Moderna (NASDAQ:MRNA), Pfizer (NYSE:PFE), and BioNTech (NASDAQ:BNTX) have commanded coronavirus headlines since their vaccines earned Emergency Use Authorization earlier this month. But there are still other vaccine candidates working their way through clinical trials. Dr. Bruce Gellin of the Sabin Vaccine Institute joined Olivia Zitkus and Corinne Cardina of the Fool.com Healthcare and Cannabis Bureau on a Dec. 18 episode of Fool Live to talk about the tortoises of the race and what could give them an edge over the hares.

Olivia Zitkus: Beyond these two mRNA vaccines that the FDA advisory committee has reviewed, are there any other candidates now still on trial basis that you find particularly promising? You alluded to a one-dose vaccine earlier in the chat a few minutes ago.

Dr. Bruce Gellin: I love the headlines. Helen Branswell who writes for Stat and covers this headline, although they never write the headlines, somebody else does that, talked about the tortoise and the hare, and I thought this is an important reminder. We're watching now the hare, those who for a lot of reasons have come out hard and fast, keep an eye on the tortoises as well. I think when you think about that, we'll look at some of the things that maybe are not front-and-center right now, technologies are still emerging. But when I looked at this, we want to look at not just the technology, but a feasibility. We've learned a lot in watching the size of situation about a vaccine has got incredible performance. But it's really a bear to operationalize. Which so we've seen these trucks, we've seen freezers, we've seen dry ice. You guys are probably investing in all those different technologies related to that. Quite clearly, this is a complicated vaccine to deliver. The logisticians are on it and they're going to do their best on it. But it's clear when you think about broad availability, not just the United States but around the world, things that are simpler are going to matter. So I'm looking at those things, things that are one dose rather than two. Things that can be given, maybe oral, or through mucosal route, nasal spray rather than injection. Doing those things, I think are going to be game changers. Another one is the requirement for temperature. If you can have the product stable, you can already project how much easier just to get things around. I think there's a broad portfolio of those, a lot of different approaches taken, but I think as trying to think of the future in terms of the feasibility of the long term. Because I think we're going to need these kind of vaccines for the long term. I don't think we're going to eradicate this virus. We're going to need to learn to live with it.

Zitkus: Right. Yeah, we've got the one dose vaccine on the trial basis from Johnson & Johnson (NYSE:JNJ), our investors at the Motley Fool probably heard plenty about Novavax (NASDAQ:NVAX) this year, which is exploring a host pandemic combination flu and coronavirus vaccine, and then an oral tablet from Vaxart (NASDAQ:VXRT). So there are all these other possibilities that make Pfizer's extra cold required vaccine look a little bit more complicated in the real world.

Gellin: In a lot of ways. It's probably lucky that they came out of the box first, because further along, people will say, "Oh man that's hard." But because of the urgency, because of the performance, you are going to have to make hard work. But I think over time we will have to be looking at the approaches that provides both the protection but also make it an easier vaccine to deliver.

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.