California will become the first state in the United States to require all teachers and staff in its K-12 public and private school systems to be fully vaccinated or undergo mandatory weekly COVID testing, Governor Gavin Newsom announced Wednesday.

Like the rest of the U.S., California has seen a concerning spike in new COVID infections due to the highly contagious Delta variant, which now has become the dominant strain in the country. This new policy is part of the state's overall effort to keep its economy open while curbing Delta's spread.

The state-wide vaccine mandate will take effect Aug. 12, just in time for the new school year, with schools required to be in full compliance by Oct. 15, according to the governor's office. California will provide free testing to staff that are not fully vaccinated.

"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. Vaccinations are how we will end this pandemic," Newsom said in a press statement.

The new policy will affect the state's 320,000 public school teachers, more than 250,000 staff and roughly 80,000 private school employees, according to the California Department of Education and Labor Unions, NPR reports.

The state's new policy comes as schools in California begin to reopen after the summer break, with many starting sessions in the coming weeks.

"There's no substitute for in-person instruction, and California will continue to lead the nation in keeping students and staff safe while ensuring fully open classrooms," said Dr. Tomás Aragón, California Department of Public Health Director and State Public Health Officer, in a press statement.

Prior to the new mandate, California had already issued an universal mask mandate for all K-12 staff and students, regardless of vaccine status, in order to keep school environments safe and optimised for in-person learning.

The California Teachers Association and the California Federation of Teachers--the state's largest teachers unions--have both signalled support for the new policy, according to NPR, stating that Delta's rising spread, particularly among children, makes the state's new policy necessary. Currently, children under the age of 12 are not eligible for the jab.

Dr. Anthony Fauci, the nation's leading infectious disease expert, also supported mandatory vaccination policies for school teachers earlier this week, in an interview with MSNBC on Tuesday, citing the need to protect younger children.

"We are in a critical situation now," Fauci stated. "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."

Fauci noted that the vaccine mandates will not come from the White House, rather vaccine requirements will come from the state and local level at this time. Fauci added that he expects mandates to gain more traction once the U.S. Food and Drug Administration fully approves COVID vaccines, with both Moderna's (MRNA  ) and Pfizer (PFE  )-BioNTech's (BNTX  ) shots currently being reviewed by the public health agency for approval.