By Kevin Liptak and Donald Judd, CNN
President Joe Biden tested positive for Covid-19 again on Saturday morning, according to a letter from presidential physician Dr. Kevin O’Connor, in what is likely a “rebound” in Covid-19 positivity the doctor noted. is “observed in a small percentage of patients treated with Paxlovid.
Biden has experienced “no recurrence of symptoms and continues to feel reasonably well” and therefore will not resume treatment, the White House said. O’Connor said the president tested negative on Tuesday evening, Wednesday morning, Thursday morning and Friday morning before testing positive on Saturday morning.
“However, given his positive antigen test, he will begin strict isolation procedures again,” the doctor noted. Biden stopped self-isolating on Wednesday after testing negative in back-to-back antigen tests, celebrating his comeback in remarks from the White House Rose Garden.
Biden’s doctor said the president has no symptoms but will self-isolate at the White House. He canceled plans to travel home to Delaware on Sunday and to Michigan, where he was due to tout on Tuesday the recently passed bill to boost U.S. semiconductor production, the White House said on Saturday. .
“Friends, today I tested positive for COVID again,” Biden wrote on Twitter. “It happens with a small minority of people. I have no symptoms but will self-isolate for the safety of everyone around me. I’m still at work and will be back on the road soon.
White House Press Secretary Karine Jean-Pierre wrote Biden is “asymptomatic, feeling well and working isolated from the residence to protect others”.
A White House official said contact tracing efforts were underway Saturday after Biden tested positive for Covid-19.
The president had resumed events at the White House after testing negative this week, although he was seen wearing a mask more regularly. White House officials said they were working to ensure social distancing at public events he held at the White House.
Biden, 79, first tested positive on July 21. During his first bout with the disease, he experienced mild symptoms including a runny nose, fatigue, a high temperature and a cough, according to his doctor. The president took a five-day course of Paxlovid, which requires a doctor’s prescription and is available through a US Food and Drug Administration emergency use authorization for the treatment of mild Covid-19. to moderate in people 12 years of age and older who are at high risk of severe disease.
When Biden first tested positive last week, the White House said he had 17 close contacts, none of whom ultimately tested positive.
First lady Jill Biden remains in Delaware, where she has been since the president first tested positive for Covid-19, a White House official told CNN. She did not return to the White House.
The first lady was expected to join the president on his trip to Wilmington on Sunday.
The US Centers for Disease Control and Prevention issued a health alert to doctors on May 24 advising them that symptoms of Covid-19 sometimes reappear, and this may be how the infection manifests in some people. , whether vaccinated or treated. with drugs like Paxlovid. The CDC said most rebound cases involve mild illness and no cases of serious illness have been reported.
Biden is fully vaccinated and has received two boosters. He received his first two doses of the Pfizer/BioNTech Covid-19 vaccine before its inauguration in January 2021, his first booster in September and his second booster in March.
White House officials had previously suggested a rebound Covid case was unlikely, based on case reports across the country. However, Biden continued to be tested and monitored.
Infectious disease experts have called on the government to study rebound cases more systematically, saying the phenomenon needs to be better characterized to understand who is most at risk and whether the standard five-day treatment with the drug needs to be extended to prevent this. Studies have shown that people can transmit the infection to others when rebounding, which is another reason to understand it better.
Pfizer, the company that makes Paxlovid, said its studies show that rebounds are rare and occur in people who take the drug as well as in those who have taken a placebo pill. Because investigators noted the phenomenon in both groups, the company does not believe it is drug-related.
The director of the National Institute of Allergy and Infectious Diseases, Dr. Anthony Fauci, also experienced the Covid-19 rebound. Her symptoms worsened when they returned after treatment, and her doctors prescribed her another course of Paxlovid.
This story has been updated with additional developments.
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CNN’s Kate Bennett, Brenda Goodman, Virginia Langmaid and Jamie Gumbrecht contributed to this report.