The Centers for Disease Control and Prevention issued a health advisory saying that people who test positive for COVID-19 after taking Pfizer's antiviral drug Paxlovid should re-isolate for five days.
"People with recurrence of COVID-19 symptoms or a new positive viral test after having tested negative should restart isolation and isolate again for at least 5 days. Per CDC guidance, they can end their re-isolation period after 5 full days if fever has resolved for 24 hours (without the use of fever-reducing medication) and symptoms are improving. The individual should wear a mask for a total of 10 days after rebound symptoms started," the agency explained.
The CDC noted that while some people may continue to test positive after ten days, they are "considerably less likely to shed infectious virus."
The CDC and the Food and Drug Administration have been investigating dozens of reports of people reporting their symptoms returned within a week of completing the five-day treatment. So far, none of the cases have been severe, with most patients reporting mild symptoms that go away after several days.
Pfizer said that rebound infections are extremely rare, and the CDC said that the drug "continues to be recommended for early-stage treatment of mild to moderate COVID-19 among persons at high risk for progression to severe disease."