California Gov. Gavin Newsom speaks at a news conference Wednesday at an elementary school in Oakland. Newsom announced that California will require its 320,000 teachers and school employees to be vaccinated or submit to weekly COVID-19 testing. Santiago Mejia/San Francisco Chronicle via AP, pool

SAN FRANCISCO — California will become the first state to require all teachers and school staff to get vaccinated or undergo weekly COVID-19 testing, as schools return from summer break amid growing concerns about the highly contagious delta variant, Gov. Gavin Newsom announced Wednesday.

The new policy applies to both public and private schools and will affect more than 800,000 employees, including about 320,000 public school teachers and a host of support staff such as cafeteria workers and cleaners, the state Department of Public Health said. It will also apply to school volunteers.

Newsom announced the new policy at a San Francisco Bay Area school that reopened earlier this week to in-person classes. Many California schools are back in session, with others starting in the coming weeks.

“We think this is the right thing to do, and we think this is a sustainable way to keeping our schools open and to address the number one anxiety that parents like myself have for young children,” said Newsom, who is a father of four. “That is knowing that the schools are doing everything in their power to keep our kids safe.”

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

California, like the rest of the country, has seen a troubling surge in COVID-19 infections because of the delta variant, which represents the vast majority of new cases. It has affected children more than previous strains of the virus, prompting a growing number of teachers unions to ease earlier opposition to vaccine mandates.

California’s two largest teachers unions, both powerful political allies to the governor, said Wednesday they fully supported Newsom’s policy.

The California Teachers Association and the California Federation of Teachers both cited state and national polling that indicates nearly 90% of educators have been vaccinated but said the rising spread of the delta variant, particularly among children, makes the new policy necessary. Children under 12 are not yet eligible to be vaccinated.

“Educators want to be in classrooms with their students, and the best way to make sure that happens is for everyone who is medically eligible to be vaccinated, with robust testing and multi-tiered safety measures,” CTA President E. Toby Boyd said in a statement.

While Hawaii Gov. David Ige announced last week that all Department of Education staffers would be required to disclose their vaccination status or face weekly testing, California’s order is far more sweeping, applying to all staff who work in both public and private schools in the country’s most populous state.

Over the past few weeks, Newsom has mandated that all health care workers must be fully vaccinated and required that all state employees get vaccinated or choose weekly testing. The weekly testing schedule is based on guidance from the Centers for Disease Control and Prevention.

For schools, Newsom had already issued a mask mandate that applies to teachers and students. But until Wednesday, he had left the decision of whether to require vaccines up to local districts.

Vaccine mandates are perilous for the Democratic governor, who faces a recall election next month fueled in part by anger over his handling of the pandemic.

California was the first state to order a pandemic lockdown in March 2020, which shuttered businesses and schools statewide. While many private schools maintained in-person classes, most public schools kept students in distance learning for up to a year. Newsom faced intense political pressure to reopen schools from Republican opponents and supporters who urged him to override powerful labor unions. Many public schools finally reopened last spring, lagging much of the country.

Newsom pushed for a full return to in-person learning this fall. But his mask mandate for schools has angered some parents and been criticized by Republican candidates vying to replace him.

Several of the GOP candidates criticized the new plan Wednesday. Former San Diego Mayor Kevin Faulconer, who has encouraged everyone to get vaccinated, said state officials “should not be pushing uniform statewide orders on every school district across the state” but should leave it to local districts.

Details of how the new policy will be enforced were not announced. Labor unions say those logistics still need to be worked out.

Matthew Hardy, a spokesman for the California Federation of Teachers, said the union supports the plan that allows an option for testing.

“We do not think people should lose their jobs over this,” he said.

Schools are required to be in full compliance with the new policy by Oct. 15, giving schools time to verify vaccination status and have in place weekly testing for unvaccinated staff, said Amelia Matier, a spokeswoman in the governor’s office.

Newsom did not rule out expanding the requirement to students after a vaccine is approved for children under 12 years old.

“We’ll consider all options in the future,” he said, in response to a question. “We believe this is a meaningful first step.”