Updated May 25, 2021 at 2:42 PM ET
The U.S. COVID-19 vaccination program has gone from zero to 50% in less than six months.
As of Tuesday afternoon, the Biden administration said, half of the country's adults are now fully vaccinated against the coronavirus.
"This is a major milestone in our country's vaccination efforts," Andy Slavitt, a White House senior adviser on the COVID-19 response, said during a midday briefing. "The number was 1% when we entered office Jan. 20."