AURORA, CO – DECEMBER 15: (EDITORIAL USE ONLY) Rocky Mountain Regional VA Medical Center investigational pharmacy technician Sara Berech prepares a dose of the Johnson & Johnson COVID-19 vaccine for a clinical trial on December 15, 2020 in Aurora, Colorado. The Johnson & Johnson vaccine could be submitted for emergency use by late January and is the only vaccine among leading candidates given as a single dose. (Photo by Michael Ciaglo/Getty Images)