An NHS nurse holds a coronavirus test kit as she addresses the media as she passes through a coronavirus testing site in a parking lot on March 12, 2020 in Wolverhampton, England.

An NHS nurse holds a coronavirus test kit as she addresses the media as she passes through a coronavirus testing site in a parking lot on March 12, 2020 in Wolverhampton, England.
Photo: Christophe Furlong (Getty Images)

A new approach to treating covid-19 may be on the horizon. Clinical trials of several antiviral candidates are expected to end within the next few months, all taken as a single pill provided before or shortly after infection is confirmed.

Antibiotics, which are used to treat bacterial infections, some most important drugs never created. But we have far fewer antivirals available, for several reasons. One limitation, for example, is that it’s harder to create drugs that can safely stop a virus compared to bacteria because viruses hijack our own cells to reproduce (some bacteria do too, but most that cause us problems do not). That’s why vaccines tend to be our first line of attack against viruses, which train the immune system to recognize a particular virus before it invades it, ideally preventing a person from getting sick in the first place.

Just as the pandemic has allowed scientists to advance in technology and vaccine development, it is hoped that it will also speed up the antiviral pipeline.

Like Kaiser Health News reported As of Monday, at least three investigational antivirals are in advanced clinical trials in the United States. These drugs are being explored as early treatments, given in the days following infection, while some are also being studied as prophylactics given just after suspected exposure to a person with covid-19 to prevent the disease. And unlike antivirals which have seen limited use so far during the pandemic, they are taken orally in pill form.

On Monday, Pfizer (the co-developer of the first covid-19 vaccine approved in the United States) announcement the start of a large trial testing its candidate, codenamed PF-07321332, as a prophylactic. Earlier this month, Merck and Ridgeback Biotherapeutics has begun a phase II / III trial of their drug molnupiravir. And earlier in the summer, the companies Roche and Atea Pharmaceuticals has begun large trials of their drug called AT-527. These companies all plan to release data from those trials in the coming months, as Merck seeks emergency authorization for its drug before the end of the year.

The pills are said to work by interfering with the coronavirus’s ability to replicate in a host cell, which hopefully lowers the viral load and makes it easier for the immune system to clear infection. Ideally, these drugs would significantly reduce the duration and severity of symptoms, thereby preventing hospitalizations and serious illness. And they may very well prevent an infection from setting in completely when taken prophylactically.

Of course, finding a highly effective treatment for covid-19 is easier said than done. The antiviral drug remdesivir, cleared for emergency use in the United States, appears to help hospital patients recover somewhat faster, but there is limited data showing that it actually helps prevent death. Other treatments, such as monoclonal antibodies, have shown more promise but are very expensive and must be given by infusion, which limits their usefulness and availability (some studies have show that early treatment with these can prevent serious illness).

Perhaps the most comparable drug would be Tamiflu, an FDA-approved antiviral designed to prevent or reduce flu symptoms. Unfortunately, Tamiflu is very poor at best, and some scientists have argued that it should never have been approved in the first place.

The United States has already agreed to purchase stocks of some of these next-generation covid-19 antivirals, if they prove to be good enough to get clearance or approval. Ideally, they will become a valuable partner for vaccines against future waves of covid-19 or even other coronaviruses in the future. But we will have to wait for the data from these ongoing clinical trials before we hope.

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