Here's what the BHF actually said about myocarditis and the vaccine, less than a month ago, on its own website.
www.bhf.org.uk/informationsupport/heart-matters-magazine/news/coronavirus-and-your-health/coronavirus-vaccine-your-questions-answered/myocarditis-and-covid-19-vaccines-should-you-be-worried
"There have been rare cases of myocarditis (inflammation of the heart muscle) following the Moderna and (even more rarely) Pfizer vaccines in the UK. Myocarditis has also been listed as a rare possible side effect of the Novavax vaccine, after a very small number of cases were reported during clinical trials.
Reports of myocarditis following any Covid-19 vaccine remain rare, and the people who have had this this have usually experienced a mild illness. Those affected have usually quickly felt better with rest and simple treatments.
Research suggests that overall, myocarditis is no more likely to be triggered by a Covid vaccine by than any other vaccine. It's also worth noting that Covid-19 itself is much more likely to cause myocarditis than the vaccine is, and people who are vaccinated have a much lower risk of getting other serious complications caused by Covid-19.
What is the risk of getting myocarditis or pericarditis after the vaccine?
The risk of getting myocarditis or pericarditis after the vaccine is very low.
According to the MHRA's Yellow Card reporting summary, even in the highest-risk age group (18-29), there were just 29 reports of suspected myocarditis or pericarditis for every million second doses of the Pfizer vaccine given in the UK up until 23 November 2022. The risk is even lower following a monovalent Pfizer booster, with just 17 reports per million people in this age group. In other age groups the risk is even lower.
For Moderna, there were 70 cases of suspected myocarditis or pericarditis for every million second doses given in the UK, in this age group. As with the Pfizer vaccine, the risk is much lower after a booster, with just 20 reports per million monovalent Moderna boosters given (up until 23 November 2022). In other age groups the risk is even lower.
The World Health Organisation has reviewed data from 744,235 doses of the Novavax vaccine given in Australia, Canada, the European Union, New Zealand, and South Korea up until 30 April 2022. Amongst these recipients, there were four reports of myocarditis, 29 reports of pericarditis, and two reports of myopericarditis. More recent data from Australia (until 21 August 2022) showed seven cases of myocarditis and 26 cases of probable pericarditis after 209,000 doses of the Novavax Covid vaccine.
Serious cases of myocarditis after the vaccine so far have been exceptionally rare, although more research is being carried out into the long-term effects."
Of course, as the risk of developing heart issues is high following Covid itself, that may be where the" ten times higher" figure comes from.