Moderna, BioNTech, AstraZeneca and Pfizer mRNA vaccines, among others, have an increased risk of myocarditis (inflammation of the heart muscle), as well as the risk of blood clots in the brain after vector vaccines such as the Vaxzevria vaccine developed by the University of Oxford and AstraZeneca.

In addition, the researchers associated vector vaccines with an increased risk of developing Guillain-Barre syndrome, an autoimmune disease in which the immune system mistakenly attacks its own peripheral nerves.

The study showed that myocarditis systematically occurred after the first, second and third doses of mRNA vaccines. The first and fourth doses of the Moderna vaccine were associated with an increased risk of pericarditis, inflammation of the lining of the heart (pericardium).

After the introduction of the vector vaccine, increased risks of transverse myelitis were identified. Researchers have associated both vector and mRNA vaccines with an increased risk of acute multiple encephalomyelitis.