A recent study published in ‘Vaccine’ (2026) by researchers including Peter Dlouhý has generated significant discussion regarding cardiac biomarker changes following mRNA COVID-19 vaccination in healthy military personnel. The study, titled "Transient elevation of NT-proBNP after mRNA COVID-19 vaccination," examined the dynamics of cardiac stress markers in a cohort of healthy service members.
The research investigated levels of N-terminal prohormone of brain natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponins in military personnel following mRNA COVID-19 vaccination. According to reports citing this research, approximately 49% of healthy troops in the study experienced a greater than 50% surge in NT-proBNP levels after receiving two mRNA vaccine doses.
NT-proBNP is a well-established biomarker released by the heart when cardiac muscle is under stress or strain. Elevations typically indicate ventricular dysfunction or increased cardiac wall tension. The study found these elevations to be transient, peaking particularly within 14 days after the second vaccine dose, with geometric mean concentrations of 36.2 pg/mL reported.
It is important to note that the study described these changes as "subclinical," meaning they were detectable through laboratory testing but did not manifest as clinical symptoms or diagnosed heart disease in the subjects. The elevations were temporary rather than permanent.
This research builds upon earlier case series documenting myocarditis following COVID-19 vaccination in military populations. A 2021 JAMA Cardiology study by Montgomery et al. identified 23 military members who developed myocarditis post-vaccination, with significantly elevated troponin levels (10-400 times normal). However, these cases represented rare events among millions of administered doses.
Cardiovascular complications following mRNA COVID-19 vaccination, particularly myocarditis and pericarditis, have been documented since early in the vaccine rollout. These events occur most frequently in young males, typically after the second dose, and usually resolve with conservative management.
The broader context of vaccine safety includes a substantial body of evidence supporting the overall benefit-risk profile of COVID-19 vaccines. A 2025 JAMA Network Open study examining 4-year all-cause mortality among 18-59 year-olds in France found approximately 25% lower mortality risk in vaccinated individuals compared to unvaccinated counterparts. Similarly, the CDC has maintained that COVID-19 vaccines have undergone intensive safety monitoring.
The Dlouhý study contributes to ongoing efforts to characterize the full physiological effects of mRNA vaccination, including subclinical biomarker changes. While transient elevations in cardiac stress markers warrant continued investigation, they should be interpreted alongside the extensive body of data demonstrating vaccine effectiveness and established safety profiles. Further research examining long-term clinical significance of these biomarker fluctuations would be valuable for comprehensive safety assessment.
