"Boosters are important, but the important thing we need to do is get more people vaccinated," Biden said, noting about 23% of Americans haven't received a first shot.

"That distinct minority is causing an awful lot of damage for the rest of the country," Biden said. "One thing's for certain: A quarter of the country can't go unvaccinated and us not continue to have a problem."

People 65 years and older, residents in long-term care settings and people 50–64 with underlying medical conditions should receive a booster shot, the CDC said Thursday. People 18–49 with underlying medical conditions and people 18-64 years who are at increased risk for exposure and transmission because of occupational or institutional setting may receive a booster, the CDC said.

The other two available vaccines – Moderna and Johnson & Johnson – have not received federal authorization for a booster shot. CDC Director Dr. Rochelle Walensky said Friday that the agency expected to review applications for booster shots from Moderna and Johnson & Johnson "with urgency" in the future.

Biden, 78, said he planned to travel to Chicago on Wednesday to speak with businesses about the importance of vaccinations. He encouraged Americans to text 438829 to find a nearby vaccination location.

Biden said he didn't have any side effects after his first or second dose. The first lady was also expected to receive a booster shot, he said.