The Los Angeles and San Diego unified school districts, which issued a joint announcement, will begin online instruction in mid-August but will “continue planning for a return to in-person learning during the 2020-21 academic year, as soon as public health conditions allow.”

Read Also: South Africa’s Children Return To School

Los Angeles Unified, the country’s second-largest school district with roughly 700,000 students, will begin instruction Aug. 18; San Diego Unified, which serves more than 100,000 students, is set to start Aug. 31.

“There’s a public health imperative to keep schools from becoming a petri dish,” Austin Beutner, the school superintendent in Los Angeles, said in a video message posted online.

In the joint announcement, the school districts said the research around coronavirus-era school safety remains “incomplete,” and that many of the public guidelines were “vague and contradictory.”

But, the districts added, “one fact is clear: those countries that have managed to safely reopen schools have done so with declining infection rates and on-demand testing available. California has neither. The skyrocketing infection rates of the past few weeks make it clear the pandemic is not under control.”

The announcements come a day after Education Secretary Betsy DeVos defended the Trump administration’s aggressive push to reopen schools in the fall amid the worsening pandemic.

In an interview with CNN on Monday, DeVos said a hybrid of virtual and in-person learning is “not a valid choice for families.” She also refused to say whether the Centers for Disease Control and Prevention’s guidelines for schools should be followed uniformly.

“The CDC guidelines are just that, meant to be flexible and meant to be applied as appropriate for the situation,” she said.

Los Angeles and San Diego, which closed schools and moved to an online learning model in mid-March, are to date the largest school districts to announce a shift to online-only instruction.

New York City, home to the largest school district in the nation, has opted for a partial reopening, with classroom attendance limited to one to three days a week. Chicago, the third-largest, has yet to announce a roadmap.

In a separate development Monday, California Gov. Gavin Newsom announced that the state would extend the closure of a range of business operations statewide, including dine-in restaurants, bars, movie theaters, zoos and museums.

The coronavirus death toll across California soared above 7,000 over the weekend.