The Covid-19 antiviral drug Paxlovid has been widely available but it could be still contagious for some people after the treatment, researchers warned.

Dr. Michael Charness of the Veterans Administration Medical Center in Boston, who along with team of researchers at the Columbia University found “two instances in which people have transmitted to others when their infection recurs”, CNN Reports.

According to CNN “In one case, a 67-year-old man infected a 6-month-old after a half-hour near the child. In another instance, a 63-year-old man infected two family members during three days of relapse after Paxlovid.”

People who experience rebound are at risk of transmitting to other people, even though they’re outside what people accept as the usual window for being able to transmit.

– Dr. Michael Charness of the Veterans Administration Medical Center in Boston (source: CNN Health)

“It indicates that you can transmit during rebound even before you develop symptoms. And you know, we studied a small number of people. It’s certainly conceivable that there are other people out there who don’t have symptoms and still have a viral rebound,” Dr Charness told CNN.

• Coronavirus can be contagious during a Paxlovid rebound, researchers warn, even if people don’t have symptoms
• Paxlovid is widely available, but details on who’s getting it are sparse

Health experts and the US Centers for Disease Control and Prevention (CDC) recommend taking precautions even after taking Paxlovid. The CDC has recently issued this Covid-19 Rebound After Paxlovid Treatment advisory.

According to the CDC, “people who test positive again and whose symptoms come back after finishing their antiviral pills should restart their isolation period and isolate for five full days. The agency says people can end their isolation period after those five additional days as long as their fever has been gone for 24 hours without fever-reducing medication and they’re feeling better. The agency also recommends that people wear a mask for 10 days after their symptoms come back.”

Quoting Dr. Charness and his research colleagues research, CNN writes “It’s not entirely clear that taht rebound is linked to Paxlovid. In studies of more than 2,200 Covid-19 patients, Pfizer, the company that makes the drug, said there were a few patients who had their Covid-19 come bouncing back after a negative test, but they were in the group that took Paxlovid as well as in those who got the placebo, suggesting that Covid just reappears in some people, even without treatment.”