AstraZeneca Plc agreed to supply the U.S. with as many as half a million more doses of its Covid-19 antibody cocktail for $205 million.

Combined with previous contracts, that brings the total U.S. supply to as many as 700,000 doses, the company said in a

statement Tuesday. The medicine, AZD7442, is in late-stage clinical trials and would help protect people who cant be vaccinated or treat those who are already infected.

The U.S. has agreed to contribute as much as $726 million for the development and supply of the antibody treatment on the condition that it gain regulatory approval.

AZD7442 has proved effective against variants of the virus in early testing, a potentially key development for vulnerable populations unable to receive vaccines.

While vaccines can protect the general population from disease, not everyones immune system can respond adequately. High-risk people such as cancer patients may need drugs like monoclonal antibodies that can neutralize the virus and mimic the necessary immune response to avoid infection. Astra is running five advanced-stage trials of its antibodies.

Other companies are also working on similar projects. A neutralizing antibody from

Eli Lilly and Co. was granted emergency approval in the U.S in November as a treatment for patients at high risk of progressing from a mild to severe case or hospitalization. Lilly also teamed up with

GlaxoSmithKline Plc and partner Vir Biotechnology Inc.

last month to test a combination of their antibodies as the virus variants present a new threat.

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