It’s fair to say that the dreadfully botched and ridiculously authoritarian response to the Covid-19 pandemic ranks as one of the great public health policy disasters in history. Not only did such policies as lockdowns lead to more deaths, and untold human misery, but the heavy-handed policies of forced vaccinations led directly to lasting public distrust of, not just Covid vaccines, but many other genuinely safe and effective vaccines. So it is that we’re seeing a resurgence of previously rare diseases such as measles.
If public health authorities and politicians behaved shockingly, though, their opponents weren’t entirely on the side of the angels, either. Loony conspiracy theorists and dyed-in-the-wool anti-vaxxers like RFK Jr used public unease over the Covid vaccines as an ideological Trojan horse.
One of their hardest-ridden hobby-horses is so-called ‘died suddenly’. Anti-Covid vax campaigners seized on reports of young people, especially, collapsing and dying from unsuspected myocarditis (inflammation of the heart muscles) and similar diseases. This, they claimed, was proof-positive that the Covid vaccines were ‘clot shots’.
Was it true, though? For a start, correlation should always be dissociated from causation. Just because you see lots of frogs around after a heavy rain doesn’t mean that it rains frogs. There is also the well-known phenomenon that people tend to notice something more when they’re made aware of it. Not to mention that a media which may not normally have reported such events suddenly had a motive to report it more often and prominently.
So, what was really going on? A new study has tried to cut through the fog of misinformation and ignorance. It’s findings undercut both the conviction that Covid vaccines were laying people low with abandon, and the counter-conviction that they never, ever, nowhere nohow, have any ill-effects.
The first dose of Covid-19 vaccines led to an overall reduction in cardiovascular events, and in rare cases, cardiovascular complications. There is less information about the effect of second and booster doses on cardiovascular diseases. Using longitudinal health records from 45.7 million adults in England between December 2020 and January 2022, our study compared the incidence of thrombotic and cardiovascular complications up to 26 weeks after first, second and booster doses of brands and combinations of Covid-19 vaccines used during the UK vaccination program with the incidence before or without the corresponding vaccination. The incidence of common arterial thrombotic events (mainly acute myocardial infarction and ischaemic stroke) was generally lower after each vaccine dose, brand and combination. Similarly, the incidence of common venous thrombotic events, (mainly pulmonary embolism and lower limb deep venous thrombosis), was lower after vaccination.
Case closed against the ‘anti-vaxxers’? Not quite.
There was a higher incidence of previously reported rare harms after vaccination: vaccine-induced thrombotic thrombocytopenia after first ChAdOx1 vaccination, and myocarditis and pericarditis after first, second and transiently after booster mRNA vaccination (BNT-162b2 and mRNA-1273). These findings support the wide uptake of future Covid-19 vaccination programs.
Do they, though? Should we be worried about those “previously reported rare harms”?
One caveat that should be noted is, as the study concedes, the characteristics of the vaccine cohorts. Those who had the second and booster doses tended, most notably, to be older.
In general, though, the study claims a similar or lower incidence of composite arterial thrombotic events (AMI, ischaemic stroke and other arterial embolism) after first, second and booster doses. Similarly, “the incidence of composite venous thrombotic events (PE, DVT, ICVT and PVT) was generally lower after first, second and booster doses vaccination, compared to follow-up before or without the corresponding vaccine dose”. The reduction in incidence of composite venous thrombotic events was lower after second and booster doses than after the first dose.
But the one that got the most attention is myocarditis. How’d that go?
The incidence of myocarditis was higher after first dose of BNT-162b2 (Pfizer) vaccine, with greatest aHR 1 week after vaccination (2.05; 95% CI 1.28–3.29), higher one week after second dose of BNT-162b2 (aHR 3.14; 95% CI 2.04–4.85) and higher after some mRNA booster vaccinations (for example, the aHR 1 week after booster BNT-162b2 vaccination was 1.65; 95% CI 1.07–2.57 following primary course of any of ChAdOx1, BNT-162b2 or mRNA-1273). Otherwise, the incidence of myocarditis after vaccination was similar to or lower than that before or without vaccination.
The incidence of pericarditis was higher after first dose of ChAdOx1 (AstraZeneca), with greatest aHR 2 weeks after vaccination (1.74; 95% CI 1.04–2.91), after first dose of BNT-162b2 (for example, the aHR 13–24 weeks after vaccination was 1.50; 95% CI 1.17–1.92), after second dose of BNT-162b2 (aHR 3–4 weeks after vaccination 2.42; 95% CI 1.62–3.62), and after mRNA-based booster vaccination (for example, the aHR 2 weeks after booster dose of BNT-162b2 vaccine following primary course of any vaccine brand was 1.73; 95% CI 1.05–2.83). Otherwise, the incidence of pericarditis after vaccination was similar to, or lower than, that before or without vaccination, with a halving in incidence beyond 4 weeks after second dose of ChAdOx1 (for example, the aHR after 13–24 weeks was 0.32; 95% CI 0.19–0.51).
Overall, the authors conclude, their study “offers reassurance regarding the cardiovascular safety of Covid-19 vaccines, with lower incidence of common cardiovascular events outweighing the higher incidence of their known rare cardiovascular complications”. Moreover, they argue, Covid itself is associated with increased incidence of cardiovascular disease. It is possible, therefore, that the generally accepted effect of Covid vaccines ameliorating the severity of Covid infection could account for the reduction in events after vaccination.
It may be, therefore, that what the ‘died suddenly’ people were noticing was the effects of Covid itself, rather than the vaccines.
