A January publication in the scientific journal Circulation titled “Circulating Spike Protein Detected in Post–COVID-19 mRNA Vaccine Myocarditis” found persistently elevated spike protein levels in those who developed heart disease following COVID-19 vaccination.
Pfizer and Moderna COVID vaccines contain synthetic mRNA that makes the body produce the virus’s spike protein, ideally triggering an immune response and subsequent protection from the virus. The vaccine is injected into the arm and enters the bloodstream, where it produces the spike protein in the muscle, lymphatic system, and other cells.
Myocarditis, which is inflammation of the heart, is recognized as a complication of coronavirus vaccinations, especially in young adult and adolescent males, with cases most often occurring only days after the second vaccine dose.
The study, authored by doctors from Harvard, MIT, and Brigham and Women’s Hospital, provides an in-depth immune system profile of patients suffering from postvaccine myocarditis and found that people who developed myocarditis after receiving the COVID vaccine have high levels of spike protein circulating in their bloodstream.
“We discovered that individuals who developed postvaccine myocarditis uniquely exhibit elevated levels of free spike protein in circulation,” the authors write.
The study also found that spike protein was not broken down or cleared from the body as expected because antibodies, which are proteins produced by the immune system to identify and neutralize foreign substances, do not recognize the spike proteins.
“In postvaccine myocarditis, the spike protein appears to evade antibody recognition” even though the anti-spike antibodies that are generated from the vaccine “are produced in adequate quantities with normal functional and neutralization capacity,” according to the authors.
While the authors state that whether circulating spike protein from mRNA vaccination directly causes myocarditis is “unclear,” they warn about a “growing” body of evidence that spike protein can cause problems in heart cells and blood vessels by affecting enzymes and causing inflammation.
“There is growing in vitro evidence that spike itself can stimulate cardiac pericytes dysfunction or inflame the endothelium, potentially by downregulating angiotensin-converting enzyme 2 expression, by impairing endothelial nitric oxide bioavailability, or by activating integrin-mediated inflammation with hyperpermeability of the endothelial cell layer,” they explain.
The authors therefore conclude that the spike protein produced in the body from the vaccine “may contribute to myocarditis” and that their new data “suggest that there is a potentially unique mechanism of myocardial injury after SARS-CoV-2 mRNA vaccination associated with a robust innate immune response.”
The researchers nevertheless claim these results “do not alter the risk-benefit ratio favoring vaccination against COVID-19 to prevent severe clinical outcomes” even though “the implications of this finding must be better understood” by future study.