Health officials track safety as COVID-19 vaccines roll out

Catalina Gonzalez-Marques, an emergency medical physician, receives the Pfizer-BioNTech coronavirus vaccine at Brigham and Women’s Hospital, Wednesday, Dec. 16, 2020, in Boston. (Brian Snyder/Pool via AP)

As COVID-19 vaccinations roll out to more and more people, health authorities are keeping close watch for any unexpected side effects.