Study: Heart attack, stroke incidence lower after COVID-19 vaccination
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Key takeaways:
- Initial vaccine doses lowered risk by roughly 10%, whereas second and third doses reduced risk by nearly 30%.
- Researchers said part of the explanation could be avoiding the cardiovascular effects of SARS-CoV-2.
The incidence of heart attack and stroke is lower among people who have been vaccinated against COVID-19 compared with before vaccination and people who have not received a vaccine, according to a study.
“Vaccines do seem to reduce heart attack and stroke, which is probably due to reducing infection rates. Infection increases the risk of heart attack and stroke,” William N. Whiteley, BMBCh, PhD, MA, MSc, FRCP, professor of neurology and epidemiology at the University of Edinburgh, told Healio.
“We are a bit less certain about this finding [though] as we are working with observational data — but it does seem to be supported by randomized trials,” he said.
SARS-CoV-2 can affect many systems in the body, including the cardiovascular system, and these affects can last beyond infection, especially for people who already have heart conditions or experience severe COVID-19, according to experts.
During the rollout of the COVID-19 vaccines in 2021, the messenger RNA-based shots manufactured by Pfizer and Moderna were also associated with slightly elevated risks for myocarditis and pericarditis in some people, and the Johnson & Johnson vaccine was linked to rare types of blood clots in unusual places.
Whiteley and colleagues analyzed data from England’s National Health Service on 45.7 million people in the United Kingdom who received a first, second or third COVID-19 vaccine between December 2020 and January 2022, comparing incidence of thrombotic and cardiovascular complications up to 26 weeks after a vaccine dose with incidence before or without vaccination.
The researchers found that among vaccinated people, the incidence of arterial thrombotic events was similar or lower after the first, second and booster doses of both the Pfizer and Moderna vaccines compared with before or without a vaccine — at 13 to 24 weeks, the adjusted HR (aHR) was 0.99 (95% CI, 0.97-1.02) and 0.9 (95% CI, 0.88-0.93), respectively. After booster doses, the aHRs at 13 to 26 weeks were 0.73 (95% CI, 0.7-0.76) and 0.8 (95% CI, 0.77-0.83), respectively.
Similarly, the risk for composite venous thrombotic events, the aHRs at 13 to 24 weeks after initial vaccination were 0.94 (95% CI 0.9-0.98) and 0.85 (95% CI, 0.81-0.88), respectively. After a second vaccine dose, it was 0.68 (95% CI, 0.63-0.73) and 0.77 (95% CI, 0.72-0.83).
Whiteley said the researchers were reassured, rather than surprised, by the study’s findings, and said the study supports the recommendation of COVID-19 vaccines, particularly in people at high risk for heart attack and stroke.
“This research further supports the large body of evidence on the safety of the COVID-19 vaccine program, which has been shown to provide protection against severe COVID-19 and saved millions of lives worldwide,” Samantha Ip, PhD, research associate in the University of Cambridge’s department of public health and primary care, said in a press release.
References:
- Ip A, et al. Nat Commun. 2024;doi:10.1038/s41467-024-49634-x.
- Incidence of heart attacks and strokes was lower after COVID-19 vaccination. https://www.cam.ac.uk/research/news/incidence-of-heart-attacks-and-strokes-was-lower-after-covid-19-vaccination. Published July 31, 2024. Accessed Aug. 12, 2024.
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