Fig. 6
From: COVID-19 vaccine development: milestones, lessons and prospects

A timeline of the preclinical and clinical trials of approved COVID-19 vaccines. Preclinical and clinical trials play important roles in evaluating the safety and protective efficacy of COVID-19 vaccines. The information of preclinical to clinical trials of several WHO-approved COVID-19 vaccines are provided in the form of a timeline, and partial Phase III clinical trials’ data were also displayed to show the total efficacy