Mayor Lori Lightfoot announced a deal with the Chicago Teachers Union on Monday that would return students to classrooms on Wednesday after a dispute over coronavirus safeguards canceled a week of classes in the country’s third-largest school district.

The deal, which city officials said included provisions for additional testing and metrics that would close schools with major virus outbreaks, was approved by the union’s House of Delegates on Monday night and was expected to be voted on later in the week by rank-and-file teachers.

Lightfoot, but they said the deal was needed given the conditions teachers are facing in the pandemic.

“This agreement is the only modicum of safety that is available for anyone that steps foot in the Chicago Public Schools, especially in the places in the city where testing is low and where vaccination rates are low,” said Stacy Davis Gates, the union’s vice president.

Union members said that the schools were not safe, that more testing was needed and that classes should be temporarily moved online.