The anti-malaria drug hydroxychloroquine has made headlines in recent weeks for its potential to help with the new coronavirus disease, COVID-19, though its benefits remain unproven. Now, a new study will test whether the drug can prevent COVID-19 transmission. For the study, researchers in New York and Washington state plan to enroll 2,000 participants who are close contacts of people with confirmed or pending COVID-19 diagnoses. Participants will be randomly assigned to take either hydroxychloroquine or a placebo for two weeks, and they will be tested daily for COVID-19, according to a statement from the University of Washington (UW), which...