A new era in treating COVID-19 could be upon us. On November 30, the Food and Drug Administration (FDA) Vaccines and Related Biological Products Advisory Committee (VRBPAC) will discuss Merck’s request for an emergency use authorization (EUA) for Molnupiravir, an oral antiviral drug to treat COVID-19. But Molnupiravir isn’t the only oral COVID-19 antiviral in the mix – in October 2021, Pfizer requested an EUA for Paxlovid, its antiviral pill. If FDA advisors recommend an EUA for Molnupiravir, and eventually Paxlovid, could it change the course of the pandemic as we know it?
The FDA has already authorized a few treatments for COVID-19, but they have serious drawbacks.
- Remdesivir the only treatment to have received full FDA approval, has limitations. For example, it has to be administered intravenously (meaning it’s difficult to provide in an outpatient setting), it’s expensive (about $2,600 for a three-day regimen), and recent research says it’s not very effective.
- Monoclonal antibodies, which have received an EUA from the FDA, offers another treatment option. While studies show monoclonal antibodies are effective at reducing hospitalization and death, they suffer from many of the same drawbacks as remdesivir – they still have to be provided intravenously, and they’re still expensive (about $2,000 per treatment).
Enter Molnupiravir and Paxlovid. Both antiviral drugs stop SARS-CoV-2, the virus that causes COVID-19, from replicating in the body, but do so in different ways. Molnupiravir, which was first developed as a flu treatment, works by fooling the virus’s RNA into creating mutations that render the virus unable to survive. Paxlovid takes a different approach by disrupting the virus’s replication by destroying enzymes vital to its reproduction.
Both treatments offer clear advantages compared to their predecessors. A prominent advantage is early intervention, which is key to administering antiviral treatments.
- Severe COVID-19 has two stages – one where the virus initially infects a person, and another when the immune system overreacts and spirals out of control. Remdesivir is typically administered in the second phase, when a patient is already hospitalized – and the damage may already be done.
- Molnupiravir and Paxlovid, on the other hand, attack the virus before it can wreak havoc and put people in the hospital, avoiding further stress on the health care system.
Additionally, both antiviral pills can be administered orally, meaning patients can take them in any setting. And unlike intravenous treatments, Merck and Pfizer’s antiviral drugs are much easier to ship and store.
- Oh, and about that name. Molnupiravir comes from Mjölnir, the mythical hammer of the Norse god Thor.
Plans for distribution of the antiviral pills are shaping up. The Biden administration purchased 1.7 million courses of Molnupiravir for $1.2 billion back in June and is now considering options to buy 1.4 million more. Based on this agreement, Molnupiravir will cost roughly $700 per patient, a more than 50% reduction from currently approved treatments.
Additionally, the administration is planning to buy enough courses of Paxlovid for 10 million people. To allow their drugs to be manufactured around the globe and sold at lower prices in poorer countries, both Merck and Pfizer have entered into license-sharing agreements.
However, Molnupirabir and Paxlovid aren’t magic bullets, and while they are far better than currently approved treatment options, they still have limitations of their own.
- First, both have a strict dosing regimen. Each must be taken over a five-day period, with Molnupiravir taken four times a day and Paxlovid taken three times a day.
- Second, both antivirals must be taken within the first five days of illness. Unfortunately, a lack of access to both rapid at-home antigen tests and testing labs that can quickly process PCR results means the onset of symptoms, a positive test result, and a prescription for an oral antiviral may exceed the five-day window.
- Third, there are questions about the efficacy of the oral antivirals. Merck originally reported in October 2020 that Molnupiravir reduces risk of hospitalization or death by 50%. However, in November, updated data from Merck revealed that its antiviral only cut the risk of hospitalization and death by 30%. Pfizer says that Paxlovid reduces the risk of hospitalization and death by 89%, but these results have yet to be peer-reviewed.
Despite these limitations, both Molnupiravir and Paxlovid could be the most important pharmaceutical development since the introduction of vaccines. However, just like vaccines won’t make a difference until people get their shots, new antiviral pills won’t help unless people take them. If the administration wants to ensure oral antivirals are utilized effectively , it needs to drastically improve the testing infrastructure and ensure adequate distribution to suppliers. Doing so will ensure as many people as necessary have access to antivirals and allow the new drugs to be an effective additional tool to fight the pandemic.