Just weeks after the school mask mandate was lifted in California, Los Angeles County is seeing an increase in school coronavirus outbreaks, health authorities said Thursday.

There were 14 school outbreaks reported in the county in the seven-day period ending April 5, including 12 at elementary schools and two at high schools, according to the L.A. County Department of Public Health.

“We’ve more than tripled the number of new outbreaks at schools this past week, and we’re seeing similar numbers of outbreaks to what we experienced during the omicron surge,” L.A. County Health Director Barbara Ferrer warned.

The rise in outbreak numbers is likely tied to the increased spread of the highly contagious BA.2 omicron subvariant, as well as the lifting of indoor masking requirements at schools and the change in the state’s quarantine guidance, Ferrer said.

California state officials and L.A. County dropped school masking requirements after March 11, though the face coverings remained strongly recommended.

The L.A. Unified School District followed suit on March 23, allowing students and teachers to shed their masks indoors in classrooms as district officials said the availability of vaccines had “changed the game.”

Restrictions were eased throughout the state as case numbers were declining following the omicron-fueled winter surge.

Now, L.A. County’s COVID-19 rates are beginning to level off and case numbers are no longer declining.

Ferrer said that while the number of school outbreaks is relatively low, it is “concerning” because it means there’s more virus transmission on campuses.

L.A. County authorities have also been seeing a higher number of cases associated with recent outbreaks, Ferrer said.

In one example, a currently-active COVID-19 outbreak at a high school began with 26 cases and has since grown to 60 cases.

The good news is that health officials have noticed that the increase in outbreaks is not linked to a spike in coronavirus test positivity.

And since L.A. County’s emergence from the winter surge, there hasn’t been an uptick in cases among staff and students at schools.

Still, health authorities are advising parents to have their children mask up at school, even if it’s no longer required. And schools are being told to improve ventilation, monitor people for COVID-19 symptoms, make sure people exposed are tested and not allowing those who test positive to come to school.

Health authorities have also been pushing for more people to get vaccinated and boosted, with Ferrer warning that outbreaks are more common in the lower grades, where there are often much lower vaccination rates for children.

“Should we continue to see increases in the number of outbreaks at schools we’re going to work with our school partners to determine what additional safety measures are warranted for those schools that experience on site transmission,” Ferrer said.