Four more regional vaccine collaboratives will join the state's pre-registration system later this week, the Baker administration announced Wednesday.
Residents will soon be able to pre-register for appointments at sites operated by regional collaboratives in Northborough, West Springfield, Palmer, and Northampton.
When the pre-registration system launched last month, it only connected to vaccine slots at the state's seven mass vaccination sites, but officials have since expanded it to include the Amherst-Northampton and Marshfield regional collaboratives.
Users can also now select their vaccination location when they get a notification that they can book an appointment, the administration said, a change from the system's earlier days when it connected participants to the mass vaccination site closest to them.
About one in five residents who pre-registered for a vaccine at one of the mass vaccination sites appear to have gone elsewhere to receive their doses. Gov. Charlie Baker said Wednesday that about 300,000 of the roughly 1.5 million adults who filled out a pre-registration form withdrew afterward, indicating they were instead able to find a slot at a pharmacy, regional collaborative or another location.
"That says to us they went and got an appointment somewhere else," Baker said. For those who are eligible to receive vaccines, he said it typically takes two to three weeks after registration to receive an alert about an appointment, depending on location.
He also said "a bunch of people" do not book the first appointment when alerted by the system but secure it on a second offering.
"Pre-registration, we've discovered, for a lot of people is what I would call the safety valve: they pre-register, and while they wait to hear back from the pre-registration system, they continue to chase appointments."