Are COVID-19 vaccines linked to an increase in myocarditis cases?

COVID-19 has been declared a global pandemic by the World Health Organization (WHO) since March 2020. It is caused by the SARS-CoV-2 virus and has infected millions of people worldwide. COVID-19 has resulted in significant morbidity and mortality, and the development of vaccines has been a crucial step towards controlling the spread of the disease.

As the vaccine rollout continues worldwide, concerns have emerged about potential adverse effects, including the possibility of myocarditis, a rare but serious condition. In this paper, we will explore whether COVID-19 vaccines are linked to an increase in myocarditis cases.

Background:

Myocarditis is a condition characterized by inflammation of the heart muscle. It can be caused by a variety of factors, including viral infections, autoimmune diseases, and toxic exposures. Myocarditis can be a severe condition that can lead to heart failure, arrhythmias, and even death. The symptoms of myocarditis can vary but may include chest pain, shortness of breath, and fatigue.

COVID-19 vaccines work by training the immune system to recognize and fight the SARS-CoV-2 virus. They have been shown to be highly effective in preventing severe illness, hospitalization, and death from COVID-19. However, there have been reports of myocarditis occurring in a small number of people who have received the COVID-19 vaccine.

Current Evidence:

The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) in the United States have been investigating reports of myocarditis following COVID-19 vaccination. The CDC has reported that cases of myocarditis have been seen in people who received the Pfizer-BioNTech and Moderna vaccines, which use mRNA technology. The majority of cases have been reported in males under the age of 30, and the cases have been more common after the second dose of the vaccine.

The European Medicines Agency (EMA) has also been monitoring the safety of COVID-19 vaccines and has reported similar findings. The EMA has reported cases of myocarditis following vaccination with mRNA vaccines, but the agency notes that the incidence of myocarditis is still very rare.

The World Health Organization (WHO) has also stated that myocarditis is a rare adverse event following COVID-19 vaccination. The organization recommends that the benefits of vaccination outweigh the risks of adverse events, including myocarditis.

A new study  investigated a cohort of patients who developed myocarditis and/or pericarditis with elevated troponin, B-type natriuretic peptide, and C-reactive protein levels as well as cardiac imaging abnormalities shortly after SARS-CoV-2 mRNA vaccination.

Contrary to early hypotheses, patients did not demonstrate features of hypersensitivity myocarditis, nor did they have exaggerated SARS-CoV-2–specific or neutralizing antibody responses consistent with a hyperimmune humoral mechanism. We additionally found no evidence of cardiac-targeted autoantibodies.

Instead, unbiased systematic immune serum profiling revealed elevations in circulating interleukins (IL-1β, IL-1RA, and IL-15), chemokines (CCL4, CXCL1, and CXCL10), and matrix metalloproteases (MMP1, MMP8, MMP9, and TIMP1). Subsequent deep immune profiling using single-cell RNA and repertoire sequencing of peripheral blood mononuclear cells during acute disease revealed expansion of activated CXCR3⁺ cytotoxic T cells and NK cells, both phenotypically resembling cytokine-driven killer cells.

In addition, patients displayed signatures of inflammatory and profibrotic CCR2⁺ CD163⁺ monocytes, coupled with elevated serum-soluble CD163, that may be linked to the late gadolinium enhancement on cardiac MRI, which can persist for months after vaccination. Together, our results demonstrate up-regulation in inflammatory cytokines and corresponding lymphocytes with tissue-damaging capabilities, suggesting a cytokine-dependent pathology, which may further be accompanied by myeloid cell–associated cardiac fibrosis.

These findings likely rule out some previously proposed mechanisms of mRNA vaccine–-associated myopericarditis and point to new ones with relevance to vaccine development and clinical care.

reference link : https://www.science.org/doi/10.1126/sciimmunol.adh3455#abstract