Expert explainer: COVID-19 vaccines for kids

Health Canada has approved the use of the Pfizer-BioNTech COVID-19 vaccine for children aged five  to 11, marking another major milestone in the country’s pandemic response.

Dr. Michelle Barton-Forbes, pediatric infectious diseases specialist and associate professor at Western’s Schulich School of Medicine & Dentistry, explains what is known, so far, about the COVID-19 vaccine for kids based on data from the Pfizer clinical trial in children. The data was recently published in the New England Journal of Medicine.

What is your message to parents who may be feeling hesitant about this vaccine for their children?

In Canada, more than 50 million doses of mRNA vaccines have been administered, allowing us to have accumulated experience and confidence in the safety and efficacy of the mRNA vaccines. The Pfizer vaccine in particular has undergone extensive testing through multiple trials and since its approval, surveillance and safety monitoring continue. Generally, the Pfizer vaccines are safe and effective, rarely causing serious adverse effects such as myocarditis. It is on this basis that Health Canada has determined that the benefits outweigh the risks. 

With Health Canada’s approval, parents can be encouraged by the knowledge that key authorities have completed extensive data review indicating the benefits of this vaccine in young children outweigh the risks. Regulatory bodies will also continue to monitor to ensure there are no safety concerns.

Currently, 20 per cent of all of Canada’s new COVID-19 cases are among children. Although death is rare and hospitalizations among children are not common, new data suggest an increasing number of children who get infected go on to have long COVID, which may be associated with long-term problems such as fatigue, insomnia, difficulty breathing and even mood changes. As some of these children report concentration difficulties and brain fog, there is growing concern about whether there could be potential long-term impacts on the brain.

More importantly, without the vaccine, children’s in-person education and extracurricular activities may also be negatively affected by repeated disruptions imposed by lockdowns or quarantines. Vaccine mandates may also restrict participation in certain activities.

Is the vaccine approved for kids the same one that is given to adults?

The Pfizer vaccine for children aged five to 11 years of age is, in essence, the same vaccine that is being used for adults, but for children, it is given at a reduced dose of 10 micrograms. That is about one-third the dose that older children and adults get.

What is the data saying about the efficacy and safety of this vaccine in children?

The vaccine was found to achieve 90.7 per cent efficacy in children.

What are the common side effects after children receive the vaccine?

The common side effects are similar to those experienced by older children and adults, but slightly less in young children.

Generally, the Pfizer vaccine may cause soreness at the injection site and some headache, muscle ache and mild fever. These symptoms usually disappear within an average of two days.

Although pain at injection site was similar in the five to 11 group and the 16 to 25 group, data shows there were less instances of muscle ache, fever, chills and headache in the five to 11 group. Most mild side effects tended to be reported after the second dose.

There were no reports of myocarditis in the clinical data. Post-rollout adverse events will need to be monitored as rare events may not be recognized until several thousands of children have received the vaccine.

Should parents be worried about myocarditis?

Myocarditis has been reported as a rare event seen in adolescents and young adults after receiving an mRNA vaccine. Reassuringly, the affected adolescents have had good recovery without severe consequences.

Emerging data suggests that male sex hormones that come into play after puberty may contribute to myocarditis. This leads scientists to believe that for the five- to 11-year-old children, who for the most part are still pre-pubertal, myocarditis may be relatively less likely to occur. Using a much lower dose could also be beneficial in this regard. Although none of the children in the recently completed trial developed myocarditis. It will still be important to monitor for rare adverse events such as myocarditis in the post-approval period.

Should parents be worried about long-term side effects for their children?

In general, we monitor for adverse effects most often within the first six weeks of receiving a vaccine, as this is the period where adverse events tend to appear. In general, the vaccine components tend to be cleared from the body quickly and we have no reason at this time to think this vaccine will have long-term side effects.

Some parents are worried that children’s immune systems won’t be able to handle the vaccine; is there any reason to worry here? 

Absolutely not. Our immune system, especially children’s systems, are accustomed to dealing with multiple antigens at the same time and the COVID-19 vaccine only presents one antigen.

If my child has natural immunity, why should my child receive the vaccine?

Natural immunity may wane over time and may not be effective against future variants of concern.

Do the benefits of COVID-19 vaccination for children outweigh the risks?

Based on the data available, Health Canada has determined that benefits of vaccination outweigh any known risk. So far, no serious adverse events have been identified with the vaccine for children aged five to 11, but safety monitoring will need to continue even after approval as we know that rare adverse events may not be detected until after millions of doses are given.

We do know that  the greatest benefits of a vaccine will be to individuals most likely to be severely affected by the disease. In the face of any vaccine supply issues, it would be essential to ensure that those most at risk are prioritized in the vaccine rollout.