We often refer to coronavirus vaccine makers as "rivals." But there actually is room for many of these players, considering global need for a vaccine. Several of these companies and their vaccines are necessary to help the world reach herd immunity. In this Motley Fool Live video recorded on Dec. 11, 2020, Healthcare and Cannabis Bureau Chief Corinne Cardina and Fool.com contributor Adria Cimino discuss the five players closest to the vaccine finish line -- and the level of immunity needed to stop the pandemic.

Corinne Cardina: I would love to talk about this great article that you wrote. The headline is: Why We Need All Five of These Coronavirus Vaccine Companies to End the Pandemic. I am dropping the article in our Zoom chat, so viewers can check it out. Can you tell me about your thesis here and what investors should know?

Adria Cimino: Sure. It kind of goes back to what I was saying earlier about the idea that everybody can be vaccinated in a short period of time isn't really realistic because basically just one of these companies doesn't have the capacity to vaccinate everyone. We really need many of them. I'm referring to Pfizer (NYSE:PFE), Moderna (NASDAQ:MRNA), AstraZeneca (NASDAQ:AZN), Novavax (NASDAQ:NVAX), Johnson & Johnson (NYSE:JNJ). Those are the five American, Western European, UK companies that are involved in this race. If we count up, they've all said how many doses they could produce by the end of next year. If we count all of that up, and we count the entire population of the world is 7.8 billion people. If we consider all the doses, and how many of those companies, they're two dose vaccines except Johnson & Johnson. Johnson & Johnson is one dose. J&J has said that they are going to do one billion doses, so that means one billion people, whereas the other companies, you have to divide it in half because of the two-dose regimen. When we total everything together, we get 8.3 billion doses, and now that fall short of 9.4 billion doses needed. At this point, we really do need all of the players. Considering that everybody wants the vaccine, we would need all of those players and probably more.

Corinne Cardina: Absolutely. A lot has been said about herd immunity. I think some of us are not really sure what that means. It makes us feel a little bit like cattle. [laughs] What does that mean and why does it matter?

Adria Cimino: It really does feel like cattle. Basically, it means that we have to have a certain percentage of the population that is immune to a certain virus. Now, we can get that from just being exposed to the virus and everybody getting sick. Or you can get that way from a vaccine so that everyone is immunized from a vaccine. Or a little bit of both. In this case, it's probably going to be a bit of both because there are obviously a lot of people who've had coronavirus and have been exposed. And now the idea is to vaccinate as many people as possible so we can reach herd immunity. Now, it depends on the percentage of the population needed to be immunized. It depends on the illness. It depends on the virus. In this case, researchers are saying it's about 67% of the population to reach herd immunity. So we have to vaccinate a good percentage to get there. It really does matter. It really is something important to get as many people vaccinated as possible to try to reach that. And the idea of that is that it would stop the transmission of coronavirus and stop the pandemic eventually.

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.