The FDA revised the emergency use authorization for AstraZeneca's Evusheld antibody cocktail Feb. 24, doubling the initial dose for immunocompromised people receiving the drug.
Evusheld involves the administration of monoclonal antibodies tixagevimab and cilgavimab. The FDA authorized it Dec. 8 as a pre-exposure prophylaxis for COVID-19 among immunocompromised people who may not mount a strong immune response to vaccination or who cannot be vaccinated for medical reasons.
The dose change increases the initial dose from 150 milligrams each of tixagevimab and cilgavimab to 300 mg each. Patients who have received the previously authorized dose should receive an additional dose to meet the new dose recommendation "as soon as possible to raise their monoclonal antibody levels to those expected for patients receiving the higher dose," the FDA said.
The agency revised the dosage due to recent data that showed "Evusheld may be less active against certain omicron subvariants."
"The dosing regimen was revised because available data indicate that a higher dose of Evusheld may be more likely to prevent infection by the omicron subvariants BA.1 and BA.1.1 than the originally authorized Evusheld dose."
Health experts have welcomed the dose change while raising concerns about supply and access.
"I think that it's great that the new data identified the ideal dosage that immunocompromised people need to be protected, and that it's actually a reassurance that with the new dosage there will be protection," Dorry Segev, MD, PhD, a physician-scientist who treats transplant recipients at Baltimore-based Johns Hopkins University School of Medicine, told CNN.
But "there already is inadequate access to this product for those who need it, and that will become more challenging now," Dr. Segev said. "Of the remaining doses, you have to basically cut them in half in terms of availability to actual people."
The government has shipped nearly 600,000 courses of Evusheld across the country since Dec. 17, HHS data shows. In January, the U.S. purchased an additional 500,000 doses of the drug.