Stanford University announced Saturday that freshman and sophomore students would not be allowed to return to campus for winter quarter, citing a surge in coronavirus cases.

In the past week, graduate and professional students, along with undergraduates with special circumstances, were allowed back on campus, according to a message from President Marc Tessier-Lavigne and Provost Persis Drell. The remaining students had been set to return to school later this month, part of a staggered move-in schedule.

"The worsening COVID-19 circumstances have now eroded our expectations about the experience we could deliver to undergraduates in the winter months," they wrote. "California and Santa Clara County have stringent public health restrictions tied to COVID-19 caseloads."

Student newspaper The Stanford Daily pointed out that the announcement comes one day after news that 43 students on campus tested positive for COVID-19, and after university officials repeatedly asserted this fall that students would be able to be on campus for winter quarter.

The 43 students, all of whom had tested positive since Jan. 2, are in isolation, according to Stanford University's coronavirus dashboard.