(CBS Detroit) — Michigan health officials on Friday said the omicron variant, which was first detected in Kent County, has been identified in Wayne, Oakland and Washtenaw Counties.

The variant was also detected in Genesee County, bringing the state to a total number of six cases as of Dec. 17. More than 20 states have confirmed omicron detections.

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Oakland County officials said the confirmed case there was determined in a resident who was vaccinated and traveled internationally but had not received the booster shot. That resident denied having any close contacts since returning home.

“We are concerned, although not surprised, about the discovery of the Omicron variant in Michigan,” said MDHHS Director Elizabeth Hertel after the first case was identified.

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“We continue to urge Michiganders ages 5 and up to get vaccinated and continue participating in measures we know slow the spread of the virus by wearing well-fitting masks properly, socially distancing, avoiding crowds, washing their hands often and testing for COVID-19. Vaccines are our best defense against the virus and how we can manage the spread of COVID-19.”

According to the Centers for Disease Control and Prevention, the omicron variant, B.1.1.529, was reported to the World Health Organization on Nov. 24. It was detected in Botswana on Nov. 11 and in South Africa three days later.

On Nov. 30, the variant was classified as a variant of concern by the CDC. The first in the United States was identified on Dec. 1.

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