About 900,000 children ages 5 to 11 received their first COVID-19 shot within the first week of eligibility, sources within the Biden administration said Wednesday.
And approximately 700,000 more have appointments to get their first dose. The source of those numbers was unclear Wednesday morning; the Centers for Disease Control declined to confirm them ahead of a planned media briefing.
The CDC cleared the way for children in this age group to get Pfizer-BioNTech’s COVID-19 vaccine on Nov. 2.
Dr. Sean O’Leary, vice chair of the committee on infectious diseases for the American Academy of Pediatrics, said he has seen a lot of joy and enthusiasm in clinics, "with parents who are so relieved to get their kids vaccinated."
The numbers represent about 3% of the more than 28 million children ages 5 to 11 now eligible for the shots.
Pfizer previously reported that its vaccine is more than 90% effective against symptomatic illness in this age group.
The White House said clinics and children's hospitals nationwide have been rolling out the shots. Minnesota, officials said, has set up more than 1,000 locations, including one in the Mall of America, which has administered more than 4,000 shots.
Public health officials in Vermont have also seen a surge in parents ready to sign their children up. Just over 1,100 children in that age group have had their first dose, according to the state's health department. An additional 17,000 have appointments.
That may be an underestimate; those numbers only reflect appointments made through the health department.
Despite the increase in childhood vaccinations, it will most likely be January before the shots make a difference in the number of people sickened with COVID-19, Kelly Dougherty, deputy health commissioner for the Vermont Department of Health, said.
The vaccines require two doses, three weeks apart. People are not considered "fully vaccinated" until two weeks after the last dose.
"We are really counting on that to help us lessen our case counts," Dougherty said, not just among children, but for those more vulnerable to the virus.
Still, while children have not been as severely affected by the coronavirus as adults, they can develop serious complications, including long COVID-19 and an inflammatory syndrome that affects multiple organs, called MIS-C. That syndrome is most common in kids ages 5 to 11.
And infections among kids have continued to rise in recent weeks. According to the American Academy of Pediatrics, the number of new pediatric cases of COVID-19 has remained above 100,000 each week for more than three months.
Overall since the start of the pandemic, nearly 2 million COVID-19 cases have been reported among children ages 5 to 11.
Side effects could be mild
It is too soon to get a full picture of the kinds of side effects kids may have, but the AAP's O'Leary said they could be mild because the kids' doses are a third of what people 12 and older get: 10 micrograms versus 30 micrograms.
"Things like fever and chills appear to be less in this age group than in older kids," he said.
This story was originally published on NBC News.