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WASHINGTON — Biden health officials are bracing for the prospect that the country’s sole preventive Covid-19 treatment for immunocompromised people could be ineffective this winter.

AstraZeneca’s Evusheld, the only monoclonal antibody authorized as a periodic injection to prevent infection, has become an essential shot for roughly 17,000 Americans with weakened immune systems. But news this month that it is not effective against a steadily climbing coronavirus strain sent health officials racing to game out other antibody options and convene a meeting with patient groups.


Top officials including Health and Human Services’ legal counsel Stephen Cha and the Food and Drug Administration’s chief medical officer Hilary Marston met with representatives for immunocompromised patients on Oct. 4, one day after the FDA quietly updated its Evusheld factsheet to note that the antibody cocktail does not work against BA.4.6, the strain that is already accounting for at least 13% of Covid-19 cases.

Complicating the matter, the next potential monoclonal antibody — an Eli Lilly treatment dubbed bebtelovimab — could be ready within two months, but it has already been shown ineffective against the other fast-rising variant, BQ.1. The federal government has purchased 60,000 bebtelovimab doses for uninsured and under-insured patients, according to two people familiar with the HHS monoclonal antibody planning.

In the HHS meeting, officials discussed the prospect that BA.4.6’s rise could render Evusheld ineffective within two months. They laid out the timelines for as many as six potential alternates in the pipeline, according to two people familiar with the discussion.


The internal deliberations reflect larger questions about the Biden administration’s ability to respond to evolving Covid-19 variants with a shrinking coronavirus response budget, according to six people familiar with the discussion. President Joe Biden last month declared the pandemic “over” even as health officials pleaded with Congress for more cash and warned of a winter surge.

Evusheld is still effective against many variants, but it is not possible for physicians to know which strains a patient using it as prophylaxis could be exposed to, an AstraZeneca spokesperson told STAT.

“Variants are rarely dominant for more than a few months — they tend to either evolve further into different subvariants or are replaced by newer variants,” the spokesperson said, adding the company is running early studies on other antibody options.

Relatively few Americans are turning to monoclonal antibodies when they are sick with the virus, instead opting for the less expensive Paxlovid, a five-day pill regimen. But the injections have become an important preventive measure for many people with cancer, recent organ transplants, and other immunodeficiencies that leave them more vulnerable to severe cases — particularly as most of the country returns to normal, taking off masks and convening at major events.

“Many of our patients have complex medical conditions that put them at increased risk from Covid,” said Karin Hoelzer, director of policy and regulatory affairs for the National Organization for Rare Disorders. “Seeing this antibody be less effective or not effective for some Covid variants is certainly a concern.”

Monoclonal antibodies are developed as targeted attacks against specific immune threats, meaning they work best against individual strains but can ultimately be brief successes against the fast-evolving virus. Other effective monoclonal antibodies from Eli Lilly, GSK, and Regeneron have already been pulled from the market as older versions of the virus faded.

But the FDA will have to walk a fine line when it comes to pulling Evusheld, particularly because no other options are currently available as a preventive injection. There is no set percentage of cases that would trigger a move. A GSK and Vir antibody, for instance, was pulled after a variant that evaded it made up approximately three-quarters of cases; Lilly and Regeneron options were yanked when 90% of new cases were Omicron-linked.

“Evusheld continues to be an important therapeutic for providing pre-exposure prophylaxis in certain individuals to help reduce their risk of developing Covid-19,” an FDA spokesperson told STAT in an email. “FDA will provide additional updates to the EUA materials, as appropriate, as new information emerges.”

Among the six potential new antibody treatments in the pipeline is one AstraZeneca hopes to pair with part of Evusheld’s cocktail. Others from Eli Lilly, Regeneron and Vir could be effective against both rising variants, but are in early trials and months away — in some cases, more than a year away — from the market, two people familiar with internal discussions among federal health officials told STAT.

Patient groups representing immunocompromised people have pressed the administration to buy more Evusheld and to fund potential antibody cocktails that could ward off emerging variants.

Biden officials complain that they cannot motivate drugmakers to pour money into development and manufacturing without additional Covid-19 funding from Congress. But congressional Republicans are actively opposing funding requests as they question how prior allotments were spent.

Drugmakers, meanwhile, are taking a bet on which treatments could be effective as the virus evolves and evades other options. While drug development is typically a gamble, making an effective monoclonal antibody for the fast-paced coronavirus has become increasingly high stakes.

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