Superintendent Kenneth Salim. (Photo: Derek Kouyoumjian)

Cambridge Public Schools are forced to return to all-remote learning starting Thursday by daily Covid-19 case counts that have sent the district past its triggers to close.

The district is giving three school days’ notice (including Wednesday, which is already a remote learning day) to help staff and families prepare for the change, superintendent Kenneth Salim said Sunday.

In-person learning will resume when the thresholds dip again, but the shift to all-remote learning will continue for at least seven consecutive days through Dec. 16, he said.

Sunday’s 29 new cases meant the seven-day average of cases was at 26.9 per every 100,000 people, when the threshold the district looks to is 25. The level of coronavirus found in sewage wastewater readings has also surged to 658.5 viral genomes per milliliter as of Nov. 3, far over the threshold of 100. The rate of positive Covid-19 tests in Cambridge over the past 14 days is at only 0.77 percent compared with the 5 percent trigger – but a switch to remote learning is triggered when two of the three limits are exceeded.

“We want to remind our families and staff that this temporary shift does not mean Cambridge is in an emergency situation,” Salim said. “Our guidelines are clear. If we exceed two of the three metrics, we must shift to temporary remote learning for all as a precautionary measure.”

Cambridge opened its public school year with remote learning Sept 21. The district invited students from junior kindergarten through first grade; select students from grades 2 and 3; and students with special needs and English-language learners for in-person school starting Oct. 13. There are 1,604 students enrolled in person, including more than half of preschool-to-grade 3 students and approximately 24 percent of the district’s overall student population.

“Seeing the joy on our students’ and families’ faces on Oct. 13 as we reopened schools for some of our learners was the highlight of this difficult year,” Mayor Sumbul Siddiqui said in a Sunday press release. “Despite this current setback, we are committed to reopening our schools and to bringing back more of our students in the months ahead.”