The workers, Unite Here Local 26 president Carlos Aramayo, and the political figure gathered outside the hotel on Tremont Street.
The current acting mayor made history in Boston, when she was elected this past March.
People of color have disproportionately received fewer doses than white residents in the state.
On March 29, the MBTA confirmed that it will "fully fund its operating budget in the coming fiscal year and begin to restore cut service."
The administration is not distributing the promised additional 20% vaccine allocation for hardest hit communities in Massachusetts.
She will be joined by colleagues and loved ones at the ceremony.
They will be joined by senator Joe Boncore and former Marriott Copley employees, fired in the middle of pandemic, calling for legislation.
Now in its second season, the program will highlight the District 6 candidate.
Marriott Copley employees tossed out in the middle of pandemic demand fair treatment after decades of service.
Barros is the fifth mayoral candidate to enter the race.