The U.S. government has committed to buying an additional 1.4 million courses of Merck’s COVID-19 antiviral pill if it’s granted emergency use authorization by the Food and Drug Administration, the drugmaker said Tuesday.

The federal government has now locked in purchases totaling 3.1 million courses of the pill between authorization and early 2022 at a price tag of about $2.2 billion. Its contract includes options to buy more than 2 million additional courses.

New Jersey-based Merck and its partner, Miami-based Ridgeback Biotherapeutics, announced last month that they have requested emergency use authorization from the FDA for molnupiravir for the treatment of mild to moderate COVID-19 in adults at risk for for severe cases or hospitalization. An FDA advisory committee is scheduled to discuss the request Nov. 30.

Preliminary data from the companies’ Phase 3 clinical trial found the pill reduced the risk of hospitalization or death by approximately 50%. The drug is intended to be taken twice a day for five days.

“We’re honored that the U.S. government has chosen to purchase more than 3 million courses of molnupiravir, our promising oral antiviral, so that molnupiravir, if authorized, will be among the vaccines and medicines available to fight COVID-19 as part of our collective efforts to bring this pandemic to an end,” Merck President of Human Health Frank Clyburn said in a news release.

Merck says it’s committed to providing timely access to molnupiravir around the world and is already producing the pills in anticipation of regulatory clearance. Britain granted the treatment conditional authorization last week.

Merck says it expects to produce 10 million courses of the pill by the end of this year, and at least 20 million more in 2022.

The company has not disclosed details on molnupiravir’s side effects, except to say that rates of those problems were similar between people who got the drug and those who received dummy pills.

The drug targets an enzyme the coronavirus uses to reproduce itself, inserting errors into its genetic code that slow its ability to spread and take over human cells. That genetic activity has led some independent experts to question whether the drug could potentially cause mutations leading to birth defects or tumors.

Britain’s Medicines and Healthcare products Regulatory Agency said molnupiravir’s ability to interact with DNA and cause mutations had been studied “extensively” and that it was not found to pose a risk to humans.

Merck has agreed to allow other drugmakers to make its COVID-19 pill, in a move aimed at helping millions of people in poorer countries get access. 

Molnupiraviris not the only pill potentially on the horizon in the U.S. Pfizer announced Friday its ritonavir pill cuts the risk of hospitalization and death by nearly 90%. Pfizer plans to submit the trial data for review and publication.

The Associated Press contributed to this report.