Regeneron Pharmaceuticals Inc. posted positive initial results from its ongoing phase III study of its monoclonal antibody cocktail, REGEN-COV (casirivimab and imdevimab), used as a passive vaccine, designed to provide immediate short-term passive immunity to prevent COVID-19 in people at high risk of infection due to household exposure to a COVID-19 patient. Eli Lilly and Co. reported upbeat news the same day, as the phase III Blaze-1 trial testing its antibody cocktail met its primary and key secondary endpoints.