance system to collect respiratory specimens and clinical information from patients with influenza-like illness for estimation of the influenza vaccine effectiveness (VE) using the test-negative case-control design. We found that the overall VE was 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. Seasonal influenza vaccine provided moderate to good protection against laboratory-confirmed influenza infection at primary care level in Hong Kong in the 2017/18 winter influenza season.

Keywords:

• influenza
• vaccine
• influenza vaccine
• epidemiology
• surveillance
• vaccine effectiveness

Acknowledgments

We thank the PHLSB for their works on laboratory testing and collation of laboratory and clinical information. We thank all participating PMP for their contributions in specimen and data collection. We thank all colleagues in the CHP who work on the sentinel surveillance system of PMP. We appreciate the helpful discussion from colleagues of EpiConcept on an earlier version of this manuscript. We thank the reviewers for their comments which help improved this manuscript.

Authors’ contribution

All authors contributed to design of the study. Desmond Chan and Miu-ling Wong analysed the data and wrote the first draft. All authors revised the draft manuscript and approved the final version.