State senators and Senate employees will need to show proof they are fully vaccinated against COVID-19 by Oct. 15, a new requirement Senate President Karen Spilka laid out Tuesday.

Spilka told senators and staff in a late afternoon email that the mandate is based on a recommendation of the Senate's Reopening Working Group, and that the Senate's human resources office will reach out to provide details on how employees can show proof of vaccination.

"Vaccines have proven to be the best tool we have to reduce transmission and are our best hope to emerge from this pandemic," the Ashland Democrat wrote in the email, a copy of which was obtained by the News Service.

The Senate's move follows Gov. Charlie Baker's announcement last week that the roughly 44,000 employees and contractors in the state's executive branch would need to be vaccinated by Oct. 17.

Vaccination policies are becoming widespread across state government, with Attorney General Maura Healey, Auditor Suzanne Bump, Treasurer Deborah Goldberg and the Trial Court already announcing policies for their workers. A House spokesperson said last week that some sort of vaccine requirement would be an "integral" part of the House's return-to-work plan, along with other virus mitigation measures.

The Senate's working group, led by Senate Majority Leader Cindy Creem, recommended that human resources develop a policy that allows limited exemptions for cases of medical disability or a sincerely held religious belief that would preclude someone from being vaccinated. The working group recommended that the exemption procedure "may provide for such employees to work remotely."

The policy, the group said, should also include a method for documenting and verifying vaccine status while ensuring the information remains confidential, and involves enforcement measures "including, and up to, the termination from employment of any employee who remains in non-compliance."

"As the Working Group does not believe that public health and safety are adequately protected by periodic or even frequent testing of individuals for the COVID-19 virus, such testing shall not be authorized in lieu of the vaccination requirement," the group wrote in a supplemental report describing its new recommendations.

The State House remains closed to the public, with no official timeline announced for a full reopening.

Spilka had previously advised Senate staff that they should prepare to return to the office in a hybrid work model after Labor Day.

"Our goal is to begin welcoming back staff after Labor Day, however with the resurgence of Covid-19 cases, and the dominance of the Delta variant, a definitive date has not been determined," she wrote Tuesday. "Offices should continue to develop their plans for an eventual return while awaiting further guidance. Later this week, Senate Human Resources will contact each Senate office to check-in and assist, as needed, with this process."