At this time, the original 5-day treatment period for Paxlovid is recommended in the product labeling and by the Centers for Disease Control and Prevention (CDC).

There is currently no evidence that a second round of Paxlovid treatment is needed after the initial 5-day treatment if COVID-19 rebound occurs. Case reports suggest that people who develop COVID rebound after completing 5 days of Paxlovid treatment usually have no symptoms or mild illness. Currently there have been no reports of severe outcomes related to COVID rebound.

It is possible that Paxlovid treatment may need to be given for a longer period of time, but studies are currently ongoing to answer this question. Some doctors have prescribed the treatment for a longer period of time in rebound cases, so you can always ask your doctor if they recommend this.

According to Pfizer, the manufacturer of Paxlovid, the clinical relevance of increases in viral RNA following Paxlovid or placebo treatment is unknown.

Paxlovid (nirmatrelvir and ritonavir) is an oral antiviral treatment and is authorized to be used for early-stage treatment (within 5 days of symptoms onset) of mild to moderate COVID-19 in people at high risk for severe disease. Paxlovid treatment should begin as soon as possible and within 5 days of COVID symptom onset among persons eligible to receive the treatment.

Do I have to isolate if I have Paxlovid rebound?

• Yes, if you test positive again after finishing Paxlovid you should restart isolation for at least 5 full days and contact your healthcare provider for further instructions. You may still be shedding virus and be contagious.
• You can end your rebound isolation period after 5 days if your fever is gone for 24 hours (without the use of fever-reducing medication) and your symptoms (such as cough, body aches, shortness of breath) are improving.
• Wear a mask for 10 days after your rebound symptoms start, even if you've ended the 5 day isolation period.
• Some people continue to test positive 10 days after COVID rebound begins, but are much less likely to be contagious by this time.

How quickly does Paxlovid rebound start?

Paxlovid (COVID-19) rebound has been reported to begin between 2 and 8 days after initial recovery in those who have used Paxlovid antiviral treatment. You may develop a recurrence of COVID-19 symptoms or a new positive viral test after having tested negative.

This rebound effect is not a new COVID infection or due to Paxlovid resistance. The CDC reported no other respiratory pathogens were identified among known cases.

Rebound with Paxlovid appears to occur in about 2% to 6% of people, but numbers might vary because some people may never retest if they remain asymptomatic. In studies, patients who took an inactive placebo also had rebound in about 1.5% of cases.

Case reports suggest that symptoms and positive test results improve or resolve most commonly within a 3 day period, but can be shorter or longer.

This is not all the information you need to know about Paxlovid (nirmatrelvir and ritonavir) for safe and effective use and does not take the place of your doctor’s directions. Review the full Paxlovid product information and discuss this information and any questions you have with your doctor or other health care provider.