A pharmacy technician prepares doses of the Pfizer-BioNTech COVID-19 vaccine at a mass vaccination event on Saturday in Denver.

DENVER, CO – JANUARY 30: Pharmacy technicians prepare doses of the Pfizer-BioNTech vaccine at a mass COVID-19 vaccination event on January 30, 2021 in Denver, Colorado. UCHealth, Colorado’s largest healthcare provider, plans to vaccinate 10,000 seniors over 70 during the drive-up event this weekend. (Photo by Michael Ciaglo/Getty Images)