All teachers in California will have to be vaccinated against COVID-19 or submit to weekly virus tests, the state's governor Gavin Newsom announced Wednesday, as authorities grapple with exploding infection rates.

The number of people testing positive for the disease has surged across the United States in recent weeks, with the highly infectious Delta variant blamed for the bulk of new cases. 

That has worried parents and educators as the most populous state in the country readies to send its largely unvaccinated children back into classrooms for the new school year.

"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. "Vaccinations are how we will end this pandemic. As a father, I look forward to the start of the school year and seeing all California kids back in the classroom."