In rare circumstances, COVID-19 mRNA vaccines can impact the vascular system. However, getting infected with COVID-19 puts someone at much higher risk of vascular problems than getting a COVID-19 mRNA vaccine. Many people who have had severe COVID-19 infections have gotten blood vessel injuries including blood clots, organ impairment, and other complications.
What our experts say
The term “vascular” refers to anything related to blood vessels, affecting blood vessels, or anything consisting of blood vessels. Blood vessels carry oxygen and nutrients throughout the body and remove waste from the tissues. There are very rare cases of heart or vascular side effects associated with COVID-19 mRNA vaccines. These side effects include:
- Myocarditis - Inflammation of the heart muscle
- Pericarditis - Inflammation of the sac that covers the outer surface of the heart (pericardium)
- Thrombosis - Blood clots which can block arteries or veins
- Thrombocytopenia - A low number of platelets/thrombocytes (tiny blood cells) in the blood which are needed to seal wounds
While none of these issues are caused by attacks on the vascular walls, they can impact blood vessels directly. Adolescents and young males are the most susceptible to these side effects which are very rare.
The American Heart Association released a statement stating that they are confident that the benefits of vaccination far outweigh the very small and rare risks of vaccination, which include vascular problems like myocarditis. The World Health Organization has issued a very similar statement.
These statements are based on what we know from scientific studies about how COVID-19 impacts the body, including the heart. COVID-19 has often been referred to as a 'blood vessel' disease. There are many ways that the virus negatively impacts the body and outcomes can be severe and long lasting.
According to the University of California Davis, about 20-30% of hospitalized COVID-19 patients show heart problems. Inflammation of the vascular walls, the risk of heart attack, and stroke are also higher among COVID-19 patients. More research is needed to understand how often infection with the COVID-19 virus causes vascular problems.
Context and background
The term “vascular” refers to anything related to blood vessels, affecting blood vessels, or anything consisting of blood vessels. Blood vessels carry oxygen and nutrients throughout the body and remove waste from the tissues.
There are very rare cases of heart or vascular side effects associated with COVID-19 mRNA vaccines.
- Antibodies induced by mRNA shots improve for months; blood cells damaged by COVID cause blood vessel problems (Reuters)
- Erythrocytes Induce Vascular Dysfunction in COVID-19 (JACC: Back to Translational Science)
- Why would a COVID vaccine cause rare blood clots? Researchers have found clues (PBS News Hour)
- Blood vessel attack could trigger coronavirus' fatal ‘second phase' (Science)
- Adverse effects of COVID-19 vaccines and measures to prevent them (Virology Journal)
- Heart inflammation, COVID-19 and the rare side effects of the vaccine (UC Davis Health)
- Myocarditis and Pericarditis After mRNA COVID-19 Vaccination (United States Centers for Disease Control and Prevention)
- Cardiovascular Complications of COVID-19 Vaccines (Frontiers in Cardiovascular Medicine)
- Vascular Disease Patient Information Page: Vascular considerations with COVID-19 vaccines (Society for Vascular Medicine)
- COVID-19 vaccine benefits still outweigh risks, despite possible rare heart complications (American Heart Association)
- COVID-19 subcommittee of the WHO Global Advisory Committee on Vaccine Safety (GACVS): updated statement regarding myocarditis and pericarditis reported with COVID-19 mRNA vaccines (World Health Organization)