COVID shots may reduce heart attack and stroke risk, England study says. What to know
Receiving a COVID-19 vaccination and its subsequent booster shots may help reduce the risk of heart attack and stroke, a new study reports.
A collaborative team of researchers from the Universities of Cambridge, Bristol and Edinburgh obtained health data from nearly 46 million adults in England, and their work was published July 31 in the journal Nature Communications.
In December 2020, England began to roll out its vaccination program, and many adults received their first COVID-19 dose from either AstraZeneca or Pfizer, according to the study. By the fall of 2023, 90% of people over the age of 12 in England had received at least one dose.
The AstraZeneca vaccine was developed by the University of Oxford and could be used in conjunction with the mRNA vaccines developed by Pfizer and Moderna, according to the World Health Organization.
AstraZeneca vaccines were pulled from the vaccine program after rare reports of blood clots linked to the shot, according to the British Heart Foundation, and are no longer available.
Since the vaccine was associated with increased risk of cardiovascular complications, the researchers wanted to know how that risk changed or stayed the same with a second COVID-19 vaccine dose and the boosters that followed.
Fewer heart attacks, strokes after vaccination
From December 2020 to January 2022, 37.3 million people received a first dose and were eligible for a second, according to the study. From these, 35.9 million received a second dose and became eligible for booster shots.
The researchers reported the incidence (the total number of cases compared to the number of people in the study) of different types of arterial thromboses, or blood clots that plug an artery and block the flow of blood to major organs like the heart or brain.
This included heart attacks, strokes, embolisms in the lungs and legs, blood clots in the brain and other hemorrhages and heart conditions, according to the study.
“The study showed that the incidence of arterial thromboses, such as heart attacks and strokes, was up to 10% lower in the 13 to 24 weeks after the first dose of a COVID-19 vaccine,” according to a July 31 news release from the British Heart Foundation Data Science Center.
“Following a second dose, the incidence was up to 27% lower after receiving the AstraZeneca vaccine and up to 20% lower after the Pfizer/Biotech vaccine,” researchers said.
Other thrombotic events, like blood clots in the lungs and legs, also had a decreased incidence in adults after they were vaccinated, according to the study.
Researchers said one explanation is that heart conditions are a known complication of contracting the virus, and if fewer people are testing positive for COVID-19, there will be fewer heart attacks and strokes. Overall, vaccinated people reported fewer heart attacks and strokes than unvaccinated ones.
Rare cardiovascular complications from COVID-19 vaccines are still possible, according to the study, but the heart benefits for vaccinated people far outweigh the very rare risks, the researchers said.
“This England-wide study offers patients reassurance of the cardiovascular safety of first, second and booster doses of COVID-19 vaccines,” British Heart Foundation Data Science Center associate director William Whiteley said.
Battling Misinformation
The AstraZeneca vaccine in England and the Johnson & Johnson vaccine in the United States both were found to cause rare — but deadly — blood clots in people with a specific genetic variation, Time reported.
The shots are adenovirus-based, compared to the mRNA vaccines of Pfizer and Moderna, and in the cases of blood clots the shots triggered antibodies with a strange structure that attacked the protein responsible for blood clotting, doctors wrote in a letter in the New England Journal of Medicine, according to Time.
While 18 million people received a Johnson & Johnson vaccine in the U.S., there were 60 cases of thrombocytopenia syndrome (blood clots) and 9 deaths, according to Yale Medicine.
Both shots were pulled from production and are no longer available.
This story was originally published August 2, 2024 at 6:04 PM with the headline "COVID shots may reduce heart attack and stroke risk, England study says. What to know."
