Teachers and other staff in Decatur have until the end of January to get a booster shot against COVID-19.

The tiny city system on Atlanta’s eastern edge is the only school district in the state known to have mandated staff vaccination so far. The further requirement for a booster shot was announced Tuesday.

“As we prepare to return to in-person learning on January 4, we anticipate a significant impact due to the Omicron variant,” the district said in a note to parents. “Getting vaccinated against COVID is the most effective and fastest way we can ensure our students and staff are able to learn and work in a safe environment.”

Boosters, plus a testing requirement for all and other recommendations, will help minimize that impact, the message said.

Last fall, City Schools of Decatur became what observers said was the only district in Georgia to mandate teacher vaccination. Superintendent Maggie Ferhman considered requiring that students get the shots, too, but backed away from that idea. It would have required school board approval but she could impose the staff mandate without asking the board.

Employees had to get vaccinated by the end of October unless they secured an exemption. Soon after the deadline, the district reported that 776 of 915 employees were fully vaccinated.

Staff writer J. Scott Trubey contributed to this article