At a high school in Washington, D.C., this past week, Bridget Cronin looked on as public school workers shuffled through the two dozen vaccination stations that lined the building's atrium.
Volunteers alternated waving green placards to usher in the next patient. Red placards were on hand to signal the need for more vaccine doses.
The mass vaccination event to immunize teachers and other public school workers in the district, held at Dunbar High School, was the culmination of weeks of long planning.