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A non-peer-reviewed study has raised concerns about heart inflammation risk in young boys who take the COVID-19 vaccine. vejaa/Getty Images
  • A new, non-peer-reviewed study concluded that healthy boys aged 12–17 years had a higher hospitalization rate due to heart inflammation after their second mRNA COVID-19 vaccination than the expected hospitalization rate for COVID-19 in that age group.
  • A non-peer-reviewed study reports on scientific research that other experts in the field have not evaluated before publication; it should not guide clinical decision-making.
  • In the case of this paper, there are several issues with the data that the researchers used, which limits the accuracy and applicability of the study’s findings.
  • A CDC analysis of reports of heart inflammation after COVID-19 vaccines is currently under review at a major peer-reviewed journal.

A non-peer-reviewed retrospective paper, released as a pre-print, analyzed the rate of post-vaccination cardiac myocarditis in children aged 12–15 and 16–17 years who had received mRNA COVID-19 vaccines.

The researchers did so by searching the Vaccine Adverse Event Reporting System (VAERS) for reports of children aged 12-17 years from January 1, 2021, to June 18, 2021. They searched using the words myocarditis, pericarditis, myopericarditis, chest pain, and a troponin lab, which identifies a heart attack and other heart conditions.

They then inferred a diagnosis of cardiac adverse events (CAE) in these children.

The Centers for Disease Control and Prevention (CDC) announced in June 2021 that it is actively monitoring for the occurrence of myocarditis and pericarditis after the COVID-19 vaccination. The CDC still recommends that everyone aged 12 years and older receive a COVID-19 vaccination.

Researchers stratified the reports they had identified as CAE rates by age, sex, and vaccination dose number. They conducted a harm-benefit analysis based on available literature concerning COVID-19-related hospitalization risk in the age group.

The study identified 257 CAEs in total and reported rates (in cases per million after the second dose) of 162.2 in boys aged 12–15 years, 94 in boys aged 16–17 years, 13 in girls aged 12-15 years, and 13.4 in girls aged 16–17 years.

The study estimated that CAE incidence was between 3.7 and 6.1 times higher than their 120-day COVID-19 hospitalization risk (August 21, 2021) in healthy boys aged 12–15 receiving their second mRNA dose. They estimated that the CAE incidence was 2.1–3.5 times higher in healthy boys aged 16–17.

The paper appears on the pre-print server MedRxiv.

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Inflammation may occur in the heart due to infections, medicines, autoimmune diseases, or environmental factors, which may cause damage and lead to health problems. Inflammation may occur in the heart muscle (myocarditis) and tissue that forms the sac around the heart (pericarditis).

Cases of myocarditis and pericarditis reported to the VAERS occurred mainly in male adolescents and young adults, usually within 7 days following the second dose of an mRNA COVID-19 vaccine (Pfizer-BioNTech and Moderna), with most resolving after conservative management.

VAERS is a post-marketing safety program in the United States that collects reports of adverse events after vaccination from patients, family members, healthcare providers, vaccine manufacturers, and the general public in the U.S.

in an interview with MNT, Dr. Danelle Fisher, pediatrician, and Chair of Pediatrics at Providence Saint John’s Health Center in Santa Monica, CA, explained: “All myocarditis causes symptoms, including chest pain, difficulty breathing, and palpitations [and] we usually [admit] children who have myocarditis [to] the hospital to monitor them.”

“However, there’s no specific treatment for myocarditis — we use supportive care — which means things such as ibuprofen for chest pain or discomfort, intravenous fluids [for hydration], and just watching and waiting — and these kids get better.”

She added, “Now, there is a small subset of myocarditis patients that will go on to have cardiac dysfunction, but it is incredibly rare. The [number] of cardiac issues that [we see] from COVID-19 disease [will] probably outweigh the [number] of kids who got the vaccine and ended up with vaccine-associated myocarditis.

The study has limitations regarding the inappropriate use of VAERS reporting data to calculate the CAE rate. VAERS serves to rapidly detect safety signals or unusual or unexpected patterns of vaccine-related adverse reactions, but the publically available database has some fundamental limitations:

  • Vaccine providers report any clinically significant health issue following vaccination to VAERS, regardless of believed cause.
  • Reports may contain missing, inaccurate, erroneous, and unverified information.
  • The number of reports alone cannot determine the presence, severity, prevalence, or incidence of adverse events associated with vaccines.
  • Data are not comprehensive for all known vaccine safety issues and intended for use in the context of other available scientific data.

Dr. Fisher commented about the study’s limitations: “The first thing that jumped out to me is that this is an evaluation of the VAERS database. […] I look at this data as being […] self-reported or […] not necessarily reviewed by physicians.

Using unverified VAERS data to calculate the incidence of heart inflammation is not recommended in the VAERS data disclaimer, limiting the accuracy and applicability of the study’s findings.

She added, “Now, on top of that, the instance of myocarditis that has been seen after the Pfizer vaccination is still a very rare number. […]. So, I’m not exactly sure that I’m ready to draw conclusions or tell my patients that I’m very concerned about myocarditis after [the] Pfizer vaccine if they are in the risk group of 12–18 years old; this is not the study that I’m going to hang my hat on as a physician.”

Scott Pauley, Press Officer, News Media Branch, Division of Public Affairs, Office of the Associate Director for Communications for the CDC, commented to MNT: “[The] CDC was not involved in the study, which used reports with limited information from a publicly accessible VAERS database [and] is not able to verify the validity of [the] methods used or the results obtained.

“However, a CDC analysis of reports to the VAERS of myocarditis after COVID-19 vaccines is currently under review at a major peer-reviewed journal.”

He added, “This analysis describes reports that have been verified to meet the CDC working definition for myocarditis or myopericarditis, by an interview with a provider involved in the patient’s care, as well as a review of available medical records associated with these reports.”

Dr. Fisher commented:

“I have a young child myself who is a boy; he’s 9.5 years old. […] I’m not worried about my son getting the Pfizer vaccine if it is indeed released by October 30 or 31. I’m still going to […] get him the vaccine because I still feel that the vaccine is truly the safest thing we can do to protect our children and our adult population from COVID disease.”

She elaborated, “I am so much more concerned about COVID disease than I am about [the] COVID vaccination, and I want to be sure that when people look at studies, they know what they’re looking at.”

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