WASHINGTON >> As extra medical doctors prescribe Pfizer’s highly effective COVID-19 capsule, new questions are rising about its efficiency, together with why a small variety of sufferers seem to relapse after taking the drug.
Paxlovid has develop into the go-to choice in opposition to COVID-19 due to its at-home comfort and spectacular ends in heading off extreme illness. The U.S. authorities has spent greater than $10 billion to buy sufficient capsules to deal with 20 million folks.
But consultants say there may be nonetheless a lot to be discovered in regards to the drug, which was licensed in December for adults at excessive danger of extreme COVID-19 based mostly on a research during which 1,000 adults acquired the remedy.
WHY DO SOME PATIENTS SEEM TO RELAPSE?
Doctors have began reporting uncommon circumstances of sufferers whose signs return a number of days after finishing Paxlovid’s five-day routine of capsules. That’s prompted questions on whether or not these sufferers are nonetheless contagious and may obtain a second course of Paxlovid.
Last week, the Food and Drug Administration weighed in. It suggested in opposition to a second spherical as a result of there’s little danger of extreme illness or hospitalization amongst sufferers who relapse.
Dr. Michael Charness reported final month on a 71-year-old vaccinated affected person who noticed his signs subside however then return, together with a spike in virus ranges 9 days into his sickness.
Charness says Paxlovid stays a extremely efficient drug, however he wonders if it is likely to be much less potent in opposition to the present omicron variant. The $500 drug therapy was examined and OK’d based mostly on its efficiency in opposition to the delta model of the coronavirus.
“The ability to clear the virus after it’s suppressed may be different from omicron to delta, especially for vaccinated people,” mentioned Charness, who works for Boston’s VA well being system.
Could some folks simply be vulnerable to a relapse? Both the FDA and Pfizer level out that 1% to 2% of individuals in Pfizer’s unique research noticed their virus ranges rebound after 10 days. The charge was about the identical amongst folks taking the drug or dummy capsules, “so it is unclear at this point that this is related to drug treatment,” the FDA said.
Some consultants level to a different chance: The Paxlovid dose isn’t robust sufficient to totally suppress the virus. Andy Pekosz of Johns Hopkins University worries that might spur mutations which can be immune to the drug.
“We should really make sure we’re dosing Paxlovid appropriately because I would hate to lose it right now,” mentioned Pekosz, a virologist. “This is one of the essential tools we have to help us turn the corner on the pandemic.”
HOW WELL DOES PAXLOVID WORK IN VACCINATED PEOPLE?
Pfizer examined Paxlovid within the highest-risk sufferers: unvaccinated adults with no prior COVID-19 an infection and different well being issues, resembling coronary heart illness and diabetes. The drug diminished their danger of hospitalization and demise from 7% to 1%.
But that doesn’t mirror the overwhelming majority of Americans right this moment, the place 89% of adults have had at the least one shot. And roughly 60% of Americans have been contaminated with the virus in some unspecified time in the future.
“That’s the population I care about in 2022 because that’s who we’re seeing — vaccinated people with COVID — so do they benefit?” requested Dr. David Boulware, a University of Minnesota researcher and doctor.
There’s no clear reply but for vaccinated Americans, who have already got a hospitalization charge far beneath 1%.
That might come from a big, ongoing Pfizer research that features high-risk vaccinated folks. No outcomes have been revealed; the research is predicted to wrap up within the fall.
Pfizer mentioned final 12 months that preliminary outcomes confirmed Paxlovid failed to fulfill the research’s objectives of considerably resolving signs and decreasing hospitalizations. It not too long ago stopped enrolling anybody who’s acquired a vaccination or booster previously 12 months, a change Boulware says suggests these sufferers aren’t benefitting.
At a minimal, the preliminary information must be launched to federal officers, Boulware mentioned. “If the U.S. government is spending billions of dollars on this medicine, what’s the obligation to release that data so that they can formulate a good policy?”
CAN PAXLOVID BE USED TO HELP PREVENT COVID-19 INFECTION?
Pfizer not too long ago reported that proactively giving Paxlovid to members of the family of individuals contaminated with COVID-19 didn’t considerably cut back their possibilities of catching it. But that’s not the tip of the story. Pfizer is learning a number of different potential advantages of early use, together with whether or not Paxlovid reduces the size and severity of COVID-19 amongst households.
“It’s a high bar to protect against infection but I’d love to see data on how Paxlovid did against severe disease because it may be more effective there,” mentioned Pekosz.