The research, led by Dr. Joseph Wu, director of the Stanford Heart and Vascular Institute, shows that these rare complications are due to a chain reaction of immune responses triggered by vaccines in a very small subset of individuals.
Dr. Wu emphasizes that messenger RNA (mRNA) vaccines have "saved countless lives" and significantly reduced severe illness and death rates from COVID-19. Billions of doses have been administered globally, and these vaccines have a strong safety profile. However, as with any medication or vaccine, uncommon side effects may occur in certain populations. One such rare side effect is myocarditis, which, according to the study, occurs in approximately 1 in 16,750 young adults (under 30) after the second dose.
Most importantly, as Wu notes, "Infection with COVID-19 itself increases the likelihood of causing myocarditis tenfold compared to vaccination."
The research team was able to identify two key components in this mechanism:
1. First stage: Immune cells called macrophages react with the vaccine, secreting large amounts of a protein called CXCL10.
2. The second stage: The CXCL10 protein attracts another type of immune cell, the T cells, which in turn stimulates them to produce excessive amounts of another protein, “interferon gamma” (IFN-gamma).
This “duo” of immune molecules leads to a series of events: direct inflammation of the heart muscle cells, the attraction of more immune cells (such as neutrophils) to the heart tissue, and the release of markers of heart damage such as cardiac troponin.
The researchers found that blocking the activity of these two molecules in laboratory models and in mice significantly reduces cardiac damage while preserving the beneficial immune response to the vaccine.
Using advanced technology, the Stanford team successfully converted human skin cells into stem cells, then directed them to develop into beating heart cells (cardiomyocytes) that form three-dimensional microscopic spheres mimicking the function of a normal heart.
When these "mini-hearts" were exposed to a mixture of CXCL10 and IFN-gamma, clear signs of stress and damage were observed, and their contractile efficiency decreased. Again, the use of inhibitors of these two molecules protected the cardiac cells.
In a remarkable turn of events, the researchers tested a natural compound called genistein, an estrogen-like substance extracted from soybeans. When concentrated, purified doses of this compound were given to the heart cells of mice before stimulation with either the vaccine or the two harmful molecules, most of the cardiac damage was prevented.
Dr. Wu confirms that the genistein used in the trials was of a higher concentration and purity than commercially available supplements.
Dr. Wu points out that the excessive inflammatory response may not be limited to the heart, but may extend to other organs such as the liver and kidneys, and that genistein may have a broader protective role.
He also points out that the mechanism of excessive cytokine activation may be a common feature of mRNA technology, given that the IFN-gamma molecule is a primary line of defense against foreign genetic material such as viral DNA.
Wu concludes with an important clarification: "Your body needs these cytokines to fight viruses; they are essential. The problem only occurs when they are secreted in very large quantities."
The importance of this study lies in the fact that it not only provides a scientific explanation, but also opens the door to potential preventive strategies that could make future vaccines safer for everyone, while continuing to emphasize that the benefits of current vaccination overwhelmingly outweigh its rare risks.
