Merck’s announcement that its experimental antiviral pill is effective against the most severe outcomes of Covid-19 is “certainly good news,” a World Health Organization official said Tuesday, as the international agency awaits clinical trial data on the drug.

“We’re looking forward to receiving the data from them,” Maria Van Kerkhove, the WHO’s technical lead for Covid, said during a virtual Q&A. “I think everybody wants earlier treatment so that we prevent people from actually, you know, getting to that severe state and actually dying from the disease.”

The U.S. drugmaker said Friday the medication – known as molnupiravir – was shown in a phase three trial to reduce the risk of hospitalization or death by around 50% for adults with mild-to-moderate cases of Covid. It works by inhibiting the replication of the virus inside the body.

Unlike Gilead Sciences’ intravenous drug remdesivir, Merck’s molnupiravir can be taken by mouth. If approved by the Food and Drug Administration, it would be the first pill to treat Covid, a potentially game-changing advancement in the fight against the virus, which is killing an average of more than 1,700 Americans per day.

While vaccinations remain the best form of protection against the virus, health experts hope a pill like Merck’s will keep the disease from progressing in those who do get infected and prevent trips to the hospital.

Pills like Merck’s are considered a sort of “holy grail” for treatments, said Dr. Mike Ryan, executive director of WHO’s Health Emergencies Program. He said the agency is still waiting to see the raw clinical trial data on the drug.

“If you can stop the virus before it makes someone very sick, then it’s a game-changer in that sense,” he said.

Other drugmakers are also working on antiviral pills. A pill developed by Pfizer, which developed the first authorized Covid vaccine in the U.S. with BioNTech, could be available by the end of this year, CEO Albert Bourla in April.

Ryan also said world leaders and public health officials should also think about how much the drug could cost patients. According to the New York Times, a five-day course of the drug will cost the federal government about $700 per patient, a third of the current cost of monoclonal antibodies.

“The cost of treating millions of people early could have a significant cost, and maybe worth that investment but we have to look at how that’s going to work,” Ryan said.