Question explored with the scientific record
Conversation so far
- 1 Is the mRNA flu jab safe
- 2 Have any mRNA flu vaccines reached larger trials, and what were the serious side effect rates?
- 3 How does the mRNA-COVID myocarditis risk compare to expected flu risk?
Answered on this page ↓
How does the mRNA-COVID myocarditis risk compare to expected flu risk?
The short version: mRNA COVID vaccines cause myocarditis at rates far above both baseline and flu vaccine background, especially in young males.
The evidence is clear on the comparison. A 2021 VAERS analysis found the proportional reporting ratio for myocarditis comparing COVID vaccines to flu vaccines was 23.7 [14]. That means myocarditis was reported nearly 24 times more often after COVID shots than after flu shots in the same surveillance system. The same analysis gave a composite causality score of 9.76 out of 10 for a causal link between COVID vaccines and myocarditis [14].
The absolute numbers tell the same story. For young males 12-17 years old after the second dose, the rate was 66 cases per million doses for Pfizer and up to 236 per million for Moderna [19, 20]. For flu vaccines, the background rate of myocarditis in the general population is 1-10 per 100,000 people per year [1]. The COVID vaccine rate in young males after dose two is roughly 10 to 50 times higher than the annual background rate, concentrated into a few days after injection.
| Group | Myocarditis rate per million doses | Source |
|---|---|---|
| Flu vaccine (all ages, VAERS) | ~0.3 per million reports | [15] |
| COVID mRNA, males 12-17, dose 2 | 66-236 per million | [19, 20] |
| COVID mRNA, males 18-29, dose 2 | 31-35 per million | [19] |
| Baseline population (annual) | 10-100 per million per year | [1] |
The short-term course is usually mild, but over half of followed patients had persistent abnormalities at 3 months [2]. The long-term consequences are not known.
My call: the myocarditis risk from mRNA COVID vaccines is substantially higher than from flu vaccines, especially in young males. Confidence: high.
Sources used 21
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Myocarditis after COVID-19 mRNA vaccination: clinical observations and potential mechanisms
This study examines the incidence and implications of acute myocarditis associated with COVID-19 mRNA vaccination compared to myocarditis resulting from COVID-19 infection, highlighting the rarity of vaccine-related myocarditis and the greater risks associated with COVID-19 itse…
DOI: 10.1038/s41569-021-00662-w -
Incidence, risk factors, natural history, and hypothesised mechanisms of myocarditis and pericarditis following covid-19 vaccination: living evidence syntheses and review
This living systematic review found that myocarditis after mRNA COVID-19 vaccination occurs most frequently in male adolescents and young adults, with moderate-certainty evidence that Moderna is associated with higher incidence than Pfizer in 18-29 year olds and low-certainty ev…
DOI: 10.1136/bmj-2021-069445 -
Disentangling a Thorny Issue: Myocarditis and Pericarditis Post COVID-19 and Following mRNA COVID-19 Vaccines
This pharmacovigilance study analyzes the incidence of myocarditis and pericarditis reported in the Vaccine Adverse Events Reporting System (VAERS) following mRNA COVID-19 vaccinations, revealing a higher incidence in young males after the second dose, but a lower risk compared …
DOI: 10.3390/ph15050525 -
Myocarditis and Pericarditis following COVID-19 Vaccination in Thailand
This study investigates the incidence and characteristics of myocarditis and pericarditis following COVID-19 vaccination in Thailand, revealing a higher incidence among male adolescents, particularly after mRNA vaccinations, while emphasizing the overall mild nature of these adv…
DOI: 10.3390/vaccines11040749 -
The incidence and clinical characteristics of myocarditis and pericarditis following mRNA-based COVID-19 vaccination in Republic of Korea adolescents from July 2021 to September 2022
This study investigates the incidence and clinical characteristics of myocarditis and pericarditis in adolescents aged 12 to 19 years in the Republic of Korea following mRNA-based COVID-19 vaccination from July 2021 to September 2022, finding that while these conditions are rare…
DOI: 10.24171/j.phrp.2023.0032 -
Myocarditis and Pericarditis following COVID-19 Vaccination: Inequalities in Age and Vaccine Types
This study investigates the incidence and risk of myocarditis and pericarditis following COVID-19 vaccination in the U.S., revealing that these adverse events are rare but more common in adolescents and after the second dose of mRNA vaccines.
DOI: 10.3390/jpm11111106 -
Incidence, Clinical Presentation, and Management of Myocarditis following mRNA-Based Covid-19 Vaccines: A Brief Report
Myocarditis after mRNA Covid-19 vaccines is rare, most common in younger men after the second dose, usually mild and self-limiting, with the benefit of vaccination outweighing the risk.
DOI: 10.1159/000522216 -
COVID-19 Vaccine–Related Myocardial and Pericardial Inflammation
This study reviews the incidence, mechanisms, and management strategies for myocarditis and pericarditis following COVID-19 vaccinations, highlighting the importance of recognizing these conditions in young males post-vaccination.
DOI: 10.1007/s11886-022-01801-6 -
Clinical Manifestations and Adverse Cardiovascular Events in Patients with Cardiovascular Symptoms after mRNA Coronavirus Disease 2019 Vaccines
This study investigates the incidence and clinical characteristics of vaccine-related adverse events, specifically myocarditis and pericarditis, in patients presenting with cardiovascular symptoms after receiving mRNA COVID-19 vaccines.
DOI: 10.3349/ymj.2023.0354 -
Myopericarditis in a Male Adolescent Following the Second Shot of COVID-19 Pfizer m-RNA Vaccine: Typical Example and Analysis of 110 Single Case Reports
This study presents a detailed case report of myopericarditis in a 16-year-old male following the second dose of the COVID-19 Pfizer mRNA vaccine, alongside an analysis of 110 single case reports that confirm a higher incidence of myocarditis in males post-vaccination, particula…
DOI: 10.3390/pediatric14040048 -
Assessing the incidence of myocarditis risk in mRNA COVID-19 vaccines: a systematic review and meta-analysis
A systematic review and meta-analysis comparing myocarditis risk after Moderna (mRNA-1273) versus Pfizer-BNT162b2 vaccines across doses and populations, finding a non-significant trend toward higher risk with Moderna and myocarditis to be overall uncommon.
DOI: 10.61505/evidence.2024.2.1.27 -
COVID-19 Vaccination-Related Myocarditis: What We Learned From Our Experience and What We Need to Do in The Future
This review examines the incidence, risk factors, clinical presentation, pathogenesis, management strategies, and outcomes of vaccine-related myocarditis (VRM) associated with COVID-19 mRNA vaccines, highlighting the need for continued surveillance and research to mitigate risks…
DOI: 10.4070/kcj.2024.0065 -
Diagnosis of Acute Myocarditis Following mRNA Vaccines against SARS-CoV-2: A Methodological Review
This methodological review investigates the incidence and diagnostic challenges of acute myocarditis following mRNA vaccination against SARS-CoV-2, highlighting clinical cases and literature findings.
DOI: 10.3390/v15040929 -
Minimizing Signal Loss and Optimizing Pharmacovigilance in VAERS
VAERS requires fundamental upgrades to support disproportionality analyses, causality assessments, and incidence calculations, which can be achieved through data cleaning, automated AI tools, and higher-granularity variables.
DOI: 10.71189/jim/2026/v02n02a06 -
Influenza Vaccination and Myo-Pericarditis in Patients Receiving Immune Checkpoint Inhibitors: Investigating the Likelihood of Interaction through the Vaccine Adverse Event Reporting System and VigiBase
This pharmacovigilance analysis of the VAERS and VigiBase spontaneous reporting databases found only 3 cases of myocarditis reporting concomitant influenza vaccine and immune checkpoint inhibitor use (out of 590 total myopericarditis reports with influenza vaccine as suspect), a…
DOI: 10.3390/vaccines9010019 -
Fulminant Myocarditis 24 Days after Coronavirus Disease Messenger Ribonucleic Acid Vaccination
This case report describes a 60-year-old Japanese woman who developed fulminant myocarditis 24 days after receiving the second dose of the BNT162b2 COVID-19 mRNA vaccine, highlighting the potential immune response related to the vaccine as evidenced by histological findings.
DOI: 10.2169/internalmedicine.9800-22 -
Self-DNA driven inflammation in COVID-19 and after mRNA-based vaccination: lessons for non-COVID-19 pathologies
This narrative review proposes that self-DNA-driven inflammation contributes to severe COVID-19 and some mRNA vaccine adverse events, drawing parallels with HIV-1, trauma, and autoimmune diseases.
DOI: 10.3389/fimmu.2023.1259879 -
Mecanismo y diseño de vacunas para el sars-cov-2, revisión narrativa
This narrative review describes SARS-CoV-2 vaccine mechanisms and designs, reporting that mRNA vaccines (BNT162b2 and mRNA-1273) demonstrate the highest efficacy (93-95%), adenovirus vector vaccines show 66.9-91.6% efficacy, and inactivated CoronaVac shows 83.5%, with rare safet…
DOI: 10.18566/medupb.v43n1.a10 -
Risk of Myocarditis and Pericarditis among Young Adults following mRNA COVID-19 Vaccinations
This study investigates the increased risk of myocarditis and pericarditis among young adults following mRNA COVID-19 vaccinations, revealing a higher-than-expected reporting rate, particularly in males aged 12-17 after the second dose.
DOI: 10.3390/vaccines10050722 -
Risk of Coronavirus Disease 2019 Messenger RNA Vaccination-Associated Myocarditis and Pericarditis – A Systematic Review of Population-Based Data
This systematic review analyzes population-based data to assess the risk of myocarditis and pericarditis associated with mRNA COVID-19 vaccination, highlighting significant variations in reported rates across different studies and populations.
DOI: 10.2147/RMHP.S422372 -
SG-APSIC1035: Prospective safety surveillance study of ACAM2000 smallpox vaccine in deployed military personnel
A prospective safety surveillance study of the ACAM2000 smallpox vaccine in deployed US military personnel found a modest, non-significant increase in myopericarditis risk with most cases being subclinical, based on a large dual-cohort observational design and adjudicated outcom…
DOI: 10.1017/ash.2023.31