Los Angeles Unified School District testing revealed more than 78,000 coronavirus cases among students and staff ahead of the start of the spring semester, authorities announced Tuesday.

The new semester began with 30% of LAUSD students absent on the first day.

The district mandated coronavirus testing for all students and staff, regardless of vaccination status, in response to a record-breaking COVID-19 surge fueled by the omicron variant. Baseline testing became available on Jan. 3, with the district also later handing out rapid at-home COVID-19 tests.

Since then, tens of thousands of students and staff were found to be positive, with 15% of employees and 17% of students testing positive, according to data from LAUSD.

Despite the case numbers, campuses in the nation’s second-largest school district welcomed hundreds of thousands of students back from the winter break on Tuesday.

“Our positivity rate remains lower than the overall county positivity rate as a result of our heightened safety measures and the continued partnership of families and employees,” the district said in announcing the case numbers.

Countywide, the coronavirus test positivity rate stood at 21%, with 34,827 new cases reported on Tuesday, according to the L.A. County Department of Public Health.

Long lines were seen outside many schools Tuesday morning, with students arriving with backpacks and negative COVID-19 test results in tow.

At a Sylmar middle school Tuesday, L.A. Mayor Eric Garcetti stressed that keeping children at school is crucial.

“This is the most important thing,” Garcetti said. “All of our efforts need to go to ensure that our kids are in school, and can stay in school, so that parents can work and we don’t go back to where we were a year ago.”

Early data showed that nearly 70% of LAUSD students attended the first day back, according to the district, which noted that that number could change.

About 2,000 teachers were also out on the first day, with substitutes and certificated non-school staff covering for them, according to LAUSD.

“We have an amazing sub staff that we utilize all the time,” L.A. Unified Interim Superintendent Megan K. Reilly said. “A lot of our alumni are kind of like coming back to help out during this period.”

At some points, long lines formed due to technical issues with the district’s health screening system, the Los Angeles Times reported.

The system, Daily Pass, is what students had to upload their negative coronavirus results so they could be allowed on campus, and it was strained during the morning rush.

But not everyone had uploaded their results onto the app. About 88% of students had their results on Daily Pass by the first school day, according to LAUSD.

District students and staff were returning to a multitude of COVID-19 safety measures, including having to mask up outdoors.

“L.A. Unified is prepared for this,” L.A. School Board Vice President Nick Melvoin said. “We’ve had the safest standards in the nation for over a year.”

Some parents told KTLA they were nervous about bringing their children back to school amid the coronavirus surge.

“I was hoping for two more weeks off, just to be safe,“ Parent Loja Moses said.

Many parents noted that their children had been eager to return to their classrooms, and wouldn’t want to return to remote learning.

“My kids have been anxious to come back,” parent Claudia Chacon said. “They want to see their friends, they want to come back to the environment.”