How Antiviral Pill Molnupiravir Shot Ahead in the COVID Drug Hunt

The pharmaceutical firm Merck announced last week that an antiviral pill it’s developing can cut hospitalizations and deaths among people with COVID-19 by half. The results haven’t yet been peer-reviewed. But if the drug candidate, molnupiravir, is authorized by regulators, it would be the first oral antiviral treatment for COVID-19. By contrast, the other currently authorized drugs must be delivered intravenously or injected.

A pill could make treating patients earlier on in their infection much easier—and more effective. It could also keep hospitals from overflowing, especially in places where vaccination rates are still low, such as many low- and lower-middle-income countries. Molnupiravir was so effective in a phase 3 trial involving COVID-19-positive people at risk of severe illness that clinicians halted enrollment early.

But whether this clinical-trial success story will translate into a global game-changer in the fight against the pandemic isn’t yet clear. Even if lower-income countries can afford the medicine, they might not have the diagnostic capacity to treat patients with molnupiravir early in the course of their illness, when treatment could make a difference.

This week, two Indian drugmakers independently testing generic molnupiravir in people with moderate illness due to COVID-19 sought to end their trials because they saw no “significant efficacy” for the experimental drug, although they plan to continue trials for people with mild illness. Merck’s findings, which were disclosed in a press release and have yet to be pored over by scientists and submitted to regulators for approval, applied to people with mild-to-moderate cases of COVID-19 who were not hospitalized. A spokesperson for Merck points out that moderate COVID-19 cases in India are defined as being more severe than in the United States and involve hospitalization.

The other therapies on offer against COVID-19, Gilead Science’s antiviral remdesivir and a monoclonal antibody cocktail from biotech firm Regeneron, must be administered intravenously or by injection. That makes it difficult for people to access the therapies before they are sick enough to land in hospital. And remdesivir is approved only for those who are already hospitalized with COVID-19.

Yet it’s better to “hit early, hit hard” with antivirals, says Richard Plemper, a virologist at Georgia State University in Atlanta. The sicker the patient, the less effective the drugs are at treating the illness. A COVID-19 pill, which simply requires a prescription and a trip to the pharmacy once symptoms appear, would make early treatment much easier.

COVID-19 is not the first disease caused by a coronavirus to seriously impact humans. But the 2002–04 severe acute respiratory syndrome (SARS) epidemic fizzled out quickly, and the Middle East respiratory syndrome (MERS) outbreak in 2012 never became widespread—meaning that drugmakers had little incentive to develop antivirals against these diseases.

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