CHICAGO (AP) — Chicago Public Schools announced Friday that it will require all its employees to be fully vaccinated against COVID-19 by mid-October unless they qualify for a medical or religious exemption.

The mandate — announced two weeks before the full-time in-person learning begins Aug. 30 — applies to all Chicago Board of Education workers, a group that includes teachers, staff, workers in the district’s central office, and regular vendors and network employees.

“Our Chicago Public School communities deserve a safe and healthy environment that will allow our students to reach their greatest potential,” Mayor Lori Lightfoot said in a statement. Gov. Gavin Newsom announced Wednesday that California would become the first state to require all teachers and school staff to get vaccinated or undergo weekly COVID-19 testing.

“This new policy enhances the district’s comprehensive reopening plan and ensures that students and staff can confidently learn in-person,” Lightfoot said. “Taking this step will further our citywide vaccination efforts and build on our progress in slowing and stopping the spread of COVID-19.”

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CPS said staffers must submit proof that they are fully vaccinated by Oct. 15, unless they have the approved exemptions. In the meantime, employees who have not reported that they are fully vaccinated will be required to be tested at least once a week until Oct 15 or until they provide proof of vaccinations. Those employees who have approved exemptions must be tested throughout the school year.

The Chicago Teachers Union voiced its support for the CPS vaccination requirement, saying in a statement that it comes in response to a formal proposal the union made this week and “mirrors” a vaccination policy agreed between the union and a charter school.

The announcement comes after the majority of CPS employees have already been vaccinated. According to he CPS, 67% of its employees are fully vaccinated, with that percentage climbing to 78% when the employees who are partially vaccinated or have vaccinations scheduled are added.