Image of doctor's gloved hand holding a vial of monoclonal antibodies

A single dose of the monoclonal antibody drug widely used in long-term care settings provides up to eight months’ protection against COVID-19, a late-stage clinical trial has shown.

One 1,200 mg. dose of Regeneron’s REGEN-COV delivered by subcutaneous injection reduced the risk of contracting COVID-19 by 82% during a 2-to-8-month follow-up period — nearly the same rate of protection found at one month, the company announced Monday, Nov. 8.

There were no hospitalizations for COVID-19 in clinical trial participants who took REGEN-COV, compared with six in a placebo group. The news could be especially encouraging for immunocompromised people who may not receive adequate protection from vaccination and can end up isolated in an attempt to stay safe, according to stakeholders.

“These results demonstrate that REGEN-COV has the potential to provide long-lasting immunity from SARS-CoV-2 infection, a result particularly important to those who do not respond to COVID-19 vaccines including people who are immunocompromised,” said Myron S. Cohen, M.D., of the University of North Carolina at Chapel Hill, who leads antibody research at the National Institutes of Health’s COVID Prevention Network.

REGEN-COV is currently authorized for treating non-hospitalized patients at risk of serious consequences from COVID-19 infection, and recently was approved as a preventive in certain cases for those who have been exposed to the disease.

The drug retained an 82% risk reduction during the first month after administration, according to results previously reported in The New England Journal of Medicine.