Editor’s Note (May 26, 2023): The Food and Drug Administration has officially approved the antiviral drug paxlovid for the treatment of novel coronavirus. This article explains how this drug works and the “Pax Rovid Rebound” phenomenon.
When President Joe Biden was diagnosed with COVID-19, he almost immediately began oral treatment with the antiviral drug Paxlovid. But four days after ending the Pax Lovid administration and testing negative, Biden again tested positive for the novel coronavirus but had no symptoms of the disease. This is probably the most high-profile example of what people are calling “Pax Lovid’s rebound.” Anthony Fauci, the president’s chief medical adviser, has experienced it. This condition has been reported in a small number of people receiving antiviral drugs and remains an active area of research.
Scientific American We spoke to an infectious disease expert about what the phenomenon is, how common it is, and what to do if you get it.
What is Pax Lovid?
Paxlovid is an oral antiviral drug that is taken as 3 tablets daily for 5 days. The drug, made by Pfizer, is prescribed to people who have contracted the novel coronavirus and are at risk of serious illness. This could include those who have not been vaccinated, the elderly, and those with other medical conditions ranging from diabetes to cancer. Two of the three tablets are nirmatrelvir, a drug that targets an enzyme specific to the virus that causes the new coronavirus and inhibits its replication. The third tablet is ritonavir, the first drug developed for the treatment of HIV/AIDS, which increases levels of the first drug by slowing its breakdown in the body.
“Everything we’ve done against COVID-19 has come out of the HIV workbook, absolutely nothing,” said Davey Smith, director of infectious diseases and global public health at the University of California, San Diego. It’s clear,” he said. That includes “vaccine development, treatment development, testing methods, epidemiology methods,” he says.
Clinical trials have shown that paxlovid is very successful in alleviating serious illness. The group that received the drug experienced an 89 percent reduction in hospitalizations and deaths from the novel coronavirus compared to the group that received the placebo sugar pill.
To ensure people have access to life-saving drugs, the Biden-Harris administration will allow everyone to be tested for COVID-19 and receive a dose of Paxlobid in a single visit to a pharmacy or treatment center. developed an inspection program to
What is Pax Lobid Rebound?
The CDC defines a paxlovid rebound as a recurrence of COVID-19 symptoms or a positive test after a previous negative test after a patient has undergone a full five-day course of treatment. there is According to this classification, if you rebound, “you could have the virus without symptoms, you could have the virus without symptoms, or both at the same time.” It’s possible,” Smith said. He added that he was a little frustrated with the catch-all classification of “rebound” because “rebound” in virology refers to the re-emergence of the virus in measurable amounts.
A Pfizer clinical trial reported that between 1 and 2 percent of people given the drug tested positive for COVID-19 after completing the Pax-Rovid course. Their illness recurred. However, these rebounds were not statistically different from those experienced by placebo-treated COVID-19 patients.
“Recurrence of symptoms following a positive test is ‘syndromic’ as defined by the study.” [Paxlovid] It’s a rebound,” says Amy Berzac, an infectious disease doctor and coronavirus researcher at Massachusetts General Hospital. “A positive test and no symptoms — nobody asked for — that would be an ‘asymptomatic Paxrobid rebound’.” that has been detected.
Adi Shah, an infectious disease specialist at the Mayo Clinic in Minnesota, said another complicating factor for patients is what distinguishes between a true recovery of symptoms after administration of paxlovid and a very slow improvement in symptoms. explains. Clinically, this is an important distinction as it can change the way people decide to isolate. These differences also have implications for research. To say exactly how many people are experiencing Pax Lovid’s rebound, we need to pinpoint it.
Important to remember. “If the patient needs it, the drug will work, even in some people’s circumstances.” [having] I’m going to rebound,” Smith said. “In clinical trials, it was very clear that this is a great drug that keeps people from being hospitalized and keeps them from dying. So you don’t have to fear a rebound.”
Who is experiencing a Pax Lovid rebound and how common is it?
“among us [work]If you’re older and have other risk factors such as diabetes, heart disease, kidney disease, or certain types of cancer, you’re at a higher risk of rebound,” Shah says. Many of these are the same risk factors for severe COVID-19.
Unfortunately, as I mentioned earlier, it’s difficult to know exactly how often Pax Lovid’s rebounds will occur, because “rebound” must be uniformly defined first. Balzac says he experiences this phenomenon, with rebounds sometimes classified as simply a recurrence of symptoms, or as multiple negative test results followed by multiple positive results. Explain that the percentage of possible people may change. Nonetheless, she still estimates that rebounds associated with virus re-emergence are higher than those reported in the first Pfizer clinical trial. “What we’re saying is somewhere between 2% and 10%.” [of people taking Paxlovid experience rebound],” she says. “I think it’s probably somewhere in that range, but I’m not.” [know] accurately. “
In a recently published retrospective review of Mayo Clinic patients, Dr. Shah found that about 1 percent of paxlovid users rebounded, which is consistent with Pfizer’s clinical trials. But after talking with patients and other doctors, “I think the actual infection rate is 5 to 10 percent higher,” he says.
Shah said it’s difficult to pinpoint exactly who’s experiencing a rebound at this point, adding, “There’s a real record of three test results: positive, negative, and positive, and a clear indication of symptoms where all symptoms have disappeared. We need a good record,” he said. Symptoms recur. ” This would be difficult to do retroactively, as clinics must have already collected all the information, and patients may not be aware that they are rebounding. It’s hard to be positive because you may not have been tested for viral infections or you may not have told anyone that you have rebounded.
Barzcak notes that only recently have doctors and researchers started enrolling Paxlovid users in rebound studies. “It takes time to actually enroll people in these prospective studies,” she explains. Once these findings are published, scientists will have a better idea of how many people are actually experiencing the phenomenon.
What to do if Pax Lovid rebounds?
“I want to emphasize that even if you rebound, the results are good,” Shah said. In general, “they do not require additional COVID-19 treatment, do not require hospitalization, and do not experience high mortality or morbidity.”
However, it is still important to isolate after rebounding. “I think it’s very likely that some individuals (perhaps not all, but some individuals who have rebound symptoms after paxlovid administration) will become newly infected during the rebound period,” Balzac said. She and her team took nasal samples from seven people experiencing rebound symptoms and were able to culture the virus from three people, demonstrating that these people could infect others. suggested. Despite the study’s small sample size, “people need to be aware that they may be infected,” she says. “If your symptoms return, think about protecting those around you, isolate, wear a mask, and get tested.”
In addition to isolating and hiding, it is important to tell your doctor that you are experiencing symptoms of COVID-19 again. “People undergoing certain types of chemotherapy, [those with] People with certain immunosuppressive conditions are at highest risk of serious illness, Smith says, so “you should talk to your doctor about that.” These are the people Smith usually treats rebounds with in Pax Lovid’s second course, as Fauci did. Others, he says, should stay home and quarantine because “there’s no reason to walk around and spread the infection.” Some experts disagree that a second course for Pax Lovid is justified in the event of a rebound.
What caused Pax Lovid’s rebound?
A rebound may occur because some patients do not receive enough doses of nirmatrelvir, part of paxlobid, which targets the novel coronavirus enzyme. Ritonavir is part of the treatment regimen because the body already needs to increase its dose. Smith’s own research found that the rebound was not the result of the virus becoming resistant to the drug. He hypothesizes that people in the “real world” may refrain from taking paxlovid because it can make food taste bad. Alternatively, those who rebound may be part of the minority of people who do not experience adequate rates of drug release with the combination of nirmatrelvir and ritonavir. In any case, when experiencing lower doses, pockets of virus that survived through treatment may reappear days later. Smith believes ongoing research really needs to focus on the idea that some patients may not have been exposed to the correct dose of paxlovid.
As scientists continue to study more about Pax Lovid’s rebound, all doctors Scientific American He emphasized that he will continue to prescribe paxlovid to patients who need it. “We can still use Paxlovid effectively,” says Barczak. “And by masking, testing, and isolating when a rebound happens, we can protect each other.”
