Virologist Peter Piot, director of the London School of Hygiene & Tropical Medicine, fell ill with COVID-19 in mid-March. He spent a week in a hospital and has been recovering at his home in London since. Climbing a flight of stairs still leaves him breathless.

Piot, who grew up in Belgium, was one of the discoverers of the Ebola virus in 1976 and spent his career fighting infectious diseases. He headed the Joint United Nations Programme on HIV/AIDS between 1995 and 2008 and is currently a coronavirus adviser to European Commission President Ursula von der Leyen. But his personal confrontation with the new coronavirus was a life-changing experience, Piot says.

This interview took place on 2 May. Piot’s answers have been edited and translated from Dutch:

“ON 19 MARCH, I SUDDENLY HAD A HIGH FEVER and a stabbing headache. My skull and hair felt very painful, which was bizarre. I didn’t have a cough at the time, but still, my first reflex was: I have it. I kept working—I’m a workaholic—but from home. We put a lot of effort into teleworking at the London School of Hygiene & Tropical Medicine last year, so that we didn’t have to travel as much. That investment, made in the context of the fight against global warming, is now very useful, of course.

I tested positive for COVID-19, as I suspected. I put myself in isolation in the guest room at home. But the fever didn’t go away. I had never been seriously ill and have not taken a day of sick leave the past 10 years. I live a pretty healthy life and walk regularly. The only risk factor for corona is my age—I’m 71. I’m an optimist, so I thought it would pass. But on 1 April, a doctor friend advised me to get a thorough examination because the fever and especially the exhaustion were getting worse and worse.

It turned out I had severe oxygen deficiency, although I still wasn’t short of breath. Lung images showed I had severe pneumonia, typical of COVID-19, as well as bacterial pneumonia...