A large proportion of patients with an immune disorder who received the drug sotrovimab because of a covid infection (Omikron variant) turned out to develop resistance to this drug very rapidly due to specific mutations in the coronavirus. Researchers from Amsterdam UMC published about this in the scientific journal JAMA. Lead researcher Emma Birnie calls the rapid onset of resistance to sotrovimab worrying: "It is more difficult for patients to get rid of the resistant corona virus, which can lead to new mutations."

In people with underlying immune disorders, corona vaccines often do not work adequately. Therefore, they face a greater risk of becoming seriously ill after a covid infection. Sotrovimab, a monoclonal antibody, is a drug that attaches to the protrusions of the coronavirus so that it does not enter the body's cells. It is one of the few agents licensed by the EMA for emergency use in this patient group.

The researchers saw that sometimes as early as 3 days after giving sotrovimab, changes had developed in the coronavirus that made it insensitive to the drug. These were mutations in the spike protein. They also found that when these mutations were found, patients carried the virus for a longer period of time.

Lead researcher Emma Birnie says: "Resistance that develops during covid-19 treatment is worrying, especially for patients with immune disorders. In addition, we see that it is more difficult for patients with resistance mutations to get rid of the virus, which means there is a chance that new mutations will emerge. Therefore, it is crucial that we continue to monitor the corona virus in patients with an immune disorder and investigate whether these new mutations pose additional risks, especially in this vulnerable patient group. In addition, future studies should focus on a cocktail of drugs, for example a combination of monoclonal antibodies with an antiviral agent."