How the UK found the first effective Covid-19 treatment — and saved a million lives

The United Kingdom is not a pandemic success story. But its massive Covid-19 trials program is.

Peter Horby couldn’t believe his eyes.

He’d just gotten his first glimpse of new data from the United Kingdom’s Recovery Trial, an experiment enrolling tens of thousands of patients at dozens of hospitals for clinical trials investigating Covid-19 therapies.

Horby and his Oxford University colleague Martin Landray had dreamed up the trial program in March 2020. Nearly three months later, more than 35,000 people were dead in the UK (and more than 100,000 in...