By Natasha Brown

PHILADELPHIA (CBS) — The COVID-19 omicron variant is ruining school lesson plans. A growing number of districts have postponed reopening after the holiday break or switched to remote instruction.

Rising COVID cases fueled by the highly transmissible Omicron variant are crippling some school districts around the region. The spike has caused a delay in Monday’s return to school for thousands of students.

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Central Bucks Schools were forced to close Monday.

The superintendent said the district is dealing with an unprecedented staffing shortage.

District administrators will be meeting to discuss plans for the rest of the week.

“The implications that this surge has with our employees,” Garnet Valley School District Superintendent Dr. Marc Bertrando said.

The Garnet Valley School District will return students to in-person learning this week, however, like other districts, COVID cases are taking a toll on staff members causing massive shortages in all areas.

“To run school you need teachers and you need support staff,” Bertrando said.

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Support staff shortages are further complicating the return to schools.

“Now with this surge making it more and more difficult to keep people at work and the need for substitutes even greater staffing issues are a major, major complication,” Bertrando said.

The School District of Philadelphia plans to return to school buildings on Tuesday, but the Philadelphia Federation of Teachers union is now requesting a seven-day pause and return to virtual learning as hundreds of teachers are COVID positive following the holidays.

“They reported 1,100 members and 2,000 households so that certainly will have an impact on whether or not our schools are going to have enough adults who are going to be able to keep the school operating,” PFT President Jerry Jordan said.

Union officials are calling for more in-school COVID testing by outside agencies and stricter masking policies to ensure schools stay safe, without critical staff shortages.

“It’s a good idea to bring everybody back if the mitigation strategies are in place,” Jordan said.

The School District of Philadelphia is continuing with plans to bring students back for in-person learning Tuesday with the support of the city’s health department.

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Meantime, health officials have boosted mask-wearing recommendations, saying in part: “With the recent surge in cases, we also recommend double masking with a well-fitting cloth mask over a paper mask or use of an N95 or KN95 for additional protection.”