wellness·8 min read

What To Know About Pfizer’s COVID-19 Vaccine for Kids Under 5

parent holding child's hand and mask
Design: theSkimm | Photo: Getty Images
Feb 11, 2022

Kids under 5 were one step closer to being able to get the COVID-19 vaccine. Pfizer asked the FDA to grant emergency use authorization (EUA) for a two-dose shot for kids in this age group earlier this month. And the FDA was planning to meet Feb. 15 to discuss. But now the FDA is postponing that meeting to wait for more information about a possible third dose. Pfizer is testing that right now. And says it should provide better protection.

This might be frustrating for some parents waiting to get their kids vaxxed. But it's still major news. And there might be some questions about the vaccine's possible dosage, side effects, and safety. So we talked to experts who have answers. Meet:

  • Dr. Jennifer Lighter, an associate professor of pediatrics at NYU Grossman School of Medicine, and a hospital epidemiologist and pediatric infectious disease specialist at NYU Langone Hassenfeld Children’s Hospital.

  • Dr. Tina Tan, a professor of pediatrics at Northwestern’s Feinberg School of Medicine and a pediatric infectious disease physician at Ann & Robert H. Lurie Children's Hospital of Chicago.

Spoiler: These docs strongly recommend getting the vaccine for your kids as soon as it’s available for their age group.

The FDA’s decision to postpone its meeting might confuse or discourage some parents. What would you tell them? 

“The delay in filing an EUA shows that the safety checks and balances around vaccine safety and effectiveness in this country work,” says Dr. Tan. “The delay is a positive thing so that enough data can be collected and analyzed to determine the optimal way that COVID-19 vaccines should be administered to the under-5 age group.” 

How is the vaccine dose for kids under 5 different from those for older children and adults?

Young children would get one-tenth the amount of vaccine that adults get per dose. For children ages 6 months to 4 years, the dose would be 3 micrograms per shot. But it’s still TBD whether they’ll get two or three doses.

“For adults, it’s 30 micrograms per shot, and there are three doses [when you include the booster],” says Dr. Lighter. “For children 5 to 11, it’s 10 micrograms each for two doses. And a booster for this age group is currently only recommended if they have an immune deficiency.”

Pfizer announced in December that two doses of its vaccine didn’t provide a strong enough immune response for some kids under 5. What’s changed since then?

That research showed that two shots were safe for everyone under 5. But more effective at protecting children under 2, Dr. Tan says. Pfizer had initially submitted the EUA request for two shots to get the ball rolling on immunizations as cases and hospitalizations among children surged last month. So that kids would be ready for a third once authorized — if they needed it. What’s changed: Pfizer says that its study on three doses is moving at a “rapid pace” and that it will wait because it believes three doses will provide a “higher level of protection” for kids under 5. It expects that data to be available for the FDA in early April.

What are the potential risks associated with a child under 5 not getting the Covid-19 vaccine?

“The vaccines are extremely safe,” says Dr. Lighter, pointing to research after about 8 million doses were given to children ages 5 to 11. And while mild reactions are possible (think: low-grade fever, a sore arm), she says they tend to happen less often in children. 

On the other hand, Dr. Tan says that not vaccinating your child could leave them vulnerable to complications from COVID-19, like MIS-C. Even if your child is generally healthy and you don't think your child's at risk of a serious infection. "We cannot predict who is going to go on to develop severe complications," says Dr. Tan. "Yes, you might think your child does not have any risk factors that would predispose them to that. But that does not mean that a child who has no risk factors can't get COVID and then get complications from it."

While the overall risk of children getting COVID-19 — especially a severe case — is lower, it still exists. Particularly for kids with certain medical conditions. The American Academy of Pediatrics estimates there have been over 12 million cases of COVID-19 in kids. And a recent CDC study found that hospitalizations in children under 5 were about five times higher during the Omicron variant peak than during the peak of the Delta variant. The CDC has reported about 1,000 pediatric deaths, with about 300 in kids under 5. Children and teens who've been admitted to hospitals with severe COVID-19 are more likely to be unvaccinated, Dr. Lighter says.

What would you tell a parent who’s on the fence about giving their child a COVID-19 vaccine?

Dr. Tan would emphasize that it does not alter your DNA (she says some people have been misinformed about this). And that it’s “the best tool to protect individuals against getting severe COVID-19.” 

“We have given out millions of doses of this vaccine. And we have a surveillance system called VAERS that monitors any type of reaction that someone can have with the vaccine,” Dr. Tan says. “The signals coming from that show that any type of [serious] side effect is very, very rare.”

Dr. Lighter would address parents’ concerns about myocarditis, an inflammation of the heart muscle. Although it’s been flagged as a rare side effect of the vaccine, it’s more likely to be caused by COVID-19 infection than by vaccination. One study in Nature Medicine estimated that out of a million vaccinated people ages 16 and older, there were an extra one to 10 instances of myocarditis. Compared to an extra 40 instances among every million people infected with COVID-19. 

Is there any reason to wait — for more info, a new variant, etc. — before getting a child vaccinated for COVID-19 once it's authorized?

Short answer: nope.

The vaccines provide some level of protection against all the variants out there, says Dr. Tan. And creating a vaccine specific to a new variant isn’t a great strategy. “The problem is that if a company were to create a specific vaccine just for that variant, by the time that vaccine gets released, there could be another variant out there,” she says. 

What if a child is close to the age where they’ll require a different dose (think: almost 5 or 12). Which dose should they get?

The dosage that’s recommended for your child is based on their age on inoculation day. So it’s OK if they’re given different doses if they have a birthday between shots. For example, Dr. Tan explains: “Say your child was 11 when they got the first dose of the Pfizer vaccine, and they turn 12 before they get the second dose. Well, the second dose should be the 12-year-old dose, which is the adult dose [30mcg].” 

Dr. Tan adds, “The way that a dose of a vaccine is chosen is based upon how much of an immune response you can generate with the smallest amount of antigen, [a substance that stokes an immune response], while causing the fewest side effects. And all of that is based on age.”

Do you anticipate that the authorization of a vaccine for young children will impact mask-wearing and other COVID-19 rules and recommendations?

Thing to keep in mind: Even if young children are approved for the vaccine, it’s unclear if or when the US will reach herd immunity. Aka when a large part of a community becomes immune to a disease, making its spread throughout that community less likely.

“But the higher the number of people in each individual age group that are vaccinated, the lower the chance that the virus is going to be circulating,” Dr. Tan says. And that might mean that places like preschools and daycares may not have to close because of COVID-19 exposures as much. Vaccinating young children, Dr. Lighter says, “gets us closer to being back to normal.”

But only about 27% of kids ages 5 to 11 and 58% of teens under 18 have been fully vaccinated. “That is much too low," says Dr. Lighter. So it’s hard to say how vaccination will impact COVID-19 policies overall.

Updated on March 21 to reflect new data on child hospitalizations during the Omicron wave.

Updated on Feb. 15 to include new comments from Dr. Tina Tan.

Updated on Feb. 11 to reflect the postponement of the FDA Advisory Committee's meeting to discuss EUA of Pfizer's vaccine for children under 5 years old.

This content is for informational and educational purposes only. It does not constitute a medical opinion, medical advice, or diagnosis or treatment of any particular condition. 


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