How soon can we expect children to get COVID-19 vaccines? It depends on the child's age, but some teenagers could be rolling up their sleeves before too long.

In the United States, the BioNTech/Pfizer vaccine is already authorized for use starting at age 16. That means some high schoolers could get in line for those shots whenever they become eligible in their area, either because of a medical condition or once availability opens up.

Pfizer and Moderna have both completed enrollment for studies of children aged 12 and older, and expect to release the data over the summer, according to The Associated Press (AP).

Pfizer Chief Executive Albert Bourla recently told Reuters that his assumption was that the vaccine should be authorized for the 12 to 16 age range by the fall.

He added that data on children aged 5 to 11 could be expected by year-end.

The Moderna vaccine is currently cleared for people aged 18 and older. Researchers started with older children because they tend to respond to vaccines most similarly to adults.

Meanwhile, top U.S. infectious disease official Dr. Anthony Fauci believes high school students should be able to receive COVID-19 vaccinations by autumn, with younger students likely to be cleared for vaccinations in early 2022.

"We project that high school students will very likely be able to be vaccinated by the fall term, maybe not the very first day, but certainly in the early part of the fall," he told Reuters.

He said elementary school children would likely be ready to receive vaccinations by the first quarter of next year after studies on safety are finished.

Testing younger groups is more complex, because they may require a different dose or have differing responses.

"Children are not just small adults,” pediatrician Dr. James Campbell of the University of Maryland School of Medicine told AP. "The younger you get, the higher the odds are that things could be different.”

Children develop serious illness or die from COVID-19 at much lower rates than adults, but can still spread the virus.

"There’s no question: we do want to immunize children,” said Drexel University pediatrics professor Dr. Sarah Long.

Pfizer and Moderna expect to start studies in children 11 and younger later this year.

"It’s unlikely we could get community protection without immunizing children,” Long added. "This is the lynchpin to getting everything back to some kind of normalcy.”