ANN ARBOR, Mich. (NewsNation Now) — Health experts are investigating a flu outbreak that is impacting the University of Michigan right before Thanksgiving break.

There have been more than 500 cases diagnosed since Oct. 6, with 77% of those afflicted not vaccinated against the flu, the university said Monday. The Centers for Disease Control and Prevention is sending health investigators to campus.

“Partnering with the CDC will accelerate our understanding of how this flu season may unfold regionally and nationally in the setting of the COVID-19 pandemic,” said Dr. Lindsey Mortenson, medical director at University Health Service in Ann Arbor.

The university is also partnering with local health officials to monitor the situation.

“While we often start to see some flu activity now, the size of this outbreak is unusual,” said Dr. Juan Luis Marquez, medical director at the Washtenaw County health department.

Experts are recommending flu shots.

“This outbreak doesn’t necessarily have an immediate impact on the broader local community, but it does raise concerns about what the flu season may bring,” Marquez said.

According to the University of Michigan’s records, there are more than 50,000 enrolled the 2021-2022 school year.

NewsNation’s Paul Gerke broke down the flu cases by season on “Morning in America.” You can watch the full smart board breakdown in the player below.