The therapeutic antibodies derived from a body’s natural antibody defenses may be able to give many people early protection against the coronavirus, ahead of vaccines. The monoclonal antibodies might also prevent infection in healthy people, though likely only for about a few months as a type of temporary vaccine for people at high risk of infection, such as nursing-home residents and possibly health-care workers.

The convalescent plasma, which are rich in antibodies, might provide some benefit and could be helpful in fighting the coronavirus, but the evidence so far has not been conclusive about when to administer it and what dose is needed.