CNN  — 

Appointment slots are quick to fill. Excited grins are hidden behind masks. Syringes are filled and shots are ready to go into arms.

The rollout of the Pfizer/BioNTech coronavirus vaccine for children ages 12 to 15 in the United States has been reminiscent of when those very first Covid-19 vaccine doses were administered late last year, said Dr. Lisa Costello, a pediatrician at West Virginia University Medicine Children’s Hospital and a member of the American Academy of Pediatrics’ Committee on State Government Affairs.

“As we’ve seen this new age category, from 12 to 15, it’s brought renewed hope. Many of the people who I know that work the various vaccine clinics, they’ve told me it felt like December when we were giving those first shots,” Costello told CNN on Tuesday. “People are so hopeful.”

It has been one week since the rollout for younger teens and pre-teens began. The US Food and Drug Administration authorized the emergency use of Pfizer/BioNTech’s coronavirus vaccine in the younger age group last Monday and then on Wednesday, the US Centers for Disease Control and Prevention recommended using the vaccine in that age group.

“In less than one week, we have vaccinated more than 600,000 12- to 15-year-olds,” CDC Director Dr. Rochelle Walensky said during a White House briefing on Tuesday.

About 3.5 million children ages 12 to 17 have received at least one dose of coronavirus vaccine so far, according to the latest CDC data.

Walensky said that her own son was one of them.

‘A pretty brisk demand’

Both CVS and Walgreens pharmacies confirmed to CNN via email on Tuesday that their retail outlets are continuing to vaccinate adolescents ages 12 to 15, but neither company provided data on how many young people they’ve vaccinated.

Walgreens noted that there was “a spike in booked appointments, indicating early interest from parents to vaccinate their children.”

It’s still too early to tell exactly how the rollout is going nationwide and where it’s heading – but it seems that there has been a “pretty brisk uptake” of vaccine among this younger age group so far, Dr. Marcus Plescia, chief medical officer of the Association of State and Territorial Health Officials, told CNN on Tuesday.

“This is kind of what we’ve seen with the vaccine – is you get these early adopters,” Plescia said. “So, there has been a pretty brisk demand. The question is, how long and what percentage of that age group will be captured with that?”

As the vaccine rollout for ages 12 to 15 continues, the National Association of City and County Health Officials is “going to keep our ears to the ground to see if anything is bubbling up in terms of particular challenges, but none so far,” said Lori Freeman, the association’s chief executive officer.

The rollout has been “so far, so good,” but it has only been a week, Freeman said.

“What has helped the most is having these various distribution routes of the vaccine into communities. They extended supply, and made a natural background for implementing another age group rather easily,” Freeman said. “The focus, though, really needs to continue to be on meeting teens where they are, where they live, where they play, where they worship. I think that’s going to be key.”

Some states already are working to do that by setting up vaccination sites at schools and pediatricians’ offices.

Pediatricians to play a big role

In West Virginia, efforts to reach adolescents appear to be going “better than expected,” Costello told CNN, adding that there has been a lot of demand for the vaccine and enough supply to meet that demand.

“Our state took preparatory action to make sure that there would be enough Pfizer product in supplies so that we would have enough to be able to offer a vaccine to that age group,” Costello said.

“But certainly I think we need to continue to work to boost confidence and share information,” she added. “We have to continue to inform the public as to where the vaccines are.”

Parents and guardians can visit to find where vaccines may be available for young teens in their area. Costello said West Virginia is now working to provide more coronavirus vaccine doses to pediatricians’ offices so that young people can receive the vaccine directly from their doctors as a part of their routine care.

Pediatricians are also expected to play a significant role in the vaccination process in Tennessee, said Dr. Michelle Fiscus, medical director of the vaccine-preventable diseases and immunization program at the Tennessee Department of Health. She described the rollout of vaccine for ages 12 to 15 as going “pretty well” in her state.

“We have about 50 pediatric practices that have vaccines. Some of those are now transitioning over to the Pfizer product so that they’ll be able to provide it to that younger age group, and then we were told yesterday by CDC, they’ve confirmed that the week after Memorial Day we’ll have smaller packages of Pfizer vaccine available,” Fiscus told CNN on Tuesday.

Pfizer said in April it will offer smaller shipment sizes of its vaccine at the end of May to give vaccination sites more flexibility in the number of doses they can order.

The current shipment size includes a 195-vial pack that contains 1,170 doses of vaccine. The new smaller shipment size will include three 25-vial packs for a total of 450 doses. Smaller shipments will be easier for physicians’ offices to manage and reduce the risk of wasting product.

“Some of them have been hesitant to order when they know that they’re not going to be able to use a big quantity of vaccines – so this is going to help significantly,” Fiscus said.

“I think the biggest challenge has been that minimum order size of 1,170 doses. It’s just more than even a really busy pediatric practice can support within the time that we have before that vaccine expires,” Fiscus said. “And then the storage and handling requirements of the Pfizer vaccine can be a little bit intimidating.”

The state of Tennessee is also working to combat vaccine hesitancy in rural communities, Fiscus said. “That’s been a pretty tough nut to crack.”

The hurdle of hesitancy

Vaccine hesitancy has been a concern in New Jersey too, Dr. Meg Fisher, a spokesperson for the New Jersey Department of Health, told CNN on Tuesday.

“We have heard from lots of children that they’re excited and interested to be vaccinated,” Fisher said. “But we know that in New Jersey, we do have a fair amount of vaccine hesitancy. We’re hoping that over time, with appropriate education and reaching out, we will be able to make the vaccine available to everyone that wants it.”

New Jersey started vaccinating 12- to 15-year-olds late last week after the CDC’s Advisory Committee on Immunization Practices made the recommendation to do so – and officials are “very pleased” with how the rollout is going so far, Fisher said.

“We’ve immunized to date 29,333, and we have about 450,000 children between the ages of 12 and 15. So we certainly have a ways to go,” she said. “We definitely have the supply and we’re just learning really about what the demand is going to be. The demand so far is good.”

Local health departments are also working with school districts to offer school vaccination clinics, Fisher said. “We think that that’s going to be an excellent way to reach children.”

One challenge so far has been that some clinics prefer that a parent or guardian be physically present to provide consent for a child to be vaccinated. Others only require a written note from the parent or for parental consent to be given verbally over the phone.

“Working out the consent process for children between 12 and 15 is a potential barrier, but we can make it very easy and that’s what we’re trying to do” Fisher said. “Many schools already give the influenza vaccine. So, this is not a huge lift.”

Get CNN Health's weekly newsletter

Sign up here to get The Results Are In with Dr. Sanjay Gupta every Tuesday from the CNN Health team.

In general, there’s state-by-state variation in terms of what is required for routine childhood immunizations – and that variation includes Covid-19 shots too, Jill Rosenthal, senior program director at the National Academy for State Health Policy, told CNN last week.

“It does look like it varies in terms of the age of the child, the issues facing the child, for instance if they were emancipated,” she said. “So it does seem like in terms of routine childhood immunizations, it really varies quite a bit.”