Last fall, the U.S. Food and Drug Administration granted Emergency Use Authorization to Ely Lilly (NYSE:LLY) and Regeneron Pharmaceuticals (NASDAQ:REGN) for antibodies used to treat the coronavirus. In this Motley Fool Live video recorded on Jan. 22, 2021, healthcare and cannabis bureau chief Corinne Cardina and contributor Adria Cimino discuss why it's been a challenge to increase use of these treatments -- and what Lilly and Regeneron say about their performance against new strains of the virus.

Corinne Cardina: We've got a little bit of bad news about these variants and it relates to the COVID-19 treatments. Not the vaccines, but the antibody cocktails and even some of the plasma treatments for people who are already infected. It's looking like some of these treatments are not holding up against the variants. There have been some scientists from South Africa that published a paper that basically says the new variant escapes from three classes of therapeutically relevant monoclonal antibodies, as well as complete escape from neutralizing antibodies in COVID-19 convalescent plasma. These treatments have already experienced quite a few problems. It seems like doctors aren't really sure when to administer these treatments because it's a little bit hairy, it's like it's for people who are not necessarily ready to be hospitalized with COVID-19, but they are basically infusion treatments. So, when the hospitals are overwhelmed, where are you going to infuse patients who don't need to be hospitalized? These treatments, they're not as straightforward as they seem. Adria, does this news about the treatments not holding up as well against the new strains impact companies like Eli Lilly and Regeneron, both of which have authorized treatments in the U.S.?

Adria Cimino: Yes, absolutely. As you mentioned, Corinne, it already has been a bit of a problem where these are infused treatments. Actually, I've heard some people actually feeling that, "Oh, I kind of feel OK so I don't want to sit around and have an infusion that will last an hour and be in contact with other COVID patients" and things like that. That's already been a challenge for these companies. Now, Eli Lilly's CEO said that the variant from South Africa could evade their medicines because it has more dramatic mutations than the U.K. -- to the spike protein -- than the U.K. one. However, he does think that the antibody drug would still work against the U.K. strain. At least one of them could be OK. But even Dr. Fauci had mentioned that the South Africa strain is more worrisome even for vaccine. That isn't surprising to hear one of these companies say that. As far as Regeneron goes, the news is a little bit better. The CEO said that their dual antibody therapy -- they're the ones making the antibody cocktail -- will likely be effective against both. But I guess we can say at this point, it's still something to monitor closely because the story isn't over.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.