Kaiser Northwest Estimate of Myocarditis/Pericarditis compared to CDC's estimate | A New Study
What this video covers
In this short January 2022 video, Prasad compares two estimates of myocarditis and pericarditis after mRNA vaccination: one from a Kaiser Permanente Northwest study using active surveillance of its own patient population, and one from the CDC based on passive reporting systems. His headline claim is that Kaiser’s estimate came out substantially higher than the CDC’s — which, he argues, shows the CDC’s surveillance was missing cases.
Prasad’s argument turns on methodology. Active surveillance — systematically searching health records for cases, as Kaiser did — tends to find more cases than passive surveillance, which relies on reports being filed. According to Prasad, the gap between the two estimates demonstrates that the CDC’s passive systems undercounted myocarditis, meaning the true risk was higher than what the public was told. He presents the Kaiser study as the more trustworthy number.
The video gets specific about both the methods and the numbers. Prasad explains that the study’s lead author, a Kaiser Permanente Northwest infectious-disease physician, went beyond the ICD-10 billing codes the CDC’s method used: she searched the free text of hospital notes for myocarditis and pericarditis language, used a “myocarditis unspecified” billing code the CDC method omitted, and captured hospitalizations at outside facilities through billing claims submitted to Kaiser — some arriving more than 30 days after the event. Every case was expert-adjudicated as confirmed or probable vaccine-associated myocarditis. The headline numbers: for boys aged 12–17 after the second dose, 377 cases per million — roughly 1 in 2,700; for men 18–24, roughly 1 in 1,900 — far above the estimates presented to the FDA’s advisory committee and the CDC’s ACIP. Prasad argues the result harmonizes the U.S. picture with the higher estimates from Israel, Norway, Hong Kong, and Ontario: people are people, he says, and the differences between countries reflected surveillance quality, not biology.
The chronicle notes the methodological debate: epidemiologists generally agree that active surveillance captures more cases than passive reporting, but they also note the two estimates covered different populations, time windows, and case definitions, making direct comparison imperfect. CDC officials at the time defended their multi-system approach and noted that all estimates described a rare event. Prasad’s video treats the Kaiser figure as the corrected record and the CDC figure as evidence of a surveillance failure.
Key points
- Prasad compares a Kaiser Permanente Northwest active-surveillance study of myocarditis/pericarditis with the CDC’s passive-surveillance estimate.
- According to Prasad, Kaiser’s estimate was substantially higher, showing the CDC’s systems were missing cases.
- The headline numbers: 377 per million (roughly 1 in 2,700) for boys 12–17 after dose 2, and roughly 1 in 1,900 for men 18–24 — far above the figures used in FDA and CDC advisory-committee deliberations.
- On methods: the study searched free text of hospital notes beyond ICD-10 codes, used a “myocarditis unspecified” code the CDC method omitted, and captured outside-Kaiser hospitalizations via delayed billing claims, with all cases expert-adjudicated.
- Prasad argues the findings harmonize U.S. estimates with those from Israel, Norway, Hong Kong, and Ontario — the differences, he says, reflect surveillance quality rather than biology.
- He argues active surveillance (systematic record searches) is more trustworthy than passive reporting for estimating true risk.
- Prasad frames the gap as evidence the public was told an understated myocarditis risk.
- Epidemiologists note, and the chronicle records, that the studies differed in population, time window, and case definitions, complicating direct comparison.
- CDC officials defended their multi-system surveillance and maintained that all estimates described a rare event.