Infected people with no symptoms sometimes have abnormal CT scans...but they are always shedding virus!

Doctors are working hard to understand COVID-19 and its symptoms. One challenge is that infected people sometimes don’t have any obvious symptoms at all. Doctors call this being “asymptomatic.”

Recently, researchers in China used contact tracing to identify and test people at high risk COVID-19. They then kept tabs on the ones who tested positive. They took scans of their lungs to check for damage. And they measured blood markers of inflammation to see how strong their immune response was.

About half of the asymptomatic people had signs of damage in their lungs on CT scans. Some people found this surprising. But doctors don’t usually get CT scans on people who don’t have symptoms. It’s possible other viruses cause similar problems and we never checked. It’s not clear if these abnormalities have any health consequences.

Asymptomatic infected patients shed virus for a median of 19 days. Some shed for 15 days. Others up to 25 days. This was longer than the patients who had mild symptoms, who shed virus for a median of 14 days. The asymptomatic infected patients also had a lower immune response and fewer antibodies to the virus.

It’s not clear what the abnormal CT scans will mean for asymptomatic patients. What is clear is that infected people who don’t have symptoms can still shed viruses for a long time--at least as long as people who get symptoms and maybe even longer. This means that there is a risk of passing the virus to others, even if you don’t feel sick.


Last update: June 26, 2020 8:20 pm ET

Science review: ERS, JAB