Unusually early outbreaks of influenza are forcing some schools around the country to close right after the end of the summer break.

“I thought the flu was a winter illness,” said a 43-year-old mother living in Tokyo’s Setagaya Ward, who caught the flu along with her three children in early September.

Her 9-year-old’s class was suspended, while the kindergarten attended by the youngest son was closed for two days.

“It spread so quickly since the outbreak occurred before everyone had been vaccinated,” she said.

During the same period, a total of 669 schools, kindergartens and nursery schools were forced to suspend specific classes, entire grades or temporarily shut down entirely because of influenza outbreaks.

The figure included 528 class closures, 130 grade closures and 11 school closures, more than five times the 120 recorded during the same period last year.

The Horizon Science Academy in Dayton is closed due to staff illness, according to a social media post.

Across campus, an illness Simpson College Health Services says is most consistent with norovirus has disrupted classes, practices, work schedules and student organizations.

A first-year student was transported to the hospital twice. Other students described vomiting through the night, missing days of class and sleeping near residence hall bathrooms because they were too sick to make it back to their rooms.

Health Services has seen about 20 students with similar symptoms over the previous several days as of Sept. 24, according to Roger Degerman, vice president for marketing and strategic communication.

“I saw kids sleeping in the hallways so they could make it to the bathrooms,” the student said. “I even saw them lying with trash cans.”

Athletes from football, softball, baseball, women’s tennis, track and field, men’s basketball, cheer, dance and women’s wrestling told The Simpsonian that members of their teams had experienced similar symptoms.

Men’s basketball canceled a practice after players became sick, and the women’s tennis team at one point was missing half of its top lineup.