Fig. 1
![Fig. 1](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs13063-021-05182-z/MediaObjects/13063_2021_5182_Fig1_HTML.png)
Flow diagram of record screening. ICTRP, International Clinical Trials Registry Platform; ChiCTR, Chinese Clinical Trial Registry; TCM, traditional Chinese medicine; COVID-19, coronavirus disease 2019; H1N1, H1N1 influenza; SARS, severe acute respiratory syndrome