It hasn't been a secret that the COVID-19 vaccines developed by Pfizer (PFE 2.40%) and Moderna (MRNA -0.58%) are highly effective. However, the Centers for Disease Control and Prevention (CDC) recently announced new data about just how effective the messenger RNA (mRNA) vaccines are. In this Motley Fool Live video recorded on June 9, Motley Fool contributors Keith Speights and Brian Orelli discuss what investors should make of the latest CDC data.

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Keith Speights: The CDC released some new data this week, Brian, on messenger RNA vaccines efficacy. Of course, they're talking about the only two mRNA vaccines that have already received Emergency Use Authorization, Pfizer's and Moderna's vaccines.

Brian, what are the key takeaways from the CDC's announcement, and was there anything that might really matter for the long-term prospects for either Pfizer or Moderna here?

Brian Orelli: The CDC data, the real-life data showed a reduction in the risk of infection by 91%. That's pretty close to what we've seen in the clinical trials which I think were in the 96% range or something in that range. This includes asymptomatic infection.

It was done in healthcare workers with routine testing, so you would expect that it would be slightly lower because the clinical trials measured people who had actual symptoms before you could actually give them the test. When you look at fully or partially vaccinated people who developed COVID-19 they spent an average of six fewer days sick, and two fewer days in bed.

They also had about 60% lower risk of developing symptoms. From a long-term investment prospect, I don't think if this really changes very much, the vaccines clearly work in the short term. The question from an investor's perspective is how long will they work, and whether they'll continue to work against the variants. This study unfortunately doesn't answer any of those questions.

Speights: To me, there were no big surprises from the CDC's latest data and nothing that changes in any material way the dynamics for either Pfizer or Moderna.

Orelli: It's good because this is a real-life study as opposed to a controlled clinical trial. Data tends to not be as good in real life than it does in controlled clinical trials because you're limiting the patient population in clinical trials.

I think that the fact that it was so close and they were actually looking at asymptomatics or would you expect to go down a little bit. I think that's generally good news, but not enough good news that we weren't expecting it.