What you should know about Paxlovide for the treatment of Covid, in particular, you should

When President Joe Biden tested positive for Covid-19 on July 21, his doctor advised him to take the antiviral drug paxlovide, which significantly reduces the chance of hospitalization or death for someone at high risk of developing severe COVID.

Biden immediately began a five-day course, and within six days he tested negative for the virus and was cleared to leave isolation, the White House said.

Dr. Anthony Fauci, Biden’s top medical adviser, took paxlovide when he contracted Covid in June, but soon after tested positive for the disease again. So he took a second round of the drug even though it wasn’t approved.

Since paxlovide became available seven months ago, it has overshadowed other therapies available to prevent severe Covid symptoms in high-risk patients. Some doctors are quick to prescribe it, but much about the Covid pandemic is controversial.

Some patients are worried about the possible return of the disease, while others have difficulty convincing their doctors that they are good candidates for the drug.

“Paxovid is still the gold standard,” although it may not be right for everyone, says Dr. Priya Nori, an infectious disease physician at Montefiore Health System.

In a clinical trial, people who had mild to moderate Covid and were at high risk of severe illness had an 88% lower risk of being hospitalized or dying from the illness if they took paxlovide within five days of symptom onset.

But while infectious disease experts praise the treatment’s effectiveness, many doctors want better data. Here are answers to some common questions about Paxlovid.

What is Paxlovid and how does it work?

Paxlovide is an antiviral drug that consists of two drugs: one that blocks a key enzyme that the coronavirus needs to replicate, and the second that blocks the metabolism of the first drug in the liver so that it does not leave the body as quickly. Patients take three pills twice a day for five days.

Who should take Paxlovid?

When the Food and Drug Administration (FDA) approved the emergency use of paxlovide, it specified that the drug be prescribed to people at high risk of serious illness. The list is long and includes people over the age of 65 and those with chronic or serious illnesses such as cancer, obesity, diabetes and heart disease.

However, seven months after its approval, some patients have two booster doses protecting against Covid, and many were previously infected with the Omicron variant. Doctors must therefore evaluate how much a patient’s history increases or decreases a patient’s risk of serious infection, weighing it against the usefulness of prescribing a drug that has a flaw.

Some people who are in high-risk categories may not be able to take paxlovide if they take any of the long list of drugs that may interact with antivirals.

Temporarily stopping certain medications on the list, such as high cholesterol or high blood pressure, until a cycle of Paxlovide is finished may not be a problem. But others, such as heartbeat or transplant drugs, “can cause catastrophic complications” when taken with paxlovide, said Dr. Scott Roberts.

Paxlovide is not recommended for people who are not at risk of severe covid. In June, Pfizer, the drug’s maker, announced it was stopping a clinical trial for standard-risk people because paxlovide did not significantly reduce hospitalizations and deaths in that group. The trial included vaccinated and unvaccinated people.

Perhaps the findings aren’t surprising, said Dr. Daniel Kuritzkes, chief of Brigham’s infectious diseases department, since “for low-risk people, their risk of hospitalization is so low that there’s no benefit to taking paxlovide” at the hospital and the Boston woman.

Also in June, Pfizer announced that it had applied to the FDA for full approval of Paxlovid.

What are the alternatives for someone who cannot take Paxlovide?

Other antiviral drugs (Veklury and Lagevrio) and a monoclonal antibody drug (Bebtelovimab) also reduce the risk of hospitalization and death from Covid. But they are less convenient, require injections or infusions, or are not as effective as paxlovide.

How often do people experience rebound infections after taking Paxlovid?

A small number of people showed symptoms of Covid and tested positive for the coronavirus again after completing a five-day course of paxlovide. But there is debate about how many patients are affected and why they rebound.

In Pfizer clinical trials, 1% to 2% of participants tested positive for Covid after completing a course of paxlovide. Because rebound occurred in both those who received the drug and those who received placebo, the FDA concluded that “at this time it is unclear whether this is related to the drug treatment.”

Mayo Clinic researchers found in a June study that less than 1% of 483 high-risk patients who received paxlovide experienced rebound symptoms.

However, anecdotal reports indicate that the number of rebounds is high. Several prominent members of the medical community have reported experiencing rebound infections and symptoms, although these are usually mild. In addition to Fauci, the director of the National Institute of Allergy and Infectious Diseases, the group includes the director of the Aaron Diamond AIDS Research Center at Columbia University. David Ho and Dr. Dr. Peter HotzDean of the National School of Tropical Medicine at Baylor College of Medicine.

“I’m still confused about it, and people I talk to are still confused, because we don’t know exactly why it happens,” said Dr. Robert Wachter, professor and head of the department of medicine at the University of California, San Francisco. In May, Wachter Tweet about the experience For the recovery of his wife, writer Katie Hafner. “Public data on frequency doesn’t sync with everyone’s experience.”

There are several theories as to why the bounce occurs. Some experts suspect that the drug does not completely clear the virus in some people with high viral loads, causing relapse after five days of treatment. Or it could be that some people clear antiviral drugs from their bodies faster than others.

“If you’re shedding quickly, you may not have the exposure you need to kill the virus,” says Ashley Brown, a virologist at the University of Florida in Orlando.

“We continue to monitor the data, but to date we have not seen the emergence of resistance in patients treated with paxlovide, and we believe that re-detection of elevated nasal viral RNA is rare and not solely related to treatment,” said Keith Longley, a Pfizer spokesman, in an email. .

Given the rebound effect, is it necessary to revise the prescribed guidelines?

Some experts question whether adjusting the timing or length of a paxlovide cycle can eliminate the rebound effect experienced by some patients. If people start taking paxlovide on day 3 of symptoms, for example, their body’s defenses may be boosted by a previous vaccination or infection, Norrie said.

Many believe a five-day course is too short, says Wachter, who wants more data. “You would think that studying five days versus seven days versus 10 days wouldn’t be that difficult,” he added.

According to Pfizer, “There may be some patient populations that may benefit from long-term or repeated treatment, and we are considering additional studies to evaluate this in some populations.”

Fauci took a second course of paxlovid after experiencing a rebound effect. Can it do anything to other patients?

usually not

Fauci said she took a second course of paxlovide after testing positive for Covid and feeling sicker in the second round with the virus.

The prescribing guidelines clearly state that “paxlovide is not approved for use for more than five consecutive days.”

Not all doctors agree with the guidelines. “For people who are really high risk, it’s hard to say, ‘Just take Tylenol,'” said Dr. David Wohl, M.D., professor of medicine in the department of infectious diseases at the University of North Carolina-Chapel Hill.

At Brigham and Women’s Hospital, doctors generally don’t recommend a second course of paxlovide for patients experiencing rebound, Kuritzkes said, “although there is some variation in opinion.”

In the FDA’s May guidance to providers, director of the Office of Infectious Diseases Dr. John Farley said: “At this time there is no evidence of benefit for a longer course of treatment (for example, 5 instead of 10 days as recommended in the paxlovide provider fact sheet) or a paxlovide treatment in patients with recurrent symptoms of covid-19 after completing a course of treatment. Repeat the course.”

Fauci’s move was puzzling to some physicians.

“I was a little surprised and surprised that the top doctor in the country would go against the guidelines,” said Yale’s Roberts. “It sends me a mixed message. I imagine I would say to patients, ‘Dr. Fauci took two courses. Why not me?'”

Are people contagious if they have a rebound? Should they isolate themselves?

If people test positive again after paxlovide treatment, they are assumed to be contagious and should be isolated from others, experts explained.

Will paxlovide become resistant to coronavirus?

That’s a concern, experts say, but there’s no evidence yet that it’s happened.

“The virus is always mutating in all regions of its genome, so at some point paxlovide will probably become less effective than it was researched a year ago,” Roberts said.

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