MARIN COUNTY, Calif (KRON) — At least 56 Marin County eighth-graders have tested positive for COVID-19 after returning from a trip to Washington D.C.

It’s an annual tradition that was paused for two years due to the pandemic. The county’s public health department has since issued health guidelines to all middle schools..

Superintendent Mary Jane Burke says the trip was not planned by the school district. Instead, a national agency organized the trip. Burke did not name which schools were involved but says the district is taking extra safety precautions.

“As we move into this time when we’re looking at COVID becoming more part of our every day lives that it will be so important that people are constantly evaluating what decisions they make for higher risk activities,” Burke said.

A subset of 77 students from two county schools returned Sunday, 22 tested positive before returning to school the next day.

As of Tuesday 56 students have tested positive and have reported mild or no symptoms. No one was hospitalized.

County Public Health officer Dr. Matthew Willis addressed the situation in Wednesday’s weekly school meeting.

“One of the reasons why this has not had a significant impact is 90% of our eighth graders are are fully vaccinated. One of the highest rates in the nation,” he said. “Safe travel means knowing the risks for spread once they are infected,” Willis said. “We have not seen evidence yet for any in school transmission.”

“As we move into this time when we’re looking at COVID becoming more part of our every day lives that it will be so important that people are constantly evaluating what decisions they make for higher risk activities,” Burke said.

Willis adds 50% of eighth-graders are boosted. He says the best protection to stay ahead of COVID-19 outbreaks and variants remains the vaccine.