Pfizer (NYSE:PFE) and Moderna (NASDAQ:MRNA) no longer have the U.S. COVID-19 vaccine market to themselves. Johnson & Johnson (NYSE:JNJ) is now scrambling to crank up capacity to ship 100 million doses of its vaccine in the first half of 2021. In this Motley Fool Live video recorded on Feb. 24, 2021, Fool.com contributors Keith Speights and Brian Orelli discuss how J&J's vaccine might shake up the U.S. vaccine market.

Keith Speights: Let's assume that Johnson & Johnson's vaccine does win EUA, which we all expect, how do you think it's going to shake up the COVID-19 vaccine market in the US?

Brian Orelli: It's a single dose and it only has to be refrigerated which certainly helps their ability to make inroads in the market. They are going to get sales one way or the other because government is already committed to buying the vaccine.

In terms of when it will get used, we won't have significant amount of doses until April so that's going to put all the doses between now and then or most of the doses between now and then are going to be Moderna and Pfizer's vaccines.

In terms of where is it going to get used? Probably more in the rural areas. I wonder how much from a person standpoint are you just, I want a vaccine in a home care, or are there people that are going to want the Moderna and Pfizer vaccines over the Johnson & Johnson because it's of maybe a little bit higher efficacy.

But then on the other hand maybe people are going to want the Johnson & Johnson vaccine because you have to get one shot in the arm. So it will be interesting to see how it plays out in the general public's desire to get one vaccine versus the other.

Speights: You hit on something I've been wondering too, and I wonder if the government or governments with state governments having influence as well. I wonder if they're going to differentiate, or will it get to a point where people have a choice between which vaccine they receive? I don't know.

Let me ask you, Brian. If you had to pick, let's say they gave you the choice, Dr. Brian Orelli, which vaccine would you prefer to get?

Orelli: Let's be clear. It's a non-MD. I'm a PhD. [laughs]

Keith Speights: Biology!

Orelli: But based on my reading, I would tend to go with the higher efficacy, but I think the comparison is a little difficult because the variance are out now, and so the question is when is the variant going to be when I need to be protected? I think that makes things just really complicated in making a firm decision.

A month or two ago I would have picked Moderna or Pfizer. Now, I feel a little less sure of that because I think the protection for the variants is going to be the main threshold for likelihood of success.

The other thing I think is, Johnson and Johnson is going to have a harder time coming up with boosters because of the way their vaccine is delivered, it's delivered with a virus. You're going to create immunity to that virus, it delivers the DNA into the patient. I think that that's a big concern, and so I think the Pfizer and Moderna have a higher chance of being able to come in with booster shots compared to Johnson and Johnson's model.

Speights: Yeah, I guess my mindset is just, "Give me the shot." Whatever [laughs] it is, "Give it to me."

All of these vaccines, while their efficacy varies overall, all of them seem to be very effective at preventing severe cases of COVID-19. As you mentioned earlier, the FDA briefing document even pointed out that with the Johnson and Johnson vaccine, there were no cases that require medical intervention 28 days after vaccination.

I think we're seeing high efficacy across the board for these vaccines in preventing those severe types of cases. I think Americans should consider themselves very fortunate that we're going to have several vaccines available. Already have two, we'll likely have three and there are more coming more than likely as well.

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.