HARTFORD — Connecticut Gov. Ned Lamont has fired the state's public health commissioner in the middle of the coronavirus pandemic because of a series of missteps dating to last year, a state official said Tuesday.

The Democratic governor announced Tuesday that he had replaced Renée Coleman-Mitchell with Deidre Gifford, commissioner of the state Department of Social Services who will also serve as acting public health commissioner. The official announcement did not say why Coleman-Mitchell was replaced.

Lamont removed her for several reasons including being slow to act on a plan to protect nursing homes from the coronavirus and refusing last year to publicly release school-by-school vaccination rates, according to the official, who spoke on condition of anonymity because they were not authorized to disclose the information.

A phone message seeking comment was left for Coleman-Mitchell on Tuesday.

“I appreciate Commissioner Coleman-Mitchell’s willingness to join my administration and lead one of our most vital state agencies, which is responsible for overseeing so many critical public health needs,” Lamont said in a statement. “Her service over the last year has been a great deal of help, particularly in the face of the global COVID-19 pandemic that has brought disruption to many throughout the world."

Coleman-Mitchell had worked for the Public Health Department for 18 years, including the past year as commissioner. She previously was a section chief for the agency, managing chronic disease programs.