Testing COVID-19 vaccines in kids is next up in the hunt for a safe, effective preventive step

The global hunt for a COVID-19 vaccine for kids is only just beginning — a lagging start that has some pediatricians worried they might not know whether any shots work for young children in time for the next school year.

Older adults might be the most vulnerable to the coronavirus, but ending the pandemic will require vaccinating children, too.

Pfizer Inc. recently received permission to test its vaccine in kids in the United States as young as 12 — one of only a handful of attempts around the world to start exploring whether any experimental shots being pushed for adults also can protect children.

“I just figured the more people they have to do tests on, the quicker they can put out a vaccine, and people can be safe and healthy,” said 16-year-old Katelyn Evans, who became the first teenager to get an injection in the Pfizer study at Cincinnati Children’s Hospital.

Multiple vaccine candidates are in final-stage studies involving tens of thousands of adults, and scientists are hopeful that the next few months will bring evidence that at least some of them are safe and effective enough for widespread use.

But when the first shots arrive, they’re unlikely to be recommended for children. Vaccines can’t be given to kids unless they’ve been tested in their age group — a major hurdle in efforts to reopen schools and resume more normal activities.

“The public doesn’t understand that,” said Dr. Evan Anderson of Emory University, who has been pushing for pediatric testing of COVID-19 vaccines.

He’s encouraged by Pfizer’s study in adolescents but said it’s “very concerning” that children younger than 12 might not have a vaccine by next fall.

Children represent about 10% of COVID-19 cases documented in the United States.

Though children are far less likely than adults to get seriously ill, about 120 have died in the United States, according to a tally by the American Academy of Pediatrics. That’s about how many die from flu in an average year.

And a small number have developed a serious inflammatory condition linked to the coronavirus.

Anderson said COVID-19′s impact on children is greater than some other diseases that require routine pediatric vaccinations.

Aside from their own health risks is the still unanswered question about how easily children can infect others. In a letter to federal health officials, the pediatricians organization, which is based in Itasca, cited recent evidence that those over 10 years old might spread the virus as easily as adults do.

Add missing school and other factors unique to children, and it’s unethical “to allow children to take on great burdens during this pandemic but not have the opportunity to benefit from a vaccine,” according to Dr. Sara Goza, president of the pediatrics academy.

Globally, little has been done to study COVID vaccines for children. In China, Sinovac and SinoPharm have opened studies that can test children as young as 3. A British study of a vaccine by AstraZeneca allows for testing of a low dose in certain children, but the company says it won’t be recruiting kids until it has “sufficient” safety data in adults.

In the United States, Moderna Inc., Johnson & Johnson and Novavax all hope to begin some pediatric research later in the year.

Doing so is critical, said Dr. Robert Frenck, who directs the Vaccine Research Center at Cincinnati Children’s.

“If we immunize adolescents — and potentially move down into younger children — we’re going to have the effect of keeping those children from getting infected,” Frenck said. “But then also they don’t bring the infection home to parents and grandparents.”

He’s finding lots of interest in Pfizer’s adolescent testing, with 90 families seeking more information in just a week after his team issued a call for 16- and 17-year-old volunteers. The researchers plan to enroll 12- to 15-year-olds soon.

It makes sense to start pediatric testing in teenagers and gradually work down in age, Frenck said, because adolescents usually receive adult-sized doses of other vaccines. So far with Pfizer’s shots, serious safety problems haven’t emerged in adult testing.

Assuming Pfizer’s shot is proven to work in adults, Frenck said the key will be whether the vaccine revs up adolescents’ immune systems the same way — without different side effects. If all goes well, it’s possible, he said, that scientists could have an answer about the 12-and-older group by spring.

But younger children need their own testing. Anderson, a pediatric infectious disease specialist at Children’s Healthcare of Atlanta, said those studies might be more complex because smaller children might need different doses or, because of their typically more robust immune systems, show different reactions.