A new systematic review of 65 studies from around the world involves a total of 97,333 health care workers and finds that 1 in 5 have experienced depression, anxiety, and/or PTSD during the ongoing COVID-19 pandemic. Yufei Li, Nathaniel Scherer, and colleagues at the London School of Hygiene & Tropical Medicine, U.K., present these findings in the open-access journal PLOS ONE on March 10.