The Food and Drug Administration has formally restricted the use of antibody treatments that lost their once-considerable effect when faced with the omicron variant, pausing a therapy that had been widely embraced, including by people who eschewed vaccinations.

Many health systems stopped using the antibody treatments weeks ago as omicron surged. And while doctors have welcomed the news of additional treatments like antiviral pills, they say the trickle of pills and other treatments are no match for the geyser of new cases.

The FDA said on Monday that it was limiting the emergency use authorisations of the Regeneron and Eli Lilly antibody treatments to say the infusions should not be used now, with the omicron variant dominant, which the Centers for Disease Control and Prevention has estimated at 99.5 per cent of all new cases nationally.

During an earlier wave driven by the Delta variant, those Regeneron and Lilly medications were effective at keeping infected people out of the hospital if given early enough. As omicron emerged, it became apparent that the treatments would not neutralise the virus, and large health systems.

Federal officials moved to pause their use soon after but were rebuked by Republican governors saying they could still help some patients with the Delta variant. That has become an increasingly shaky position, given the difficulty most doctors have in figuring out which variant each patient has.

(New York Times News Service)