A newly isolated antibody that blocks SARS-CoV-2 from infecting cells could one day be used to treat infections caused by current and future variants of the virus that causes COVID-19, and even infections from related viruses1.

David Veesler and his colleagues at the University of Washington, Seattle, searched the blood of an infected person for antibodies that bind the SARS-CoV-2 spike protein, which lets the virus enter human cells. They uncovered one particularly potent antibody, called S2K146, that protected cells from infection with the original strain of SARS-CoV-2, as well as the Alpha, Beta, Delta and Kappa variants. (The authors have now shown in a separate study2 that S2K146 protects cells from the Omicron variant, too.)

S2K146 also binds spike protein from the two related viruses: SARS-CoV, which caused an outbreak of respiratory disease in 2002–2003, and WIV-1, which infects bats and has the potential to infect humans. Administering S2K146 to hamsters infected with SARS-CoV-2 greatly reduced or eliminated viral replication.

The team found that mutations that prevented S2K146 from binding to spike protein also rendered SARS-CoV-2 much less effective at infecting cells. This suggests that the virus is unlikely to mutate its way out of S2K146’s grasp.