COVID Symptoms Unlikely to Relapse After Taking Paxlovid

woman pulling down her mask to take a pill

Lara Antal / Verywell

Key Takeaways

  • There are some patients who reported having symptoms of COVID-19 after completing a course of Paxlovid treatment.
  • More studies are needed to determine exactly why a relapse of symptoms occurs in some patients.
  • Patients who are relapsing should not take an additional round of Paxlovid pills for treatment, according to the FDA.

There are growing reports that some patients who are treated with Pfizer’s Paxlovid antiviral pills can experience symptoms of the disease or a resurgence of COVID-19 shortly after recovering from an initial infection. 

According to a recent case study that is still under review, a fully vaccinated and boosted 71-year-old man saw his COVID-19 symptoms clear up after two days of taking Paxlovid pills. However, researchers claim four days after finishing the full course of Paxlovid, his symptoms, including a runny nose and sore throat returned for a few more days. Experts say, however, that these cases are rare.

Paxlovid is an antiviral medication used to prevent the virus from reproducing itself and works incredibly well at reducing the amount of virus in the body, Jeffrey Klausner, MD, MPH, an infectious disease specialist and clinical professor of Population and Public Health Sciences at the University of Southern California, told Verywell. 

“[Paxlovid] allows people’s immune system to clear the infection faster,” Klausner said. “People who are at high risk for going to the hospital, which are elderly people, obese people, people with diabetes and other chronic medical conditions, there was an 89% reduction in the likelihood of going to the hospital.”

The medication has also been found to be highly effective at reducing someone’s chance of hospitalization or death from COVID-19 by almost 90% when taken within five days of developing symptoms. Paxlovid pills have been prescribed since December when the Food and Drug Administration (FDA) granted emergency use authorization for people at high risk of severe COVID. 

Despite this, there are increasing calls for federal agencies and scientists to provide more guidance and clarification on how patients and healthcare providers should respond in the rare event that a patient “relapses”—showing symptoms or testing positive for COVID-19—after taking Paxlovid pills for the medication’s recommended course (which is three pills twice daily for five days coming out to 30 pills total).

Pfizer’s Chief Executive Officer Albert Bourla told Bloomberg in an interview that those who suffer from a relapse in COVID-19 symptoms after taking the first round of Paxlovid pills should take more of the treatment. 

However, the FDA said in a statement that there is “no evidence of benefit” at this time for taking more pills of Paxlovid to help patients who see a relapse of the disease.

“FDA is aware of the reports of some patients developing recurrent COVID-19 symptoms after completing a treatment course of Paxlovid,” John Farley, MD, MPH, director of the Office of Infectious Diseases, said in a statement. “We are continuing to review data from clinical trials and will provide additional information as it becomes available.”

What Does Relapse After Paxlovid Look Like? 

According to Klausner, an overwhelming 98% of people who take Paxlovid pills get better and don’t have any kind of relapse, but in the rare case that someone does, people tend to experience some congestion, fatigue, or mild symptoms again.

“A few people have a relapse, it’s about one to 2% which is maybe one out of 100 to one in 50, so it’s not common at all,” Klausner added. “No one has ever ended up—so far at least—in the hospital because of that relapse and then those symptoms do clear, people don’t have any complications.”

Other people tend to experience fever, shortness of breath, cough, and potentially other symptoms that occurred at the time of the original infection, Prasanna Jagannathan, MD, an assistant professor of medicine and infectious disease at Stanford University, told Verywell.

“If you have a recurrence of your original symptoms and you test positive again, that could be suggested that you’re having a relapse,” Jagannathan said. “There’s no reason to think that it’s a new infection. If anything, these relapses probably do represent a true relapse of an existing infection.”

Why Does a Relapse Occur? 

While more research studies are needed to determine why relapses may occur after Paxlovid treatment, Jagannathan said it’s likely that some people may take a little longer than five days after treatment is finished to completely clear the virus.

He added five days of therapy may not be sufficient to allow for complete eradication of the virus. There could be some residual virus left within the body which is why some people may “rebound” and experience symptoms of COVID-19 again after the initial infection.

“Another possibility is that there’s something about the individuals that are taking the medications that might predispose them to have a rebound after they stop treatment,” Jagannathan said. “But again we don’t know the answer to that question, this is largely anecdotal.”

Klausner explained with any drug there may be differences in how people absorb medication and the level of medication that gets into the bloodstream. Some people might also be faster at metabolizing medicine or medicine gets cleared through their body faster compared to others.

“There’s a reason why there are three pills that people have to take for Paxlovid because one pill is actually a booster for the other pill,” Klausner said. “Nirmatrelvir—which is the main antiviral—does not get into the bloodstream on its own at a very high level, it requires a booster medicine—that’s ritonavir. Some drugs other people take could accelerate the metabolism of the medicine, but in others, it may not work as well.” 

Jagannathan noted more studies need to explore human behavior and whether or not missing certain doses of medications plays a role as well.

Should You Take an Additional Round of Paxlovid? 

The FDA states there is no evidence that supports taking a second round of Paxlovid pills if you show symptoms of relapsing.

Jagannathan agrees with the FDA’s decision and states at this time there aren’t any studies that explore extending Paxlovid treatment.

“There’s probably not much harm in taking an extra dose but I would like that to be done within the context of a study first before I was to make a large recommendation to say that this is a good idea,” he said.

Even though there are known benefits of taking Paxlovid, there is no evidence of benefit for a second round of the medication. Until there’s well-documented evidence of benefits, patients should not continue Paxlovid treatment after the initial course, and doctors are not encouraged to re-prescribe another course of Paxlovid to patients, Klausner said.

There may be some subpopulations including severely immunocompromised and bone marrow transplant patients that may benefit from continuing treatment, Klausner added, but that will be a decision made by a patient and their physician.

The National Institute of Allergy and Infectious Diseases (NIAID) told Verywell in a statement, that the National Institute of Health scientists, the Centers for Disease Control and Prevention (CDC), and the FDA are looking into possible ways to better understand why patients develop symptoms again after completing a course of Paxlovid.

“NIH currently does not have studies underway, but the agency is actively discussing potential studies to learn more about who this is affecting, how often it is occurring and if a longer regimen would be more effective in certain cases,” NIAID stated.

What This Means For You

If you completed a course of Paxlovid treatment but are showing a relapse of COVID-19 symptoms, it is not recommended to take a second round of the medication. You should continue to follow health protocols like masking, isolating, and social distancing.

What to Do If You Relapse

Individuals who are showing symptoms or test positive for COVID-19 after completing a course of Paxlovid pills should continue to practice behavior that would reduce the likelihood of spreading the virus to others.

“If my symptoms are similar or maybe slightly not as bad as when I originally was sick, I would just isolate to take care of myself, treat my symptoms and just monitor them closely,” Jagannathan said.

Other measures that people can take include: 

  • Stay at home away from others and isolate/quarantine 
  • Wear a mask (when going out or when in contact with others)
  • Take a rapid test to determine if you are still contagious
  • Ask a healthcare professional about other types of therapeutic treatment such as monoclonal antibodies
  • Visit a healthcare provider if any symptoms like shortness of breath worsen

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

1 Source
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Library of Medicine: DailyMed. PAXLOVID- nirmatrelvir and ritonavir kit [drug label].

By Alyssa Hui
Alyssa Hui is a St. Louis-based health and science news writer. She was the 2020 recipient of the Midwest Broadcast Journalists Association Jack Shelley Award.