How effective are COVID-19 mRNA vaccines in the real world?

Dr. Jen Ashton has the latest vaccine efficacy numbers from the CDC.
2:06 | 03/30/21

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Transcript for How effective are COVID-19 mRNA vaccines in the real world?
Let's start as we often do, of course, giving you an update on where we are in this country with the numbers that we get from Johns Hopkins university. 127.6 million cases diagnosed around the world. New tragic milestone reached in the U.S., 550,000, more than 550,000 American lives lost to this virus. CDC updating the numbers here of vaccinated, though, of folks with doses in the arm, more than 145.8 million doses have been given out. So some encouraging news from the CDC about efficacy of mrna vaccines in real world situations. That's key. That is the key, T.J., because clinical trial data is important but we want to see what happens in real world situations and environment and yesterday we got an early look at that by the CDC so let's take a look at what they did. They looked at about 4,000 people, most of them healthcare workers, essential workers, first responders, so high rates of exposure to covid, and they found the risk of infection was reduced by 90%, that's symptomatic and asymptomatic infection two weeks after both doses and guess what, after just one dose, two weeks after the first dose, lowered the risk of infection by 80%. Really, really good news and as I said, this was really one of the first studies that showed these vaccines did lower the risk of asymptomatic infection because, remember, that was an unknown when we got fda authorization. Okay, encouraging news from the CDC and an ominous warning from the CDC as well. Here's the bottom line. We are seeing cases go up in at least 24 states. The assumption is that is being driven by these variants which are more transmissible. We cannot take our foot off the gas about these mitigation measures right now. We have to be able to walk and chew gum at the same time or we jeopardize that light at the end of the tunnel which is looking at us and within reach. But if our behavior doesn't fall in line with that, we'll end up taking steps back. Dr. Ashton, thank you.

This transcript has been automatically generated and may not be 100% accurate.

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