Updated 3:38 p.m.

Massachusetts residents 75 and older will be eligible for the COVID-19 vaccine after Feb. 1, Gov. Charlie Baker said Monday.

People 65 and older will be eligible at an as yet unspecified date in February under the terms of the revised plan Baker announced.

Before the 65-and-over population can receive their first shot, those with one or more co-morbidities — such as diabetes or heart conditions — will be vaccinated.

Baker also announced the opening of 165 public vaccination centers throughout the state, including "mega" centers in Boston, Springfield and Danvers, as well as a system to distribute doses through existing medical and pharmacy locations.

The plan would boost the state's capacity to deliver doses to 305,000 per week by mid-February. But Baker warned that that number is far higher than the amount of vaccine trickling into the commonwealth from federal supply lines.

"If we continue to get the same number of doses we're getting now, we may end up with some empty seats and empty appointments at some of our sites," Baker said. "But I think we think it's better to over plan at this point in the process and hope that the feds can get there."

Baker defended himself against criticism of his choice to focus the first phase of the vaccination plan on the relatively limited number of medical workers, congregate care residents and first responders in the state instead of targeting broader sections of the population the way some states have done.

"I do believe at the end of the day, we made the right decision out of the gate. The fact that we're going to add literally dozens and dozens of sites that will bring our capacity — whether we have the vaccine or not — up to hundreds of thousands of people per week who can access and get vaccinated should deal with many of the issues in the questions that people have raised," Baker said.