The pills must be given early in the course of infection, which means access to timely, accurate test results will be crucial.
Before the end of the year, Americans who contract the coronavirus may be able to purchase an effective treatment on a trip to their neighborhood pharmacy.
Two new antiviral pills — both of which have shown promise in preventing hospitalizations and deaths in people at high risk for severe Covid-19 — are currently being reviewed by the U.S. Food and Drug Administration.
One of the drugs, developed by the pharmaceutical company Merck, could receive emergency authorization as early as this week. Another, made by Pfizer, is likely to be close behind.
Although the drugs are not a replacement for vaccination, they could drastically expand access to treatments for a disease that is still killing 1,000 Americans a day.
But the pills, which interfere with viral replication, are designed to be taken as soon as possible after symptoms appear. Fully harnessing their benefits is likely to depend upon timely, accurate Covid testing — something that the United States has struggled to achieve since the beginning of the pandemic. At times, especially in the summer and fall of 2020, getting tested for the virus has required an hourslong wait in line, followed by a weeklong wait for results.
Much has improved since then, and supply of the new drugs is likely to be extremely limited initially. Merck, for instance, is expected to supply enough of its drug to treat slightly more than 3 million Americans before February.
Still, the new antivirals could put America’s still shaky testing infrastructure to the test, experts said. And officials will need to ensure that quick, affordable virus tests are available in the communities that have been especially hard hit by Covid.
“People have to want to get tested, and we have to be able to get tests to people quickly,” said Dr. David Boulware, an infectious disease specialist at the University of Minnesota. “Can that happen?”
Timing is everything
Currently, the most effective treatments available for Covid in the U.S. are monoclonal antibody drugs, which bind to the virus and stop it from infecting cells. But these treatments are typically administered intravenously by health care workers. This can pose logistical challenges both for hospitals, many of which are overburdened and short-staffed, and for patients, who may not be able to get to clinics or infusion sites.
The new antivirals are different. “You could potentially pick up your prescription and go home,” said Dr. Michelle Barron, the senior medical director of infection prevention and control for UCHealth, a health care system in Colorado.
The Merck and Pfizer treatments, which involve taking 30 or 40 pills over the course of five days, should be given early in the course of infection, while the virus is replicating quickly.
In clinical trials, which enrolled only unvaccinated people at high risk for serious disease, Merck’s regimen reduced the risk of hospitalization and death by about 30 percent when given within the first five days of symptoms, while Pfizer’s cut those risks by 89 percent when given within the first three days of symptoms.
Replicating these results in the real world will require people to act swiftly, perhaps at the first sign of the sniffle.
“It starts with the public education such that when people start to have mild symptoms, early in the course of their illness, they think, ‘This might be Covid-19, and I should get a test,’” said Alyssa Bilinski, an expert on public health policy at Brown University. “Then, of course, we have to have access to tests that have to ideally be affordable. Then people need to get their test results back and they need to get them back quickly.”
She added, “All of this needs to happen within three to five days.”
It is not yet clear whether officials will require patients to take a certain kind of Covid test before the drugs are prescribed. In Britain, which already authorized the Merck pill, regulators specified only “a positive SARS-COV-2 diagnostic test.”
Most experts expected U.S. regulators to provide similar flexibility, allowing the pills to be prescribed after a positive result on either a P.C.R. test, the highly sensitive laboratory-based diagnostic, or a rapid antigen test, which is generally less sensitive but can be used at home without a prescription.
But both kinds of tests come with challenges. For P.C.R. tests, the biggest concern is turnaround time. Although some labs can return P.C.R. test results within a day, others take far longer.
“It is not unheard-of for people to have wait times of five days,” Dr. Bilinski said. That delay alone could put patients at the edge of the prescription window, even if they got tested the moment they first felt symptoms.
Supply shortages
Because of this lag time, rapid antigen tests, which can return results in about 15 minutes, are likely to play an important role in getting the new pills to patients, experts said.
“The idea is access,” Dr. Barron said, noting that she accepted photos of positive at-home test results as proof of infection when prescribing monoclonal antibodies. “The whole notion of this is, How can we keep people from progressing and ending up in the hospital?”
But rapid antigen tests are more prone to false negatives, especially in people who are early in the course of their infection, when their viral loads are still low. These errors are less likely in people who have symptoms, and taking two tests, a day or two apart, can reduce the odds of missing an active infection.
Still, the antiviral pills raise the stakes of a missed diagnosis, said Susan Butler-Wu, a clinical microbiologist at the Keck School of Medicine of the University of Southern California. “It’s not just knowing my status,” she said. “It’s now like, ‘Oh, this result could get me this really lifesaving medication.’”
Antigen tests are generally less prone to false positives, but those errors will become an increasing concern when the virus becomes less prevalent. (Ellume, which makes a popular at-home test, recently recalled two million test kits over concerns about higher than expected rates of false positives.)
Asking patients to take a second, confirmatory test, especially one overseen or conducted by a medical professional, could cut down on both test and user errors, but would chew up more time and may not be practical or even, at the moment, feasible. “I don’t know that we have the scale to do that right now,” Dr. Butler-Wu said.
In the near term, the biggest challenge with rapid antigen tests is likely to be finding them.
“In the United Kingdom, you can go to a pharmacy and get a box of seven antigen tests for free,” Dr. Bilinski said. “In the U.S., you have to be refreshing Walmart’s website to hopefully get BinaxNOW tests during the 15 minutes that they’re in stock.”
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The supply crunch could ease soon, experts said. The Biden administration has taken several steps to increase availability, and a number of testing companies are scaling up manufacturing.
“We’re optimistic that the production capacity from both the big players, like Abbott and Quidel, as well as some of the newer smaller players are all hitting the ramp up phase at this point,” said Nathaniel Hafer, a molecular biologist at UMass Chan Medical School.
But the rising case numbers and holiday get-togethers are fueling a surge in demand, and the supply of at-home tests remains unpredictable and uneven. “The availability is still a little bit in fits and starts,” said Gigi Gronvall, a testing expert at Johns Hopkins University.
Dr. Gronvall was, at that very moment, in her car, searching for rapid antigen tests after some of her son’s friends tested positive for the virus. (“The first place didn’t have any, and now I’m about to try a second,” she said.)
Ensuring equity
Even when the tests are in stock, they are not affordable for all Americans. The Abbott BinaxNOW, for instance, generally runs from $14 to $24 for a pack of two.
Although experts do expect prices to come down as more companies have their tests authorized and competition increases, that may not happen this winter.
“Hopefully the market will bring prices down, but if there is such a huge demand and relatively little supply, there won’t be a lot of incentive to bring the price down,” said Dr. Laura Gibson, an infectious disease specialist at UMass Chan Medical School.
So while the Covid pills are likely to be more accessible than monoclonal antibodies, they may still be out of reach for Americans who cannot afford to purchase their own tests or do not have the time or money to travel to a free testing site.
“I worry,” Dr. Barron said, “that this is going to be the case where certain communities will not necessarily have access to the testing and therefore will not have access to the drug.”
Moreover, she added, people who cannot afford to miss work or stay home with a sick child may be especially reluctant to seek testing when their symptoms are mild.
Experts agreed that the rollout of the drugs would need to be accompanied by a robust messaging campaign to ensure that people know that treatments are available — and that success would depend on early testing and diagnosis.
“We’ve seen time and time again, both before and during the pandemic, that the U.S. health care system can pair these incredible breakthroughs in biotechnology with mediocre deployment strategies in terms of access and affordability,” Dr. Bilinski said.
It has long been clear that Covid’s toll has been unequal. Low-income workers, for instance, have been at especially high risk of catching the virus, while Black and Latino Americans have been more likely to die from it than white Americans have.
Depending on how well officials address barriers to access, Dr. Bilinski said, the antiviral pills “have the ability to either reduce or reinforce the disparities that we’ve seen in severe Covid outcomes.”
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