SAN FRANCISCO (AP) — California will become the first state in the nation to require all teachers and school staff to get vaccinated or undergo weekly COVID-19 testing.

The statewide vaccine mandate for K-12 educators comes as schools return from summer break amid growing concerns of the highly contagious delta variant.

Democratic Gov. Gavin Newsom announced the new policy Wednesday as he visited a San Francisco Bay Area school that has already reopened after summer break.

Several large school districts in the state have issued similar requirements in recent days, including San Francisco, Oakland, San Jose and the Long Beach Unified school districts.