The group’s antibody is not expected to be in human trials until late December, but it may be worth the wait. Unlike the antibodies made by Regeneron and Eli Lilly, which fade in the body within weeks, Prometheus’s antibody aims to be effective for up to six months.

“A single dose goes a long way, meaning we can treat more people,” said Kartik Chandran, a virologist at Albert Einstein College of Medicine and the group’s leader.

In mice and laboratory tests, Prometheus’s antibody protects against not just the coronavirus, but also the SARS virus and similar bat viruses — suggesting that the treatment may protect against any coronaviruses emerging in the future.

A study published last year recorded about 400 strains of bat-origin coronaviruses in China, some of which had already spilled over into people.

Among scientists, Dr. Chandran and Prometheus are famous for careful and clever work that has unearthed critical insights into deadly pathogens. While working on Ebola, for example, the team discovered a new entryway into human cells used by the virus, and used that information to design an antibody combination that works against all major strains of Ebola.