No one is complaining about the efficacy of Pfizer's (NYSE:PFE) COVID-19 vaccine in providing protection against the currently dominant coronavirus strain in the United States. However, there are concerns about how effective the vaccine might be against emerging variants. In this Motley Fool Live video recorded on April 14, 2021, Motley Fool contributors Keith Speights and Brian Orelli discuss whether or not Pfizer's vaccine will be able to beat the South African variant.

Keith Speights: Results from a real-world study conducted in Israel were announced recently and it showed that the South African variant that's caused a lot of concern, the South African variant could evade Pfizer's COVID-19 vaccine. Brian, what do you make of this particular analysis, and could Pfizer's vaccine face some big problems with this coronavirus variant?

Brian Orelli: This wasn't a placebo-controlled trial, it was more of a surveillance study. They looked at people who were infected with the coronavirus over the same time period and then they broke them into two different groups, the group that had been previously vaccinated and the group that hadn't been previously vaccinated, and then they asked what strains of the virus had caused the infection.

In unvaccinated people, the South African variant was 0.7% infections, so that would be like basically the baseline of the viruses in Israel. Then people who had been vaccinated with Pfizer and BioNTech's vaccine, the South African variant, meet up 5.4%, seven times as much as something, eight times as much.

It's hard in a study like this to back that out and put it as an efficacy number because obviously, there's a heck of a lot less people who were vaccinated that got infected than there were unvaccinated people who got infected if you look at the two populations. But that's not what we're measuring. We're just assuming they got infected what percentage of the people have the South African variant.

All this tells us really is that the vaccine is less protective against the South African variant than it is against the regular variant. But clearly, as we already knew, the vaccines are 100%.

Speights: It's not surprising in the least that any of these vaccines would be less effective against the South African variant. I think that's old news. We've known that for at least a couple of months probably, that none of the currently available vaccines are quite as effective, we don't know exactly how effective they are going to be against the South African variant.

It's also important to remember that several of these top companies have efforts under way targeting these variants specifically. Pfizer, for example, is already evaluating a third booster dose to see how that works. The company is looking at a modified version of its vaccine that targets the variance specifically, Moderna is testing a modified version of its vaccine that targets the South African variant.

I think there's reason for optimism that we're going to have vaccines that are safe and effective against any of these new emerging variants.

Orelli: Pfizer did do a study where they showed 100% efficacy against the South African variant. But I think if I recall correctly, it was like six or eight in the placebo group and none in the vaccinated group. Even if it's 95% or 90% or 80%, I don't think you would have expected to see 1 in 6 necessarily.

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