The Biden administration has largely responded to the near vertical rise in coronavirus cases by pushing for more people to get not only their initial doses of vaccine, but booster shots as well.
This week, federal health officials endorsed boosters for youths 12 to 17 who had initially gotten the Pfizer-BioNTech vaccine. The government also changed the definition of “up to date” Covid vaccination to include boosters.
But even as the United States has moved rapidly to expand who is eligible for boosters, progress in persuading Covid-fatigued Americans to get them has stalled.
About 62 percent of Americans — about 206 million people — are fully vaccinated, according to federal data. But according to a C.D.C. database, only about 35 percent of Americans have received a booster since mid-August, when additional shots were first authorized, even as eligibility has greatly expanded.
On Nov. 19, the F.D.A. authorized boosters for everyone 18 and older who had received two doses of the Moderna and Pfizer vaccines, and on Dec. 9, it authorized boosters of the Pfizer vaccine for 16- and 17-year-olds.
Those changes led to more Americans getting boosters, according to the federal database, but that has since leveled off.
After the discovery of the Omicron variant in late November, the pace of all vaccinations sped up, but it peaked in early December, and then it plateaued. (Reporting lags around the Thanksgiving, Christmas and New Year’s holidays have affected the daily numbers throughout this period.)
Omicron, which is highly transmissible, has shown that it is better at evading vaccines than other variants. But scientists say booster shots can offer substantial protection, especially against severe disease.
The United States is averaging a staggering 585,000 cases a day, a record and a 247 percent increase from two weeks ago. Hospitalizations are rising more slowly, up 53 percent in the past two weeks, and a smaller percentage of patients are landing in intensive care units or requiring mechanical ventilation, compared with those in previous waves. Deaths are down by 3 percent.
The Centers for Disease Control and Prevention went even further in encouraging booster shots on Wednesday, when health officials recommended that to remain up to date, people should get three doses of Pfizer’s or Moderna’s vaccines. The agency also recommended that recipients of Johnson & Johnson’s one-dose vaccine receive a second dose, preferably of Moderna’s or Pfizer’s.
“There really isn’t debate here in what people should do,” the C.D.C.’s director, Dr. Rochelle P. Walensky, said in an interview on Tuesday. “If they’re eligible for a boost, they should get boosted.”
Still, the expansion of booster shot eligibility has not been met with an equal amount of demand. Dr. Rebekah E. Gee, the former health secretary of Louisiana, chalked up the resistance to boosters to pandemic fatigue.
Referring to the pandemic’s many problems, Dr. Gee said some people simply “don’t want this to be there” and are trying to “will it out of existence.”
