Michigan health officials are investigating a flu outbreak at a state university, which has resulted in more than 500 cases, according to ABC News.

The state has also seen a surge in flu activity in several schools.

Since October, the University of Michigan’s Ann Arbor campus in Washtenaw County has reported more than 525 cases among students – about three-quarters of them among people unvaccinated against the flu, according to school officials.

The university officials said they are tracking a “large and sudden increase” in flu cases, which have been reported in the past two weeks.

Dr. Juan Luis Marquez, Medical Director, Washtenaw County Health Department, said, “While we often start to see some flu activity now, the size of this outbreak is unusual.”

Officials from the Centers for Disease Control and Prevention (CDC) are helping the university and local and state health departments investigate the outbreak.

Meanwhile, the Michigan Department of Health and Human Services is urging people to get vaccinated against the flu.

The state department of health said, “This outbreak comes at a time when COVID-19 infections are again surging in Michigan, with case rates, positivity rates, hospitalizations and deaths all increasing.”

“State and local public health officials are concerned with the potential for increased strain on health systems if COVID-19 and influenza cases surge at the same time this winter,” it added.

Other universities are also experiencing flu outbreaks. For instance, Rowan University in Glassboro, New Jersey, has reported 150 flu cases since November 1.

Joe Cardona, Vice President for University Relations, Rowan University told ABC News that most of these cases occurred in the last week. The university has been holding flu vaccination clinics for students and staff this week.

Earlier this month, Florida State University and Florida A&M University also reported a spike in flu cases, according to the Associated Press.

Health experts have warned that this flu season might be more severe.

Dr. Lisa Maragakis of the Johns Hopkins Health System said, “We thought that the 2020-2021 flu season would be severe, but that didn’t materialize. It’s likely that because so many people were taking infection precautions against COVID-19 last year, that translated to a lower flu transmission rate as well.”

Dr. Natasha Bagdasarian, Chief Medical Executive, Michigan Department of Health and Human Services, said, “As we head into respiratory virus season, it is important to take every mitigation measure we can to prevent outbreaks of the flu, RSV, and COVID-19.”

“Wearing masks, washing hands, social distancing, and getting vaccinated for the flu and COVID-19 will help prevent the spread of illness,” she added.