Signs of SARS-CoV-2 resistance to sotrovimab, the main monoclonal antibody treatment used in Australia, has been detected in a world-first clinical study in Sydney.

The discovery will likely lead to intense genomic monitoring of patients to ensure resistance doesn’t render the drug ineffective, researchers say.

A team examining the first 100 patients to receive the biologic during the 2021 Delta wave detected viable sotrovimab-resistant virus in four patients more than 10 days after treatment.

“Up to 24 days after one patient received sotrovimab, we could still culture the virus in a lab, which is a sign they were still infectious,” Dr Rebecca Rockett (PhD), a senior research fellow at the Sydney Institute for Infectious Diseases, told Australian Doctor.