On its face, it was a major finding: Antimalarial drugs touted by the White House as possible COVID-19 treatments looked to be not just ineffective, but downright deadly. A study published on 22 May in The Lancet used hospital records procured by a little-known data analytics company called Surgisphere to conclude that coronavirus patients taking chloroquine or hydroxychloroquine were more likely to show an irregular heart rhythm—a known side effect thought to be rare—and were more likely to die in the hospital.
Within days, some large randomized trials of the drugs—the type that might prove or disprove the retrospective study’s analysis—screeched to a halt. Solidarity, the World Health Organization’s (WHO’s) megatrial of potential COVID-19 treatments, paused recruitment into its hydroxychloroquine arm, for example.