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The US government is buying more doses of monoclonal antibody treatments for Covid-19, and the Biden administration is taking over distribution in order to avoid shortages of the key therapeutics.

The moves come as demand for monoclonal antibodies has increased as cases surged due to spread of the Delta variant and low vaccination rates in some areas of the country.

Monoclonal antibodies are lab-engineered immune system proteins that kickstart an immune response against an infection. The US Department of Health and Human Services says that as of September 10, 2.17 million doses of monoclonal antibodies have been shipped to all sites, and 938,000 doses have been used since December. About 43% of the distributed doses have been used as of September 3.

An HHS spokesperson said seven states have accounted for 70% of orders for the therapy. Those seven states are Florida, Texas, Mississippi, Tennessee, Alabama, Georgia and Louisiana.

“Given this reality, we must work to ensure our supply of these life-saving therapies remains available for all states and territories, not just some,” the HHS spokesperson said.

The distribution, which is similar to a system employed earlier this year, will fall to HHS, which will allocate product to states and territories each week, rather administration sites ordering them directly.

“HHS will determine the amount of product each state and territory receives on a weekly basis. State and territorial health departments will subsequently identify sites that will receive product and how much,” the spokesperson said. “This system will help maintain equitable distribution, both geographically and temporally, across the country - providing states and territories with consistent, fairly-distributed supply over the coming weeks.”

US buys more antibody treatments

Regeneron announced on Tuesday the Biden administration has contracted with the company for 1.4 million additional doses of its Covid-19 treatment, bringing the total to 3 million doses purchased by the US.

The treatment is a cocktail of two monoclonal antibodies, authorized for emergency use by the US Food and Drug Administration to reduce the risk of hospitalization and death in some Covid-19 patients and close contacts of infected people.

Regeneron said it will provide the additional doses by the end of January 2022 and begin supplying them this month, the company said in a statement. Regeneron said it will supply the treatment for $2,100 per dose to the government, which will continue to provide it to patients at no cost. The company was awarded $2.94 billion for the additional doses, the US Department of Defense (DOD) said in a statement.

On Wednesday, Eli Lilly and Company announced the US government purchased 388,000 doses of its Covid-19 monoclonal antibody treatment etesevimab to complement previously purchased doses of its bamlanivimab monoclonal antibody.

About 200,000 doses are expected to ship in the third quarter of 2021, and the remaining will ship in the fourth quarter, the company said.

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Shipments of Eli Lilly’s treatments had previously been stopped because they did not work against the Beta and Gamma coronavirus variants, but distribution resumed earlier this month as antibody treatment demand surged. There’s evidence that bamlanivimab and etesevimab together are effective against the Delta coronavirus variant that’s dominating in the United States.

“The recent increase in Covid-19 cases has caused a substantial rise in the utilization of monoclonal antibody drugs, particularly in areas of the country with low vaccination rates,” Dr. Daniel Skovronsky, Lilly’s chief scientific and medical officer and president of Lilly Research Laboratories, said in a statement. “Lilly developed bamlanivimab and etesevimab for administration together, in anticipation of variants such as the highly contagious Delta variant, which currently accounts for more than 98 percent of all identified Covid-19 cases in the U.S.”

CNN’s Jamie Gumbrecht contributed to this report.