New Information: COVID-19 Vaccines Are Effective at Preventing Severe Illness in Young Children

Child wearing a mask and looking slight off camera

In clinical trials, children ages 5 through 11 experienced only mild side effects from the COVID-19 vaccine.

The Centers for Disease Control and Prevention (CDC) recommends that children ages 5 through 11 be vaccinated with the Pfizer-BioNTech COVID-19 vaccine (Comirnaty®). The decision follows an emergency use authorization for the vaccine issued on October 29, 2021, by the US Food and Drug Administration (FDA).

“While COVID-19 tends to be milder in children compared with adults, it can make children very sick and cause children to be hospitalized,” according to the CDC. “In some situations, the complications from infection can lead to death.”

On February 28, 2022, research was published online showing that vaccinated children had less protection against COVID-19 infection due to the Omicron variant but that severe disease was rare. See below for more information.

Mini Kamboj, Memorial Sloan Kettering Cancer Center’s Chief Medical Epidemiologist, has answers to your questions about COVID-19 vaccines for children.

This information is about the COVID-19 vaccine for children age 5-11.

Read about the vaccine for children age 12-17 »

Which vaccine can young children receive?

Children ages 5 through 11 are now eligible to be immunized with the Pfizer vaccine. Children 12 and older were already eligible to receive the Pfizer vaccine.

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How do I schedule a COVID-19 vaccine for my child if they are an MSK patient?

You can schedule a vaccination by talking to your child’s primary doctor at MSK.

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Is MSK offering COVID-19 vaccines to children of MSK staff, members of the public, or siblings of MSK patients?

No, we are providing the vaccines only to pediatric patients at MSK.

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How do we know the vaccine is safe and effective in this age group?

According to data submitted to the FDA in October 2021, before the emergence of the Omicron variant, the vaccine was over 90% effective in preventing COVID-19 cases in children ages 5 through 11. That research also showed that the vaccine was safe and that serious side effects were rare. In addition, a study to monitor vaccine safety after almost 8 million doses were given to this group showed no major safety concerns. This study was conducted after FDA authorization.

Most importantly, cases of heart inflammation have been rare among vaccinated children in this age group. 

Vaccines have been less effective in preventing Omicron cases in all age groups, but protection against severe disease remains strong. A recent study conducted by the New York State Department of Health reported that vaccinated children had less protection against COVID-19 infection due to the Omicron variant but that severe disease was rare. As of February 28, 2022, that study was published online and was in the peer review process.

“It is encouraging to know that vaccinated children age 5 through 11 are protected from severe COVID-19 illness — that is what matters most,” says Dr. Kamboj. “These results are similar to what we saw among adults during the Omicron surge: Vaccinated people were getting infected, but most did not experience severe illness.”

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Are the side effects in children different from those in adults?

No, the side effects are not different. Children ages 5 through 11 in the trial experienced only mild side effects, which were more frequent after the second dose. The most common were pain at the injection site, fatigue, and headache. Side effects typically occurred within two days after vaccination, and most went away within one to two days.

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If children are at lower risk of serious complications from COVID-19, why should they get vaccinated?

Children are at a lower risk overall of becoming severely ill with COVID-19 compared with adults; however, the CDC also reports children can still become very sick. Like adults, children can also have both short-term and long-term health complications after COVID-19.

Most important, children ages 5 to 11 are at least as likely to be infected as adults and spread COVID-19 to others, including in the household and at school.

Multisystem inflammatory syndrome in children (MIS-C) is a severe but rare complication of COVID-19 infection in young children. Studies among vaccinated adolescents have shown that the Pfizer vaccine is 91% effective at preventing MIS-C. In a study published in January 2022, 95% of children hospitalized for MIS-C had not been vaccinated, and all patients who required life support for organ damage due to MIS-C were unvaccinated. 

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Is there risk from heart problems after the vaccine?

Research has shown that there is a greater risk of heart problems from being infected with COVID-19 than from being vaccinated. 

Studies from Israel and the United States link some COVID-19 vaccines to a rare heart condition called myocarditis or pericarditis (inflammation of the heart muscle or its lining). This complication is primarily seen in young males and has rarely been described in 12- to 15-year-old children after COVID-19 vaccination (estimated 60 cases per million doses). Although the risk of this complication for 5- to 11-year-olds is unknown, it is expected to be even smaller based on the lower likelihood of similar heart problems in general and the use of a lower COVID-19 vaccine dose in this age group.

The CDC has a very robust tracking system that closely follows the occurrence of heart inflammation cases following vaccination, and this information is routinely reported on their website and shared with the public.

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Do children with moderate to severe immunosuppression require a third dose of the Pfizer vaccine?

Children 5 through 11 who meet eligibility criteria can receive a third dose 28 days after the second Pfizer dose. The CDC updated its recommendation for a third dose to include this younger age group on January 4, 2022.

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How is the vaccine dose for young children different from the one for adults?

Children ages 5 through 11 will receive a dose that is one-third the size of an adult dose, delivered with smaller needles and stored in different vials to avoid mix-ups with adult doses. The smaller dose was chosen to minimize side effects while still producing a strong immune response. Children in this age group will receive a second shot three weeks after the first dose.

What To Know About Myocarditis, a Rare COVID-19 Vaccine Side Effect in Young People
You may have read about a troubling potential side effect from the COVID-19 vaccines. Cardiologist Michelle Johnson says these heart issues are very rare and treatable.
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What about children younger than 5? Is the vaccine available to them?

Not yet. In children younger than 5, very small doses of the vaccine — one-tenth of the adult dose — are being tested in clinical trials. But not enough data is yet available for this age group to determine effectiveness and safety.

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Should a child who has already had the COVID-19 infection take the vaccine?

Yes, the CDC recommends vaccination for children who have fully recovered from COVID-19 infection. Approximately 9% of children in Pfizer’s clinical trial had evidence of past infection. The vaccine was safe and effective for this group of children and is expected to increase the protection from future infection.

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Can children take the vaccine with other scheduled childhood vaccinations?

Yes, the other vaccines may need to be administered at a different site. No specific time interval is recommended between routine vaccinations and the COVID-19 vaccine for children.


March 1, 2022


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