President Joe Biden tested positive for COVID-19 for a third straight day on Monday, in what appears to be a rare case of “rebound” following treatment with the antiviral Paxlovid.

In a letter noting the positive test, Dr. Kevin O’Connor, the White House physician, said Sunday that the president “continues to feel well” and will keep on working from the executive residence while he isolates, the Associated Press reported.

Paxlovid, which was developed by Pfizer Inc. PFE, +0.17%, can cause a rebound case of the virus that leads patients to test positive again two to eight days after testing negative, as MarketWatch has reported. In some cases, symptoms recur, although that does not appear to be the case for Biden.

“A brief return of symptoms may be part of the natural history of SARS-CoV-2 (the virus that causes COVID-19) infection in some persons, independent of treatment with Paxlovid and regardless of vaccination status,” the Centers for Disease Control and Prevention said back in May.

The CDC still recommends the treatment for people who are at high risk of severe disease. The FDA authorized Paxlovid in December in a move that essentially sent a sigh of relief through the medical community and many members of the public. Not only is Paxlovid a pill that someone can take at home, taking it can dramatically reduce the possibility they’ll be hospitalized or die. 

The fact that a rebound rather than a reinfection possibly occurred is a positive sign for Biden’s health once he’s clear of the disease.

“The fact that the president has cleared his illness and doesn’t have symptoms is a good sign and makes it less likely he will develop long COVID,” said Dr. Albert Ho, an infectious disease specialist at Yale University’s School of Public Health.

Don’t miss: Paxlovid has been given to Biden and millions of Americans infected with COVID-19. In the U.K., it sits on the shelf.

The news comes as new U.S. cases remain close to 130,000 a day, but not all data are being captured as many people are testing at home. The average stood at 123,553 on Sunday, according to a New York Times tracker, down 5% from two weeks ago.

For more, see: Moderna and Pfizer to start clinical trials for COVID-19 boosters that target BA.5 ‘in the near future’

The daily average for hospitalizations rose to 44,389 up 8% in two weeks. The daily average for deaths is up 2% to 435. Cases are rising modestly in about half the states, and falling modestly in the other half, according to the Times.

Coronavirus Update: MarketWatch’s daily roundup has been curating and reporting all the latest developments every weekday since the coronavirus pandemic began

Other COVID-19 news you should know about:

• There are growing concerns that rich countries are responding to the monkeypox outbreak in the same way as they did to COVID, namely by hoovering up all available vaccines and declining to share with Africa, the AP reported. Critics fear a repeat of the catastrophic inequity problems seen during the coronavirus pandemic that left millions of people in poorer countries exposed and allowed new variants to emerge. “The mistakes we saw during the COVID-19 pandemic are already being repeated,” said Dr. Boghuma Kabisen Titanji, an assistant professor of medicine at Emory University.

• North Korea said it had no new cases of COVID on Saturday, raising doubts about the accuracy of its statistics, the AP reported separately. The highly secretive nation first disclosed that it had any COVID cases in May, after claiming to have successfully kept the virus out despite a long and porous border with China. Some experts say North Korea has likely manipulated the scale of illness and deaths to help leader Kim Jong Un maintain absolute control amid mounting economic difficulties. The North’s anti-epidemic center said via state media it had found zero fever patients in the latest 24 hours, maintaining the country’s total caseload of about 4.8 million. Its death count remains at 74, with a mortality rate of 0.0016% — the world’s lowest, if true.

North Korea is facing a surge in fever cases after reporting its first local Covid-19 infection in mid-May. WSJ examines Kim Jong Un’s strategy to battle the pandemic in the impoverished country, which has little testing capacity and an unvaccinated population. Photos: KCTV; STR/AFP

• Austria is mourning the death by apparent suicide of a doctor who had received death threats from anti-vaccination activists and coronavirus pandemic conspiracy theorists, CNN reported. “Let’s put an end to this intimidation and fear mongering. Hate and intolerance have no place in our Austria,” President Alexander Van der Bellen said, hailing Lisa-Maria Kellermayr as a doctor who stood for healing people, protecting them from disease and taking a cautious approach to the pandemic. The doctor’s body was found in her office in Upper Austria on Friday along with a suicide note. She had often given media interviews about fighting the pandemic and promoting vaccinations.

• The Hong Kong government’s COVID-19 advisory panel recommended on Monday to lower the minimum age for vaccines to six months from three years, public broadcaster RTHK reported, according to Reuters. Chinese gambling hub Macao, meanwhile, is reopening after detecting zero COVID cases for nine straight days.

Here’s what the numbers say

The global tally of confirmed cases of COVID-19 topped 577.4 million on Monday, while the death toll rose above 6.40 million, according to data aggregated by Johns Hopkins University.

The U.S. leads the world with 91.2 million cases and 1,029,926 fatalities.

The Centers for Disease Control and Prevention’s tracker shows that 223.2 million people living in the U.S. are fully vaccinated, equal to 67.2% of the total population. But just 107.9 million have had a booster, equal to 48.3% of the vaccinated population, and just 19.9 million of the people 50 years old and over who are eligible for a second booster have had one, equal to 30.9% of those who had a first booster.