Early testing indicates that the mutations in the Omicron variant of coronavirus may hamper the ability of Regeneron’s antibody drug to treat Covid-19, the company said, indicating that some therapies may have to be adapted to tackle the virus’s latest evolution.

The findings are a first indication that treatments developed to tackle Covid-19 may have lost effectiveness as the virus evolves. “The individual mutations present in the Omicron variant indicate that there may be reduced neutralization activity of both vaccine-induced and monoclonal antibody conveyed immunity,” Regeneron said on Tuesday.

Tests so far have been carried out using lab samples and modelling. “Further analyses are ongoing to confirm and quantify this potential impact using the actual Omicron variant sequence,” it added.