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Two simple fractions.
Oct. 27th, 2025 07:39 amI am still spreading antivax agenda online, and here is a very common counter-argument I am often confronted with. An official USA CDC publication: Cardiac Complications After SARS-CoV-2 Infection and mRNA COVID-19 Vaccination presumably proving that heart inflammation from covid is more common than one from the vaccine in both sexes and each age bracket.
When reading this paper first I thought that they compare heart inflammation risk(HIR) in the vaccinated groups vs unvaccinated groups, and proved that the latter is bigger. That would certainly change my mind about the subject! Unlike covid vaccination enthusiasts who just believe in science, my beliefs can be changed with new evidence.
Then I realised they don't compare HIR/vac vs HIR/unvac groups, I thought that maybe they compare HIR/vac vs HIR/(unvac&infected). No, it is not quite the case either.
What they compare is (HIR)/vac vs (HIR+MIS)/(positive covid PCR test), and latter is larger. Which makes total sense because not every covid infection gets PCR tested in hospital or testing site, especially with Omicron+ versions of the virus. So the second fraction gets significantly larger because of small denominator.
So they are correct: the HIR from vaccination is less common than HIR from severe covid. But parents are more interested in HIR from vaccination vs HIR from not vaccinating, which is entirely different Bayesian reasoning game.
How can I estimate/quantify the difference? The numbers in the article are the following: "Among males aged 12–17 years, the incidences of myocarditis and myocarditis or pericarditis were 50.1–64.9 cases per 100,000 after infection, 2.2–3.3 after the first vaccine dose, and 22.0–35.9 after the second dose; incidences of myocarditis,
pericarditis, or MIS were 150.5–180.0 after infection. So, TEEN BOYS (ages 12-17 years) had 2-6X the risk of heart complications after infection compared to after vaccination."
However, noting severity of Omicron+ in children, more than 80% of the cases were asymptomatic or so mild that no parent would bring a child for PCR testing, at most there is just at-home antigen test used. (According to MMWR seropositivity study by February 2022 ~55M children were seropositive and 12M children tested positive in US) This makes second fraction 5x smaller if we count all infections.
Which makes final comparison show that vaccination is 0.8x-2x more dangerous than covid infection for young boys. (Assuming the chance of infection is 100%, which is also not the case).
Maybe that is why an official FDA representative recently wrote the following words in an opinion piece published in JAMA : "During the COVID-19 pandemic, broad, one-size-fits-all mandates were aggressively pursued, requiring vaccines in populations with potentially net-negative benefit-risk profiles. This ... in part, [may] be responsible for widespread loss of trust in public health and medicine and growing hesitancy against all vaccination. Public trust takes decades to build, but can be forfeited in a single action."
When reading this paper first I thought that they compare heart inflammation risk(HIR) in the vaccinated groups vs unvaccinated groups, and proved that the latter is bigger. That would certainly change my mind about the subject! Unlike covid vaccination enthusiasts who just believe in science, my beliefs can be changed with new evidence.
Then I realised they don't compare HIR/vac vs HIR/unvac groups, I thought that maybe they compare HIR/vac vs HIR/(unvac&infected). No, it is not quite the case either.
What they compare is (HIR)/vac vs (HIR+MIS)/(positive covid PCR test), and latter is larger. Which makes total sense because not every covid infection gets PCR tested in hospital or testing site, especially with Omicron+ versions of the virus. So the second fraction gets significantly larger because of small denominator.
So they are correct: the HIR from vaccination is less common than HIR from severe covid. But parents are more interested in HIR from vaccination vs HIR from not vaccinating, which is entirely different Bayesian reasoning game.
How can I estimate/quantify the difference? The numbers in the article are the following: "Among males aged 12–17 years, the incidences of myocarditis and myocarditis or pericarditis were 50.1–64.9 cases per 100,000 after infection, 2.2–3.3 after the first vaccine dose, and 22.0–35.9 after the second dose; incidences of myocarditis,
pericarditis, or MIS were 150.5–180.0 after infection. So, TEEN BOYS (ages 12-17 years) had 2-6X the risk of heart complications after infection compared to after vaccination."
However, noting severity of Omicron+ in children, more than 80% of the cases were asymptomatic or so mild that no parent would bring a child for PCR testing, at most there is just at-home antigen test used. (According to MMWR seropositivity study by February 2022 ~55M children were seropositive and 12M children tested positive in US) This makes second fraction 5x smaller if we count all infections.
Which makes final comparison show that vaccination is 0.8x-2x more dangerous than covid infection for young boys. (Assuming the chance of infection is 100%, which is also not the case).
Maybe that is why an official FDA representative recently wrote the following words in an opinion piece published in JAMA : "During the COVID-19 pandemic, broad, one-size-fits-all mandates were aggressively pursued, requiring vaccines in populations with potentially net-negative benefit-risk profiles. This ... in part, [may] be responsible for widespread loss of trust in public health and medicine and growing hesitancy against all vaccination. Public trust takes decades to build, but can be forfeited in a single action."
