Messenger RNA (mRNA) is a new class of drugs that involves injecting mRNA that code for specific proteins into a patient and letting the patient's cells make the protein. In this video from Motley Fool Live recorded on November 23, Corinne Cardina, bureau chief of healthcare and cannabis, and Brian Orelli, Fool.com contributor, discuss how the technology can be used to create vaccines and the differences between the vaccine candidates that are under review by the Food and Drug Administration.

Corinne Cardina: Let's back up a little bit and look at the data that we got over the past couple of weeks from Pfizer (NYSE:PFE) and Moderna (NASDAQ:MRNA). Both of these companies shared very impressive efficacy data from their phase 3 trials of their respective candidates, Pfizer with its German partner, BioNTech (NASDAQ:BNTX). They actually submitted for emergency use authorization to the FDA. They have that application, and I don't think Moderna will be too far behind. Brian, can you remind us a little bit about how the mRNA approach works and why it will be so exciting if an mRNA vaccine is launched on the market?

Brian Orelli: Yeah, it's a new class of vaccines. No other vaccines have ever used this technology, but it was in development. The technology was in development before the coronavirus pandemic started. If you remember back to your high school biology, I guess you just start off with DNA -- DNA makes mRNA, and then mRNA makes the actual protein, so instead of where AstraZeneca and Johnson & Johnson are putting in DNA, and then I skip that step when I was explaining it, but it makes mRNA and then mRNA makes the protein. Instead of starting with DNA, they are starting with the mRNA. They put the mRNA in cells, and then it works the same way as the other vaccines.

Cardina: Great. Are there any differences between Pfizer's trial and Moderna's trial that investors should take note of?

Orelli: Yeah, so the Pfizer trial looked at, the readout was one week after the second dose. So when you start measuring the COVID-19 cases, they started counting. So if you got COVID-19 between your first dose and your second dose, or even a few days after your second dose, they didn't count any of those, whether you were in the vaccine group or the placebo group, and then Moderna used two weeks later. So in theory, Pfizer can say that they're protecting people a week earlier than Moderna. We don't actually know if that's the case, because Moderna just didn't count any of those cases. But that's the difference. Then in terms of diversity for the two different clinical trials, they were about the same. Pfizer had 42% diversity, but some of that came from outside the U.S. So if you look at just the U.S. it was 30%, Moderna was 37%, and they were all in the US,. In terms of age, the data that I found is sort of harder to compare because they don't break down the age groups completely. So Pfizer had 45% U.S., participants were age 56-85, and then Moderna had 23% of patients that were over the age of 65. So they're definitely including older people, though it's sort of hard to tell because Pfizer goes down to 56, and Moderna starts at 65.

Cardina: Great. So let's talk a little bit about what we do know and what we don't know about the Moderna and Pfizer vaccine candidates. So both of them require two injections. Moderna's is two injections that are four weeks apart, Pfizer's are two injections that are 21 days apart. Moderna's, their interim data showed 94% effective. Pfizer said that theirs was 95% effective in preventing COVID-19, and there's some differences in how these vaccine doses have to be stored. So Pfizer's requires more, colder refrigeration, so there's a little bit of a distribution challenge. They did announce a pilot delivery program in Rhode Island, Texas, New Mexico and Tennessee, to try and address some of these distribution challenges. I know the CEO has said, ''I don't think this is going to be as big of a deal as people think it is; we're going to figure it out.'' Do you have any thoughts on the cold chain and the refrigeration requirement of Pfizer's dose?

Brian Orelli: Yeah, I mean, I think it's definitely going to be a challenge, but I think it's going to be doable. I think the biggest issue is like long-distance shipping; that can be a problem because we don't have that many trucks, and I know that there aren't any ships that can move things at that cold of a temperature. Then in terms of storage, we don't have that many freezers that are at that temperature, and they're definitely going to be, so it's more likely that it's going to be a big distribution where it will be one area that everybody will come to, versus everybody going to different pharmacies. So if the Moderna's can be stored at frozen temperature which is just average everyday freezer, so that one can be distributed individually to individual doctor's offices and pharmacies, where I think Pfizer's is most likely going to be, everybody will come to one central location and they'll do it out there.