Eli Lilly (NYSE:LLY) announced that it had amended purchase agreements with the U.S. government to prioritize using two monoclonal antibodies — bamlanivimab and etesevimab — in tandem. In March, the U.S. government announced that it would stop using bamlanivimab alone, given its reduced efficacy against some SARS-CoV-2 variants. But pairing anti-SARS-CoV-2 monoclonal antibodies together can offer more…