If You Got Pfizer, You're More Likely to Have This Delayed Side Effect

This heart condition is more frequently affecting those who've had the Pfizer shot.

The Pfizer and Moderna COVID shots share a similar profile: both are mRNA vaccines which boast roughly the same efficacy, and they share most of the same—usually minor—side effects. However, The Centers for Disease Control and Prevention (CDC) and Food and Drug Administration (FDA) have recently acknowledged one difference between the two. Those who have received the Pfizer jab have more frequently reported an alarming symptom, which the CDC notes can be delayed after vaccination. Read on to find out what symptom to look out for, and what to do if it happens to you.

RELATED: Pfizer's Vaccine Protects You for at Least This Long, Study Finds.

In rare cases, the Pfizer vaccine has triggered inflammation of the heart.

man holding his chest in pain indoors.

According to both the CDC and FDA, there has been a recent increase in reports of myocarditis and pericarditis, inflammation of the heart muscle and the outer lining of the heart. Both conditions are triggered by the immune system's reaction to an infection, injury, or in this case, the COVID-19 vaccine. According to the Heart, Lung, and Blood Institute, myocarditis and pericarditis can cause heart damage over time, and can lead to irregular heartbeat or even heart failure.

The CDC revealed that the cases have occurred "mostly in male adolescents and young adults age 16 years or older," with a median age of 30 after dose one, and 24 after dose two. The inflammation typically surfaces within two to three days after COVID vaccination.

For more COVID vaccine news sent directly to your inbox, sign up for our daily newsletter.

Moderna has received fewer reports of the side effect.

Two vials of vaccine and a syringe in front of the Moderna logo

Recipients of the Moderna vaccine have also reported these symptoms following vaccination, though at lower rates. Data collected via the Vaccine Adverse Event Reporting System (VAERS) revealed that Pfizer recipients reported a total of 488 cases of this symptom, while Moderna recipients reported 301 cases as of May 31, 2021. Consistently across the two types of inoculation, reports of these symptoms were significantly higher following the second dose of the vaccine compared with the first.

RELATED: Moderna Caused This Reaction in 82 Percent of People, New Study Says.

Most people with this symptom have fared well in their recovery.

Woman talking to doctor

Thankfully, there's good news. While myocarditis and pericarditis can be serious, the CDC has shared that in COVID vaccine-related cases, "most patients who received care responded well to medicine and rest and quickly felt better." The health authority adds that "patients can usually return to their normal daily activities after their symptoms improve, and they should speak with their doctor about returning to exercise or sports."

The CDC and FDA say they are actively monitoring these reports, and will continue to review data and medical records to better understand any possible connection between the reported cases and COVID-19 vaccination.

The CDC still urges vaccination against COVID-19.

woman receiving covid-19 vaccine at home.

Heart inflammation may sound alarming and it's true that at their most severe and advanced stages, these two conditions can cause serious damage. However, the CDC still stresses that the danger and likelihood of COVID complications including "long-term health problems, hospitalization, and even death" far outweigh the risk of this particular side effect.

Given that over 172 million Americans have received at least one COVID vaccine dose to date and only several hundred cases have been associated with heart inflammation, your personal odds of developing myocarditis or pericarditis are considered exceedingly rare. For this reason, the CDC "continues to recommend COVID-19 vaccination for everyone 12 years of age and older."

RELATED: This Vaccine Reaction Means You May Have Already Had COVID, Study Says.

Lauren Gray
Lauren Gray is a New York-based writer, editor, and consultant. Read more
Filed Under