CHICAGO (CBS) — For the first time, we’re learning there are cases of the COVID-19 variant called Delta in Chicago.

The fast-spreading variant devastated India and is now the dominate strain in the UK.

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CBS 2’s Jim Williams reports on the new variant and how well the COVID vaccine works against it.

First detected in India, and spreading rapidly there, the Delta variant is now the dominant strain of the coronavirus in the United Kingdom with an estimated 60% of new cases in the UK.

University of Chicago infectious disease Doctor Anu Hazra said there’s good reason to be concerned.

“The Delta variant has shown to be more contagious and more lethal both in South Asia and in the UK,” Hazra said.

That is, more contagious and more lethal among those who have been not been vaccinated.

Those who’ve had the shots are largely protected against the Delta variant, according to Doctor Hazra.

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“In the UK, we have a good amount of evidence to show while there may be vaccinated people who become infected with the Delta variant, their hospitalizations and deaths remain low to nothing in those folks,” Hazra said.

“All three of our existing COVID vaccines in the U.S. continue to be broadly protective against all of the known variants.”

Chicago Department of Public Health Commissioner Doctor Allison Arwady said 12 cases of the Delta variant have turned up in the city.

“The good news is that, at this point, we have not seen concerns with variants making people significantly sicker here or the Delta one being very widespread,” Arwady said.

But with so many Americans still unvaccinated and communities opening up this summer, millions could be vulnerable to the Delta variant.

“It’s important to note 50% of the United States is still unvaccinated,” Hazra said. “And so those folks are still at risk and particularly at risk of this more contagious variant particularly as begin to open up and start to re-socialize this summer.”

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The World Health Organization said the Delta variant has spread to 62 countries, but it is hitting young people the hardest.