Attorney General Maura Healey doesn't know why the Baker administration set up the COVID-19 vaccine appointment website the way it did.

"You can't have seniors waking up at midnight to see what's become refreshed on some of these systems," Healey told Boston Public Radio on Thursday.

"There's a lot of information there, but it's way more complicated than it needs to be," she added. "If you're talking about vulnerable populations, you're talking about seniors, you know how hard that is."

The Baker administration has come under growing criticism over the state's vaccine rollout, which critics say has been confusing and inefficient.

Currently, people who are eligible for vaccination must go online, enter personal information, then search every individual location across the state that is administering the vaccine to find an available slot. They must also verify their eligibility to sign up, raising concerns about how navigable the site is for the very people the state is trying to get vaccinated first: the elderly.

Healey said the state's current system to sign up for the COVID-19 vaccine is too decentralized to meet the urgency of the moment, especially considering that the state had months to prepare for a vaccine rollout.

"We need to approach this as kind of a war time endeavor, very centralized, top down, and do something we haven't done before," she said. "That sort of decentralization — I understand it's a philosophy that works in other realms, but it's not going to work to cover the millions of people we need to have covered within a certain time once vaccine becomes available."

Healey said a "lack of details" coming out of the Baker administration about the limited number of doses the state has on hand likely led to increased frustration as people tried to sign up for an appointment this week.

"If the public knew we've only been receiving 80,000 doses of vaccine a week for a population of 7 million, maybe that would have helped in terms of expectation setting," she said, noting that the state is working to build out an infrastructure of vaccination sites. "The problem is, the shots aren't there, we don't have the doses, which is why people can't actually get appointments."

But logistics and limited supply issues do not account for the widespread frustration residents expressed when trying to navigate the system on behalf of themselves or their family members.

One caller into the show said she had successfully signed her mother up for a vaccine appointment yesterday — the first day people over 75 were able to go online and start scheduling their appointments — only to later receive an email cancelling her appointment because the slots were only reserved for people eligible in Phase 1, like frontline workers. Others said they waited on the virtual system for an extended time after inputting personal information, only to get through the process to find there were no available appointments at a specific location, forcing them to back out and start over.

During a press conference Thursday, Baker said the state would explore a call center to assist those having difficulties navigating the online-only system.

Healey said the direct human contact and accessibility a call center offers is "critical."