Patrick, a 9-year-old in Houston, petted a hospital therapy dog named Bailey while a nurse administered a shot that made him one of the first American elementary-schoolers to get vaccinated against the coronavirus.

In Connecticut, 7-year-old Kareem shouted over applause that his shot didn't hurt after he was injected on camera. In Columbus, Ohio, a children's hospital handed out capes and encouraged kids to pick a superhero name for a superhero themed vaccine clinic.

Almost a year after their parents and grandparents became eligible, young U.S. children are now lining up for vaccines to protect them from the virus that upended their childhoods, in many cases keeping them away from schools, playdates and vacations. The Centers for Disease Control and Prevention signed off late Tuesday night on smaller doses of the Pfizer-BioNTech coronavirus vaccine for children ages 5 to 11.

Soon after, doctors and nurses began administering the first shots, and parents started scrambling to book appointments, many hoping their children could be partially vaccinated before Thanksgiving. White House officials have cautioned pediatric vaccinations won't start in earnest until next week after initial shipments of 15 million doses arrive, medical professionals undergo training on administering the shots, and doctors and hospitals plan clinics.

"Over the next 24 hours alone, there will be millions more doses in the air and on trucks heading to cities and towns across the country," White House coronavirus response coordinator Jeffrey Zients said Wednesday. "As we hit full strength next week, finding a site nearby and scheduling an appointment will become easier and easier."

This is a long awaited moment in the country's grueling fight against the coronavirus. The nation is recovering from a summer surge driven in part by soaring cases among children that resulted in record high pediatric hospitalizations. The vaccine authorization came as millions of families hope to revive big holiday gatherings, to restore a semblance of normalcy in their children's lives and to feel less anxious about severe cases of covid-19 when their children develop sniffles and coughs.

Suzanne Berman, a pediatrician in Crossville, Tenn., said her doctor friends have been posting photos online, showing them smiling as they pop open boxes of the vaccine. She said her office has ordered 600 doses to start.

Berman said she anticipates the first 100 doses or so will be administered almost immediately, but the rest will be given out over the next couple of weeks.

"We have some families who are so eager to get the COVID vaccine for their kids that they're listening for the crackle of us opening the box," she said.

Following the CDC's recommendation, Hartford HealthCare in Connecticut was among the first to crack open its vaccine boxes. During a news conference, half a dozen 5- to 11-year-olds lined up at Hartford Hospital to get some of the first pediatric doses in the country, many eager to roll up their sleeves.

After the first child, Kareem Omar, got his shot, he shouted over the applause, reassuring his peers that it didn't hurt. The 7-year-old then clapped his hands and leaped off the stage.

His mother, Reem Nouh, said during a follow-up media briefing Wednesday morning that her son kept asking when it would be his turn to get a shot after his parents and 14-year-old sister got vaccinated.

"He went to school super excited today. He's going to tell all his friends," Nouh, from Simsbury, Conn., told reporters. "I'm hoping that all the kiddos from last night are an inspiration to their friends, to their families and to their communities so that we can all get past this. We're just beyond grateful and excited."

Texas Children's Hospital marked the occasion by vaccinating brothers Paxton, a 5-year-old who had leukemia during the pandemic, and Patrick, 9, on camera, with therapy dogs cuddling near them as they got their shots.

After the shot, Patrick told reporters he will tell his friends: "I got my vaccine, I got to play with Bailey and Pluto and give them treats," he said, referring to the dogs.

The hospital averaged 1,000 appointments an hour when it opened sign ups after the Food and Drug Administration's Friday approval of the Pfizer vaccine for children, said Jermaine Monroe, co-chair of the hospital's COVID task force. Now it has 37,000 appointments booked and plans to partner with schools and churches for on-site clinics in neighborhoods with low vaccination and high infection rates.

Away from cameras, some parents felt confused as they scrambled to vaccinate their children.

Heidi Belka, 43, showed up for an 11:30 a.m. appointment at the Salt Lake City health department to vaccinate her 5-year-old son Freddy. But she was told the department didn't have the vaccine yet, even though she'd made the appointment the night before. After holding on the phone for an hour, she was told the county did have the vaccine and to come back Wednesday afternoon.

Belka said she was relieved to have the first dose — for the community, for her family and for Freddy, who has asthma. Fresh after getting his first shot, Freddy said the flu shot felt worse.

"I didn't feel it so much," he said as he sipped an apple juice box, having already gotten a strawberry-flavored sucker for being brave. "Actually I wasn't nervous at first, then I was afraid, then I was brave."

Other parents vying to get their kids at the front of the line Wednesday found disappointment.

Matt Dayton of Chicago said his two kids, ages 9 and 10, cheered when he told them over dinner Tuesday that they were now eligible for vaccines.

"It's just been so in the news, it's been pervasive and I think they see it as one more way for them to try to be able to return to normal," said Dayton, a 48-year-old financial executive.

Dayton hoped they could get their first doses on Wednesday to maximize time for their immune systems to learn to fight the virus before they joined his parents and three siblings for a roughly 19-person Thanksgiving dinner.

But vaccines.gov did not list locations for pediatric vaccines (and may not until Friday, federal officials warn). His pediatrician wasn't taking appointments yet either. Another hospital required advanced registration.

The Daytons will instead have to wait for a Sunday appointment, which provides enough time for partial Thanksgiving protection with a smaller group of people, and ample time to build the children's immunity ahead of a Christmas trip to California and to allow their parents to feel more comfortable dining indoors during Chicago's bitter cold winter.

While children generally are at lower risk for severe complications from COVID-19, the authorization of vaccines couldn't have come soon enough for parents of medically vulnerable children.

Soon after the CDC approval, Amie Marston, 48, of Seattle, began combing websites to book a vaccine appointment for her 7-year-old daughter, Poppy, who has viral-induced asthma.

At the start of the pandemic, Poppy's pulmonologist warned that COVID-19, the illness caused by the coronavirus, could land her in the hospital, so Marston said she and her daughter have not gone anywhere indoors without KN95 masks since March 2020.

"There was a risk of her being hospitalized, intubated, dying. With the vaccine, will she get sick and need some inhalers? Maybe. But she will not die," Marston said.

She wants Poppy to have a more typical childhood.

"It has been a year and a half of an almost 8-year-old's life," she said. "Does she even remember what life was like before masks and COVID? I don't know. So this is about getting us back to where she can go to a sleepover and not have to wear a mask indoors. She can play in her treehouse out back with her friends and not have to wear a mask, or maybe just a surgical mask to be safe. We can go on a vacation, one that isn't camping."

At Nationwide Children's Hospital in Columbus, which held the superhero vaccine clinic, Wednesday's first jabs were the start of a longer road. Pediatricians are still vaccinating adolescents at a steady pace as parents who initially wanted to wait decide they're ready to vaccinate 12- to 17-year-olds months after they became eligible.

"This isn't just a quick two month process to get people vaccinated and then we are done," said Sara Bode, the hospital's medical director of school health and mobile services.

The rollout for 5- to 11-year-olds also presents challenges. Many pediatrician's offices are reporting limited capacity for vaccination while they deal with staff shortages and an influx of patients coming in with a wide range of respiratory viruses.

An early rush for children's vaccines does not guarantee high demand overall. About a third of parents wanted vaccines for their 5- to 11-year-olds as soon as it was authorized, according to a national survey by the Kaiser Family Foundation. Public health authorities are bracing for an uphill battle to vaccinate children in some areas where adults and adolescents are avoiding shots.

Since the start of the pandemic, about 1.9 million children between the ages of 5 and 11 have been infected with COVID-19 in the United States. And although severe disease is less common among children, more than 8,300 in that age group have been hospitalized — many requiring intensive care — and 146 have died, according to federal health officials. In addition, more than 5,200 children have suffered a rare but serious condition called multisystem inflammatory syndrome (MIS-C), which is associated with COVID-19 and can cause inflammation of the heart, lungs, kidneys, brain, eyes and other organs, according to the CDC.

Some families decided to get vaccinated after contracting the virus. Aaron Walker, 43, of Salt Lake City, said his wife Denise tested positive for COVID while pregnant with their third child — the day before she was to be vaccinated. She had difficulty breathing, required a trip to the emergency room and oxygen when she got home, he said, scaring their sons Elias, 11, and Andre, 8.

The family was convinced they all needed to be vaccinated, Walker said. And as Utah Jazz season ticket holders, the requirement to be fully vaccinated to attend NBA games in person this year also played a big role in their decision. The Walkers are hoping to get their sons on the list to be vaccinated when they boys go to an annual checkup next week.

"Elias is looking forward to [getting the shot] so he can go to games," Walker said as he and his wife left a doctor's appointment for their 3-week-old daughter, Lilian.

For others, anxieties about the virus and low vaccine uptake are fueling the urgency, especially in hard-hit areas.

When the delta variant sparked a rapid surge in cases across Oklahoma as students were set to return to school, Heather Cody said her jitters about sending her only child off to first grade in Tulsa turned into panic and desperation. She enrolled Alayah in a Moderna vaccine trial for children seven hours away in Omaha.

Just 15 minutes after learning her daughter had received placebos, Cody scheduled Alayah's first dose and a booster shot for herself on Saturday.

"I don't think I'm extra cautious. It's just my job doesn't allow me to stay home," said Cody, 31, who does professional development for teachers.

Doctors are also gearing up to reassure parents who were eager to get vaccinated themselves but find themselves more wary about vaccinating their children.

Katharine Clouser, medical director of the pediatric covid recovery center at Joseph M. Sanzari Children's Hospital in Hackensack, N.J., found herself fielding more questions about the ingredients in the vaccine and the results of clinical trials. And she's perfecting her pitch for vaccination:

"It's a great way to protect kids and to get back to the really normal things that kids want to do," she said. "They want to play sports without wearing masks, to go to school dances. I think getting vaccinated is the way we're going to be able to go back to normal."

The Washington Post's Katie Shepherd in Washington, Kevin Armstrong in New Jersey, Andy Becker in Salt Lake City, Andrea Eger in Tulsa, Kristen Millares Young in Seattle contributed to this report.