Dr. Gabriela Andujar Vazquez was the first person at Tufts Medical Center to get the COVID-19 vaccine. The associate hospital epidemiologist, who regularly sees COVID-19 patients, didn’t flinch at all as she was injected with the Pfizer vaccine Tuesday afternoon.

“It's definitely a relief,” she said, adding that her concern wasn’t about infection within the hospital. “Because I firmly believe that PPE works and that it protects our health care workers. But more so to protect everyone outside the hospital, like my nieces, my nephews. And [I'm] doing this for the community. Not only for us, but for everyone else.”

Andujar Vazquez said she did consider carefully whether to get the vaccine.

“I looked at the data and I talked to many experts in vaccinology and epidemiology,” she said. “I made an informed decision that vaccinating is the way to go.”

Gov. Charlie Baker said Tuesday that four hospitals in the state have gotten 6,000 first doses of the two-stage Pfizer vaccine, and the federal government was expected to ship out more than 53,000 additional doses to 17 more Massachusetts hospitals on Tuesday.

“It is very bittersweet today because we have hit that milestone of 300,000 deaths, and we know that we still have our long winter ahead of the surge and hospitalizations and death and suffering," Dr. Shira Doron, hospital epidemiologist at Tufts Medical Center said Tuesday, shortly after receiving the vaccine herself. “But at the same time, it's a good day to have hope. It's a good day to have the first vaccines going out in Massachusetts and to be confident, finally, that there's some light at the end of this dark, dark and long tunnel.”

Doron said the speed at which the vaccine was developed shouldn’t undermine trust that it’s safe.

“Although we made history here — the U.S., the world made history in getting a vaccine out in less than one year — that was a feat of efficiency,” she said. “It doesn't represent cutting corners on safety.”

While the Pfizer vaccine is just beginning to be rolled out, a new vaccine by Cambridge-based Moderna is expected to be right on its heels. The FDA said Tuesday that new data shows the Moderna vaccine is safe and effective. A panel of outside experts is expected to vote to recommend the formula on Thursday, with the FDA's green light coming soon thereafter.

Dr. Helen Boucher, chief of Infectious Diseases at Tufts Medical Center, also received the vaccine on Tuesday. There’s a push, she said, to get healthcare workers vaccinated as soon as possible.

“And next, it'll be our long-term care residents, and on and on and on, until we can get to that 70 percent immunity that we need, so we'll be able to go back to life,” she said.

But Dr. Boucher emphasized that there’s still a long way to go until that happens, so it’s crucial that people remain cautious about spreading the virus.

“So we have to, mask up, keep our distance, avoid crowds, wash our hands and not travel,” Dr. Boucher said. “And it's really, really hard because everyone's tired and everyone wants to be together for the holidays,” she said. “But the plea I have is to remember this is one holiday. We will be together again next year for the holidays. And so please make those hard decisions to keep yourself and your family safe.”

The Associated Press contributed to this report.