A Cambridge Public Schools teacher runs a remote class, as seen in a district video from Dec. 21.

All classes will stay remote until at least Jan. 11, Cambridge Public Schools superintendent Kenneth Salim said Wednesday.

The guess at mid-Month, after coronavirus levels rose high enough to trigger the cancellation of in-person learning, was that all classes would be remote until at least Jan. 4. To reopen for in-person learning, two of three metrics looking at coronavirus levels need to be below their threshold for seven consecutive days – but the arrival of winter break Dec. 24 meant there wouldn’t be enough evidence gathered for consecutive until January.

Though current guidelines would allow in-person learning to resume next week, an extension of all-remote learning was “made out of an abundance of caution” in consultation with city Public Health Department officials, Salim said.

“Given the projected post-holiday increase in cases and because fewer individuals have participated in testing during the holiday week so far, current data do not provide us with a complete picture of the projected increase in transmissions over the winter break due to gatherings and travel,” Salim said in an email. “It is in the best interest of students and staff to administer staff testing the week of Jan. 4 and continue to work with the Cambridge Public Health Department to monitor data in preparation for a return to in-person learning.”

Cambridge opened its public school year with remote learning Sept 21 and began in-person classes for 1,604 students – mainly younger ones – starting Oct. 13. That is expected to expand in February, because schools don’t appear to be big spreaders of the virus, Salim said. Expansion plans are on the agenda for Tuesday’s meeting of the School Committee.