(Reuters) - Regeneron Pharmaceuticals Inc said on Monday a single dose of its antibody cocktail reduced the risk of contracting COVID-19 by 81.6% in the two to eight months period following the drug's administration in a late-stage trial.

       The results showed that antibody therapy, REGEN-COV, has the potential to provide long-lasting immunity from COVID-19 infection, said Myron Cohen, who leads monoclonal antibody efforts for the U.S. National Institutes of Health-sponsored COVID Prevention Network.

       Such immunity is particularly important for immunocompromised people and those not responding to vaccines, the company said.

       The therapy had previously shown an 81.4% risk reduction during the first month after administration.

       During the 8-month assessment period, there were no hospitalizations for COVID-19 in the REGEN-COV group, but in the placebo group 6 such incidents were recorded, Regeneron said.

       The U.S. health regulator in July expanded REGEN-COV's authorization to enable its use as a preventive treatment in people exposed to infected individuals, and those at high risk of such exposure in settings such as nursing homes or prisons.

       It was authorized in the United States last November to treat people with mild-to-moderate COVID-19 disease.

       (Reporting by Manojna Maddipatla in Bengaluru; Editing by Shinjini Ganguli)