Speed, Evidence, and Safety Characteristics of Vaccine Approvals by the US Food and Drug Administration

Study of the 21 FDA vaccines approved between 2010 and 2020 found the average time of clinical development to be 8 years, with a median of 7 clinical trials, including at least 2 trials that were randomised, masked, and used a comparator group and with 6 months follow up.

SPS commentary:

Authors conclude that given the urgency of developing a COVID-19 vaccine, trials will need to be larger than those supporting prior vaccine approvals and include sufficient follow-up time for emergence of adverse effects.

JAMA Internal Medicine