mRNA Vaccines Causing Rare Heart Inflammation? Here's What We Know

Is the rare heart inflammation reported in some people post immunisation linked to the Pfizer and Moderna vaccines?

mRNA Vaccines Causing Rare Heart Inflammation? Here's What We Know

(Update: The meeting conducted by the vaccine safety panel including advisory groups of the US FDA and CDC concluded on Wednesday 23 June, that the instances of the rare heart inflammation reported in the US are likely linked to the mRNA vaccines.

The health authorities, however, continue to recommend the vaccine for everyone over the age of 12 as the benefits outweigh the risks.)

Higher than expected cases of myocarditis amoung recipients of the Pfizer and Moderna vaccines has prompted the US Centre for Disease Control and Prevention (CDC) to probe the incidents further for a causal link between the two, reported Reuters.

The US CDC has been monitoring incidents of heart inflammation in people who have received mRNA vaccines since April 2021.

A report from a vaccine safety meeting held on Thursday, 10 June, with the Vaccines and Related Biological Products Advisory Committee, however, finds the cases of myocarditis to be much higher after the second dose, sparking concerns.

In response to the data, the US CDC has called for another meeting to be held on 18 June to determine if the cases of inflammation are a result of the mRNA covid vaccines.

meanwhile, the CDC continues to recommend the COVID vaccines to everyone over the age of 12 on the grounds that the condition is very rare and the risks associated with the infection far outweigh that of the vaccine.


What is myocarditis?

Myocarditis is a type of inflammation of the heart muscles.

Although it is usually caused as a result of viral infections, it can also be caused by a reaction to certain drugs,and autoimmune conditions.

According to WebMD, "when your body produces cells to fight the virus, these cells release chemicals. If the disease-fighting cells enter your heart, some chemicals they release can inflame your heart muscle."

A similar response could explain myocarditis being caused by COVID vaccines which essentially work by triggering the immune system like the actual infection would.

Symptoms of myocarditis include fatigue, chest pain, shortness of breath, fluttering or pounding heart.

The CDC recommends seeking immediate medical attention if any young person experiences these symptoms within a week of being vaccinated.

According to the US CDC, cases of myocarditis post-vaccination,

  • Typlically developed several days after vaccination

  • Were higher after the second dose

  • Patients returned to their normal activity after the symptoms were resolved.

Which vaccines are suspected to be causing myocarditis?

The cases of myocarditis or inflammation of the heart have been recorded in those who have received the mRNA vaccine. Although, no causal link has been established as yet.

Considering mRNA vaccines are thought to be the cause, both the mRNA vaccines that have been approved for emergency use, Pfizer-BioNtech and Moderna are under review.

Who is at a higher risk?

According to the US CDC, most of the cases of inflammation post vaccination have been reported in young people and adolescents between the ages of 12 to 24.

How many cases of myocarditis have been reported so far?

According to the data submitted to the Vaccine Adverse Event Reporting System (VAERS), 216 people developed myocarditis after their first dose, and 573 have experienced it after the second dose.

This drastic jump in cases of myocarditis is what has prompted the CDC to further look into a possible causal link.

Moreover, most of the cases followed the second dose of the Pfizer vaccine.

Have cases of myocarditis post vaccination been reported in any other country?

On 1 June, Israel's health ministry had flagged cases of myocarditis in (mainly) young men between the ages of 16 and 30, who received the Pfizer vaccine, although no causal link has been established as yet, reported Reuters.

On 11 June, the European Medical Agency released a statement saying they, too, were assessing reports of myocarditis.

How serious is the condition?

According to the CDC, most people who developed heart inflammation only experienced mild symptoms and 81 percent of them have fully recovered so far.

"This issue of a transient myocarditis associated with a vaccine is at the moment a theoretical and unproven risk," Reuters quoted Dr. Paul Offit, director of the Vaccine Education Center at Children's Hospital of Philadelphia.

(written with inputs from Reuters, The New York Times)

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