The U.S. has already secured hundreds of thousands of doses of experimental antibody treatments for COVID-19 in anticipation of regulators authorizing their emergency use, federal health officials said on Friday.

The government expects to have one million doses of the so-called monoclonal antibody treatments on hand before year-end.

The treatments have come into the spotlight after U.S. President Donald Trump received one such experimental therapy last week for his case of COVID-19.

Eli Lilly & Co. and Regeneron Pharmaceuticals Inc. this week asked the U.S. Food and Drug Administration for emergency-use authorizations for their antibody therapies but haven’t yet received clearance. Trump has since repeatedly promised to hasten their approval, widen access and provide them to Americans for free.

“We have engaged in a number of contracts for procurement of these monoclonal antibodies already,” said Paul Mango, deputy chief of staff for policy at the Department of Health and Human Services. The government is acquiring doses through its Strategic National Stockpile as they are manufactured, he said.

Mango spoke during a briefing on the latest developments of Operation Warp Speed, the White House-led effort to expedite the development, manufacturing and distribution of coronavirus vaccines and treatments.

Early data from Lilly’s single antibody and Regeneron’s antibody cocktail suggest both are effective in keeping people infected with the new coronavirus out of the hospital.

“The interest in the monoclonal antibodies is quite high,” said Janet Woodcock, director of the Center for Drug Evaluation and Research at the FDA. Woodcock, who is serving as a part of Operation Warp Speed, has recused herself from taking part in the approval decisions related to coronavirus therapeutics.

The greatest challenge ahead, Woodcock said, will be coordinating sites where patients can receive the antibody treatments, which must be administered intravenously by health-care professionals, unlike vaccines, which can be given from the more convenient confines of a pharmacy.