British researchers based their conclusion on NHS data from nearly 46 million people
New research by British academics has claimed that vaccination with either Covid-19 vaccine actually reduced the incidence of heart attacks and strokes and therefore outweighed the risks of adverse effects.
Researchers from the universities of Cambridge, Bristol and Edinburgh were able to analyse millions of anonymised health records of adults in England, provided by the National Health Service (NHS) and dating from December 2020 to January 2022. At that time, more than 90% of the UK population over the age of 12 had received at least one dose of the vaccine.
“We study [Covid]-19 vaccines and cardiovascular disease in 45.7 million adults in England and found a similar or lower incidence of common cardiovascular diseases, such as heart attacks and strokes, after each vaccination than before or without vaccination,” said Dr Samatha Ip of Cambridge, lead author of the study.
Ip and 16 other researchers based their conclusions on linked data from general practices, hospital admissions and death records, in a secure setting provided by the NHS. They were looking at the incidence of cardiovascular events before or without vaccination compared with after.
According to their findings, published this week in the journal Nature CommunicationsThe incidence of heart attacks and strokes fell by almost 10% in the 13-24 weeks after the first dose of the vaccine. This fell to 27% lower after the second dose of the AstraZeneca vaccine, and 20% lower after the second Pfizer shot.
“This England-wide study provides patients with reassurance of the cardiovascular safety of first, second and booster doses of [Covid]-19 vaccines,” said William Whiteley, associate director of the BHF Centre for Data Science and professor at the University of Edinburgh.
The benefits of the second dose and the booster dose, Whiteley added, “overcome very rare cardiovascular complications.”
Previous studies have found an increase in myocarditis and pericarditis after mRNA-based vaccines — such as those from Pfizer/BioNtech and Moderna — and vaccine-induced thrombotic thrombocytopenia (blood clotting) after adenovirus-based vaccines, such as the one from AstraZeneca.
While this study confirmed these findings, it did not identify any new cardiovascular conditions and “provides more assurance that the benefits of vaccination outweigh the risks,” said the authors.
The vaccination program, Ip said, “has been shown to provide protection against serious diseases [Covid]-19 and saved millions of lives around the world.”
The study used a technique called Cox regression to estimate adjusted hazard ratios and corresponding 95% confidence intervals across time intervals since vaccination, adjusted for a wide range of comorbidities, age, sex and previous Covid-19 infections.
Critics of vaccination mandates adopted by many countries — including the United Kingdom — have argued that the vaccines have not been tested for safety, have failed to prevent transmission of the virus and potentially pose greater risks to healthy people than the virus itself.