The U.S. Food and Drug Administration (FDA) said Thursday that it is withdrawing emergency use authorization for a Covid-19 drug as it is unlikely to be effective against new variants circulating in the population.

The drug in question is Evusheld, manufactured by British-Swedish pharmaceutical and biotechnology company, AstraZeneca. It was first authorized in December 2021 as pre-exposure prophylaxis against SARS-COV-2 for immunocompromised individuals as they are less likely to produce antibodies from vaccination, as per ABCNews.

It is a type of monoclonal antibody treatment, containing antibodies that are produced in a lab that mimic the ones the body naturally generates when it encounters the virus. It is a combination of two antibodies, tixagevimab, and cilgavimab, that bind to the spike protein of the virus that causes COVID-19 and prevents it from entering and infecting cells.

Evusheld does not neutralize several omicron subvariants including BQ.1, BQ.1.1, BF.7, BF.11, BA.5.2.6, BA.4.6, BA.2.75.2, XBB, and XBB.1.5, the FDA said in a press release.

These subvariants are believed to be the cause of 90% of cases in the U.S., according to the Centers for Disease Control and Prevention.

"This means that Evusheld is not expected to provide protection against developing COVID-19 if exposed to those variants," the FDA said in the press release.

"Today's action to limit the use of Evusheld prevents exposing patients to possible side effects of Evusheld such as allergic reactions, which can be potentially serious, at a time when fewer than 10% of circulating variants in the U.S. causing infection are susceptible to the product," the press release continued.

The FDA had previously touched upon this topic. On Jan. 6, the FDA said that it was skeptical that Evusehld would be able to neutralize the XBB.1.5 subvariant "because of its similarity to variants that are not neutralized by Evusheld," the outlet reported.

Meanwhile, AstraZeneca said in a statement that it will continue to cooperate with the FDA’s decisions.

"AstraZeneca will continue to work with the FDA and other health authorities to collect, assess and share relevant data regarding Evusheld and SARS-CoV-2 variants," the statement read. "Evusheld currently remains authorized in other countries where it is approved for COVID-19 pre-exposure prophylaxis and treatment, including the EU and Japan."

Despite revoking the emergency use authorization status of the medication, the FDA advised providers of the drug to not discard their products just yet.

"The U.S. Government recommends that facilities and providers with Evusheld retain all product in the event that SARS-CoV-2 variants which are neutralized by Evusheld become more prevalent in the U.S. in the future," the FDA said in its press release.