Scientists have discovered that coronavirus could linger in patients for more than a month, which means it’s possible they could transmit the virus long after symptoms subside.

The duration of viral shedding — which is the length of time the virus can be transmitted from someone infected — was found in one instance to be 37 days after the person contracted the illness. The median duration was 20 days.

The findings, published in the Lancet this week, indicate that the current recommendation for isolation — two weeks — may not go far enough to prevent transmission of the virus.