COVID vaccines from companies like Pfizer, Moderna and AstraZeneca have been linked to rare occurrences of heart, brain and blood disorders, according to the largest vaccine study to date.
A report first published by Bloomberg says researchers from the Global Vaccine Data Network analyzed at least 99M people who received jabs in 8 countries and monitored for increases in 13 medical conditions.
The study found the vaccines were linked to a slight spike in neurological, blood and heart-related medical conditions.
Rare cases of myocarditis (inflammation of the heart muscle) were found in the first, second and third doses of Pfizer-BioNTech’s and Moderna’s mRNA vaccines.
Another heart condition, pericarditis, the inflammation of the cardiac muscle, had a 6.9-fold increased risk in those who received a third dose of AstraZeneca’s viral-vector shot, the study found.
Meanwhile, a first and fourth dose of Moderna’s jab had a 1.7-fold and 2.6-fold increased risk, respectively.
An increased risk also was identified of a type of blood clot in the brain from viral-vector shots such as the one developed by the University of Oxford and manufactured by AstraZeneca, Bloomberg said.
There was a 2.5 times greater risk of developing Guillain-Barre syndrome, a rare neurological disorder in which the immune system attacks the nerves, among people who received AstraZeneca’s jab, according to the study.
Possible safety signals for transverse myelitis, a spinal cord inflammation, were identified after viral-vector vaccines, as was acute disseminated encephalomyelitis, the inflammation and swelling in the brain and spinal cord, after both viral-vector and mRNA vaccines, the researchers found.
The experts at GVDV in New Zealand — a research arm of the World Health Organization — examined 13 medical conditions that they considered “adverse events of special interest” among the subjects, aiming to identify higher-than-expected cases after a vaccine.
More than 13.5 billion doses have been administered worldwide since the start of the pandemic. A small proportion of those immunized were harmed by the shots, stoking debate about the benefits of the jabs versus the risks.
“The size of the population in this study increased the possibility of identifying rare potential vaccine safety signals,” lead author Kristýna Faksová of the Department of Epidemiology Research, Statens Serum Institut in Denmark, said in a release.
