The research, which was conducted in numerous sites around the world, was stopped early because the results were so promising, Merck says. The drug was even effective against variants like Delta and Mu. Based on this interim analysis in 775 people, the company plans to submit an application for Emergency Use Authorisation (EUA) to the U.S. Food and Drug Administration as well as regulatory bodies in other countries, including the U.K., in hopes the drug can be made available. When that will happen is not clear, but the U.S. government has already agreed to purchase 1.7 million courses of treatment at $700 (£515) each, Merck notes.

Who can get the drug?

In the U.S. healthcare landscape, it’s also not known who would ultimately be authorised to take the medicine. The study included only people who were sick and unvaccinated and had at least one risk factor for developing a severe case of COVID-19, says Aaron Weinberg, national director of clinical research at Carbon Health, a for-profit provider of primary and urgent care, and a principal investigator of the study. This includes people who are older than 60, obese, immunocompromised from another condition, or have underlying heart or pulmonary disease, among others.

If the FDA does authorise the drug in the U.S., it could limit who gets it to people like those in the research, Javaid says.

Although this drug looks promising, it’s a treatment – not a prophylactic like the vaccine. The medicine does not negate the need for unvaccinated people to get their shot, Shaw says. Some people taking the pills still got sick enough to be hospitalised. And while side effects in this study were mild—generally gastrointestinal issues, Weinberg says, and at comparable rates in the treatment and placebo groups—safety issues might emerge when the drug is given more broadly, Shaw says. Meanwhile, hundreds of millions of people have already had the vaccines with no major consequences.

Still, the results of this study should be celebrated, Javaid says. “Saving eight lives is huge, as is halving hospitalisation,” he says. Perhaps another drug being studied will later prove to be more effective, reducing hospitalisation by 80 or even 100 percent, he says. “But this is better than any oral antivirals we have right now, which is none,” he says.