But in California, cases have been declining since hitting a peak early this year, with the state now averaging around 2,700 new cases a day, the lowest figure since June. The C.D.C. said that, as of Tuesday, 35 percent of the state’s total population had received at least one vaccine shot, and 18 percent were fully vaccinated.
“With more than 20 million vaccines administered across the state, it is time to turn the page on our tier system and begin looking to fully reopen California’s economy,” Gov. Gavin Newsom, a Democrat, said in a statement. “We can now begin planning for our lives post-pandemic.”
Many public health experts say that the nation is in a race between the vaccines and the variants and that, for the moment at least, the vaccines appear to have the upper hand. But public health officials are worried that future iterations of the virus may be more resistant.
At the same time, they are watching an uptick in cases among young people, particularly those ages 18 to 24. Dr. Walensky told reporters on Monday that the C.D.C. was working with states to investigate outbreaks in young people that she said may be related to extracurricular activities or sports.
Mr. Biden spoke on Tuesday after visiting a vaccination clinic at the Virginia Theological Seminary in Alexandria, Va., which is working with community health centers to offer inoculations. Making the rounds of the makeshift clinic, he showed flashes of his old self — the sunny retail politician who likes to get close to people, with a pat on the arm or a squeeze on the shoulder.
“He’s gonna be hard — he’s got so much muscle mass there,” the president joked to a nurse as he squeezed the shoulder of a muscular man who was about to get his shot. “I tell you what, I could have been an All-American if I had those.”
But his lightness belied the seriousness of the message he would later deliver at the White House. There, he marked a milestone: Since Mr. Biden has been in office, more than 150 million Covid-19 shots have been administered to Americans, which puts the nation on track to reach his goal of 200 million shots by his 100th day in office, at the end of this month.