Vaccine development and use depend on data-driven assessment of benefits and risks, first by regulatory bodies, and then more subjectively, millions of times over, by individual physicians and patients. Some vaccines have transformed public health (polio, smallpox, measles), whereas others have failed to work (HIV, malaria) or were later found to have important unexpected adverse effects (rotavirus, the 1976 influenza vaccine).
Regulatory review of the numerous coronavirus disease 2019 (COVID-19) vaccine candidates will occur under intense clinical, economic, and political pressure. In early August 2020, President Trump predicted that a vaccine could be available before election day. Less than a week later, Russia claimed to have developed its own vaccine and was beginning widespread administration without completion of the large-scale testing that Western countries routinely require, bringing efficacy-risk questions to even wider public attention. Acknowledging the pressure the US Food and Drug Administration (FDA) faces on this front, its leadership has stated that no vaccine would receive formal approval unless it met the agency’s published standards.1