The National Institutes of Health on Thursday recommended that patients with mild to moderate COVID-19 who are at high risk of worsening disease should be treated with monoclonal antibody cocktails. The recommendation was issued by the NIH's COVID-19 Treatment Guidelines Panel for Regeneron Pharmaceuticals Inc.'s /zigman2/quotes/203149337/composite REGN -0.11% casirivimab-imdevimab combination therapy and Eli Lilly & Co.'s /zigman2/quotes/200106384/composite LLY +0.65% bamlanivimab-etesevimab. (Prescribing bamlanivimab as a standalone treatment is no longer recommended because of its lack of efficacy against some of the new variants.) The panel said that in regions where variants are more common, it recommends using the Regeneron cocktail rather than the Lilly one, because it includes bamlanivimab. Lilly and Regeneron both received emergency authorizations for the first round of monoclonal antibody therapies in November; since then, both companies have released additional clinical-trial data and the authorizations for those products have been updated. Executives at both companies previously told MarketWatch that there has been slower-than-expected utilization of these therapies. Since the start of the year, Regeneron's stock is down 1.4%, shares of Lilly are up 8.1%, and the S&P 500 /zigman2/quotes/210599714/realtime SPX +1.49% has rallied 8.%.