U.S. President Joe Biden on Monday received his coronavirus vaccine booster shot, after health authorities approved a third shot of Pfizer Inc.'s vaccine for older and higher-risk individuals last week.

"Boosters are important," the 78-year-old president said, while noting that "the most important thing we need to do is get more people vaccinated."

Under a recommendation issued by the U.S. Centers for Disease Control and Prevention on Friday, people 65 years of age and older as well as long-term care residents should receive a booster shot of Pfizer's COVID-19 vaccine at least 6 months after their second dose of the two-shot inoculation.

U.S. President Joe Biden receives a third dose of the Pfizer/BioNTech Covid-19 vaccine at the White House on Sept. 27, 2021 in Washington. (Getty/Kyodo)

People aged 50-64 years with underlying medical conditions such as cancer or diabetes should also take the extra shot, while those aged 18-49 years with such conditions may receive a booster shot "based on their individual benefits and risks," according to the CDC.

People over age 18 who are required to be in high-risk settings -- such as healthcare workers, teachers and grocery store workers -- may also receive a booster shot.

"With the Delta variant's dominance as the circulating strain and cases of COVID-19 increasing significantly across the United States, a booster shot will help strengthen protection against severe disease in those populations who are at high-risk for exposure to COVID-19 or the complications from severe disease," the CDC said in a statement issued Friday.

The CDC also said the same day it will evaluate available data in the coming weeks to make additional recommendations soon for people who got the Moderna Inc. or Johnson & Johnson COVID-19 vaccines.

While the third dose is being rolled out, 23 percent of adults in the United States have not received even their first shot, according to CDC data.