A health care worker with the Florida Department of Health administers a Pfizer-BioNtech COVID-19 vaccine at a retirement community in Pompano Beach, Fla. New Trump administration guidance arrived Tuesday, urging states to make all people over 65 eligible for the vaccine. Joe Raedle/Getty Images hide caption

The incoming Biden administration has plans to speed up distribution of COVID-19 vaccines, by not holding doses in reserve. Paul Sancya/AP hide caption

U.S. COVID-19 vaccination programs are off to a slow start, but with more funding, better coordination and public awareness campaigns, things could speed up, experts say. Joseph Prezioso/AFP via Getty Images hide caption

Contact tracer Toni Parlanti of Stamford, Conn., calls a person identified as having been potentially exposed to the coronavirus this week. States and territories report they have more than 70,000 people working on contact tracing as of December. John Moore/Getty Images hide caption

Following similar decisions in the United Kingdom and Canada, the U.S. has authorized the Pfizer-BioNTech vaccine for distribution. Matthew Horwood/Getty Images hide caption