U.S. Officials Are Reportedly Investigating This Moderna Side Effect

New research suggests that the risk may be higher among people who get the Moderna vaccine.

It's been eight months since the Moderna vaccine was approved by the U.S. Food and Drug Administration (FDA) for emergency use authorization (EUA), the second of three vaccines given EUA in the U.S. So by now, anyone who's gotten inoculated or plans to do so likely knows the side effects that come with the COVID vaccine: symptoms like pain at the injection site, fatigue, headache, muscle and joint pain, fever, nausea, vomiting, and diarrhea. But in recent months, a growing number of incidences of one side effect have been reported, and now, the FDA and Centers for Disease Control and Prevention (CDC) are reportedly looking into whether or not Moderna is more often linked to it. Read on to find out the latest.

The CDC and FDA are reportedly looking into data that suggests the Moderna vaccine is up to 2.5 times more likely to result in myocarditis.

Moderna vaccine

The Washington Post reports that the CDC and FDA are looking at data that suggests that Moderna's COVID-19 vaccine may be linked to a higher risk of heart inflammation—also known as myocarditis and pericarditis—in young adults as compared to the Pfizer vaccine.

The CDC and FDA review is reportedly based on data from Canada and is still being evaluated by scientific authorities, but two people familiar with the study told the Post that Moderna has been linked with increased cases of myocarditis, inflammation of the heart, and pericarditis, inflammation of the tissue around the heart. According to one of the newspaper's sources, who spoke on the condition of anonymity, the Canadian report "indicates there might be a 2-½ times higher incidence of myocarditis in those who get Moderna compared with the Pfizer-BioNTech vaccine."

However, the anonymous source went on to say that researchers have yet to come to a conclusion about the side effect's link to Moderna specifically. "The data are not slam bang," they said.

Both the Moderna and Pfizer vaccines have previously been linked to myocarditis and pericarditis.

A young man sitting at a desk wearing a face mask and gloves grabbing his chest due

Scientists have known for months that the mRNA vaccines, Moderna and Pfizer, have a possible link to myocarditis and pericarditis. In June, the CDC reported that its Vaccine Adverse Event Reporting System (VAERS) had logged more than a thousand calls to its hotline of cases of myocarditis and pericarditis following vaccination. VAERS logs self-reports of adverse vaccine effects and is not vetted by medical professionals. The bulk of the cases reported at that time occurred in young men between the ages of 16 and 30, and happened after their second dose. Patients reported feeling the effects within several days of the vaccination.

The VAERS report aligns with the European Medicines Agency data, which reviews COVID-19 treatment across the entire European economic area. A July report from the EMA found cases of myocarditis and pericarditis in both people who got the Moderna and Pfizer jabs. The agency found 145 cases of myocarditis and 138 cases of pericarditis out of 177 million doses of Pfizer (called Comirnaty in the E.U.). It recorded 19 cases of myocarditis and 19 cases of pericarditis among 20 million Moderna (called Spikevax in the E.U.) jabs. Among all reported cases of myocarditis and pericarditis, five resulted in death.

Those numbers, according to the EMA, are not statistically significant, all amounting to less than .00008 percent of recipients effected.

RELATED: Moderna Says These 3 Things Will Cause More Vaccinated People to Get COVID.

The Moderna vaccine has not been given EUA in people under 17.

Moderna vaccine

In June, Moderna asked the FDA to review a request to expand its mRNA vaccine for use in people between the ages of 12 and 17. While its fellow mRNA technology vaccine, Pfizer, received the green light for use among 12- to 15-year-olds in May, Moderna is still waiting for approval.

It is not known if the incidences of myocarditis and pericarditis have affected Moderna's approval among young people, who seem to be more likely to experience heart inflammation. But scientists and health professionals stress that the potential side effects of myocarditis and pericarditis should not dissuade people from getting vaccinated. Even if cases of cardiac inflammation are more likely with the Moderna jab than the Pfizer jab, both remain relatively rare, and the risk outweighs the dangers of remaining unvaccinated, experts caution.

The CDC and the Department of Health and Human Services, along with more than a dozen other public health organizations, issued a statement in June urging families to vaccinate their children 12 and older. "This is an extremely rare side effect, and only an exceedingly small number of people will experience it after vaccination," the statement said. "Importantly, for the young people who do, most cases are mild, and individuals recover often on their own or with minimal treatment."

The CDC adds in their online guidance that "the known and potential benefits of COVID-19 vaccination outweigh the known and potential risks, including the possible risk of myocarditis or pericarditis."

Nevertheless, both Moderna and Pfizer now carry a warning label listing myocarditis and pericarditis as potential side effects.

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If you're worried about myocarditis or pericarditis, here's what to look for.

A young woman lies on the couch while covered by a blanket and a tired expression on her face

The CDC recommends that if you're concerned that you or someone you love is experiencing vaccination-related myocarditis, whether they received Moderna or Pfizer, you should look for the following symptoms:

  • Chest pain
  • Shortness of breath
  • Feelings of having a fast-beating, fluttering, or pounding heart

Symptoms of pericarditis, according to Cedars-Sinai, include:

  • Chest pain behind the breastbone or beneath the collarbone, neck, or shoulder
  • Fever
  • Weakness and fatigue
  • Coughing
  • Trouble breathing
  • Pain when swallowing
  • Heart palpitations

Those experiencing these symptoms should seek out medical care immediately. The bulk of patients who do so usually recover quickly, the CDC points out.

RELATED: Dr. Fauci Warns Not to Do This If You Got Pfizer.