Less than a day after testing positive for Covid-19 in June, Miranda Kelly was sick enough to be afraid. At 44, living with diabetes and high blood pressure, Kelly, a certified nursing assistant, had difficulty breathing, symptoms severe enough to send her to the emergency room.
When her husband, Joe, 46, also fell ill with the virus, she really worried, especially for their five teenage children at home: We have children. Who will raise these children? “
But the Kellys, who live in Seattle, agreed just after their diagnosis to participate in a clinical trial at the nearby Fred Hutchinson Cancer Research Center that is part of an international effort to test an antiviral treatment that could stop Covid early in its course.
The next day, the couple took four tablets, twice a day. Although they were not told whether they received an active drug or a placebo, after a week, they said, their symptoms improved. Within two weeks, they had recovered.
“I don’t know if we received the treatment, but I feel like we did,” said Miranda Kelly. “To have all of these underlying conditions, I felt like the recovery was very quick.”
The Kellys have a role to play in the development of what could be the world’s next chance to thwart Covid: a short-term regimen of daily pills that can fight off the virus early after diagnosis and possibly prevent symptoms from developing afterwards. ‘exposure.
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“Oral antivirals have the potential not only to shorten the duration of your Covid-19 syndrome, but also have the potential to limit transmission to people in your household if you are sick,” said Timothy Sheahan, virologist at the University. from North Carolina. -Chapel Hill who helped start the therapies.
Antivirals are already essential treatments for other viral infections, including hepatitis C and HIV. One of the best known is Tamiflu, the widely prescribed pill that can shorten the duration of the flu and reduce the risk of hospitalization if administered quickly.
Medicines, developed to treat and prevent viral infections in humans and animals, work differently depending on the type. But they can be designed to strengthen the immune system to fight infections, block receptors so viruses cannot enter healthy cells, or reduce the amount of active viruses in the body.
At least three promising antivirals for Covid are being tested in clinical trials, with results expected as early as late fall or winter, said Carl Dieffenbach, director of the AIDS Division at the National Allergy Institute and of infectious diseases, which oversees the development of antivirals. .
“I think we’ll have some answers on the capabilities of these pills in the next few months,” Dieffenbach said.
The main competitor is a drug from Merck & Co. and Ridgeback Biotherapeutics called molnupiravir, Dieffenbach said. This is the product tested in the Kellys’ Seattle trial. Two others are a candidate from Pfizer, known as PF-07321332, and AT-527, an antiviral produced by Roche and Atea Pharmaceuticals.
They work by interfering with the ability of the virus to replicate in human cells. In the case of molnupiravir, the enzyme that copies viral genetic material is forced to make so many mistakes that the virus cannot reproduce itself. This, in turn, lowers a patient’s viral load, shortening infection time and preventing the type of dangerous immune response that can cause serious illness or death.
So far, only one antiviral drug, remdesivir, has been approved to treat Covid. But it is given intravenously to patients sick enough to be hospitalized, and it is not intended for early and widespread use. In contrast, the main candidates for the study can be packaged in pill form.
Sheahan, who also did preclinical work on remdesivir, conducted an initial study in mice that showed molnupiravir could prevent early illnesses caused by SARS-CoV-2, the virus that causes Covid. The formula was discovered at Emory University and later acquired by Ridgeback and Merck.
Clinical trials followed, including a preliminary trial of 202 participants last spring that showed molnupiravir rapidly reduced levels of infectious virus. Merck chief executive Robert Davis said this month that the company is awaiting data from its larger Phase 3 trials in the coming weeks, with the option to apply for emergency use authorization from the Food and Drug Administration “before the end of the year.”
Pfizer launched a combined Phase 2 and 3 trial of its product on September 1, and Atea officials said they are awaiting the results of the Phase 2 and Phase 3 trials later this year.
If the results are positive and emergency use is allowed for any product, Dieffenbach said, “distribution could start quickly.”
This would mean that millions of people could soon have access to a daily oral drug, ideally a single pill, which could be taken for five to 10 days upon first confirmation of Covid infection.
“When we get there, that’s the idea,” said Dr. Daniel Griffin, an expert in infectious diseases and immunology at Columbia University. “To have it all across the country, so that people get it the same day they’re diagnosed.”
Once sidelined for lack of interest, oral antivirals to treat coronavirus infections are now the subject of fierce competition and funding. In June, the Biden administration announced that it had agreed to obtain approximately 1.7 million molnupiravir treatments from Merck, at a cost of $ 1.2 billion, if the product received emergency clearance. or full approval. That same month, the administration announced that it would invest $ 3.2 billion in the antiviral program for pandemics, which aims to develop antivirals for the Covid crisis and beyond, Dieffenbach said.
The pandemic sparked a long neglected effort to develop powerful antiviral treatments for coronaviruses, Sheahan said. Although scientists were scared of the original SARS virus in 2003 – followed by Middle East Respiratory Syndrome, or MERS, in 2012 – research efforts slowed when outbreaks did not persist.
“The commercial drive to develop products has only collapsed,” said Sheahan.
A challenge of recruiting participants
Widely available antiviral drugs would join monoclonal antibody therapies already used to treat and prevent serious illness and hospitalizations caused by Covid. Laboratory-produced monoclonal antibodies, which mimic the body’s natural response to infection, were easier to develop but must be administered primarily by intravenous infusion.
The federal government covers the cost of most monoclonal products at $ 2,000 per dose. It is still too early to know how the price of antivirals might compare.
Like monoclonal antibodies, antiviral pills would not replace vaccination, Griffin said. They would be another tool in the fight against Covid. “It’s good to have another option,” he said.
A challenge in the rapid development of antiviral drugs has been to recruit enough participants for clinical trials, each of which must enroll several hundred people, said Dr. Elizabeth Duke, a Fred Hutch research associate overseeing his molnupiravir trial. .
Participants must be unvaccinated and enrolled in the trial within five days of positive Covid tests. Every day, interns make 100 calls to people newly positive for Covid in the Seattle area – and most say no.
“Generally speaking, there is a lot of mistrust of the scientific process,” said Duke. “And some people say nasty things to interns.”
If antiviral pills prove to be effective, the next challenge will be to set up a distribution system that can quickly get them to people as soon as they test positive. Griffin said it would need something akin to the program put in place last year by UnitedHealthcare, which sent Tamiflu kits to 200,000 at-risk patients enrolled in the insurer’s Medicare Advantage plans.
Merck officials predicted the company could produce more than 10 million treatments by the end of the year. Atea and Pfizer have not released similar estimates.
Even more promising? Studies evaluating whether antivirals can prevent infection after exposure.
“Think about it,” said Duke, who is also overseeing a prophylactic trial. “You could give it to everyone in a household or everyone in a school. Then we talk about a return, perhaps, to a normal life.
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