New positive phase III study results for Regeneron Pharmaceuticals Inc.’s COVID-19 monoclonal antibody cocktail show a single dose reduced the risk of contracting the virus by 81.6% during a two- to eight-month follow-up period. The strong data go along with Pfizer Inc.’s recent positive results for its oral antiviral, Paxlovid, hinting that COVID-19 therapeutics could begin cutting into powerful mRNA vaccine margins from Pfizer Inc.-Biontech SE and Moderna Inc.