..
..
..
Some are saying that the BMJ study shows vaccines are a higher risk for causing severe myocarditis than covid. That’s wrong. If anything it says you’re ~4 times less likely to get myocarditis, ~23 times less likely to get heart failure, and ~80 times less likely to die. 1/12
First off the study is here. https://bmjmedicine.bmj.com/content/2/1/e000373.abstract?ct= The study only attempts to look at consequences if people got myocarditis. 2/
To be honest this isn’t a thread I was even going to do! This isn’t a study designed to answer the prevalence/excess burden question! But there are very bad attempts to do this analysis undermining vaccination, so I feel I should show what it looks like when done properly. 3/
Ok so first thing is first, the study records the raw number of myocarditis cases w/in 28 days of vax, 28 days of confirmed infection, and in neither group. So what was the denominator for each? 4/
You might ask why I included the number of doses, surely the risk of a course of vaccination is what counts? Yes and no. Because the background rate of myocarditis isn’t zero, people getting 2-3 doses of vaccine will spend 56-84 days “at risk” and the number will be higher. 5/
So we can very easily convert this to how many million person years were spent “at risk” (i.e. able to have the event) in each category. So in our dataset there were: ~300,000 person years post infection ~3,600,000 person years post vax ~110,000,000 person years neither 6/
(Side note: this is based on a population of ~27mil vs 23mil in the study because it doesn’t exclude children.) 7/
So combined with our events what do we see? There are more cases of myocarditis after vaccination than expected by baseline risk! But that doesn’t translate to a higher risk of heart failure or death. After infection though is much higher than expected on all three metrics! 8/
So what if we subtract the expected number of events that would happen in each group based on the baseline rate? The results are dramatic, virtually no serious consequences from the excess myocarditis after vaccination. Myocarditis after infection though seems very serious. 9/
My conclusions: – There WERE extra cases of myocarditis after vaccination above what would have happened anyway. – These didn’t result in heart failure or death. – Infection resulted in far more cases of myocarditis, heart failure, and death. 10/
Remember, if somebody is trying to compare the number of events WITHOUT calculating person time at risk or a baseline rate, they’re probably not worth listening to. 11/
A note, I said at the beginning this isn’t an analysis I particularly wanted to do. The public data doesn’t perfectly match the study cohort (eg age). But there’s enough bad versions out there I at least wanted to show what it would look like if done as well as possible. 12/12
.
..
BMJ Journals
Clinical outcomes of myocarditis after SARS-CoV-2 mRNA vaccination in four Nordic countries: population based cohort study
- Anders Husby1,
- Hanne Løvdal Gulseth2,
- Petteri Hovi3,4,
- Jørgen Vinsløv Hansen1,
- Nicklas Pihlström5,
- Nina Gunnes2,
- http://orcid.org/0000-0002-4577-1808Tommi Härkänen6,
- Jesper Dahl7,
- Øystein Karlstad8,
- Tiina Heliö9,
- Lars Køber10,
- http://orcid.org/0000-0002-0654-4530Rickard Ljung11,12 and
- http://orcid.org/0000-0002-7509-9127Anders Hviid1
- Correspondence to Dr Anders Husby, Department of Epidemiology Research, Statens Serum Institut, Copenhagen, 2300, Denmark; andh@ssi.dk
Research
Clinical outcomes of myocarditis after SARS-CoV-2 mRNA vaccination in four Nordic countries: population based cohort study
- http://orcid.org/0000-0002-7634-8455Anders Husby1,
- Hanne Løvdal Gulseth2,
- Petteri Hovi3,4,
- Jørgen Vinsløv Hansen1,
- Nicklas Pihlström5,
- Nina Gunnes2,
- http://orcid.org/0000-0002-4577-1808Tommi Härkänen6,
- Jesper Dahl7,
- Øystein Karlstad8,
- Tiina Heliö9,
- Lars Køber10,
- http://orcid.org/0000-0002-0654-4530Rickard Ljung11,12 and
- http://orcid.org/0000-0002-7509-9127Anders Hviid1
- Correspondence to Dr Anders Husby, Department of Epidemiology Research, Statens Serum Institut, Copenhagen, 2300, Denmark; andh@ssi.dk
Abstract
Objective To investigate the clinical outcomes of myocarditis associated with mRNA vaccines against the SARS-CoV-2 virus compared with other types of myocarditis.
Design Population based cohort study.
Setting Nationwide register data from four Nordic countries (Denmark, Finland, Norway, and Sweden), from 1 January 2018 to the latest date of follow-up in 2022.
Participants The Nordic myocarditis cohort; 7292 individuals aged ≥12 years who had an incident diagnosis of myocarditis as a main or secondary diagnosis, in a population of 23 million individuals in Denmark, Finland, Norway, and Sweden.
Main outcome measures Heart failure, or death from any cause within 90 days of admission to hospital for new onset myocarditis, and hospital readmission within 90 days of discharge to hospital for new onset myocarditis. Clinical outcomes of myocarditis associated with SARS-CoV-2 mRNA vaccination, covid-19 disease, and conventional myocarditis were compared.
Results In 2018-22, 7292 patients were admitted to hospital with new onset myocarditis, with 530 (7.3%) categorised as having myocarditis associated with SARS-CoV-2 mRNA vaccination, 109 (1.5%) with myocarditis associated with covid-19 disease, and 6653 (91.2%) with conventional myocarditis. At the 90 day follow-up, 62, nine, and 988 patients had been readmitted to hospital in each group (vaccination, covid-19, and conventional myocarditis groups, respectively), corresponding to a relative risk of readmission of 0.79 (95% confidence interval 0.62 to 1.00) and 0.55 (0.30 to 1.04) for the vaccination type and covid-19 type myocarditis groups, respectively, compared with the conventional myocarditis group. At the 90 day follow-up, 27, 18, and 616 patients had a diagnosis of heart failure or died in the vaccination type, covid-19 type, and conventional myocarditis groups, respectively. The relative risk of heart failure within 90 days was 0.56 (95% confidence interval 0.37 to 0.85) and 1.48 (0.86 to 2.54) for myocarditis associated with vaccination and covid-19 disease, respectively, compared with conventional myocarditis; the relative risk of death was 0.48 (0.21 to 1.09) and 2.35 (1.06 to 5.19), respectively. Among patients aged 12-39 years with no predisposing comorbidities, the relative risk of heart failure or death was markedly higher for myocarditis associated with covid-19 disease than for myocarditis associated with vaccination (relative risk 5.78, 1.84 to 18.20).
Conclusions Compared with myocarditis associated with covid-19 disease and conventional myocarditis, myocarditis after vaccination with SARS-CoV-2 mRNA vaccines was associated with better clinical outcomes within 90 days of admission to hospital.
..
weehingthong 