Covid-19 antibody drugs have been challenged by Omicron, preliminary tests indicate

Preliminary tests indicate that the Covid-19 antibody drug cocktail from Regeneron Pharmaceuticals Inc. will lose effectiveness against Omicron, the company said on Tuesday, a sign that some products in an important class of therapies may need modifications if the new strain becomes widespread.

Separate testing of another authorized Covid-19 antibody drug cocktail, from Eli Lilly & Co., indicates that it is also not as effective against Omicron, external researchers said. Lilly said it is testing the new variant against the antibody treatment and will not speculate on what the results will be.