Updated 7:25 p.m.

Republican Gov. Charlie Baker defended the state's rollout of COVID-19 vaccines in the face of sometimes biting questions from Democratic legislators during an oversight hearing Thursday.

The bedrock of Baker's defense: Massachusetts leads the nation for first doses administered per capita among states with populations of five million or more. Statistics from the federal Centers for Disease Control and Prevention verify Baker's assertion.

Early on in his virtual testimony before the Joint Committee on COVID-19 and Emergency Preparedness and Management, Baker acknowledged the rollout had been "lumpy and bumpy." But he placed much of the blame on limited vaccine supply from the federal government.

"It has not been lumpy and bumpy," State Sen. Eric Lesser, D-Hampden and Hampshire, responded. "It has been a failure. My constituents, and all of our constituents, are justifiably outraged and are asking why the governor of Massachusetts, in the health care and technology capital of the country, cannot figure out how to operate a website."

Baker accepted blame for challenges with the state's registration website that have frustrated thousands of residents and ultimately left many without appointments to receive a vaccine.

"What happened to the websites is on us," Baker said.

Lesser shot back, asking if the governor would apologize to those who have had trouble with the site.

"Of course. Absolutely. Definitely, yes," Baker replied, going on to repeat that the challenge stemmed from a lack of supply. That didn't sit well with Lesser.

"What happened was that the website crashed," Lesser said. "Not that there weren't enough doses, but that people were cut out of even finding out whether they could book an appointment."

Baker replied that despite the web problems, on the first day the site opened up to residents 65 and over, every available appointment was ultimately booked.

"It was a it was a bad user experience, I acknowledge that ... And we need to continue to do things to improve the quality of the site," Baker said. "But the single biggest thing that would make people's experience with the site better would be if we had a lot more supply and a lot more appointments that people could book."

Baker also faced questions on his administration's efforts to ensure an equitable distribution of the vaccine. Rep. Jon Santiago, D-Suffolk, an emergency room physician who announced a run for mayor of Boston earlier in the week, asked how Baker was addressing that as the state prioritizes the efficiency of mass vaccination sites.

"How do you balance that with the need to vaccinate equitably across communities, particularly communities of color?" Santiago asked. "How do you determine if what we're doing is enough?"

"I don't think anybody's going to be able to do this with a single answer," Baker said. "I think in the end, it's going to be a variety of approaches that's ultimately going to be the way you try to cover the playing field."

Again, Baker emphasized that increased supply from the federal government will reduce some of the concerns.

"There are two things that frustrate people about this," he said. "The first is not being able to get a vaccine. And the second is the waiting."

Baker began the virtual back-and-forth with an opening statement in which he painted a positive picture of a state that's turning the corner on the pandemic.

The governor said the state's new case count is at its lowest level since November, dropping by 75% since its peak in January. He said hospitalizations have fallen from 2,428 patients in January to 875 on Wednesday.

On the vaccination front, Baker said Massachusetts currently leads the nation in first doses per capita among the 24 states with more than five million people.

He acknowledged a slow start to the vaccination effort but said that was a result of the decision to focus first on vaccinating especially vulnerable groups that were not prioritized in other states, including staff and residents of group homes for the developmentally disabled and the mentally ill, residents and staff of homeless shelters, inmates and correctional officers, personal care assistants and home health care workers.

Baker said despite a bumpy beginning, there's been significant progress in vaccinating residents aged 75 and over. He said 65% of that population has already received a first dose.

"I know how frustrated people are with the pace of the vaccine rollout and how anxious they are to get themselves and their loved ones vaccinated," he said. "But it's critically important for everyone to remember that we get about 450,000 requests for first dose vaccines each week from hospitals, regional collaborators, community health centers and a wide array of entities that are part of our vaccination community. And we receive about 130,000 first doses of vaccine weekly from the federal government."

Baker said more than a million people are currently eligible to get their first dose.

"We're putting every dose we get to work each week. That's why we're a national leader in vaccinating our residents. But we don't receive anywhere near enough vaccine each week from the feds to provide our existing vaccinators with what they request or to work through most of the currently eligible population that wants a vaccine now."

Baker was asked if he would return in two weeks to provide the committee with an update on the vaccine rollout.

“Well, this one's been so much fun, I'll certainly look forward to coming back,” he replied.

The hearings continued with testimony from more than a dozen other speakers focused on different aspects of the vaccine rollout.

Among them was Harvard Medical School professor Dr. Bisola Ojikutu, who said she understands the need to expedite the delivery of vaccines.

"But I feel like there's been this false dichotomy that's been created between speed and equity," she said. "And these two concepts, they aren't mutually exclusive."

She said everyone agrees that the hardest-hit communities should be prioritized.

"What needs to be emphasized, is if there's political will to do this, that it can be done quickly. You know, speed doesn't have to be compromised," she said.

Ojikutu said this is an opportunity to address and dismantle structural racism and shift power back into the hands of communities. She said the administration should invest in Black and Latino organizations to help in the vaccine distribution and partner with community-based organizations.

Meredith O’Leary, Northampton's Public Health Director, testified about her city's efforts to set up its own vaccine distribution center only to have the state pull vaccines from municipal sites, instead favoring more doses for mass vaccination locations.

"In what perhaps was the most disappointing and enervating moment in my whole public health career, after taking all these extraordinary steps to ramp up our clinics to meet the needs of the state and the needs of our region, we were informed last week that vaccine distribution was being streamlined once again," O’Leary said.

The state was requiring sites to be able to vaccinate 750 people a day, five days a week. Northampton wound up partnering with neighboring communities to set up a regional vaccine center.

In her testimony at the end of the day, Health and Human Services Sectrary Marylou Sudders said that was actually the goal.

"What we said was ... we would no longer support individual municipal clinics. But if they came together in regional collaboratives, we would support," Sudders said, adding that the state wants local boards of health to focus on vaccinating their most vulnerable residents, like those who are home-bound or living in low-income and senior housing. "So trying to leverage local boards of health in areas that they know better than anyone."

Sen. Julian Cyr, D-Cape and Islands, questioned Sudders on the state's emphasis on mass vaccination sites, three of which are run by CIC Health, a private company.

"Why do we choose contracted vendor over years of local investments and investments in community health?" Cyr asked.

Sudders emphasized the progress the state has made in increasing the number of vaccinated people. She said there are just under 600 registered providers in the state's vaccine program.

"With a limited constraint of supply, it is not possible to manage ... So, yes, we streamlined, absolutely, at this point, in order to take that dismal number and to improve shots in arms," she said.

After the hearing, committee chairman Bill Driscoll, D-Norfolk, told GBH News he felt the governor's administration blamed supply issues from the federal government for process problems that aren't directly linked, and he said more information is needed on what's going to change.

"The administration can't just say that we're going to have a bigger, faster, stronger vaccine rollout," he said. "You have to tell us what's going to change and how. And then when is it going to be active?"

He said he hopes the state's in a better position in two weeks, when the committee will hear again from Baker and Sudders.