Toronto’s Scotiabank Arena hosts a children’s COVID-19 vaccine clinic in December, 2021. A new study says that among children, some health risks from COVID-19 infections were higher and longer lasting than those from a COVID-19 vaccination.Chris Young/The Canadian Press
Children face longer-lasting and higher risks of rare heart and inflammatory conditions after a COVID-19 infection than after vaccination against coronavirus, new research shows.
The study, published in The Lancet Child & Adolescent Health medical journal on Tuesday, is the largest of its kind for the age group of 18 and younger. Health records from nearly 14 million young people in England, who had COVID-19 between Jan. 1, 2020, and Dec. 31, 2022, were analyzed.
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Researchers concluded that the risk of serious health conditions – such as blood clots in veins and arteries, and inflammation affecting the heart – persisted beyond one year after infection. After the first COVID-19 vaccination, there was an elevated risk of myocarditis or pericarditis, both inflammatory conditions of the heart, in the first month but actual instances were rare.
One of the study’s authors, Angela Wood, a professor of biostatistics at the University of Cambridge, took The Globe and Mail through the findings.
What is the high-level take-away?
The main findings were that we saw more higher risks following a COVID infection, rather than a COVID vaccination. And after the infection, the risks remained higher for almost a year.
Whereas after a COVID vaccination, we did see high risks only for myocarditis or pericarditis, so one of the five conditions we considered, but that high risk only remained elevated for around four to six weeks, after which it declined or went back to the baseline risk.
How does this study differ from others that analyzed adverse events after COVID-19 vaccination and infection?
Most of the research has focused very much on just the first few weeks following a COVID vaccination and first few weeks following a COVID infection. For this study, we had up to two years of follow-up. For vaccination, it was slightly shorter because people didn’t start vaccination until later on in the pandemic, but we still had so much more than anyone’s looked at before.
And one of the main features of our study is that we were able to directly compare after infection with after vaccination. At six months, we were able to make that direct comparison of the number of excess cases we would have expected to see because of these two events.
The study, published Tuesday in The Lancet Child & Adolescent Health medical journal, was able to directly compare outcomes after a vaccination with outcomes after an infection.Nathan Denette/The Canadian Press
How rare, exactly, is the risk of myocarditis or pericarditis, which are inflammatory conditions that affect the heart, after vaccination?
We’ve got what’s called the incidence rate, which tells you how many events we would expect to see in 100,000 children and young people per year. So, for myocarditis, pericarditis in this population, it was around four-and-a-half cases per year.
How should policy-makers and caregivers interpret these findings?
Policy-makers really need to look at a range of different evidence to support their decisions. Our objective was to provide this balanced, data-driven, scientific evidence to support public health priorities and decisions, but also to help parents, clinicians and policy-makers know that the information is coming from somewhere with quantitative evidence.
I would hope that the take-home message here is that this is giving clear and impartial evidence of this trade-off between a COVID infection and a COVID vaccination in terms of the risks associated with inflammatory and vascular diseases.
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Do you believe this study can help address the ongoing issue of vaccine fears, hesitancy and misinformation?
There’s been so much debate about the vaccination risks. And the key thing is that decisions that people make need this clear and impartial evidence. Sometimes we don’t know what to trust.
We are a multidisciplinary team of health data scientists. It includes people who are specialists in analyzing cardiovascular data, those who understand how to navigate secure environments to access data and included professor Pia Hardelid, who is a child and young person expert in population health and also a clinical neurologist.
I hope that this represents quite a diverse group of scientists who just want to do the best research to answer these kind of questions. It’s not an opinion piece. It’s a piece of data-driven, quantitative evidence.
Are there any limitations to this study?
We only considered first infections and first vaccine doses, so we didn’t evaluate repeated infections or booster doses or later pandemic variants.
We think that the risks might be quite different now. In today’s context, I expect that the vaccine-related risks that we’ve presented are likely to remain rare and short-lived as the results have showed in this paper. But what is more likely to change are the risks following the infection, because they’ll change as the variants emerge and immunity shifts.
This interview has been edited and condensed.