Heart Arrhythmia After COVID-19 Vaccine: A Very Rare Side Effect

Health Line

6 hours ago

Arrhythmia is not a known side effect of COVID-19 vaccines. But ongoing monitoring has shown rare instances of heart complications in people who have received the Pfizer-BioNTech or Moderna mRNA vaccines.
Arrhythmia affects the rate or rhythm at which the heart beats. Your heart might beat too fast (tachycardia), too slow (bradycardia), too early (premature contraction), or erratically (fibrillation).
Arrhythmia can also be a sign of myocarditis, or inflammation of the heart muscle. Myocarditis is a very rare side effect of Pfizer-BioNTech or Moderna mRNA COVID-19 vaccines.
You're more likely to experience arrhythmia or myocarditis caused by COVID-19 itself than from the COVID-19 vaccine.
At least 2 out of every 10 people hospitalized with COVID-19 experience heart problems, including damage to their heart muscle and arrhythmia. This is what scientists mean when they say the benefits of vaccination outweigh the risks.
Keep reading to learn more about heart arrhythmia and myocarditis following COVID-19 vaccination.
What the research says
Data from the Centers for Disease Control and Prevention (CDC) shows that higher than normal cases of heart inflammation have been reported in the United States after COVID-19 vaccination with the Pfizer-BioNTech or Moderna vaccines.
These heart issues occurred mostly in males between ages 12 and 39 after they received the second dose of the vaccine, usually within a few days of receiving the vaccine. This side effect hasn't been observed in people who received the Johnson & Johnson vaccine or the Novavax protein subunit vaccine.
The Pfizer-BioNTech and Moderna vaccines are messenger RNA (mRNA) vaccines. These vaccines contain genetically engineered mRNA that teaches your cells how to create antibodies capable of fighting the coronavirus that causes COVID-19.
Traditional vaccines, like the Johnson & Johnson COVID-19 vaccine, contain genetic material from the virus, which also helps your body create antibodies.
A 2021 analysis of CDC data found that people ages 12 to 39 who received their second COVID-19 mRNA vaccine had about a 13 in 1 million chance of experiencing heart inflammation. In other words, this side effect is exceedingly rare.
Another 2021 study involved people ages 16 and up who were vaccinated against COVID-19. It also found slightly increased risks of heart inflammation after participants' first and second doses of COVID-19 vaccines in the first 28 days after vaccination. This research included the Oxford-AstraZeneca vaccine as well as the Pfizer-BioNTech and Moderna vaccines.
This risk of myocarditis did appear to be a bit higher after a second dose of the Moderna vaccine — not the other vaccines studied — and was only observed in people younger than 40.
Vaccination for people with preexisting heart conditions
Even though arrhythmias are sometimes associated with myocarditis, no direct association was found between arrhythmia and COVID-19 vaccination.
The American Heart Association recommends that anyone with heart disease get vaccinated against COVID-19 as soon as possible. This is because they're at a much greater risk of heart-related complications from the coronavirus than they are from any COVID-19 vaccine.
However, if you or your child has experienced myocarditis after a vaccine before, discuss your options with your doctor before getting vaccinated.
What are the symptoms of heart arrhythmia?
Arrhythmia doesn't always cause symptoms — that's why you'll sometimes hear it called 'asymptomatic.'
But possible symptoms can include:
chest pain
shortness of breath
feeling like the heart is fluttering or pounding (palpitations)
rapid heartbeat
slow or irregular heartbeat
A 2021 study suggests that most people suspected to have myocarditis after COVID-19 experienced chest pain about 2 or 3 days after the second dose of a COVID-19 mRNA vaccine.
Arrhythmia during COVID-19
Arrhythmias are more often seen after developing COVID-19 than after vaccination.
In small studies conducted in Wuhan, China, during the initial outbreak of COVID-19, arrhythmias occurred at a rate of 16.7% of people hospitalized with COVID-19, with 44.4% of those who were hospitalized being treated in the intensive care unit (ICU).
A retrospective 2021 study of 3,970 COVID-19 admissions at Mount Sinai Hospital in New York City found that atrial fibrillation and atrial flutter (AF/AFL) happened in 10% of study participants. AF/AFL was also associated with a 46% higher risk of death — compared with 26% of study participants who had no arrhythmias.
Viral infection is the most common cause of inflammation in the heart muscle in children. Children who develop myocarditis after COVID-19 also typically experience a more severe case than if it happens after a COVID-19 vaccination.
Heart complications can occur even after you recover from COVID-19.
Common vaccine side effects
Heart problems are a very rare side effect of COVID-19 vaccines.
More common side effects are mild and temporary, including:
fever
pain and soreness at injection site
fatigue
headache
chills
body aches
These side effects occur as the vaccine triggers a response from your immune system. In other words, these side effects mean the vaccine is doing its job.
Is the COVID-19 vaccine still effective?
When first studied in earlier coronavirus variants, COVID-19 vaccines were shown to be roughly:
95% effective at preventing coronavirus infection
94% effective at preventing COVID-19 hospitalizations and deaths among fully vaccinated adults
Yet viruses constantly change. Several new variants have emerged since the novel coronavirus first appeared.
But even though the first COVID-19 vaccines aren't as effective at preventing infection by the Delta or Omicron variants, they offer significant protection against these variants by reducing your risk of:
severe illness
hospitalization
death
Research published in 2022 estimates that COVID-19 vaccines are still up to 90% effective at preventing severe outcomes of COVID-19, including the need for invasive mechanical ventilation or death.
People who are fully vaccinated and received a third booster had the highest level of protection against severe disease and hospitalization. Newer boosters have since been developed.
Who should get a COVID-19 vaccine?
Under the new administration, the CDC recommends that most people ages 18 years and older get an annual COVID-19 vaccine, while those 6 months to 17 years old and pregnant people make a personal decision with their loved ones.
However, the American Academy of Pediatrics (AAP) recommends vaccination for every child 6 months or older, and the American College of Obstetricians and Gynecologists (ACOG) recommends vaccination for all pregnant people.