Seroprevalence of influenza A (H9N2) virus infection among humans in China: A meta-analysis.

Herein, we conducted a meta-analysis aimed at comprehensively assessing avian influenza A (H9N2) virus infection seroprevalence and infection-related risk factors among humans in China. We reviewed published studies pertaining to H9N2 seroprevalence of in China from inception to March 20, 2020, with PubMed, Clinical Trial, VIP, CNKI and databases being used to identify English and Chinese articles. After excluding the incomplete literature and data, 45 studies about risk factor of human H9N2 viral infections in China were analyzed by systematic review and meta-analysis. Our results showed that 45 studies (59,590 total patients) met the inclusion criteria. Overall H9N2 infection seroprevalence in China was estimated to be 5.56% (95%CI = 3.88-7.28), while that from central China the seroprevalence was 22.72% (95%CI = 12.18-33.84), with this prevalence being greater than that observed in other regions. H9N2 infection seroprevalence was related to sampling time, testing methodology, gender, and other demographic factors. This review will provide a basis for further understanding the risk factors of H9N2 infections in China, and it is necessary to study how to formulate strict and targeted measures to prevent the spread of the virus.