A new approach to treating covid-19 may be on the horizon. Clinical trials of several antiviral candidates are expected to finish within the next few months, all taken as a simple pill provided before or soon after an infection is confirmed.
Antibiotics, which are used to treat bacterial infections, are some of the most important medicines ever created. But we have far fewer antivirals available, for several reasons. One limitation, for instance, is that it’s harder to create drugs that can safely stop a virus compared to bacteria, since viruses hijack our own cells to reproduce (some bacteria do as well, but most that cause us trouble don’t). 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, ideally preventing a person from becoming sick in the first place.
Just as the pandemic has allowed scientists to make advances in vaccine technology and development, there’s hope that it will speed up the antiviral pipeline, too.
As Kaiser Health News reported Monday, there are at least three experimental antivirals going through late-stage clinical trials in the U.S. right now. These drugs are being explored as early treatments, given within days of infection, while some are also being studied as prophylactics that are given right after a suspected exposure to someone with covid-19 to prevent illness. And unlike the antivirals that have seen some limited use so far during the pandemic, they’re taken orally as a pill.
On Monday, Pfizer (the co-developer of the first approved covid-19 vaccine in the U.S.) announced the start of a large trial testing out its candidate, code-named PF-07321332, as a prophylactic. Earlier this month, Merck and Ridgeback Biotherapeutics began a Phase II/III trial of their drug molnupiravir. And earlier in the summer, the companies Roche and Atea Pharmaceuticals began large trials of their drug called AT-527. These companies all intend to release data from these trials within the next few months, while Merck is looking for an emergency use authorization of 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, hopefully leading to a lower viral load and making it easier for the immune system to clear the infection. Ideally, these drugs would greatly reduce the length and severity of symptoms, preventing hospitalization and serious illness. And they may very well prevent an infection from taking hold altogether when taken as a prophylactic.
Of course, finding a highly effective treatment for covid-19 is easier said than done. The antiviral remdesivir, authorized for emergency use in the U.S., does seem to help hospitalized patients recover slightly faster, but there’s limited data showing that it actually helps prevent death. Other treatments, like monoclonal antibodies, have shown more promise but are very costly and need to be delivered via infusion, limiting their usefulness and availability (some studies have shown that early treatment with these can prevent severe illness).
Perhaps the most comparable drug would be Tamiflu, an FDA-approved antiviral meant to prevent or reduce flu symptoms. Unfortunately, Tamiflu is very mediocre at best, and some scientists have argued that it never should have been approved in the first place.
The U.S. has already agreed to buy stockpiles of some of these newer generation antivirals for covid-19, should they turn out to be good enough to win authorization or approval. In the best-case scenario, they’ll become a valuable partner to vaccines against future waves of covid-19 or even other coronaviruses in the future. But we’ll need to await the data from these ongoing clinical trials before getting our hopes up.