Conflict of interest
YH is current employee of Sinovac Life Sciences Co., Ltd. SL, XY, and YQ are current employees of Sinovac Biotech Co., Ltd. Both companies are subsidiaries of Sinovac holdings. QS is a current employee of Beijing Key Tech Statistics Technology Co., Ltd.The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.The authors declare that this study received funding from Sinovac Life Sciences Co., Ltd., Beijing, China. The funder had the following involvement in the study: study design, interpretation of data, the writing of this article or the decision to submit it for publication.