What to Know About the COVID-19 Vaccine and Young Kids

Two leading pediatric specialists share why it’s important for children ages 5 to 11 to get vaccinated.

About 28 million children became eligible for the COVID-19 vaccine after the Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC) approved and created guidelines for children ages 5 to 11 to receive the Pfizer/BioNTech COVID-19 vaccine. But as the vaccine rollout begins for younger kids, many parents may have questions.

Health Matters spoke to Dr. Karen Acker, a pediatric infectious diseases specialist and hospital epidemiologist at NewYork-Presbyterian Komansky Children’s Hospital and assistant professor of clinical pediatrics at Weill Cornell Medicine, and Dr. Melissa Stockwell, chief of the division of child and adolescent health at NewYork-Presbyterian Morgan Stanley Children’s Hospital and NewYork-Presbyterian/Columbia University Irving Medical Center and associate professor of pediatrics at Columbia University Vagelos College of Physicians and Surgeons, to share what parents should know about the vaccine for children in this age group — its safety, side effects, and how effective it is at protecting kids from COVID-19.

Why is it important for young kids to get vaccinated?
Since the pandemic began, about 2 million children ages 5 to 11 have been infected with SARS-CoV-2, the virus causing COVID-19, and 8,300 have been hospitalized, a third of whom have needed intensive care. While the number of children who have died of COVID-19 in the past year is fortunately small, COVID-19 is still among the top 10 causes of death in this age group. This is something we can help prevent by getting children vaccinated.

We know that children have been greatly impacted by the COVID-19 pandemic, whether they were infected with the virus or not. We have also seen that children who live in areas with low vaccination rates are much more likely to get infected and be hospitalized with COVID-19. When younger children are vaccinated, parents can be assured that their kids can go to school safely, play with other children their age, and stay safe while resuming their normal lives. The sooner we and our children can get vaccinated, the sooner we can feel reassured that we have done our best to keep our children protected from COVID-19.

Dr. Karen Acker

How well does the Pfizer/BioNTech COVID-19 vaccine work in kids ages 5 to 11?
The vaccine was found to be very effective in children ages 5 to 11 years old in a clinical trial involving about 4,500 children. In the trial, vaccination resulted in robust antibody levels similar to that seen in adolescents and young adults 16 to 25 years old and was shown to be 90.7% effective in preventing symptomatic COVID-19.

Is the Pfizer/BioNTech COVID-19 vaccine safe for kids ages 5 to 11?
Yes. The vaccine was found to be safe and well-tolerated in this age group. Side effects were generally similar to those seen in adolescents and adults 12 years of age or older enrolled in the trial, with pain at the injection site being slightly lower in the 5- to 11-year-old group, but redness and swelling slightly higher. Systemic effects like fever, fatigue, headache, chills, and muscle pain were generally reported less frequently and were milder in severity in the 5- to 11-year-old group compared to individuals 12 years of age or older.

What is nice about the lower dose for this age group is that it may result in fewer of these mild side effects.

What is the exact dose for kids in this age group and how was that determined?
The dose for children 5 to 11 years old is 10 micrograms compared to 30 micrograms for 12 years and older. This dose was determined during the Phase 1 part of the trial, and they identified this dose as optimal in balancing side effects and the immune response to the vaccine. The dose depends only on age; weight is not a factor.

Dr. Melissa Stockwell

Dr. Melissa Stockwell

When are kids considered to be fully vaccinated?
As of now, the definition of fully vaccinated is the same for all ages — after two weeks have passed since the last dose of the vaccine series. In the case of mRNA vaccines, like Pfizer, that’s two weeks after the second dose.

We do not know yet if boosters will be recommended for children. Based on what we know from older age groups, those who were vaccinated more than 6 months ago are still protected against severe disease and hospitalization. Certain adults have been approved for boosters, and whether this will expand to other groups in the future is uncertain.

Which kids should not get vaccinated?
Anyone who has had a severe immediate reaction (e.g., anaphylaxis) to a previous dose or ingredient of the COVID-19 vaccine should not receive the same vaccine. The only ingredient in the mRNA vaccine thought to cause allergic reactions is polyethylene glycol. This is the main ingredient in Miralax, which many children and adults use for constipation. If your child has had no issues with Miralax, it is highly unlikely that your child will have an allergic reaction to this ingredient.

“The sooner we and our children can get vaccinated, the sooner we can feel reassured that we have done our best to keep our children protected from COVID-19.”

Is there a risk of myocarditis?
Developing myocarditis, or inflammation of the heart muscle, after the COVID-19 vaccine is overall very rare. Most patients with myocarditis who received care responded well to medicine and rest and felt better quickly. No cases of myocarditis have yet been observed in children less than 12 years old who received the mRNA vaccine. It is also important to remember that COVID-19 infection itself can cause both myocarditis as well as multisystem inflammatory syndrome in children (MIS-C), a very serious condition that affects the heart, lungs, kidneys, brain, skin, eyes, and/or gastrointestinal organs. The median age of patients with MIS-C is 9 years. There have already been over 5,200 cases of MIS-C in the U.S. Most importantly, the known risks of COVID-19 illness including myocarditis and MIS-C far outweigh the potential risks of having a rare adverse reaction to vaccination, including the possible risk of myocarditis.

How do we know there won’t be long-term side effects for children?
Long-term side effects are very uncommon for any vaccine, and nearly all side effects from vaccines are seen in the first six weeks after a vaccine is given. We have not seen other age groups develop long-term side effects, and it is very unlikely we will discover long-term side effects in younger children.  We do know, however, that children can develop long-term side effects from COVID-19 itself, also known as “long COVID.”

Pfizer started enrolling children ages 6 months to 11 years in March 2021, so they have data and will continue to follow these children for two years. This is one of the most highly scrutinized vaccines in our history, and all side effects, both short- and long-term, are being monitored very closely.

Additional Resources

  • See more informational videos at NewYork-Presbyterian’s COVID-19 Vaccine Education Center.

  • Learn more about the COVID-19 vaccine and kids.

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