Acknowledgements
The study was funded by Lanzhou Institute of Biological Products Co., Ltd (LIBP) of Sinopharm, and Beijing Institute of Biological Products Co., Ltd (BIBP) of Sinopharm. X.J.G., X.Y.M., H.W., and J. Zhang are employees of the funders. The funders did not participate in design of the trial, analysis of the data, or writing of the manuscript.