(CNN) — Federal regulators are considering limiting the authorization of certain monoclonal antibody treatments that have not proved effective against the omicron variant of the coronavirus, a source familiar with the decision-making told CNN.
The US Food and Drug Administration could decide in the coming days to take steps to curb the use of antibody treatments produced by Eli Lilly and Regeneron, the source said, pointing to the growing body of evidence that shows their monoclonal therapies don't effectively neutralize the virus’ omicron variant.
The National Institutes of Health had recently updated its guidelines to advise clinics against using these treatments on patients with mild to moderate COVID-19 due to their diminished effectiveness against the omicron variant.
This past week, senior health officials in the administration, including Dr. David Kessler, chief science officer of the White House's COVID Response Team, and assistant secretary for Health Dr. Rachel Levine, called the offices of governors and state health officials. They urged against using these treatments with omicron now accounting for nearly all positive cases, a source familiar with the calls said.
The Centers for Disease Control and Prevention estimates more than 99% of cases nationwide have the omicron variant.
The treatments have remained popular among some governors, who continue to push them despite the recent data. Over the last two weeks, states have distributed nearly 110,000 doses of the Lily and Regeneron treatments, according to a federal database maintained by the Department of Health and Human Services.
Earlier this month, amid a record-breaking surge of new coronavirus cases in Florida, Gov. Ron DeSantis assailed the Biden administration for pausing shipments of the monoclonal antibodies, and has pushed for the treatment to remain widely available.
During a Jan. 3 press conference, DeSantis contended his administration had seen the treatments work on Omicron patients, though he didn't provide further evidence.
“Omicron is not the only variant that's out there,” DeSantis said. “And it’s something that we actually have seen applied with omicron patients and we have seen symptoms resolved.”
Omicron has accounted for more than 95% of cases in the Southern region of the U.S. since the week of Dec. 19, according to the CDC. Regeneron has publicly stated its monoclonal antibody treatment is not effective against the omicron variant.
Nearly 13,000 doses of Regeneron were used in Florida over the past two weeks, more than any three other states combined. DeSantis’ office did not immediately respond to a request for comment on Saturday.
DeSantis has made monoclonal antibodies a cornerstone of his response to surges of coronavirus cases in his state, often pushing the treatment more vigorously than vaccines. Last summer, he introduced new clinics where individuals could receive the treatment at the onset of symptoms or exposure to someone with COVID-19. His news conferences often feature first-hand accounts of people who have recovered from coronavirus after receiving treatment.
Other states followed DeSantis’ lead. Texas Gov. Greg Abbott last year opened state-sponsored “infusion centers” where COVID-positive patients could receive monoclonal antibody treatment. Abbott himself received Regeneron’s monoclonal antibody therapy treatment when he tested positive for coronavirus in August when its Delta variant was predominant.
The fast-spreading omicron variant was first detected in the U.S. on Dec. 1, and quickly became the predominant variant.
The Biden administration agreed to provide shipments of the Regeneron and Lily treatments in the weeks to follow while delta remained a prevalent, albeit diminishing, variant. The potential for a positive outcome in the small percentage of delta patients was a calculated trade-off to potentially giving an omicron patient ineffective treatment, a senior official said. The vast majority of coronavirus cases are not sequenced to determine the variant, and doctors often make treatment decisions without knowing which strand of the virus the patient is infected with.
But with delta now accounting for a very small share of cases in most regions, the Biden administration had hoped most states would have moved away from the monoclonal antibody treatments, a senior official said.
There are also concerns widespread use of the treatments could put people at unnecessary risk for the adverse effects from receiving monoclonal antibodies. According to the National Institutes of Health, some patients have reported rashes, diarrhea, nausea and dizziness after treatment. A small percentage of patients had severe allergic reactions.
The Biden administration has pushed for states to pivot to other treatments that have demonstrated greater effectiveness against the omicron variant, including the Merck and Pfizer antiviral pills, GlaxoSmithKline's monoclonal antibody, AstraZeneca's pre-exposure prophylaxis, and commercially available remdesivir.
On Friday, the US Food and Drug Administration expanded the use of the antiviral remdesivir for treatment of mild to moderate COVID-19 to children and people who aren't hospitalized.