The COVID-19 pandemic poses another puzzling question that is concerning several patients who have taken Pfizer's COVID antiviral drug, Paxlovid, and are experiencing rebounding symptoms after initially feeling better.
Matthew Boyd, 32, lives on the Lower East Side of Manhattan and tested positive for coronavirus on May 6 with a sore throat, sinus congestion and a mucus-filled cough. The next day he started taking Paxlovid and finished the medication series five days later —only to find symptoms coming back.
"I took Paxlovid for the five days. On the first day off [Paxlovid], I felt kind of 'iffy' and by Friday, I was having mucus and feeling sick again, in a lot of pain, and then started feeling better after two days past," Boyd told NBC New York.
For Boyd, this marks the third time sick with coronavirus within just over two years pre- and post- COVID vaccination. He also suffers from pre-existing conditions and long COVID, where patients endure lingering symptoms after recovering from an acute infection.
While Boyd is just one example of a "rebound" from taking the COVID pill, medical experts say this is nothing to fret but remain cautious of contaminating others.
What is a Paxlovid rebound?
Paxlovid is an antiviral medication to combat the SARS-CoV-2 virus and is recommended to take during the first five days of developing symptoms. The therapy is authorized by the Food and Drug Administration (FDA) for people over the age of 12 and prescribed to those facing a high risk of severe COVID infection.
In recent weeks, patients who have taken Paxlovid have come forward with returning COVID symptoms.
Dominique Delzio, 30, of Long Island took to Twitter to share her relapse after finishing her Paxlovid series. She contracted coronavirus as New York state is riding out the fifth wave, and Nassau County reached a high alert level last week.
Certain physicians like Dr. Bob Wachter, Chairmain at the UCSF Dept. of Medicine, have shared their concerns over social media. He questions how infectious are patients during a rebound and if these cases are clinically mild.
Dr. Daniel Griffin, Chief of Infectious Diseases at ProHealth, says the rebound is just a mild recrudescence for two to three days. He reiterates that the FDA still recommends taking Paxlovid for five days.
"The interesting thing that I don't think a lot of people realize is whether you take Paxlovid or not, the same percentage of people are going to have that two to three day where they don't feel great and test positive again," Dr. Griffin told NBC New York.
The reason for this effect is not totally clear, and some researchers believe it may have to do with a lack of time for the immune system to fight off the SARS-CoV-2 virus.
"Many people think that when you start the medication early, which you should do because it works best then, that you don't give the immune system time enough the recognize the pathogen and start making the appropriate immune response," said Dr. Bruce Farber, Chief of Public Health and Epidemiology for Northwell Health, to News 4.
Dr. Farber notes that for those patients who do relapse, it is important to remember to isolate themselves again, which the CDC recommends for at least five full days.
Are relapsing COVID symptoms common?
According to Pfizer's Paxlovid study, the reoccurrence of COVID symptoms after taking the drug is around two percent, which was about the same percentage for those rebounding trial patients who took the placebo pill.
Late last year, Pfizer released a study showing that the oral drug significantly reduced deaths and hospitalizations among high-risk patients by just under 90%.
"I'm not sure it's so much a rebound as this is the nature of the disease, but we're still getting what we want from Paxlovid. We're still seeing that 90% reduction in progression," said Dr. Griffin.
Boyd and Delzio both shared with News 4 that they would take Paxlovid again in the event of another future COVID infection.
With limited studies on the matter, including just one medical pre-print from Research Square, more research is to be done.
During a White House briefing, Chief Medical Advisor, Dr. Anthony Fauci announced that Pfizer and the U.S. National Institutes of Health are planning to look into whether a longer course is needed to take Paxlovid in order to prevent reinfection.