Originally Published: 11 AUG 21 11:02 ET

Updated: 11 AUG 21 16:16 ET

By Kyung Lah, Cheri Mossburg, Sarah Moon and Ray Sanchez, CNN

(CNN) -- California Gov. Gavin Newsom announced Wednesday that teachers and other school employees must either be vaccinated against Covid-19 or submit to regular testing.

California will become the first state in the nation to implement such a requirement.

"To give parents confidence that their children are safe as schools return to full, in-person learning, we are urging all school staff to get vaccinated," Newsom said in a statement. "Vaccinations are how we will end this pandemic."

Two unions representing more than 550,000 California teachers and school employees expressed support for the requirement on Wednesday.

The order from the California Department of Public Health will take effect Thursday and schools must be in full compliance by October 15, according to the statement. All school staff must either show proof of full vaccination or be tested at least once a week.

"We think this is the right thing to do," Newsom told reporters. "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, and that is knowing that the schools are doing everything in their power to keep our kids safe."

The order will closely mirror a similar mandate that all California health care workers become vaccinated.

The mandate was first reported by Politico on Tuesday night.

School districts in San Francisco, Oakland, Sacramento, and Long Beach have already implemented such a measure. The state's largest school district, Los Angeles Unified, has required weekly Covid testing, but stopped short of mandating educators be vaccinated.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, has voiced his support mandating that teachers be vaccinated.

"I'm going to upset some people on this, but I think we should," he told MSNBC on Tuesday, when asked if he thought teachers should be required to get vaccinated.

"We are in a critical situation now," he added. "We've had 615,000-plus deaths and we are in a major surge now as we're going into the fall, into the school season. This is very serious business. You would wish that people would see why it's so important to get vaccinated."

'This disease is now a choice'

Most districts and unions in California have been supportive of the health order, according to sources.

Randi Weingarten, president of the American Federation of Teachers, who has noted that 90% of its teachers are vaccinated, told CNN Tuesday that union affiliates in California support the mandate.

"We know that vaccines are the single most important tool for us confronting Covid and protecting people," she said.

Newsom's statement on the mandate included endorsements from California Teachers Association President E. Toby Boyd; California Federation of Teachers President Jeff Freitas; Association of California School Administrators President Charlie Hoffman; California County Superintendents Educational Services Association President and Alameda County Superintendent of Schools L.K. Monroe; and California Charter Schools Association President and CEO Myrna Castrejón.

Boyd said the mandate was an "appropriate next step to ensure the safety of our school communities and to protect our youngest learners under 12 who are not yet vaccine eligible from this highly contagious Delta variant."

The California Teachers Association, which represents roughly 310,000 educators in the state, said nearly 90% of teachers had already been vaccinated.

The order also has the backing of the California School Employees Association, which represents more than 250,000 school support staff, including those in transportation, food services, security, maintenance and others.

California is home to more than 1,000 school districts employing more than 300,000 teachers, with about 6.1 million students.

"This disease is now a choice," Newsom said. "The one thing that can end this pandemic once and for all is available in abundance to everybody."

California leads the nation in vaccinations, with more than 46 million doses administered and over 77 percent of those eligible having received at least one dose, but Newsom's statement said the state is seeing increasing numbers of unvaccinated people being admitted to the ICU and dying.

Last month, Newsom said California will require all state employees and health care workers to provide proof of vaccination status or get regular testing amid a surge of cases from the highly contagious Delta variant.

Employees are required to prove they have received the vaccine by showing their vaccination cards or through a verification code provided by the California Department of Public Health.

Unvaccinated state employees are required to get tested at least once a week and to wear N95 masks at all times. Unvaccinated health care workers have to get tested at least twice a week, health officials said.

The Department of Veterans Affairs and New York City have similar Covid-19 mandates for employees.