Real-world data study confirms lower incidence of heart attacks and strokes after COVID-19 vaccination

The study of nearly 46 million adults in England published in Nature Communications sheds light on the cardiovascular safety of different vaccination doses, and supports the continued use of COVID-19 vaccines as a critical component of public health strategies.

The research, conducted by the Universities of Cambridge, Bristol, and Edinburgh, analyzed de-identified longitudinal electronic health records from 45.7 million adults in England between December 2020 and January 2022. The analysis, supported by the BHF Data Science Centre, aimed to compare the rates of cardiovascular events before and after first, second and booster doses of COVID-19 vaccines. The researchers analyzed real-world data (RWD) from GP practices, hospital admissions, and death records within the NHS England Secure Data Environment. By including nearly the whole adult population of England, the study allowed for robust comparisons across different vaccine types and doses. The analysis adjusted for numerous confounding factors, including age, sex, prior COVID-19 infection, and existing health conditions, to ensure accurate results.

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Key findings

The study found that the incidence of arterial thromboses, such as heart attacks and strokes, was up to 10% lower in the 13 to 24 weeks following the first dose of a COVID-19 vaccine. The reduction was more pronounced after the second dose: up to 27% lower for the AstraZeneca vaccine and up to 20% lower for the Pfizer/BioNTech vaccine. Additionally, common venous thrombotic events, including pulmonary embolism and deep venous thrombosis, followed a similar pattern of decreased incidence post-vaccination.

Dr Samantha Ip, co-first author and Research Associate at the University of Cambridge and member of the BHF Data Science Centre CVD-COVID-UK/COVID-IMPACT Consortium, noted,

“We… found a similar or lower incidence of common cardiovascular diseases, such as heart attacks and strokes, following each vaccination than before or without vaccination. This research further supports the large body of evidence on the effectiveness and safety of the COVID-19 vaccination program, which has been shown to provide protection against severe COVID-19 and saved millions of lives worldwide.”

While previous research has identified rare cardiovascular complications associated with some COVID-19 vaccines – such as myocarditis and pericarditis with mRNA vaccines and vaccine-induced thrombotic thrombocytopenia with adenovirus-based vaccines – the current study did not find new adverse cardiovascular conditions linked to vaccination. Instead, it corroborated known risks while affirming the overall safety profile of the vaccines.

Professor William Whiteley, Associate Director at the BHF Data Science Centre and Professor of Neurology and Epidemiology at the University of Edinburgh, emphasized, “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 including heart attacks and strokes after vaccination, outweigh the very rare cardiovascular complications.”

The study highlighted the value of RWD in providing representativeness of the whole population and allowing transportability of the findings to countries with similar demographics and healthcare systems.

Dr Venexia Walker, co-last author and Research Fellow at the University of Bristol and member of the BHF Data Science Centre CVD-COVID-UK/COVID IMPACT Consortium, explained:

“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.”