Several, but not all, of the human monoclonal antibodies used clinically to prevent patients from becoming severely ill from COVID-19 may not be protective against the omicron variant now sweeping across the United States, researchers reported Jan. 19 in the journal Nature Medicine.

The laboratory study, led by researchers at Washington University School of Medicine in St. Louis, Missouri, tested five antibody combinations including precursor antibodies discovered at Vanderbilt University Medical Center that subsequently were optimized by AstraZeneca and which were authorized for emergency use in patients last month.

Several antibodies, including those in clinical use by Celltrion, Regeneron and Eli Lilly, completely lost the ability to neutralize the omicron variant in cell culture, whereas the antibodies discovered at VUMC had a reduced neutralizing ability, and an antibody developed by Vir Biotechnology was minimally affected, the study found.

"Omicron escapes recognition by several of the monoclonal antibodies that are being used for therapy," said James Crowe Jr., MD, director of the Vanderbilt Vaccine Center, whose team discovered the monoclonal antibodies later optimized by AstraZeneca into a long-acting antibody combination called Evusheld.