The U.S. Centers for Disease Control and Prevention is backing booster shots for the Pfizer and BioNTech COVID-19 vaccine for Americans aged 65 and older.
From Friday, millions of Americans, including nursing home residents and those aged 50 to 64 with underlying health problems, will be able to receive the additional dose.
Those in high-risk occupational and institutional settings can get the shot too.
This is a dramatic scaling back of the Biden administration's previous plan to administer booster shots to nearly all Americans.
The U.S. has fully vaccinated around 55 percent of its population.