LONDON — The European Union’s drug regulator said Thursday it was recommending that an antibody medication developed by AstraZeneca be authorized to help some vulnerable people avoid getting sick with the coronavirus.

The European Medicines Agency said in a statement that it was advising that the new drug, sold as Evusheld, be used in people age 12 and over before they were exposed to COVID-19, to prevent future infections.

The drug was previously cleared by the U.S. Food and Drug Administration in December for people with serious health problems or allergies who can’t get adequate protection from vaccination. Britain also authorized Evusheld last week.

“When the antibodies in Evusheld attach to the spike protein, the virus cannot enter the cells to multiply and is unable to cause COVID-19 infection,” the EMA said. The agency said it had assessed data on the drug from more than 5,000 people and found Evusheld reduced the risk of infection by 77%, with protection estimated to last at least six months.

EMA said that the drug’s side effects were mostly mild, with some people reporting reactions at the site where the drug is injected. The agency noted that research was done before the emergence of the hugely infectious omicron variant and said that it was evaluating data to determine if a different dose might be needed.

Although antibody drugs have been a standard treatment for treating COVID-19 infections for more than a year, the AstraZeneca antibody drug is the first intended for long-term prevention against COVID-19 infection, rather than a short-term treatment.

People who could benefit from the antibody drug include cancer patients, organ transplant recipients and people taking immune-suppressing drugs for conditions like rheumatoid arthritis.