AstraZeneca Plc said its coronavirus antibody cocktail was found to be 77% effective in preventing symptomatic COVID-19 in high-risk people in a key trial, and the U.K. approved its first antibody treatment for the disease.

Results from Astra’s study found no one in the trial who received the cocktail contracted severe COVID-19 or died in relation to the disease, the company said in a statement Friday. The trial of 5,197 participants, which started in November, was looking at whether the drug could prevent infection in at-risk groups and took place in the U.S., U.K., Belgium, France and Spain.

The result comes as the U.K. approved its first monoclonal antibody drug against COVID-19 Friday, giving a green light to a treatment from Regeneron Pharmaceuticals Inc. and Roche Holding AG. The product was first authorized in the U.S. in November and European authorities have said they’re on track to complete their review this year. Demand has jumped amid the delta variant surge, growing from a trickle to more than 120,000 doses a week, according to Regeneron. 

For Astra, the outcome is a relief after another study testing whether the cocktail could prevent symptomatic COVID-19 in people explicitly exposed to the virus failed in June. The findings may also salvage a deal with the U.S. to purchase the drug. The U.S. had ordered as many as 700,000 doses for delivery in 2021, the value of which was partly contingent on the earlier trial result.

Astra said in June it was in “ongoing” discussions with the U.S. government and awaiting results of this latest study — named Provent — before deciding how to proceed. In an interview Friday, Mene Pangalos, Astra’s head of biopharmaceutical research, said he believed the U.S. government was keen to pursue discussions if the data were positive.

“The U.S. government remains interested in this based on the conversations we’ve had,” said Pangalos. There are “some patient populations that aren’t responding as well to the vaccines or even where the vaccine immune response maybe isn’t as long lasting, so I think this is going to be an important potential therapy.”

The company said it’s preparing to submit the data to regulators for potential emergency-use authorization or conditional approval. Astra’s shares traded 0.8% lower at 9:58 a.m. in London.

The trial accrued 25 symptomatic COVID-19 infections for the primary analysis, 17 of which were in the placebo group and eight among those that had received the drug. Volunteers were given the AZD7442 cocktail on a 2:1 randomized drug-to-placebo ratio. The cocktail is administered through two intramuscular injections, making it more user-friendly than a number of antibody treatments that have to be delivered by intravenous infusion.

While more analysis needs to be done, Pangalos said he’s confident the cocktail held up against all of the variants based on preclinical and other data the company has examined. The cocktail is expected to provide protection for at least 12 months. 

Antibody drugs are viewed as a way to potentially protect people, such as cancer patients, who may not respond as well to vaccination, but they are more difficult to mass produce. Trials for both prevention and treatment options against COVID-19 have seen mixed success. GlaxoSmithKline Plc and Vir Biotechnology Inc. received U.S. emergency-use authorization for their product in May after it showed it could keep at-risk patients from worsening, though an earlier trial for hospitalized patients failed.

(Adds details from Astra interview, Regeneron approval)