Biden tested positive in rebound case, says White House doctor

WASHINGTON－US President Joe Biden tested positive for COVID-19 on Saturday in what was called a rebound case, days after ending isolation and treatment, his doctor said.

White House physician Kevin O'Connor wrote in a memo that Biden "has experienced no reemergence of symptoms, and continues to feel quite well", but will reinstate strict isolation procedures.

"This being the case, there is no reason to reinitiate treatment at this time," O'Connor added. "But we will obviously continue close observation."

Biden, 79, first tested positive for the coronavirus on July 21 before receiving negative test results last week.

Fully vaccinated and twice boosted, Biden took Paxlovid, an antiviral therapy produced by Pfizer and given to patients with COVID-19.

Small percentage

There is potential for so-called rebound COVID-19 positivity observed in a small percentage of patients treated with Paxlovid, O'Connor said.

White House COVID-19 coordinator Ashish Jha told reporters on July 25 that data "suggests that between 5 and 8 percent of people have rebound" after Paxlovid treatment.

According to the Centers for Disease Control and Prevention, those with rebound COVID-19 should isolate for at least five days, ending that if a fever has resolved itself for 24 hours without medication and symptoms have improved. The patient should wear a mask for a total of 10 days after rebound symptoms started. Some people will continue to test positive after day 10, but are considerably less likely to shed infectious virus.

Both the Food and Drug Administration and Pfizer say that the virus levels of 1 to 2 percent of people in Pfizer's original study on Paxlovid rebounded after 10 days. The rate was about the same among people taking the drug or dummy pills, "so it is unclear at this point that this is related to drug treatment", the FDA said.

While Biden was testing negative, he returned to holding in-person indoor events and meetings with staff at the White House and was wearing a mask, in accordance with CDC guidelines. But the president removed his mask indoors when delivering remarks on Thursday and during a meeting with CEOs on the White House complex.

Asked why Biden appeared to be breaching CDC protocols, press secretary Karine Jean-Pierre said:"They were socially distanced. They were far enough apart. So we made it safe for them to be together, to be on that stage."

Regulators are still studying the prevalence and virulence of rebound cases, but the CDC in May warned doctors that it has been reported to occur within two to eight days after someone has initially test negative for the virus.

Xinhua - Agencies