Rolling up your sleeve to get the COVID-19 vaccine at Gillette Stadium has been an unforgettable experience for many who have been vaccinated there and especially for those who received their shots during the site's early days. Betty Sparks, a registered nurse who came out of retirement to help administer the vaccine, said the process was much like standing in line at a Disney ride. The end was worth the wait, but getting there could be torture.

"The line zigzagged. Up and down, up and down, all the way to the parking lot. People would get out of their cars when a big screen on the building flashed their appointment time, and then they'd start the zigzag." She said the weather wasn't kind either. "It could be windy, snowy, rainy and cold," she recalled.

The decision by the Baker administration to close four of the state's seven COVID-19 mass vaccination sites by the end of June means Sparks will soon say goodbye to the job she's held for the last several months. The other mass vaccination sites shutting down are the Hynes Convention Center in Boston, the DoubleTree Hotel in Danvers and the Natick Mall. All Massachusetts mass vaccination sites are now accepting walk-ins, and Sparks said it's so much easier for people to get vaccinated now. "People were driving hours to get to Gillette because they couldn't get an appointment anywhere else."

Sparks said working at Gillette has been a fulfilling experience. "I have seen absolute joy. It's amazing as a nurse who has done so many different things to have patients — clients, as we call them — that really want to see us. They are just so happy when they walk in the door. They want to give me virtual hugs because they can't give me real ones, and they absolutely cry, both men and women."

She said she's not surprised by the tears, though many who are receiving the shots are taken aback by their strong reaction. "They start crying and say they didn't expect to feel so emotional, the sense of release and relief."

Sparks worked for 45 years as a nurse at Brigham and Women's Faulkner Hospital in Jamaica Plain and at Newton-Wellesley Hospital in Newton. She is also a member of one of the federal government's Disaster Medical Assistance Teams. As a DMAT nurse, Sparks has traveled around the world as a volunteer disaster responder. She was in New Orleans after Hurricane Katrina in 2005, in Haiti after the 2010 earthquake and in Puerto Rico after Hurricane Maria in 2017. She also was working in the medical tent at the finish line when the bombs went off at the Boston Marathon in 2013.

Sparks said that working at the Gillette mass vaccination site is different from those previous experiences. She remembered St. Patrick's Day in particular and laughed as she tells the story. "I actually had a guy come in all dressed up in a kilt, and it was a party atmosphere," she said. 'Everyone was whistling at him."

Then there are those whose experience is tinged with sadness when they sit down in her chair. "I just lost it when a woman told me her husband had died in January," she said. "I didn't know the reason. I didn't ask, but she said they were season ticket holders, and she hadn't been to Gillettte since last season."

The love between family members are precious moments she's witnessed, too. "I had a 100-year-old woman who came in and her grandson was with her," she said. "And just the way he took off her coat, caring for her — it's just so rewarding."

Sparks said she's noticed changes in people's reactions as they enter the stadium now that they know what to expect. "People now have a lets-get-this-over with attitude, but not initially." She said when seniors began arriving in January she saw fear in their eyes: "It was the first time many of these people were out of their homes and they come to Gillette Stadium, in line with hundreds of other people."

Sparks is now getting ready to enjoy her summer at home and feels good about the work she's been doing at Gillette. "I guess we are making history like back in the days of polio. We're part of history and down the years, hopefully, it's going to be seen in a real positive light."