COVID-19 vaccines are now available for kids under 5. Here’s what parents should know.

illustration of a doctor administering a vaccine to a small child
(Images: Adobe Stock. Illustration: David Chrisom, Boston Children’s Hospital)

Children under age 5 can now be vaccinated against COVID-19. The Centers for Disease Control and Prevention (CDC) recently approved the use of vaccines produced by Pfizer-BioNTech and Moderna in children ages 6 months and older.

We spoke with Dr. Kristin Moffitt, a pediatric infectious disease specialist at Boston Children’s, to get answers to your questions.

How are the vaccines different?

The Moderna vaccine is a 25-microgram (mcg) dose for children 6 months to 5 years old. It is a quarter of the dosage for adults, and it is given twice, with shots spaced four weeks apart. The Pfizer vaccine, for children 6 months to 4 years old, is a 3-mcg shot, one-tenth of the adult dose, given three times. The first two shots are three weeks apart, and the third one is two months after the second shot. The third dose was added when it was noted that the immune response to the first two doses in this age group was not as high as it had been in older individuals who had received two doses. The reason for this is unclear, but it may be because of the lower dose used in this age group.

How effective are the vaccines?

They both generate similar immune responses in kids under age 5 as have been seen in older children, teens, and adults. In studies, both vaccines also decreased the rates of symptomatic COVID-19 in kids under 5. As with the adult vaccine, many providers will only offer either Moderna or Pfizer, and we recommend choosing whatever is available and works for your family’s schedule.

Are the vaccines safe? Do they cause side effects?

Based on the data we have available, both vaccines look very safe. For Moderna and Pfizer, the most common side effect reported in vaccine recipients was pain at the site of the injection. And both had a low frequency of fever in the days following inoculation. Fatigue was the most common systemic side effect of the Pfzier vaccine; headache and fatigue for Moderna’s. There were no cases of myocarditis, the type of heart inflammation found in some young men who received the COVID-19 vaccine.

Will my child need a booster dose?

Although more research is needed, it’s likely that — just like older kids, teens, and adults — this younger age group will benefit from a future booster dose.

My child already had COVID-19. Do they really need to be vaccinated?

We still recommend that children with a prior COVID-19 infection get vaccinated. If your child had a confirmed COVID-19 infection with in the past month or two, it’s reasonable to wait a few weeks to get your child vaccinated. However, we know that a COVID-19 infection that was more than several months ago is less likely to confer immunity, especially against the Omicron variant. And vaccination can boost any immunity that your child did get from natural infection.

I was vaccinated when I was pregnant with my child. Do they still need to be vaccinated?

It’s possible that infants likely got some antibody immunity from their mother if she was immunized against COVID-19 during pregnancy. But we know that immunity that’s passed on to infants starts to wane around six months after birth. So we still recommend that infants 6 months and older be vaccinated against COVID-19.

Is the COVID-19 vaccine safe for my child to get at the same time as other scheduled immunizations?

While we don’t yet have data for kids under age 5, we do now have quite a bit of experience with older children and adults who received COVID-19 vaccines at the same time as other vaccines — and we know that this is safe. We encourage families whose children are scheduled for routine immunizations to also consider COVID-19 vaccination at that same visit. If you have any questions about getting multiple vaccines at the same time, talk with your child’s pediatrician.

Should my child continue to wear a mask and social distance when appropriate?

I still recommend wearing a mask when heading indoors for those who live in a community where the COVID-19 level is moderate to high. And at any level, individuals may choose to wear a mask based on their own risk of serious COVID-19 or personal preference.

Why should I vaccinate my child against COVID-19 if children are less likely to get severely sick?

While it is true that the majority of children get a mild infection, there have been thousands of children who needed to be hospitalized for COVID-19. Hundreds have died from it. The rate of those serious outcomes is similar to the rate we see from pediatric influenza infections. So we recommend COVID-19 vaccine for the same reasons we recommend influenza vaccines, because we know these vaccines are very good at preventing serious infection from COVID-19.

Get more answers for your family about COVID-19.

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