Ask Dr. Paul: COVID-19 Vaccines for Children Aged 6 Months to 17 Years

Hi, I’m Dr. Paul. As a pediatrician of 35 years and the Eastern Ontario Health Unit’s Medical Officer of Health, I understand that parents only want the best for their children, and that many are questioning whether they should get their children vaccinated against COVID-19.

I wholeheartedly believe that the COVID-19 vaccines are safe for our children and that they represent our way out of this pandemic. Below you’ll find the questions I receive most often from parents regarding the COVID-19 vaccines, and my answers. Please consult this page often as I’ll be updating it regularly throughout the rollout of the COVID-19 vaccines for children.

Development and approval of the vaccine

Side effects

Eligibility and special considerations

Dosage

General Questions

What COVID-19 vaccines for children have been approved by Health Canada and are available in Ontario?

The following vaccines are approved and available in Ontario as primary series vaccines or as boosters for children aged 6 months to 17 years of age:

PRIMARY SERIES

  • Pfizer-BioNTech vaccine for children aged 6 months to 4 years
  • Moderna vaccine for children aged 6 months to 5 years
  • Pfizer-BioNTech vaccine for children aged 5 to 11 years (recommended vaccine for this age group – see exception below*)
  • Pfizer-BioNTech vaccine for ages 12 years and older (recommended vaccine for this age group)
  • Moderna vaccine for ages 6 years and older

BOOSTER                                              

  • Pfizer-BioNTech bivalent vaccine for ages 5 and older (recommended booster for this age group)
  • Moderna bivalent vaccine for ages 18 years and older (also available for ages 12 to 17 years with moderate to severe immunocompromising conditions)

* Children who are 5 years old and who have started (but not completed) their primary vaccine series using a Moderna vaccine must complete their series using the Moderna vaccine for 6 months to 5 years of age. Mixing of Pfizer and Moderna vaccines is not recommended for the primary pediatric vaccine series due to their different dosing instructions.

The development and testing of vaccines usually takes longer. How can Health Canada approve new vaccines so quickly?

As a pediatrician and a parent, I understand that parents don’t want to give their children a vaccine that some still perceive as experimental. The truth is that Health Canada only gives approval to a vaccine after subjecting it to the same rigorous standards as all other drugs approved for use in the country.

The main reason COVID-19 vaccines were developed so quickly is that scientists from all around the world collaborated on the research and development, in a tremendous global effort to end the pandemic. In the past, that wasn’t always the case.

The other element to keep in mind is that mRNA technology is not new. The technology has been studied in humans for 20 years and scientists had been working on mRNA vaccines for a decade before the pandemic hit.

In fact, researchers are developing mRNA vaccines for several infectious diseases, like Influenza, Zika, Rabies and Malaria. I predict a growing number of vaccines in the future will use mRNA technology.

What are the known side effects of the COVID-19 vaccines in children?

Studies performed by the vaccine manufacturers have shown no major side effects. Researchers know that most side effects from vaccines occur within the first week after vaccination, and some children may not experience any side effects at all.

The side effects children have experienced in the clinical trials are mild and like the ones experienced by adults:

  • Sore arm at the injection site
  • Fatigue
  • Headache
  • Muscle aches
  • Fever and chills

Real-world data has backed up the findings in the clinical trials. As of November 2022, more than 34 million children in Canada and the US have safely received the COVID-19 vaccine, and serious side effects remain extremely rare.

Can the children's COVID-19 vaccines cause myocarditis or pericarditis?

While a very small number of adolescents and young adults (especially males) have experienced myocarditis (inflammation of the heart muscle) or pericarditis (inflammation of the lining around the heart) following COVID-19 vaccination, it’s important to emphasize that these side effects are extremely rare. When they have occurred, they have mainly happened in adolescents and young adults who were vaccinated with the Moderna vaccine. For this reason, the Pfizer vaccine is the preferred vaccine for people aged 5-29.

It's also important to know that the current data shows that the risks of developing myocarditis or pericarditis are far higher following COVID-19 infection than following vaccination.

Can the COVID-19 vaccines impact fertility?

There is no evidence that COVID-19 vaccines cause male or female infertility, or that they will cause infertility. I believe these concerns are the result of misinformation spread on social media.

Can mRNA vaccines alter a person’s DNA?

No, once again, this is a myth. Vaccines using mRNA technology can’t change a person’s genetic makeup as they never interact with a person’s DNA.

Could receiving the vaccine cause a COVID-19 infection or cause the person to shed the virus and infect others?

No, the vaccines currently in use can’t infect people with the COVID-19 virus because they do not contain the virus. Receiving the vaccine does not create a risk of shedding the virus and infecting others because a person can only shed a virus if they are infected.

The vaccines that have been approved for use in Canada strictly teach the immune system how to recognize the virus so the body can fight it off. Getting vaccinated remains the best way for folks to protect their family and friends.

If a child is currently under 6 months old, are they eligible to receive the COVID-19 vaccine?

No, children must be 6 months or older when they receive the COVID-19 vaccine.

Can parents book a vaccination appointment if their child is under 6 months old?

Parents and caregivers can schedule a vaccination appointment at a later date for their child who is under 6 months old. However, children must be at least 6 months old on the day of their appointment.

At what interval must children receive the doses of the COVID-19 vaccines to be fully vaccinated from COVID-19?

For optimal protection, it is recommended that children receive their second dose 8 weeks (56 days) after their first one for both Pfizer and Moderna. Children 6 months to 4 years old who receive the Pfizer vaccine should also wait 8 weeks (56 days) between their second and third doses.

Though cases of myocarditis/pericarditis in children following the second dose of an mRNA COVID-19 vaccine are extremely rare, waiting 8 weeks between the first and second dose may further reduce this risk.

If your child has a COVID-19 infection between doses, wait between one month and 90 days after the start of COVID-19 symptoms or a positive test before continuing the primary series. Children who are not immunocompromised should wait 2 months (56 days) before getting their next dose, and children who may be immunocompromised should wait 1 to 2 months (28 to 56 days). If your child has a history of multisystem inflammatory syndrome in children (MIS-C), they should wait to receive their next dose until they have recovered or ≥90 days since the onset of MIS-C, whichever is longer. You may also wish to discuss the wait period with your child’s health care provider.

At what interval must children receive their first booster dose of the COVID-19 vaccine following their primary series?

Children aged 5 and older should get their booster dose at the following recommended intervals since their last dose or following a COVID-19 infection:

  • 6 months, for children aged 5 and older who are not at high-risk of severe COVID-19 illness
  • 3 months, for children aged 5 and older who are at high risk of severe COVID-19 illness or who are immunocompromised (talk to your child’s health care provider for specific recommendations)

Children under age 5 are not yet eligible for a booster dose.

Can children receive their COVID-19 vaccine at the same time as other vaccines?

Children aged 6 months and over (as well as adults) may receive their COVID-19 vaccine at the same time as other vaccines, including the flu shot.

If a child has medical issues, should they receive the COVID-19 vaccine?

Yes, while parents should consult their child’s healthcare provider, I strongly encourage children with medical conditions to receive the vaccine as their medical condition may put them at higher risk of complications from COVID-19.

Can children with allergies get the COVID-19 vaccine?

Yes, children with severe allergies to food, medication or insect bites should all receive the COVID-19 vaccine. However, I recommend parents speak to their child’s healthcare provider if their child has had a severe allergic reaction to a vaccine or other medical product in the past.

Can children on medication get the COVID-19 vaccine?

Yes, children on medication can generally get the COVID-19 vaccine as it doesn’t interfere with other medications. But, just to be sure, I recommend parents speak to their child’s healthcare provider before they receive their COVID-19 vaccine.

If a child has previously had COVID-19, should they still get the COVID-19 vaccine?

Yes, I strongly recommend that children receive the COVID-19 vaccine, even if they have previously had COVID-19. While infection alone provides some protection, vaccination combined with previous infection provides stronger and longer protection against future reinfection and serious illness.

However, children who have recently had a COVID-19 infection must wait 8 weeks following the onset of symptoms (or a positive test if they’re asymptomatic) before receiving their COVID-19 vaccine if it is part of their primary series. If they have completed their primary series, they should wait at least 3 months to get their booster, however waiting as long as 6 months before getting their booster may provide even better protection.

Are the COVID-19 vaccines for children the same as the ones given to adults?

No, the COVID-19 vaccines for children aged 6 months to 11 years old contain the same active ingredients as the ones for adults, but in smaller doses. This is common practice amongst vaccines for children.

  • Pfizer’s vaccine for children aged 6 months to 4 years is 1/10 the size of the dose for teenagers and adults (3 micrograms compared to 30 micrograms for adults).
  • Pfizer’s vaccine for children aged 5 to 11 is 1/3 the size of the dose for teenagers and adults (10 micrograms compared to 30 micrograms for ages 12 and over).
  • Moderna’s vaccine for children aged 6 months to 5 years old is ¼ the size of the dose for teenagers and adults (25 micrograms compared to 100 micrograms for ages 12 and over).
  • Moderna’s vaccine for children aged 6 to 11 years old is ½ the size of the dose for teenagers and adults (50 micrograms compared to 100 micrograms for ages 12 and over).

The COVID-19 vaccines for children 12 and older are the same doses as the ones for adults.

Do the COVID-19 vaccines for children offer the same level of protection as the adult vaccines despite the smaller dose?

The short answer is yes. In fact, the vaccines may even offer children better protection from the COVID-19 virus than the adult version. That’s because younger children generally have stronger immune systems than teenagers and adults, so their body generates more protective antibodies when they receive a vaccine.

As a bonus, smaller doses usually mean fewer side effects, if any.

If my child is between 6 months and 4 years old, can I choose if they get the Pfizer or Moderna vaccine?

Yes. Parents and guardians will be offered the choice between vaccines at their child’s appointment. Both vaccines have been tested and studied for safety and effectiveness and have met Health Canada’s strict approval guidelines. It’s important to note that the Moderna vaccine for this age group is a two-dose series, while the Pfizer vaccine is a three-dose series, and once your child has received their first dose, they must receive that vaccine for their whole primary series.

If my child received the Moderna vaccine for children 6 months to 5 years as their first dose, can they receive the Pfizer vaccine for children 6 months to 4 years as their second?

No. As the vaccines have different numbers of doses to be considered completely vaccinated (Moderna is 2 doses and Pfizer is 3), mixing the vaccine brands is not recommended for children in this age group.

If my child is 5 years old, can I choose which COVID-19 vaccine they will receive?

For children who are age 5, the following COVID-19 vaccines are available at the EOHU's community clinics:

  • Moderna vaccine for children aged 6 months to 5 years  
  • Pfizer-BioNTech vaccine for children aged 5 to 11 years old

Note: Pediatric COVID-19 vaccines cannot be mixed and matched. Children aged 6 months to 5 years who started their primary COVID-19 vaccine series using Moderna vaccine must complete their 2-dose series with a Moderna vaccine. Children who started their primary COVID-19 vaccine series using the pediatric Pfizer vaccine for ages 6 months to 4 years must complete their 3-dose series with Pfizer vaccines.

For children aged 5 and over who have not yet started their primary series, the Pfizer vaccine for ages 5-11 years is the preferred vaccine. With informed consent, parents can request to have their children aged 5 and over vaccinated with Moderna’s vaccine by calling the EOHU at 613-933-1375 or 1 800 267-7120.

If a child received a first dose of Moderna’s COVID-19 vaccine when they were 4, but have since turned 5, should they receive a second dose of the Moderna vaccine for children aged 6 months to 5 years old, or the Pfizer vaccine for children aged 5 to 11?

If your child received a first dose of Moderna’s COVID-19 vaccine when they were 4 years old, and have since turned 5, they will receive a second dose (or third dose if they are moderately to severely immunocompromised) of the Moderna vaccine to complete their primary vaccination series.

If my child received their first or second dose of the Pfizer COVID-19 vaccine for 6 months to 4 years old, but has since turned 5, should they receive the Pfizer vaccine for 6 months to 4 years old or the Pfizer vaccine for 5 to 11 years old as their next dose(s)?

If your child turns 5 years old after they receive their first or second dose, they should receive the Pfizer vaccine for children 5 to 11 years old to complete their series. Three doses are still needed for a full series, whether it is 2 doses of the 6 months to 4 years and 1 of the 5-11 years, or 1 dose of the 6 months to 4 years and 2 of the 5-11 years.

If a child is 11 years old, should they wait to receive the adult dose when they turn 12, or receive the child-sized dose now?

I recommend that children who are 11 years old receive the child dose. As previously mentioned, the vaccines children receive are often not based on their size or weight, but their body’s immune response, which is based on their age.

If a child received a first dose of the COVID-19 vaccine when they were 11, but have since turned 12, should they receive a second dose of the child version, or the adult version?

A child who received a first dose of the child COVID-19 vaccine should receive a second dose of the adult version if they have since turned 12. However, a 12-year-old who receives a second dose of the child vaccine will still be considered fully immunized.

Why should children receive the COVID-19 vaccine?

While children and youth who get infected with COVID-19 typically experience mild symptoms, some can get very sick, resulting in hospitalization or ICU admission. Others can experience serious and longer-lasting symptoms. Sadly, some children have died from a serious condition known as multisystem inflammatory syndrome due to the COVID-19 virus (MIS-C). Children who develop this syndrome suffer from severely inflamed organs and tissues. The syndrome can affect several organs, such as their brain, heart, lungs, and digestive system, amongst others.

I don’t want to see any children get seriously ill or die from this virus, and I believe the COVID-19 vaccines can help us achieve that goal.

What should parents do if they’re on the fence about having their children vaccinated against COVID-19?

I recommend that parents who are worried about vaccinating their children against COVID-19 speak to their healthcare provider. Parents can also consult alternate sources of information, as long as they ensure they’re credible. I have seen lots of misinformation shared on social media.

Where can I get more information?