More than 3.7 million infections and more than 140 000 deaths due to coronavirus disease 2019 (COVID-19) have occurred in the US in the past 6 months. As case counts continue to increase, robust vaccine development efforts unprecedented in scale and speed are being pursued. More than 130 COVID-19 vaccines are in preclinical development using a variety of established and new platforms, and 17 candidate vaccines are undergoing evaluation in clinical trials in the US, Europe, and China.1 The US government has invested in the development of 5 vaccines as part of Operation Warp Speed.2 On June 25, the Chinese government approved the first COVID-19 vaccine (Ad5-nCoV) for use in the military population.