The city of Chicago will require COVID vaccinations for all city employees, including police officers, this fall, Mayor Lori Lightfoot announced Wednesday.

The policy will take effect on Oct. 15 and requires all city employees and volunteers to be fully vaccinated by that date.

“The data shows that getting vaccinated is the best way to protect yourself and those you come in contact with from serious illness, hospitalization, or death from COVID-19,” Chicago Department of Public Health Commissioner Dr. Allison Arwady said in a statement. “Adopting and implementing this requirement is the responsible, common-sense approach, which is why we’re seeing so many other government agencies, companies, institutions, and organizations pursue this course of action.” 

“Fully vaccinated” is defined as two weeks past the second dose of a two-dose mRNA vaccine or two weeks past a single dose of the Johnson & Johnson vaccine. Employees will need to submit proof of vaccination through an online COVID-19 Vaccine Portal, NBC Chicago reports.

News of a potential mandate for the thousands of city employees came earlier this week, on the same day the U.S. granted full approval for Pfizer's COVID-19 vaccine.

Chicago's Fraternal Order of Police is opposing the mandate and may seek legal relief.