A paper in Nature Communications in July 2024 explores the effect of COVID-19 vaccines on cardiovascular diseases by examining longitudinal health records from 45.7 million adults in England between December 2020 and January 2022. The authors find that the incidence of common arterial thrombotic events and the incidence of common venous thrombotic events were lower after vaccination. However, there was a higher incidence of previously reported “rare harms” after vaccination. Overall, the researchers offer their findings in support of “wide uptake of future COVID-19 vaccination programmes”.
The study
Although SARS-CoV-2 vaccination “prevented 14.4 million deaths from COVID-19″ across the world in the first year of the pandemic, the authors identify a need to understand the risk of thrombotic and cardiovascular complications. COVID-19 vaccines are associated with rare cardiovascular complications:
- mRNA-based brands are associated with myocarditis
- Adenovirus-based brands are associated with vaccine-induced thrombotic thrombocytopenia (VITT)
In their study, the authors use whole population longitudinal electronic health records for 45.7 million adults in England to quantify associations of first, second, and booster doses of mRNA and non-mRNA COVID-19 vaccine brands with subsequent thrombotic and cardiovascular events. Through Cox regression, they estimated adjusted hazard ratios (aHRs) and corresponding 95% confidence intervals in time intervals since vaccination, adjusted for various co-morbidities, age, sex, and prior COVID-19.
“We show that the incidence of thrombotic and cardiovascular complications was generally lower after each dose of each vaccine brand, except for previously recognised rare complications of the ChAdOx1 vaccine and the mRNA vaccines.”
Findings and implications
Although the incidence of thrombotic and cardiovascular complications was “generally lower” after each dose of each vaccine brand, the authors highlight exceptions. These are consistent with previous findings:
- ChAdOx1 vaccine (ICVT and thrombocytopenia)
- mRNA vaccines (myocarditis and pericarditis)
“These findings, in conjunction with the long-term higher risk of severe cardiovascular and other complications associated with COVID-19, offer compelling evidence supporting the net cardiovascular benefit of COVID vaccination.”
Some of the key findings include:
- The incidence of composite arterial thrombotic events (AMI, ischaemic stroke, and other arterial embolism) was similar or lower after first, second, and booster doses of ChAdOx1 and BNT-162b2 vaccines and booster doses of mRNA-1273, compared to follow-up before or without the corresponding dose.
- The incidence of composite venous thrombotic events (PE, DVT, ICVT, PVT) was generally lower after first, second, and booster doses vaccination, compared to follow-up before or without the corresponding vaccine dose.
- Myocarditis incidence was higher after first dose of BNT-162b2 vaccine, higher one week after second dose of BNT-162b2, and higher after some mRNA booster vaccinations.
- Pericarditis incidence was higher after the first dose of ChAdOx1, after first dose of BNT-162b2, after second dose of BNT-162b2, and after mRNA-based booster vaccination.
The paper offers “reassurance” on the cardiovascular safety of COVID-19 vaccines, finding lower incidence of common cardiovascular events that outweighs the higher incidence of their known rare cardiovascular complications. Additionally, no novel cardiovascular complications or associations with subsequent doses were identified.
“Our findings support the wide uptake of future COVID-19 vaccination programmes. We hope this evidence addresses public concerns, supporting continued trust and participation in vaccination programmes and adherence to public health guidelines.”
Commenting on their paper, the authors emphasise the importance of gathering evidence on the risks and benefits of the COVID-19 vaccination programme. Dr Samantha Ip, co-author from the University of Cambridge, says that the research adds to a “large body of evidence” on the programme, which has “been shown to provide protection against severe COVID-19 and saved millions of lives worldwide”. Professor William Whiteley from the University of Edinburgh reflects that “over 90% of the population over the age of 12” received “at least one dose by January 2022”.
“This England-wide study offers patients reassurance of the cardiovascular safety of first, second, and booster doses of COVID-19 vaccines. It demonstrates that the benefits of second and booster doses, with fewer common cardiovascular events include heart attacks and strokes after vaccination, outweigh the very rare cardiovascular complications.”
Dr Venexia Walker of the University of Bristol emphasises the need to “continue to study” COVID-19 vaccines.
“The availability of population-wide data has allowed us to study different combinations of COVID-19 vaccines and to consider rare cardiovascular complications. This would not have been possible without the very large data that we are privileged to access and our close cross-institution collaborations.”
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