[The discussion of related issues in the efficacy evaluation of COVID-19 vaccine]

The COVID-19 swept across the countries and regions all over the world in the past one year. The marketing of an effective and safe COVID-19 vaccine is expected to control the spread of the disease. A placebo-controlled field efficacy trial is generally considered in the pivotal study of COVID-19 vaccine to observe whether it is able to reduce the incidence rate of the disease effectively. This paper is to introduce and discuss the considerations in study design and the choice of endpoint, statistical evaluation methods, primary estimand choosing and the strategies to various intercurrent events in the COVID-19 efficacy trials.