Why Tens Of Thousands Of People Are Key To Testing A COVID-19 Vaccine

Volunteers getting the shot help determine if a candidate vaccine works. But what with social distancing and masks, scientists must discern if it's the shot or these other measures preventing illness.(Image credit: Taimy Alvarez/AP)

Source: NPR Health and Science - September 23, 2020 Category: Consumer Health News Authors: Joe Palca Source Type: news