A variety of pills on a surface.
Illustration: PGN

Leer en español

What you need to know

  • Some people experience a COVID-19 rebound after taking Paxlovid, but the drug is still an effective treatment for high-risk individuals.
  • Rebound symptoms seem to be mild or even nonexistent, but infected individuals are contagious and at risk of spreading the virus to others.
  • People who are experiencing COVID-19 rebound should follow the CDC’s isolation guidelines.

Pfizer’s Paxlovid antiviral pill is one of the highly effective treatment options against COVID-19 infection. The medication helps prevent hospitalization and death due to the virus and has been crucial to protecting high-risk individuals from severe illness.

But in rare cases, people who complete the treatment and recover from infection can test positive again a few days later. President Joe Biden is currently experiencing a COVID-19 rebound case. After taking Paxlovid and recovering from the virus last week, Biden tested positive again on Saturday, though the White House reports he is not experiencing a return of symptoms.

What is “Paxlovid rebound”?

Paxlovid is an FDA-authorized COVID-19 treatment pill developed by Pfizer. The CDC recommends the drug for treatment of mild-to-moderate COVID-19 in high-risk individuals. If taken during the early stage of infection, the drug can stop the virus from replicating, thereby minimizing the chance of severe illness and aiding quick recovery. 

In May, the CDC issued a health advisory in response to reports of “Paxlovid rebound” cases. Some people who completed their five-day Paxlovid course reported testing negative and then experiencing a return of symptoms or testing positive again typically two to eight days later. Symptoms the second time around seem to be mild, but the infected individual is still at risk of spreading the virus to others.

To ensure that you do not spread the virus to others unintentionally, it’s best to continue testing for up to eight days following the completion of your Paxlovid course.

Why are these rebounds happening?

More research is needed to determine the cause of these rebound cases, but one hypothesis is that Paxlovid may not entirely eliminate the infection within the five-day treatment period. If there is still some COVID-19 virus that remains in the body after treatment ends, those leftover viruses could start replicating and cause people to test positive again. Pfizer says its studies show that about 2 percent of people who take Paxlovid experience COVID-19 rebound, but some health care professionals believe the rate is much higher.

Is Paxlovid still effective?

Paxlovid remains an extremely effective treatment option despite these concerns. The drug is nearly 90 percent effective at preventing hospitalization and death due to COVID-19 among unvaccinated, high-risk individuals. The CDC has warned of the rebound phenomenon but makes clear that it continues to recommend Paxlovid for people at high risk of developing severe illness.

Am I eligible to take Paxlovid and how can I access it?

The FDA authorized Paxlovid for anyone ages 12 and older who weighs at least 88 pounds, but in order to obtain a prescription you have to test positive for COVID-19 and be at high risk for severe disease. If you test positive for COVID-19 and intend to take Paxlovid, know that you have to start the regimen within five days of developing symptoms. 

To receive a Paxlovid prescription, contact your medical provider once you test positive. If you don’t have a medical provider, you can access the pills at “test-to-treat” sites, where you can get tested and receive treatment in one sitting. You can also get a prescription from a community health center and then visit a location that fills the prescription. Telehealth options through platforms like Plushcare and eMed offer online visits to assess COVID-19 tests and symptoms and prescribe medications.

What should I do if I experience a “rebound” case?

According to CDC Director Dr. Rochelle Walensky, if people experience a return of COVID-19 symptoms after taking Paxlovid, “They should test. They should put their mask back on. And if their test is positive, restart the isolation protocol.” The agency does not recommend that people retake the five-day Paxlovid course if they experience COVID-19 rebound.

Per CDC isolation guidance, people who receive a positive test should stay at home and isolate themselves from others for at least five days. Many people continue to be infectious after the five-day period, so the safest option is to isolate until you receive a negative rapid test or wear a mask if you have to leave isolation without a negative test.