The U.S. is unlikely to meet its goal of vaccinating 20 million Americans by the end of the year, health officials said this week.

A pharmacist dilutes the Pfizer COVID-19 vaccine while preparing it to administer to staff and residents at the Goodwin House Bailey’s Crossroads, a senior living community in Falls Church, Virginia, on December 30, 2020. (Photo by Brendan Smialowski / AFP) (Photo by BRENDAN SMIALOWSKI/AFP via Getty Images)