Workers, including Clarivel Amy (right), at a mobile vaccination site organized by Holyoke Health Center try to convince people to pull into the parking lot outside the Boys and Girls Club in Chicopee, Massachusetts. (Karen Brown/NEPM) Although Massachusetts has one of the highest COVID-19 vaccination rates in the country, Hampden County has the lowest rate in the state — with major racial and ethnic disparities among who is getting the shot. Local health departments are focused on making the vaccine as visible and convenient as possible for hard-to-reach populations, but that’s often not enough. On a recent afternoon outside the Boys and Girls Club in Chicopee, a sound system plays festive music under a tent, next to a large bus that says “COVID-19 VACCINE” on the side.