Eli Lilly & Co. will begin testing its Covid-19 antibody drug in nursing homes, a treatment with potential to protect vulnerable groups that vaccines may not cover.

The trial, dubbed BLAZE-2, will kick off on Monday at several nursing homes in the U.S. and marks the third phase of testing for the monoclonal antibody that Lilly co-developed with Canadian start-up AbCellera Biologics Inc. The study will enroll up to 2,400 participants across nursing homes who are either diagnosed with Covid-19 or at the risk of exposure.

They will be given one dose of the antibody — isolated from one of the first Covid-19 patients to recover in the U.S. — to see how it can reduce infection rates, or treat those already infected, in four and eight weeks’ time respectively, the company said in a press release.

Read more at Bloomberg.