Shortly before Christmas, as Oregon schools faced their 10th month under some of the nation’s sternest coronavirus restrictions, Gov. Kate Brown began a major push to reopen classrooms.

She offered to help districts pay for masks, testing and tracing, and improved ventilation. Most important, she prioritized teachers and school staff members for vaccination — ahead of some older people.

Her goal: to resume in-person classes statewide by Feb. 15.

But today, roughly 80 percent of Oregon’s 560,000 public schoolchildren remain in fully remote instruction. And while some districts are slowly bringing children back, two of the largest, Portland and Beaverton, do not plan to reopen until at least mid-April — and then only for younger students.

Oregon’s halting efforts to return children to classrooms are being repeated up and down the West Coast. The region’s largest city school districts — from Seattle to Portland to San Francisco to Los Angeles — have remained mostly closed, even as Boston, New York, Miami, Houston and Chicago have been resuming in-person instruction.

And the release on Friday of guidelines from the Centers for Disease Control and Prevention that urge school districts to reopen has not changed the minds of powerful teachers’ unions opposed to returning students to classrooms without more stringent precautions.

Tough state health restrictions imposed by Ms. Brown, a Democrat, helped protect the state from experiencing the high death tolls occurring elsewhere. But by December, she was growing alarmed at the toll social isolation was having on children.

“Eleven- and 12-year-olds were attempting suicide,” she said in a recent interview.

Worried that schools would not reopen until the 2021-22 school year if she waited to vaccinate teachers along with other essential workers, Ms. Brown rejected federal guidelines and bumped school employees up in priority, before people 65 and older, even though that constituency would — and did — protest.

Oregon was among a handful of states at the time, and the only one on the West Coast, to single out school employees for the vaccine. (About half of states now prioritize teachers.)