Cathie and Donald Macrelli recently rolled up their sleeves in Boston's Dorchester neighborhood to get their second and final dose of the Pfizer BioNTech COVID-19 vaccine.It's a scene that's been repeated more than three million times in Massachusetts alone. But the Macrellis had some reservations."I understand why people are afraid. I do," said Cathie Macrelli.Vaccines are a painful topic for the Macrellis. Their 18-month-old son David died in 1996 after receiving a Diphtheria-Pertussis-Tetanus vaccine, which led to a financial judgment from the federal government.Less than 24 hours after he received the shot that he was dead. "I know it's rare, but if you are that rare person, your life is destroyed," said Cathie Macrelli.The Macrellis say they're not anti-vaxxers. Still, the newness of the COVID-19 vaccines made them hesitant, at first."I did it. You can do it. And I hope that you get over your fear. Educate yourself," Cathie Macrelli said.Now, they want others to see their willingness to be vaccinated against COVID-19, and do the same."I don't want David to have died in vain," Cathie Macrelli said.While Massachusetts is one of the most vaccinated states in the country, our sister station WCVB's analysis of state data shows a wide disparity among cities and towns, and even among residents of those towns.There are 80 cities and towns where at least half of residents are fully vaccinated.But there are also 24 cities and towns where a third or less of residents are fully vaccinated. That includes some of the cities hardest hit by COVID-19 like Brockton, where 31% of residents are fully vaccinated, Lawrence, where 28% are fully vaccinated, and Springfield, where just 25% are.Along racial and ethnic lines, the disparities are even greater. That's true in urban areas like Lawrence, where white residents are vaccinated at nearly nine times the rate of Black residents, and more suburban and rural communities like Norfolk, where white residents are fully vaccinated at eight times the rate of Hispanic residents.Richard Carpiano, professor of public policy and sociology at University of California, Riverside, who studies reasons why people don't get vaccinated, says hesitancy is just part of the reason."There are many people from minority racial and ethnic backgrounds who have had bad personal experiences in dealing with the health care system," he said. Then there is the speed with which the COVID-19 vaccine was created and approved."Lots of concerns have been raised about the fact that this might have come out too quickly," he said. "Also not helping things, though, has been the extent of disinformation that's been circulating online."He says giving people easy access to vaccines from trusted sources right in their communities is also key. "Meet them where they are. Make sure that we were able to answer their questions, make them as convenient as possible to get," Carpiano said. It's not clear what impact Massachusetts' fully reopening later this month will have on vaccination rates. Carpiano said some people may be more motivated to get a vaccine, but others may feel the opposite. David is always on the Macrellis' minds. But they say that was especially true as they received their COVID-19 vaccines."I'd like to think that David would have been proud of us," Cathie Macrelli said. "If just one person could get the vaccine because I said, 'It's OK, you know, I did it. I think you can do it. You have to get over your fear.' That would make me happy," she said.