Subclinical Myocarditis - NEW Report from Switzerland - Vital Findings
What this video covers
In this solo commentary, Dr. Vinay Prasad — then a hematologist-oncologist and professor of epidemiology and biostatistics — walks through a newly published prospective study from Basel, Switzerland, measuring cardiac troponin levels in hospital employees before and after receiving an mRNA COVID-19 booster. The study (Buergin et al., published in the European Journal of Heart Failure) is a “before and after” design: researchers drew blood at baseline, then again on day three after the booster, and looked for elevations in high-sensitivity troponin T, a biomarker that signals injury to heart muscle.
Prasad’s central focus is the study’s headline finding that 2.8% of participants showed troponin elevations consistent with what the authors called subclinical (asymptomatic) myocarditis, with the signal concentrated in women in this cohort. He emphasizes the distributional finding — that troponin levels shifted upward across the whole vaccinated group relative to baseline — and argues this implies some degree of cardiac injury was common, even when recipients felt fine. The episode mirrors his Plenary Session podcast installment on the same paper.
The video is classic Prasad: a single study, dissected paper-first, then used to question the risk-benefit balance of recommending boosters to broad, low-risk populations. He frames the findings as evidence that regulators should have demanded more rigorous cardiac safety data before mass booster campaigns.
He adds two specifics worth capturing. First, corroboration: a Thai study of adolescent boys found troponin elevations in 7 of 202 boys — a 3.5% subclinical rate, essentially the same order of magnitude as the Swiss result, which Prasad notes was also in line with smallpox-vaccine data. Second, the measurement problem: the Swiss team checked troponin only on day three (and day four for those elevated), and since levels were already falling between days three and four, Prasad relays lead author Christian Mueller’s point that the true peak — on days one or two — was never measured, so 2.8% is likely an underestimate. He also quotes drug-safety expert Walid Gellad of the University of Pittsburgh, who wrote that the FDA’s own words admitted existing surveillance “would be insufficient” to pick up subclinical myocarditis, asking: “how could CDC possibly recommend everyone get another booster even young healthy people with prior infection without these data?”
Key points
- Prasad argues the Basel study’s prospective design — measuring troponin before and after the booster in the same people — makes its findings harder to dismiss than retrospective safety reports.
- He reports the study’s finding that 2.8% of participants had troponin elevations consistent with subclinical myocarditis, and highlights that elevated levels were seen across the cohort, not just in the small minority with the largest rises.
- According to Prasad, the signal was more pronounced in women in this study — a contrast with the young-male pattern seen in clinical myocarditis reports, which he notes as a reason the finding deserved attention.
- He contends that troponin elevation indicates heart muscle injury, and questions whether regulators adequately investigated cardiac effects before recommending boosters broadly.
- Prasad uses the paper to argue that booster policy should have been risk-stratified — i.e., that recommending boosters for young, healthy, previously infected people was difficult to justify if even asymptomatic cardiac injury was occurring at measurable rates.
- He suggests the findings undermine the reassurance that post-vaccine myocarditis is “rare and mild,” arguing that subclinical cases would never appear in passive surveillance systems at all.
- He cites a Thai study of adolescent boys finding troponin elevations in 7 of 202 (3.5%) — corroborating the Swiss result — and relays lead author Christian Mueller’s point that troponin was only measured on day three, when levels were already falling, so the true rate was likely higher.
- He quotes drug-safety expert Walid Gellad: “how could CDC possibly recommend everyone get another booster even young healthy people with prior infection without these data?”
- Context the video does not dwell on: the study authors themselves characterized most elevations as mild and transient, and clinicians disagree about how to interpret small troponin rises of unclear clinical significance — Prasad’s reading is his own interpretation of the data.