News that President Joe Biden has developed a rebound case of COVID-19 may have you wondering: How common are rebound cases and why do they occur?
Biden, who is vaccinated and boosted, took the medication Paxlovid to treat his initial COVID-19 infection. Paxlovid, a five-day course of oral antiviral medications that blocks COVID-19 from replicating in the body, has been shown to be a highly effective treatment for mild or moderate COVID-19 among individuals at heightened risk for the disease.

For reasons researchers are still studying, a small percentage of people who have received Paxlovid have subsequently developed rebound COVID-19. A rebound case is when a patient tests positive for the disease or experiences a recurrence of symptoms after testing negative for the disease.
“Rebound cases of COVID-19 are typically quite mild, don’t appear to occur frequently and generally don’t require any additional treatment,” says Dr. Gerald Harmon, vice president of medical affairs at Tidelands Health. “However, it’s important to be aware of the possibility because people who experience a rebound case may be able to spread COVID-19 and should take precautions such as isolating themselves from others.”

Rebound cases have been reported two to eight days after a person recovers from their primary COVID-19 infection. It’s unclear exactly what causes them; some researchers believe it may be a natural part of the way the COVID-19 virus works unrelated to Paxlovid treatment or that higher doses of Paxlovid or associated treatment modifications are needed to help people completely eradicate the virus from their bodies.

Either way, Dr. Harmon says, the fact that rebound cases can occur shouldn’t discourage people from taking Paxlovid. The medication has been shown to be 89 percent effective at preventing hospitalization and death from COVID-19. Meanwhile, there has yet to be a single report of someone being hospitalized for a rebound case of COVID-19 after treatment with Paxlovid.
“Paxlovid is extremely effective at limiting the risk from COVID-19 among eligible people,” Dr. Harmon says. “It’s one of the best weapons we have against the disease.”
People experiencing a rebound infection should re-isolate for five full days and wear a mask for a total of 10 days after rebound symptoms start, according to the CDC. On average, post-Paxlovid rebound cases resolve in about three days without further treatment.

The U.S. is now experiencing a wave of new COVID-19 infections driven by the BA. 4 and BA.5 strains of COVID-19 omicron variant.
Although these subvariants have been shown to be more adept at evading the body’s immune defenses, it’s still very important to be vaccinated against the disease, Dr. Harmon says, and to stay up to date with booster shots.
“Vaccination remains vitally important to preventing severe disease,” Dr. Harmon says. “If you’re vaccinated, you may still experience symptoms, but the chances that you’ll end up in the hospital are much smaller.”