On a frigid morning in January, Trudy Ronnel settled into her favorite sofa chair at the Westminster Place senior-living community in Evanston, Ill., pulled down the neckline on her red blouse and braced herself for a shot she’d anticipated for almost a year. At 92 years old, with multiple medical conditions, she spent most of 2020 fearful of contracting the COVID-19 plague that ravaged the world outside her first-floor window. To protect herself, for the past few months she’d avoided Westminster’s communal rooms, which had provided a means to stay active and engaged but risked becoming a pathogenic petri dish. Whenever she left her room, she dutifully wore a surgical face mask and maintained the mandated 6-ft.