Enlarge / Stephen Hahn, Commissioner of Food and Drugs at the US Food and Drug Administration (FDA), speaks during a Senate Health, Education, Labor and Pensions Committee hearing on June 30, 2020, in Washington, DC. (credit: Getty | Al Drago) Any experimental COVID-19 vaccines aspiring to earn regulatory approval from the Food and Drug Administration will need to prevent or decrease the severity of disease in at least 50 percent of people, the agency announced Tuesday. The criterium is part of a larger set of guidelines released by the agency for developing a vaccine to halt the spread of pandemic coronavirus, SARS-CoV-2—which causes COVID-19 and is now accelerating in much of the country after months of sustained devastation. With the guidelines, the FDA tried to dispel fears that the rush to develop a COVID-19 vaccine may come at the expense of adequate safety testing.