AstraZeneca (NASDAQ:AZN) still isn't a player in the U.S. market with its COVID-19 vaccine. However, the big drugmaker recently filed for U.S. Emergency Use Authorization (EUA) for a promising COVID-19 antibody therapy. In this Motley Fool Live video recorded on Oct. 6, Motley Fool contributors Keith Speights and Brian Orelli discuss how big the market opportunity might be for AstraZeneca's COVID-19 therapy.

Keith Speights: On Tuesday, AstraZeneca filed for Emergency Use Authorization for its COVID-19 antibody therapy. Brian, how does this therapy work and there are others already on the market. Do you think there's a big market opportunity here for AstraZeneca?

Brian Orelli: This is an antibody unlike Regeneron's and Eli Lilly's and then there's also one from GlaxoSmithKline and Vir Biotechnology. They use these treatments. They can also be used as post-exposure prophylaxis. You know somebody who got COVID-19 and then you start taking these antibodies so that you can prevent you from getting COVID-19.

But AstraZeneca is using it as a prevention in people who otherwise couldn't develop antibodies. Let's say you're on chemotherapy or you're taking an immunosuppressant for an organ transplant, this is before you might get exposed, but you're pretty sure that your vaccine is not creating antibodies at a level that would protect you. It's two antibodies in this drug and then it's been optimized with AstraZeneca's YTE half-life extension technology.

That more than triples the durability of the antibodies compared to conventional antibodies. They can last much longer in your system. They inject them into patients and then they just hang out there and if they come across the coronavirus, then they bind to it and they stimulate the rest of the immune system to react to the coronavirus. The antibodies reduce the risk of developing symptomatic COVID-19 by 77%.

It seems like the drug is definitely working and helping these patients. I think it's a fairly small market here so we're talking about only people who are on a chemotherapy or an immunosuppressant who can't develop antibodies to a vaccine. Basically, the only people who are going to get this are people who would normally get a vaccine but can't get a vaccine.

If you're not willing to get a vaccine, you're probably also not willing to go get an AstraZeneca shot to prevent COVID-19. That doesn't make any sense. You must just go get the vaccine. I think that rather than people who are otherwise exposed might be more likely to go get a --

That's probably the larger market than what AstraZeneca is going after, where it's just people who are in this rare situation where they would want to get a vaccine, but they either maybe even did get a vaccine. But their doctor's pretty sure that the vaccine is not going to help them as much as somebody else as it would help somebody else and so you would also could this antibody shot.

Speights: I think you're right, Brian, and the other thing is, there are companies including Merck and Pfizer who are testing oral therapies, pills that could be used for post-exposure prophylaxis and obviously, if you have a choice of a prophylactic that you can take in pill form versus having to go get a needle stuck in you, you're going to go with the pill.

Orelli: Yeah, it's obviously a lot easier.

Speights: Yeah, I think AstraZeneca's opportunity here is fairly small, as you said.

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