Most patients with COVID-19 in Australia now have the BA.2 subvariant of Omicron, posing a dilemma over the use of the monoclonal antibody sotrovimab, doctors have been told.

Infectious diseases physician Associate Professor Bridget Barber told a federal Department of Health webinar on Thursday night that experts were developing new advice for use of the treatment.

Sotrovimab, which costs almost $3000 per dose, has been recommended for patients who are unvaccinated, immunocompromised or have multiple risk factors to prevent disease progression and is delivered as a 500mg IV infusion.

But Professor Barber, co-chair of the COVID-19 Clinical Evidence Taskforce therapeutics panel, said this advice may change given the lack of efficacy of sotrovimab against BA.2.