COVID jabs cut the risk of heart complications in kids

Children are at half the risk of a heart complication if they're vaccinated against COVID-19 compared to being infected with the virus.

Scientists, in the largest study of its kind in children, reviewed the health records of nearly 14 million people aged under 18 in England between January 2020 and December 2022 to assess the short and long-term risks of COVID-19.

They found kids who received a Pfizer vaccine were associated with half the risk of developing myocarditis or pericarditis, a rare but serious heart inflammation, within six months compared to those who got COVID-19.

The results were in line with what was known about the risks associated with COVID-19 infection, vaccination, and heart inflammation in children, University of Queensland infectious diseases physician and microbiologist Paul Griffin said.

"What we've known, and this provides further evidence for, is that the risk from COVID itself was more significant than the risk posed by the vaccines," he told AAP.

Young people often experience mild or no symptoms following a COVID-19 infection, but a small number develop serious diseases, such as myocarditis, pericarditis or blood vessels becoming blocked due to blood clots and low platelet count.

The Pfizer vaccine has also been linked to rare cases of myocarditis or pericarditis in young people, especially boys and young men.

The Lancet Child & Adolescent Health study found an additional 1.84 cases of myocarditis or pericarditis per 100,000 children vaccinated within the first four weeks after inoculation, compared to a more substantial, but still small, increased risk after a COVID-19 diagnosis.

That risk increased to 2.24 additional cases per 100,000 kids who got COVID-19 as opposed to those who didn't get it over six months.

For vaccinated kids, there were an extra 0.85 cases per 100,000 children compared to before vaccination over the same period.

Professor Griffin, who has memberships on the medical advisory boards of vaccine groups, including Pfizer, said the study demonstrated risks of severe diseases from COVID-19 were not restricted to those in advanced age and with comorbidities.

Australia's COVID-19 vaccine guidelines are based on age and health risk, with the youngest children not eligible for the vaccine, while it is considered for those aged five to 18 if they're immunocompromised.

"This (these guidelines) sends a message that (kids) definitely should not be vaccinated, which studies like this reinforce that may not be the best way of recommending vaccines in that group," Prof Griffin said.

He hopes the study, despite its focus on another nation and a different time period, can lead Australian regulators to revisit the evidence and ensure guidelines reflect current evidence.