Regeneron's Antibody Drug Cut Risk of Covid-19 by 82%, Company Says The data from a late-stage study suggest a potential use for the antibody drug as a prophylactic for the immunocompromised or others who aren’t well protected by vaccination. The data from a late-stage study suggest a potential use for the antibody drug as a prophylactic for the immunocompromised or others who aren’t well protected by vaccination.