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Kids on Cusp of Adult Covid Shots Set Off Queries for Doctors

Oct. 4, 2021, 9:25 AM

The questions started pouring into adolescent medicine specialist Hina Talib’s inbox almost as soon as Pfizer Inc. announced its Covid-19 vaccine for 5- to 11-year-olds was safe and effective: What about children on the cusp of adult and pediatric doses?

A vaccine for nearly all school-age children could become available by the end of October, after Pfizer and its partner BioNTech SE announced they sent initial data to the Food and Drug Administration about the use of their Covid-19 vaccine in children ages 5 to 11. It is the only vaccine that’s fully approved for everyone 16 and up, with an emergency use authorization for 12- to 15-year-olds.

If authorized, it would be the first Covid-19 vaccine that’s administered at a different dosage. Everyone 12 and up gets the same two-dose regimen of 30 micrograms three weeks apart. The pediatric vaccine is a third of the adult shot with a two-dose regimen of 10 micrograms that’s also administered three weeks apart.

With that difference in dosage, some parents started asking what they should do with kids who are closer to the upper age range for kids or the lower age range of adult doses. Talib, who runs the adolescent health content and vaccine education Instagram account TeenHealthDoc, said she received at least 100 direct messages on this question about children on the cusp of pediatric and adult vaccines.

“I was flooded with this question—I mean, flooded—with people asking what to do with their 11 turning 12, or 10 turning 11, or 12 turning 13 and how to make that decision,” said Talib, an associate professor of pediatrics at the Children’s Hospital at Montefiore in New York and spokesperson for the American Academy of Pediatrics.

Everyone should take the appropriate vaccine for their age group as soon as they can, pediatricians and infectious disease specialists told Bloomberg Law. The risks of getting Covid-19 are much greater than any perceived benefit of an 11-year-old waiting to turn 12 and get the adult vaccine.

“There’s so many other risks by waiting. I mean, we see that now, right? You can get exposed to Covid, you can get Covid, you can get very sick from Covid, and you could transmit Covid,” said Tina Q. Tan, a professor of pediatrics at the Feinberg School of Medicine at Northwestern University, and a pediatric infectious disease physician at Lurie Children’s Hospital of Chicago. “If a vaccine is available for you now, you should get that vaccine now.”

Urge to Jump the Line

At the same time, doctors said parents of children under 12 shouldn’t try to jump the line to get a vaccine off label.

Sally Goza, a pediatrician in Fayetteville, Georgia, said she’s been counseling parents on the need for the vaccine to go through the proper vetting for kids.

“They’ll say, ‘Well, they’re like a 12-year-old, or they seem like a 12-year-old,’” Goza, a past president of the American Academy of Pediatrics, said about parents who ask if she can just give their children the vaccine now. “No, we have to wait and make sure that the safety and efficacy is checked and the FDA and the [Centers for Disease Control and Prevention] Advisory Committee on Immunization Practices, approve it for that age group, and for what dose and for what interval and all those kinds of things.”

Unlike with medications, height and weight generally don’t factor into figuring out vaccine doses because they don’t circulate in the bloodstream the way medications would. Instead vaccines try to jump-start the immune system with enough antigens to produce a robust immune response. And the aim in developing vaccines is to get that immune response with the smallest amount possible to mitigate side effects.

“If you take amoxicillin, you want to make sure that you have a certain quantity of that drug per milliliter of blood so that it can be effective,” Paul A. Offit, director of the Vaccine Education Center and professor of pediatrics in the Division of Infectious Diseases at Children’s Hospital of Philadelphia, said. “Vaccines don’t work that way. If you give a vaccine, for example, in the arm, it’s taken up by a local draining lymph node and processed and then presented to the immune system.”

Children generally need a smaller dose of a vaccine than an adult to elicit the same immune response, Vidya Mony, a pediatric infectious diseases doctor, said. In general, children get exposed to many viruses and infections but tend to bounce back more quickly than adults.

“When we get sick, we’re down for the count for a little bit,” Mony, the associate medical director of infection prevention of the Santa Clara Valley Medical Center in San Jose, California, said. “Kids also can feel pretty crummy. But they recover much quicker than us.”

Avoiding Side Effects

The vaccine dose is based on the immune response, and not body weight composition. Administering a large dose to a child who doesn’t need the higher amount means they could experience a lot more side effects.

“We’re trying to find the smallest dose that will create a robust immune response without having a lot of side effects,” Tan said. “You’re just really trying to find that perfect dose for whatever the age group that person is, to stimulate their immune system to develop a response.”

The age cutoff is “to some extent arbitrary,” Offit, who’s co-inventor of the rotavirus vaccine, said. “If you’re 11-and-a-half years old, there’s not a big biological difference between you and a 12-year-old. These sort of rules are made to just provide some sanity as you move forward on this, for the most part.”

But the bottom line, he said, is to stick to the recommended use of the vaccines, assuming they become available. “Just so parents don’t drive themselves crazy, if you’re the parent of a 12-year-old, small or not, give the 30 microgram dose. If you’re the parents of an 11-year-old, small or not, give what’s going to be the 10 microgram dose, assuming the vaccine gets approved.”

Regardless, Pfizer’s vaccine has been made available for 12- to 15-year-olds through an emergency use authorization, which means providers have to adhere strictly to the terms of the EUA and can only administer the vaccine as directed. Likewise, the pediatric vaccine will likely become available through an EUA, which means it could only be given to the 5- to 11-year-old population as it’s intended to be administered.

On the Horizon

“Vaccines for children under 12 are now on the horizon,” Surgeon General Vivek Murthy said Oct. 1 at a White house press briefing.

The FDA has scheduled an advisory committee meeting for Oct. 26 in anticipation of receiving a request from Pfizer to allow its pediatric vaccines to be administered to children 5 to 11.

Grace Lee, a pediatrician at Stanford University School of Medicine and chair of the CDC Advisory Committee on Immunization Practices, said if the FDA makes the pediatric vaccine dose available under an EUA instead of a full approval, then the committee can only make recommendations on how to administer it around that EUA language.

“We’re just going to have to go on the data that they give us,” Lee said. “Once we are able to review the data on effectiveness and safety, and then once we take a look at what’s authorized, that’s going to define our ability to make recommendations around the use of vaccines.”

Until those vaccines become available for the 5- to 11-year-olds, Goza said, she frequently reminds parents one of the best ways they can protect their children from Covid-19 is to get the vaccine themselves. Hospitalizations among children and adolescents rose fivefold this summer as the delta variant began to dominate, according to a CDC analysis.

“We’re going to be very excited if and when this vaccine is approved because I think we’re going to be able to protect a lot of our children that we’ve not been able to protect at this point against the delta variant.”

To contact the reporter on this story: Jeannie Baumann in Washington at

To contact the editors responsible for this story: Brent Bierman at; Karl Hardy at