More than 10 percent of those with serious COVID-19 infections have been frontline health-care workers. Now, an international group, led by researchers at Washington University School of Medicine in St. Louis, is launching a trial to see whether the drug chloroquine might help those workers. The drug trail won’t treat doctors, nurses and others after they get sick. Instead, the health-care workers will take medication prophylactically, to see whether it might be worth adding low doses of chloroquine to other personal protective equipment, such as masks, gowns and gloves. Michael Avidan, MBBCh, the Dr. Seymour and Rose T. Brown Professor and head of the Department of Anesthesiology, is leading the international study, which has sites in England, Ireland, Africa, Canada, and South America. The group is called the CROWN collaborative (COVID Research Outcomes World Network). With funding from the COVID-19 Therapeutics Accelerator — an initiative launched by the Bill & Melinda Gates Foundation Wellcome, Mastercard and an array of public and philanthropic donors — the researchers want to learn whether low doses of chloroquine can keep healthcare workers from getting COVID-19 at all or, if they do get sick, whether treatment with the drug might lead to less severe symptoms.