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People infected with omicron have better outcomes than those with delta, study says


The U.S. is now reporting more than 500,000 new cases of COVID a day, more than twice the previous record set during last winter's surge. One of the big questions with this new omicron variant has been disease severity. And now researchers have published the first data looking at how severe omicron is in the U.S. compared to previous variants. Here to explain what they found is NPR's global health correspondent Michaeleen Doucleff. Hey there.


KELLY: So this new study - what specifically were researchers looking at?

DOUCLEFF: The study comes from Case Western Reserve University in Cleveland, but it looked at data from hospitals across the whole country, specifically health records for more than a half a million people. Now, most of the people were infected during the delta wave right before omicron arrived. But about 14,000 were likely infected with omicron near the end of December. And then the researchers looked to see if there was a difference in a person's risk of having severe COVID between the two groups - so the risk of having to visit the ER, being admitted to the hospital, ending up in the ICU or even being put on a ventilator.

KELLY: Well - and what'd they find? Was there a big difference between omicron and delta?

DOUCLEFF: Yeah. There was a clear and substantial difference. Dr. Pamela Davis is a pulmonologist at Case Western and a senior author on this paper. She says if you're infected during the omicron surge, the risk is lower for all the outcomes I just mentioned. For example, the risk of an ER visit drops by 70%.

PAMELA DAVIS: Hospitalization's a 56% reduction, ICU admissions, 66% - and mechanical ventilation, gosh, that's 84%.

DOUCLEFF: And Davis points out the risks were lower across all age groups, even in kids under age 5 who haven't been vaccinated and for kids ages 5 to 11 who haven't been boosted.

DAVIS: So it was remarkably consistent across the age groups when there are different conditions of vaccination across the age groups.

KELLY: OK. So hang on. She's saying, if I'm hearing her right, this is not just because more of us are vaccinated than when delta was at the peak of its surge - that this is something specific to omicron.

DOUCLEFF: Yeah, that's exactly what the study suggests. Davis and her team believe about 60% of the people in this study were vaccinated. So some of this could be due to vaccination, but the data altogether also suggest that omicron inherently in some way causes less severe disease compared to delta.

KELLY: OK. So if this is the case and this - we now have some data confirming what a lot of folks have been observing anecdotally, which is that people don't seem to be getting as sick with omicron, then help us square that with why we are seeing hospitalizations surging in a lot of places - here in D.C. and New York, New Jersey, Illinois, Maryland. A lot of states are seeing record numbers of people being admitted for COVID to the hospital.

DOUCLEFF: Yes. So hospitalizations are definitely surging and are expected to surge really across the whole country. And here's why. This number that Davis just mentioned are known as what's called relative risk. They tell you how much your risk is reduced, but they don't tell you your actual risk of getting hospitalized. That depends on personal factors like your age and your overall health. So for example, Davis says if you're over 65, even with omicron, your risk of being admitted to the hospital is still 5%. That means 1 in 20 people in this age group infected with omicron are going to end up in the hospital. And if you have heart disease or are overweight, that risk is likely even higher.

DAVIS: It's not as if you get off scot-free just because you happen to be in the omicron time. You get up in the older age range, as we saw earlier in the pandemic, you know, it's a nasty disease, even if it's less than the delta.

DOUCLEFF: So she says there are still going to be many, many people who are hospitalized and are in the ICU. And she urges everyone to get vaccinated and boosted to cut that risk.

KELLY: That message, at least, is consistent. Get vaccinated. Get vaccinated. Get vaccinated.


KELLY: NPR's Michaeleen Doucleff there with some of the first data looking at how severe omicron is here in the U.S. Michaeleen, thank you.

DOUCLEFF: Thank you. Transcript provided by NPR, Copyright NPR.

Michaeleen Doucleff, PhD, is a correspondent for NPR's Science Desk. For nearly a decade, she has been reporting for the radio and the web for NPR's global health outlet, Goats and Soda. Doucleff focuses on disease outbreaks, cross-cultural parenting, and women and children's health.