LOUISVILLE, Ky. — After the green light was given to begin administering the Pfizer vaccine to children as young as 12, some of Kentucky's first vaccinated pre-teens couldn't hide their excitement on Thursday.

"I’ll probably brag about it a little bit, but not too much, because I think I’m the first kid in my class to get it," laughed Maggie, 13. "It’s really exciting."

A steady flow of families filed into a Norton Children's Hospital strip mall clinic in Louisvile's east end. At a line of tables moms hovered nearby, watching their child's face as they awaited the needle.

As of Thursday, 266,000,000 COVID-19 vaccine doses had been administered in the United States, so it's no wonder nurses have become skilled at giving them with little to no pain felt by even the most needle-averse.

Fully into conversation about prom, one boy seemed perplexed when his nurse said he could pull his sleeve back down over his shoulder.

"You did it?" he asked. The nurse and his mother laughed.

"You didn't even know," the nurse said confidently.

3,500 teens and pre-teens had pre-registered through Norton by the time its six vaccination sites opened Thursday morning. They reached 700 adolescent arms in one day, aiming to stick the same number on Friday.

"Seeing thousands of kids here ready to get vaccinated, ready to do their part to fight the pandemic, it makes me elated," said Daniel Blatt, MD, a pediatric infectious disease professor with the Louisville School of Medicine. "I’m so happy to see that. It’s a very safe and a very effective vaccine."

13-year-old Tatiana had had a long year in virtual middle school, and was quite ready to see friends again when we met her after her shot.

"I want things to go back to a normal life [with] me going into high school," she said. "Seventh grade was not normal. I didn’t even get to see my friends until April."

Despite thousands reserving their spot, Norton doctors know some families have questions. They hosted a Q&A for parents hours after the first vaccines went out.

For some, like 13-year-old Maggie, Thursday lifted a weight off of their shoulders.

"It’s really relieving because the past year has just been so crazy, and it feels great to not have to worry about it as much anymore," she said.

With a year and a half of COVID-19 in their lives and 580,000 American deaths so far, Maggie's shoulders and that of her generation shouldn’t have had to carry the load.

But now they have a fighting chance.