Here’s What to Know About ‘Anti-COVID’ Pills, Including If They Really Treat COVID-19

So-called “anti-COVID pills” are in the news once again. Advisers for the U.S. Food and Drug Administration (FDA) are meeting today to vote on whether or not molnupiravir, a new antiviral for COVID-19 produced by Merck and Ridgeback Biotherapeutics, should be recommended for coronavirus patients. If the panel votes to authorize it, molnupiravir would be the first oral take-home medication approved to treat mild to moderate COVID-19, NPR reports. Paxlovid, a COVID-19 antiviral pill produced by Pfizer, is also currently under review by the FDA.

The hope is that these pills could have a significant impact on keeping people from the most severe stages of the disease. But how are anti-COVID pills supposed to work?

When the SARS-CoV-2 virus that causes COVID-19 enters our cells, it uses the cell’s own machinery to make copies of itself—lots and lots of copies. Those copies break out of the cell and then go on to infect other cells, repeating the same process. Both pills aim to work by reducing how much the virus can replicate in our system—but their methods are different.

Molnupiravir is what’s known as a polymerase inhibitor. It tricks polymerases, which are enzymes that copy ribonucleic acid for the virus, into creating mutational errors. Instead of the original virus getting copied, this new error is copied instead, until there are so many errors the virus can’t survive. However, there’s some concern that the drug could affect other enzymes in our body, as NBC News reports, particularly if taken for a longer period of time. A course of molnupiravir would be 40 pills prescribed over five days.

Paxlovid, on the other hand, uses an experimental molecule called PF-07321332 that works as a protease inhibitor, as CNBC explains. Protease is an enzyme that divides viral proteins so they can spread easier. Paxlovid essentially dulls the protease, not allowing it to slice the proteins. The bigger strands of viral protein don’t allow the virus to replicate. Unlike Merck’s drug, no mutations are introduced. A course of Paxlovid would be 30 pills over five days (with some being Paxlovid and some being the antiviral ritonavir, which seems to help keep Paxlovid working in the body for longer).

Initial data from Merck’s clinical trials suggested high-risk unvaccinated people with mild or moderate COVID-19 who started taking molnupiravir within five days of the start of their symptoms saw a 50% reduction in hospitalization and death, compared to those who got a placebo. But the final analysis of the clinical trial suggested only a 30% drop in hospitalization and death compared to placebo groups, the New York Times reports.

The early clinical trials for Pfizer’s pill appear more promising. For unvaccinated patients with at least one condition that made them high-risk, those who took Paxlovid within three days of the start of their symptoms saw an 89% reduced risk of hospitalization and death, as the New York Times reports. For people who started within four or five days of symptoms, their risk was reduced by 85%.

Currently, the only FDA-authorized treatment for COVID-19 patients with mild to moderate cases (and who are at high risk of becoming severely ill) is monoclonal antibodies, which reduce the risk of hospitalization and death by 70%. Monoclonal antibodies are lab-made molecules that act as a substitute for natural antibodies in people who haven’t had prior vaccination or infection, and they can also help enhance existing immunity, according to the FDA. They may help prevent the virus from attaching to human cells, and they may help neutralize coronavirus. (Remdesivir, which you may have also heard about, is FDA-approved specifically to treat COVID-19 cases requiring hospitalization, not ones that are mild or moderate.)

Monoclonal antibodies must be delivered intravenously and in a clinical setting. As NPR explains, pills would be easier to get to people, easier to take, and they’re much cheaper to make. But first, we’ll have to wait on the FDA’s verdict.

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