LONDON – Regeneron Pharmaceuticals Inc.’s antibody cocktail, Regen-Cov, has been shown to significantly reduce mortality in seriously ill hospitalized COVID-19 patients who have failed to mount their own immune response against the SARS-CoV-2 virus. Among these seronegative patients, the casirivimab/imdevimab monoclonal antibody mixture reduced deaths by 20% (p=0.001) in the U.K. Recovery trial.