What to Know about COVID-19 Vaccines for Children 6 Months Through 4 Years Old

Child with their mother and a doctor

After COVID-19 vaccination, your child could experience irritability and crying; sleepiness or fatigue; loss of appetite; soreness, redness, or swelling at the injection site; headache; body aches and joint stiffness; and fever and chills.

The Centers for Disease Control and Prevention (CDC) recommend that children age 6 months through 4 years be vaccinated with the Pfizer-BioNTech (Comirnaty®) vaccine or Moderna (Spikevax™) vaccine.

This follows emergency use authorization from the U.S. Food and Drug Administration (FDA) for both vaccines for children in this age group on June 17, 2022.

Mini Kamboj

Mini Kamboj

“COVID-19 illness is typically not serious in very young children, but there is a chance of severe complications, and children can still spread the disease,” says Mini Kamboj, MSK’s Chief Medical Epidemiologist. “It’s very important for kids this age to get vaccinated so they can resume their social interactions with other children.”

Dr. Kamboj has answers to questions you may have about vaccination for your young child.

This information is about the COVID-19 vaccine for children age 6 months through 4 years.

Read about the vaccine for children age 5 through 11 »

Read about the vaccine for children age 12 through 17 »

Which vaccine can very young children receive?

They can receive either the Pfizer or Moderna vaccine.

The FDA has authorized:

  • 3 doses of the Pfizer vaccine for children age 6 months through 4 years
  • 2 doses of the Moderna vaccine for children age 6 months through 5 years
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Which brand of vaccine is better for my child?

Both brands of vaccines are safe and effective. COVID-19 vaccines are not interchangeable, though. After your child gets their first shot, they must finish their vaccination series with the same brand.

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How are the vaccine doses different for young children different from the one for adults?

Both the Pfizer and Moderna vaccines use smaller doses for children than what is given to adults.

The schedule of shots for your child depends on the brand, and whether your child has a weakened immune system (called immunocompromised).

Pfizer Vaccine for Children Age 6 Months Through 4 Years

1st dose

2nd dose — This must be given between 3 weeks (21 days) and 8 weeks after a child’s first dose.

  • Children who are immunocompromised should get the dose 3 weeks after their first dose.
  • Children with a healthy immune system (who are not immunocompromised) should get the second dose 8 weeks after their first dose.

3rd dose — This must be given at least 8 weeks after a child’s second dose, and it must be a Pfizer shot.

At this time, children in this age group who have a weakened immune system do not need to receive any additional doses of the Pfizer vaccine.

Moderna Vaccine for Children Age 6 Months Through 5 Years

1st dose

2nd dose — This must be given between 4 weeks (28 days) and 8 weeks after a child’s first dose.

  • Children who are immunocompromised should get the dose 4 weeks after their first dose.
  • Children with a healthy immune system (who are not immunocompromised) should get the second dose 8 weeks after their first dose.

Children in this age group who are immunocompromised should receive a 3rd dose of the Moderna vaccine. The third dose should be given at least 4 weeks (28 days) after their second dose.

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Should children who have a weakened immune system get vaccinated?

Yes. Children who are moderately to severely immunocompromised should get vaccinated. Just like immunocompromised adults, children with weakened immune systems are especially vulnerable to severe COVID-19 illness.

  • Children who receive the Moderna vaccine as their first dose should get an additional shot (which would be their 3rd shot) of the Moderna vaccine.
  • Children who receive the Pfizer vaccine as their first dose should only get the standard 3-dose series of Pfizer shots (as recommended for others in this age group).
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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 COVID-19 vaccination by talking to your child’s primary doctor at MSK. On July 1, we will begin offering vaccinations for children age 4 and younger.

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How do we know the vaccines are safe and effective in this age group?

Pfizer conducted a clinical trial of nearly 5,000 children, and Moderna conducted a clinical trial of more than 14,000 children. The FDA then conducted their own analyses of these data.

For both vaccines, the FDA determined that the smaller doses were similarly effective in generating an immune response in children compared to the larger doses given to adults.

Importantly, there were no new or unusual side effects seen in any of the Pfizer or Moderna studies on young children compared with what has been seen in older children or adults. The most common side effects in young children were irritability and crying; sleepiness or fatigue; loss of appetite; soreness, redness, or swelling at the injection site; headache; body aches and joint stiffness; and fever and chills.

It is important to know that heart inflammation after vaccination is expected to be rare in this age group. In contrast, heart complications that can develop after infection are prevented by the vaccine. Read more about myocarditis, a rare COVID-19 vaccine side effect »

The FDA, CDC, Pfizer, and Moderna will continue to monitor new data as more young children continue to get vaccinated to ensure that the vaccines are safe.

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

The side effects are not different for children.

Your child could experience irritability and crying; sleepiness or fatigue; loss of appetite; soreness, redness, or swelling at the injection site; headache; body aches and joint stiffness; and fever and chills.

The exact risk of heart inflammation after vaccine is not known, but is expected to be rare.

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

Yes, it’s recommended that children who have been infected with COVID-19 should still get vaccinated. Vaccination after infection increases protection against future infection and severe disease.

Those who were recently infected can get vaccinated 3 months after testing positive.

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Can children take the vaccine with other scheduled childhood vaccinations?

Yes. The COVID-19 vaccines remain effective and safe when given with other vaccines. There is no specific time interval that is recommended between routine vaccinations and the COVID-19 vaccine for children.

However, many vaccinations come with a risk of mild side effects. You may want to schedule your child’s COVID-19 vaccination at a different time from other vaccinations, to reduce the chance that they experience several side effects all at once.

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

It’s true that children are at a lower risk overall of becoming severely ill with COVID-19 compared with adults. However, the CDC reports children can still become very sick. Like adults, children can also experience symptoms of long COVID that can affect their quality of life and daily activities. These symptoms are prevented by the vaccine.

Multisystem inflammatory syndrome in children (MIS-C) is a severe but rare complication of COVID-19 infection. Approximately 1 in 3,000 people who are younger than 21 will develop MIS-C. 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.

Most importantly, very young children are at least as likely to be infected as adults and spread COVID-19 to others, including in the household and at school. Additionally, vaccination gives added protection even to those who were previously infected.


June 28, 2022


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