As part of the studies to build evidence for the coronavirus disease-2019 (COVID-19) conducted by the Japan Society for Oriental Medicine, the observational research and the clinical trials were designed to examine the effectiveness of Kampo medicine in the treatment of COVID-19. These studies were initiated in the context of limited information about the clinical findings of COVID-19 and previous clinical study. Therefore, through literature review, we compared these studies with clinical trials on oral antiviral drugs in terms of endpoint, analysis methods, and results. Results of this review showed that the rate of severe disease and time to symptoms relief, which were focused on in observational research and clinical trials of Kampo medicines, were also used in antiviral drug trials. Furthermore, we discussed that when interpreting the results of clinical studies, it was important to take into account factors that may affect the results, such as the number of cases, the characteristics of the endpoint, and the characteristics of the target population.

At the 73rd Academic Conference of the Japan Society for Oriental Medicine held in June 2023, a report on an establishment of evidence for the coronavirus disease-2019 (COVID-19) was presented. As part of this project, we reported how we conducted the observational study and the clinical trial that evaluated the effectiveness of Kampo medicine on the acute symptoms of mild to moderate COVID-19 patients. In this article, we have summarized our experience in these studies from the viewpoint of a statistician, including important things to be considered when writing a research plan and selecting endpoints and statistical analysis methods.