How Covid vaccines can cause heart damage | 10 Dec 2025 | Covid mRNA vaccines can cause heart damage by triggering immune cells to go on the attack, scientists have found. More than 2,000 people in Britain suffered inflammation of the heart [myocarditis] or heart lining [pericarditis] following vaccination, with young men particularly vulnerable. The majority of cardiac problems were caused by mRNA jabs, such as Pfizer and Moderna, which delivered a blueprint of the Covid spike protein to cells. Now Stanford University has found that the immune system can lock on to the foreign RNA from the vaccine, which triggers a fierce response and in some cases can inflame heart cells. It is likely to be a problem with other mRNA jabs, they warn. Vaccine-associated myocarditis occurs in about one in every 140,000 people vaccinated after a first dose and rises to one in 32,000 after a second dose. Incidence peaks among males aged 30 or below, at one in 16,750 vaccinations, but is still very rare. [LOL: “Rare.” In their dreams…]