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Researchers are getting pushback over a that relied heavily on Vaccine Adverse Event Reporting System (VAERS) data to characterize myocarditis risk with the COVID-19 vaccine in adolescents, particularly young boys.

The report by Tracy Høeg, MD, PhD, of the University of California Davis, and colleagues found that rates of "cardiac adverse events" after the second dose were higher than previous CDC estimates, at 162 per million among boys ages 12 to 15 and 94 per million among boys ages 16 to 17. (Rates were much lower for girls, at about 13 per million for each age group.)

The authors also concluded that the risk of hospitalization for cardiac adverse events following vaccination is higher than the risk of being hospitalized with COVID for healthy boys in both age groups.

The findings led to an uproar by physicians on social media, who pointed out that they're unreliable due to the nature of VAERS and its known limitations -- and that the authors are running the risk of serious misinterpretation of their findings by groups with bad intentions.

For instance, Rep. Marjorie Taylor Greene (R-Ga.) already that took an uncritical approach to the findings, holding it up as evidence that vaccines are riskier than COVID for boys.

Physicians haven't been kind in their reviews, with one physician blogger calling it a "" into a dataset that's full of well-known flaws, adding that these authors should have known better. VAERS is an early warning system that can generate hypotheses that require adjudication of reports; it was never intended to be used as a research dataset, said blogger David Gorski, MD, PhD, of Wayne State University in Detroit.

Gorski also raised concerns about confirmation bias -- particularly because one co-author is a member of "Rational Ground," a group that promotes anti-masking and anti-lockdown stances.

Høeg responded to questions from 麻豆传媒 via email. (John Mandrola, MD, the cardiologist on the team, recused himself because he writes for one of 麻豆传媒's competitors.)

Høeg said the group used the same definition of myocarditis that the CDC did for its previous estimates using VAERS data, and that cardiologist Mandrola was key in vetting reports. She also pointed to the established fact that VAERS often provides an underestimate of the true prevalence of an adverse event.

Several physicians, however, have asked why this group would bother repeating the CDC's own analysis, especially if they are using the same definition of myocarditis -- and working without CDC's adjudicated data.

"We repeated the project because we were concerned about the symptom search criteria the CDC used being too narrow," Høeg told 麻豆传媒. "We found around 40% of our cases simply using expanded symptom search criteria from theirs but requiring the same objective evidence they did of myocarditis (which we called in our paper 'cardiac adverse event')."

She said they also wanted to stratify risk by age groups 12-15 and 16-17, which CDC hadn't done: "As a mom of 10- and 13-year-old boys, this was important information for me to see and I know many other parents feel the same way."

Nonetheless, outside researchers noted that Høeg and colleagues could have assessed previously adjudicated reports from the CDC, or that they could have assessed data from the CDC's Vaccine Safety Datalink (VSD) research dataset instead.

"The benefit of using the VAERS first was this is a rare event, which we were just beginning to track in the U.S., and VAERS gave us quick access to the largest number of reported cases," Høeg said. "We could also easily identify instances of post-vaccination cardiac injury in terms of troponin levels, along with case descriptions (which we have made publicly available) and directly compare our rates with those that the CDC found, demonstrating that there may be a significant amount of missed post-vaccination cardiac damage in this age group, specifically in the youngest group, compared to what the CDC had initially reported."

Høeg has a PhD in epidemiology and public health from the University of Copenhagen, but her medical specialty is physical medicine & rehabilitation. She is employed by Northern California Orthopaedic Associates. Her bio for that group says she's a "Voluntary Assistant Professor at UC Davis."

Mandrola is a cardiac electrophysiologist affiliated with Baptist Health in Louisville, Kentucky.

The other two authors on the paper appear to be medical communications professionals. Allison Krug, MPH, is an epidemiologist and principal of Artemis Biomedical Communications.

Josh Stevenson lists Truth in Data, as his primary affiliation on the paper, and is also listed under the , where he is described as a "data visualization expert who focuses on creating easy to understand charts and dashboards with data," with a background in computer systems engineering.

Rational Ground has been known for challenging mask mandates and lockdowns. For instance, it offers sample letters to summer camps, school boards, and college presidents, describing how the COVID pandemic has "drummed up unnecessary panic."

"Did the authors' biases lead to this analysis?" Gorski wrote in his blog. "Who knows? I just know that the result is definitely not good, and the involvement of Josh Stevenson in particular makes this whole study very suspect indeed."

Gorski emphasized the typical pathway for evaluating a hypothesis generated by VAERS: CDC will follow up to see if the event is actually associated with vaccination, and if correlation is established, it will investigate whether causation is plausible.

"Other databases, active surveillance system databases like the VSD and [Clinical Immunization Safety Assessment], are required to test these hypotheses, because again -- VAERS data are, by the design of the database, unsuitable for this purpose," he noted.

Gorski, like other physicians on social media, acknowledged that early data, including from other countries such as Israel, do seem to indicate an increased risk of myocarditis in younger boys.

"There's a signal," he wrote. But, from the evidence we have thus far: "It's not yet clear how large the risk of myocarditis is in this age group."

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