The US Food and Drug Administration has authorized clinicians to prescribe chloroquine and hydroxychloroquine for patients admitted to hospital with covid-19, despite warnings from scientific advisers that no randomized controlled trial has been conducted to support the drugs’ safety and efficacy in this population.

In the emergency use authorization issued on 28 March,1 the agency acknowledged that the approval was based on “limited in-vitro and anecdotal clinical data.”

The FDA action followed President Trump’s statements at a press conference last week that hydroxychloroquine showed “tremendous promise” for patients with covid-19, adding, “I think it’s going to be great.”2

Trump cited a controversial French study of 20 patients published the previous day. Anthony Fauci, head of the National Institute for Allergies and Infectious Diseases at the National Institutes of Health, corrected Trump’s comments, saying that they were based on anecdotes and not a controlled clinical trial.3