In the early 1950s, psychiatrists began treating schizophrenia with a new drug called chlorpromazine. Seven decades later, the drug is still used as an anti-psychotic.

But now scientists have discovered that the drug, also known as Thorazine, can do something entirely different. It can stop the new coronavirus that causes Covid-19 from invading cells.

Driven by the pandemic’s spread, research teams have been screening thousands of drugs to see if they have this unexpected potential to fight the coronavirus. They’ve tested the drugs on dishes of cells, and a few dozen candidates have made the first cut.

They’re startlingly diverse. Some, like chlorpromazine, have been used for years — not for viral infections, but for conditions including cancer, allergies, arthritis, even irregular menstrual periods. Other drugs have not yet been approved by the Food and Drug Administration, but they have already proven safe in clinical trials. Their track records might help them get approved faster than a drug designed from scratch.