LONDON (AP) — AstraZeneca, the Anglo-Swedish drugmaker that developed one of the first COVID-19 vaccines, has asked the U.S. Food and Drug Administration to authorize the emergency use of an antibody treatment to prevent the disease.

The company said Tuesday that the treatment, known as AZD7442, would be the first long-acting antibody combination to receive an emergency use authorization for COVID-19 prevention. The treatment may help protect people whose immune systems don't respond adequately to vaccination, AstraZeneca said.

Late-stage human trials showed that AZD7442 reduced the risk of developing symptomatic COVID-19 by 77%. More than three-quarters of the participants had suppressed immune systems and other conditions that made them more susceptible to severe disease.

"Vulnerable populations such as the immunocompromised often aren't able to mount a protective response following vaccination and continue to be at risk of developing COVID-19," Mene Pangalos, AstraZeneca's executive vice president for pharmaceutical research, said in a statement. "With this first global regulatory filing, we are one step closer to providing an additional option to help protect against COVID-19 alongside vaccines."

U.S. demand for antibody treatments soared over the summer, particularly in states like Florida, Louisiana and Texas, where hospitalizations among unvaccinated patients threatened to overwhelm the health care system.

The drugs are laboratory-made versions of virus-blocking antibodies that help fight off infections. The treatments help the patient by supplying concentrated doses of one or two antibodies.

The main antibody treatment being used in the U.S. is Regeneron's dual-antibody cocktail. The FDA has also authorized the Regeneron product as protection for high-risk people against severe COVID-19.