--- title: "The two LARGEST COVID \"vaccine\" safety studies EVER done (n=184 MILLION) confirm…" source: "https://x.com/nichulscher/status/2089699223776231681" platform: "X / Twitter" factual_accuracy: 18 overall_accuracy: 5 tags: ["vaccine safety", "covid-19 vaccine", "misinformation", "public health", "adverse events", "vaccine risk data"] --- # Source fact-check: The two LARGEST COVID "vaccine" safety studies EVER done (n=184 MILLION) confirm… Original post: https://x.com/nichulscher/status/2089699223776231681 Factual accuracy: 18% · Overall accuracy: 5% ## Source post **Target post by @nichulscher** > The two LARGEST COVID "vaccine" safety studies EVER done (n=184 MILLION) confirm they are NOT SAFE FOR HUMAN USE: > > 📈 Heart Attack: +286% (dose 2) > 📈 Stroke: +240% (dose 1) > 📈 Brain Clots: +223% (dose 1) > 📈 Brain Inflammation: +278% (dose 1) > 📈 Myocarditis: +510% (dose 2) > 📈 Coronary Artery Disease: +244% (dose 2) > 📈 Cardiac Arrhythmia: +199% (dose 1) > 📈 Guillain-Barré Syndrome: +149% (dose 1) > [attached video 0](https://video.twimg.com/amplify_video/2089699122261393408/vid/avc1/2160x2160/W2cc6gnKkmP95bcS.mp4?tag=29) > > Video transcript: two largest Covid vaccine safety studies ever conducted. The first one's by Fuksova and colleagues. Um this had 99 million people in it. They found 500% increase risks of myocarditis, 300% increased risk of spinal cord inflammation, which can be permanently disabling. Um it can cause paralysis. And then we have the second largest vaccine safety study ever conducted, which was published a few weeks ago that had 85 million people in it, and had a control group. So it's about 40 million vaccinated, 40 million weren't. It was a meta analysis. They found 300% increased risk of heart attack. They found 200% increased risk of arrhythmias. They found about 250% increased risk of stroke. And so so now we have the largest population sizes ever studied that were vaccinated, and we find these massive risks. ## Post analysis Verdict: 5% · Model: Kimi K2.6 · Checked on: 18/08/2026 The post accurately notes that the two cited studies are among the largest COVID-19 vaccine safety analyses conducted, together covering roughly 184 million participants[^1][^2]. Beyond that framing, however, the post is a severe misrepresentation. The studies’ authors explicitly concluded that no overall increased risk of heart attack, arrhythmia, or stroke was observed after vaccination, and that benefits far outweigh risks[^3][^4][^5][^6]. The post instead cherry-picks isolated, often contradictory subgroup findings from a single meta-analysis and presents them as the studies’ main conclusions[^6][^4][^3]. For instance, the 286% heart-attack and 244% coronary-artery-disease figures are second-dose subgroup odds ratios from a meta-analysis that overall found no increased heart-attack risk and even a protective effect after the third dose; that paper also contains overlapping outcome definitions and implausible results[^4][^7][^8]. The 240% stroke and 199% arrhythmia claims are first-dose subgroup findings that the same study’s abstract explicitly refutes by stating no significant stroke or arrhythmia risk was detected[^6][^9][^10]. The 223% brain-clot signal applies only to the AstraZeneca (ChAdOx1) first dose, not to COVID-19 vaccines generally, and the absolute risk was extremely rare[^11]. The 278% brain-inflammation figure refers to acute disseminated encephalomyelitis after the first Moderna dose, was not replicated in follow-up analyses, and represents roughly one case per 1.75 million doses[^12]. The 510% myocarditis value is an observed-to-expected ratio for the Moderna second dose only, but the post omits the absolute rarity of the event and implies it applies to all vaccines[^13]. The 500% myocarditis and 300% spinal-cord-inflammation claims attributed to the 99-million-person Faksova study are fabricated or misattributed; that study did not report a 500% myocarditis increase and found no increased risk of transverse myelitis[^14][^5]. Finally, the 149% Guillain-Barré syndrome signal occurred only after the first dose of the AstraZeneca vaccine in the 99-million cohort, not across all COVID-19 vaccines, and the separate 85-million meta-analysis did not examine GBS at all[^15]. Because the post relies almost entirely on cherry-picked, out-of-context, or misrepresented data to support a sweeping conclusion that the studies themselves reject, its overall validity is extremely low. **Overall validity**: 5% [^1]: [The study by Fuksova and colleagues (99 million participants) and the meta‑analysis of 85 million participants are the largest COVID‑19 vaccine safety studies ever conducted.](#O5gcIf0mCtVdiJ8My9be) [^2]: [The two cited COVID‑19 vaccine safety studies together included a total of 184 million participants.](#nQgrLAIGrKxHBhnm44Gc) [^3]: [The meta‑analysis of a COVID‑19 vaccine safety study that included about 85 million participants reported a 200% increase in the risk of cardiac arrhythmias among vaccinated individuals compared to unvaccinated controls.](#CWXl72gOwpRxIBbwxCFn) [^4]: [A COVID‑19 vaccine safety meta‑analysis of 85 million participants (approximately 40 million vaccinated and 40 million unvaccinated) reported a 300% increased risk of heart attack among the vaccinated.](#bZG86VLug2qUz9zWOt4F) [^5]: [The study by Fuksova and colleagues, which included 99 million participants, reported a 300% increase in risk of spinal cord inflammation associated with COVID‑19 vaccination.](#PG2OjPhukvPMSn8Qg3pf) [^6]: [The meta‑analysis of approximately 85 million people (about 40 million COVID‑19 vaccine recipients and 40 million unvaccinated controls) reported a 250 % increase in risk of stroke among the vaccinated group.](#phgofmAOJWxOIESzx1mT) [^7]: [The risk of heart attack increased by 286% after the second COVID-19 vaccine dose.](#OH81EFX74bIDcBuB64Q8) [^8]: [The risk of coronary artery disease increased by 244% after the second COVID vaccine dose.](#ZNfT44o2v7iv4ENj0N8m) [^9]: [The risk of cardiac arrhythmia increased by 199% after the first COVID‑19 vaccine dose.](#cN3QMVEfc4kRT9Wck5RJ) [^10]: [The risk of stroke increased by 240% after the first dose of a COVID‑19 vaccine.](#Uds4gUrvjrz7P0JtVlLe) [^11]: [The risk of brain clots increased by 223% after the first dose of a COVID‑19 vaccine.](#MdINity2E8e270Osu5Xd) [^12]: [The risk of brain inflammation increased by 278% after the first dose of a COVID‑19 vaccine.](#aBkgFnrcny23qzUSxICW) [^13]: [The risk of myocarditis increased by 510% after the second COVID‑19 vaccine dose.](#REkC5nA9bG5HXxOYl6Mo) [^14]: [A COVID‑19 vaccine safety study conducted by Fuksova and colleagues with 99 million participants reported a 500% increase in the risk of myocarditis.](#BLl5amR6m1ELrIRCjRNi) [^15]: [The risk of Guillain‑Barré syndrome increased by 149% after the first dose of a COVID‑19 vaccine in the two largest COVID vaccine safety studies involving 184 million people.](#U4mEPe53fw0zFe1VLbWs) ## Claims found (15) ### 1. The meta‑analysis of a COVID‑19 vaccine safety study that included about 85 million participants reported a 200% increase in the risk of cardiac arrhythmias among vaccinated individuals compared to unvaccinated controls. — 10% Model: Kimi K2.6 · Checked on: 18/08/2026 · Detail: /claim/CWXl72gOwpRxIBbwxCFn - The claim appears to reference a March 2025 systematic review and Bayesian meta‑analysis by Karimi et al. in the *International Journal of Preventive Medicine*, which included 15 studies covering roughly 85 million people (about 46 million vaccinated and 40 million unvaccinated or inactive‑vaccine controls)[^1][^2]. - The paper’s primary Bayesian analysis explicitly concluded: “No increased risk of heart attack, arrhythmia, or stroke was observed post‑COVID‑19 vaccination”[^3][^4]. - A subgroup analysis by dose (irrespective of vaccine type) did find a first‑dose association with arrhythmia (OR 2.98, 95% CrI 1.41–6.32), which is roughly a 200% increase in odds[^1]. This was a secondary, dose‑specific finding, not the study’s main conclusion. - The social media post cherry‑picks this subgroup result and presents it as the meta‑analysis’s overall finding, while ignoring the authors’ primary conclusion of no overall increased arrhythmia risk[^2]. - Because the claim strips essential context and misrepresents the study’s principal conclusion, it is highly misleading. **Overall validity**: 10% [^1]: [COVID-19 Vaccination and Cardiovascular Events - PMC - NIH](https://pmc.ncbi.nlm.nih.gov/articles/PMC11970839) [^2]: [Increased Risk of Heart Attack, Stroke, and Arrhythmia Following COVID Shots](https://www.parkallergy.com/increased-risk-of-heart-attack-stroke-and-arrhythmia-following-covid-shots) [^3]: [COVID-19 Vaccination and Cardiovascular Events](https://pubmed.ncbi.nlm.nih.gov/40191438) [^4]: [COVID-19 Vaccination and Cardiovascular Events: A... : International Journal of Preventive Medicine](https://journals.lww.com/ijom/fulltext/2025/03210/covid_19_vaccination_and_cardiovascular_events__a.6.aspx) ### 2. The study by Fuksova and colleagues, which included 99 million participants, reported a 300% increase in risk of spinal cord inflammation associated with COVID‑19 vaccination. — 0% Model: Kimi K2.6 · Checked on: 18/08/2026 · Detail: /claim/PG2OjPhukvPMSn8Qg3pf - The study is real, but the lead author is **Kristýna Faksova** (not “Fuksova”), and the cohort included roughly 99 million vaccinated individuals across eight countries[^1]. - The study did **not** report a 300 % increase in the risk of spinal cord inflammation (transverse myelitis). For transverse myelitis, the observed-to-expected ratios were **0.74** for the Pfizer/BioNTech vaccine and **1.5** for the Moderna vaccine; the authors concluded there was **no increased risk** of transverse myelitis[^2]. - For acute disseminated encephalomyelitis (ADEM), which involves inflammation of the brain and spinal cord, the study observed **7 cases versus 2 expected** after the first Moderna dose. That signal corresponds to a roughly **250 % increase** (not 300 %), and the authors calculated the absolute risk as **1 case per 1.75 million doses** if causal[^3]. - A separate Australian study (6.7 million people, not the 99‑million Faksova study) later reported an ADEM relative incidence of 3.74 with the AstraZeneca vaccine, but these findings were not part of the 99‑million cohort analysis[^4]. - The claim misattributes findings, overstates the magnitude of any signal, and ignores the study’s conclusion that benefits of vaccination vastly outweigh the risks, and that COVID‑19 infection itself carries a higher risk of these rare neurological events[^4]. **Overall validity**: 0% [^1]: [COVID-19 vaccines and adverse events of special interest](https://researchprofiles.ku.dk/en/publications/covid-19-vaccines-and-adverse-events-of-special-interest-a-multin) [^2]: [Causal Association on the Development of Transverse ...](https://www.worksafebc.com/resources/health-care-providers/guides/causal-association-development-transverse-myelitis-post-mrna-covid-19-vaccination?lang=en&direct=) [^3]: [Study Largely Confirms Known, Rare COVID-19 Vaccine Side Effects](https://www.factcheck.org/2024/02/study-largely-confirms-known-rare-covid-19-vaccine-side-effects) [^4]: [Two rare vaccine side effects detected in large global study](https://www.bmj.com/content/384/bmj.q488) ### 3. A COVID‑19 vaccine safety meta‑analysis of 85 million participants (approximately 40 million vaccinated and 40 million unvaccinated) reported a 300% increased risk of heart attack among the vaccinated. — 5% Model: Kimi K2.6 · Checked on: 18/08/2026 · Detail: /claim/bZG86VLug2qUz9zWOt4F - The meta-analysis referenced is Karimi et al. (2025) in *International Journal of Preventive Medicine*. It included roughly 77.6 million participants in the primary analysis (\~37.7 million first‑dose recipients and \~39.9 million unvaccinated or inactive‑vaccine controls), which is close to the “≈85 million” figure cited in the claim[^1]. - However, the study’s **overall** (primary analysis) result for myocardial infarction (heart attack) was an odds ratio of 0.76 (95% CrI 0.51–1.14), showing **no significant increase** in heart‑attack risk among vaccinated people overall[^2]. The authors explicitly state in their abstract and conclusion: “No increased risk of heart attack, arrhythmia, or stroke was observed post‑COVID‑19 vaccination”[^2]. - The ≈300 % figure appears to be a rounded version of a **subgroup** finding for the **second dose** (OR 3.86, 95% CrI 2.28–6.60), which translates to a 286 % increased odds relative to unvaccinated, but only for that specific subgroup and not for the vaccinated population as a whole[^2]. - The claim therefore cherry‑picks a subgroup result and presents it as the overall conclusion of the meta‑analysis, which is a misrepresentation. **Overall validity: 5%** [^1]: [COVID-19 Vaccination and Cardiovascular Events: A Systematic Review and Bayesian Multivariate Meta-Analysis of Preventive Benefits and Risks](https://www.ovid.com/jnls/ijom/fulltext/10.4103/ijpvm.ijpvm_260_24~covid-19-vaccination-and-cardiovascular-events-a-systematic) [^2]: [COVID-19 Vaccination and Cardiovascular Events - PMC - NIH](https://pmc.ncbi.nlm.nih.gov/articles/PMC11970839) ### 4. The two cited COVID‑19 vaccine safety studies together included a total of 184 million participants. — 95% Model: Kimi K2.6 · Checked on: 18/08/2026 · Detail: /claim/nQgrLAIGrKxHBhnm44Gc - The claim matches social-media posts that cite two specific studies as “the two LARGEST COVID‑19 vaccine safety studies” and sum their participant counts to 184 million[^1]. - The first study, Faksova et al. (2024), is a multinational Global Vaccine Data Network cohort that included **99,068,901** vaccinated individuals[^2][^3]. - The second study, Karimi et al. (2025), is a systematic review and meta-analysis whose primary analysis of 11 controlled studies included roughly **85.9 million** people (about 46 million vaccinated and 40 million unvaccinated/control)[^4][^5]. - Adding the two reported participant totals gives approximately **185 million**; the commonly cited rounded figures (99 million + 85 million) equal **184 million**, so the claim is a reasonable rounded estimate[^1]. - Caveats: Karimi et al. is a meta-analysis of multiple separate cohorts rather than one unified cohort, and there may be slight geographic overlap between the two studies, but the participant totals cited for each individual study are accurate. **Overall validity**: 95% [^1]: [The two LARGEST COVID-19 “vaccine” safety studies EVER done ...](https://www.instagram.com/reel/DcLsnxQxkNQ) [^2]: [COVID-19 vaccines and adverse events of special interest](https://pubmed.ncbi.nlm.nih.gov/38350768) [^3]: [99 Million People Included in Largest Global Vaccine ...](https://brightoncollaboration.org/press-release-gvdn-largest-global-vaccine-safety-study) [^4]: [Increased Risk of Heart Attack, Stroke, and Arrhythmia Following COVID Shots](https://www.parkallergy.com/increased-risk-of-heart-attack-stroke-and-arrhythmia-following-covid-shots) [^5]: [COVID-19 Vaccination and Cardiovascular Events - PMC - NIH](https://pmc.ncbi.nlm.nih.gov/articles/PMC11970839) ### 5. The meta‑analysis of approximately 85 million people (about 40 million COVID‑19 vaccine recipients and 40 million unvaccinated controls) reported a 250 % increase in risk of stroke among the vaccinated group. — 0% Model: Kimi K2.6 · Checked on: 18/08/2026 · Detail: /claim/phgofmAOJWxOIESzx1mT - A meta-analysis by Karimi et al. (2025) in *International Journal of Preventive Medicine* did review roughly 85 million people, but it included about **45 million vaccinated** and 40 million unvaccinated participants—not “about 40 million” in each group[^1]. - The study’s **overall conclusion** was that **no increased risk of stroke** was observed post-COVID-19 vaccination[^1]. - In **subgroup analyses by dose and vaccine type**, the authors reported increased stroke odds after the **first dose only** (OR 3.40, a 240% increase for all vaccines; OR 3.69, a 269% increase for the Pfizer first-dose subgroup)[^1][^2]. - The claim incorrectly presents these **first-dose subgroup findings** as the overall result for “the vaccinated group” generally, and the 250% figure does not match any reported overall estimate. - The same study actually found a **protective effect** against stroke after the third dose (OR 0.20), and other large-scale meta-analyses have found vaccination is associated with a **reduced** risk of ischemic stroke or no significant increase[^3][^4]. **Overall validity**: 0% [^1]: [COVID-19 Vaccination and Cardiovascular Events: A Systematic Review and Bayesian Multivariate Meta-Analysis of Preventive Benefits and Risks](https://pmc.ncbi.nlm.nih.gov/articles/PMC11970839) [^2]: [Increased Risk of Heart Attack, Stroke, and Arrhythmia Following COVID Shots - Park Allergy Center](https://www.parkallergy.com/increased-risk-of-heart-attack-stroke-and-arrhythmia-following-covid-shots) [^3]: [COVID-19 vaccination and the risk of cardiovascular and thromboembolic events after SARS-CoV-2 infection: a systematic review and meta-analysis | medRxiv](https://www.medrxiv.org/content/10.64898/2026.05.21.26353568v1.full-text) [^4]: [Ischemic Stroke After Bivalent COVID-19 Vaccination](https://publichealth.jmir.org/2024/1/e53807) ### 6. The study by Fuksova and colleagues (99 million participants) and the meta‑analysis of 85 million participants are the largest COVID‑19 vaccine safety studies ever conducted. — 95% Model: Kimi K2.6 · Checked on: 18/08/2026 · Detail: /claim/O5gcIf0mCtVdiJ8My9be - The Faksova et al. GVDN cohort study (published Feb 2024) included **99,068,901 vaccinated individuals** across 10 collaborator sites in 8 countries[^1]. It is explicitly described by multiple authoritative sources as the largest vaccine safety study to date or the largest of its kind[^2][^3][^4]. - The Karimi et al. systematic review and Bayesian multivariate meta-analysis (published March 2025) included 15 studies, with 11 controlled studies in the primary analysis comprising approximately **86 million participants total** (\~46 million vaccinated and \~40 million unvaccinated/control)[^5]. - The next-largest formal COVID-19 vaccine safety studies and meta-analyses identified are substantially smaller (e.g., a long-term safety study of \~28 million adults[^6] and a meta-analysis of \~3.4 million older adults[^7]). - No larger formal COVID-19 vaccine safety study or meta-analysis was found in the search. The name “Fuksova” in the claim is a minor misspelling of “Faksova,” and the meta-analysis total rounds to \~86 million rather than exactly 85 million, but these are minor discrepancies that do not alter the core claim. **Overall validity**: 95% [^1]: [COVID-19 vaccines and adverse events of special interest](https://pubmed.ncbi.nlm.nih.gov/38350768) [^2]: [Two very rare Covid vaccine side-effects detected in global study ...](https://www.theguardian.com/australia-news/2024/feb/23/two-very-rare-covid-vaccine-side-effects-detected-in-global-study-of-99-million) [^3]: [Big data detects COVID-19 vaccine safety signals](https://www.mcri.edu.au/news/news-stories/big-data-detects-covid-19-vaccine-safety-signals) [^4]: [99 Million People Included in Largest Global Vaccine ...](https://brightoncollaboration.org/press-release-gvdn-largest-global-vaccine-safety-study) [^5]: [COVID-19 Vaccination and Cardiovascular Events - PMC - NIH](https://pmc.ncbi.nlm.nih.gov/articles/PMC11970839) [^6]: [Massive four-year study finds no increase in deaths linked ...](https://www.gavi.org/vaccineswork/massive-four-year-study-finds-no-increase-deaths-linked-covid-19-mrna-vaccination) [^7]: [A systematic review and meta-analysis of the effectiveness ...](https://pmc.ncbi.nlm.nih.gov/articles/PMC10020204) ### 7. A COVID‑19 vaccine safety study conducted by Fuksova and colleagues with 99 million participants reported a 500% increase in the risk of myocarditis. — 0% Model: Kimi K2.6 · Checked on: 18/08/2026 · Detail: /claim/BLl5amR6m1ELrIRCjRNi - The study exists and was led by **Faksova** (not “Fuksova”), Kristýna Faksová, published in *Vaccine* in 2024. It included 99,068,901 vaccinated individuals across eight countries[^1][^2]. - The study did find that myocarditis and pericarditis risks were significantly increased after mRNA COVID-19 vaccines, but it described these as confirming **pre-established safety signals** for rare adverse events, not as a new or alarming 500% increase[^1][^2][^3]. - The specific observed-to-expected (OE) ratios reported in study summaries for other conditions were 2.49 for Guillain-Barré syndrome, 3.23 for cerebral venous sinus thrombosis, and 3.78 for acute disseminated encephalomyelitis. For myocarditis, summaries only state the OE ratios were significantly increased with lower 95% confidence-interval bounds \> 1.5; none of the available abstracts or press releases cite a 500% (OE ratio \~6.0) increase for myocarditis[^1][^3][^2]. - FactCheck.org reviewed this exact study and found that social-media posts misrepresented it by exaggerating risks and omitting information about the **rarity** of the side effects and the benefits of vaccination[^4]. - USA Today rated a similar claim that COVID-19 vaccines raise heart-attack risk by 500% as **False**, finding no credible study supporting that figure[^5]. **Overall validity**: 0% [^1]: [COVID-19 vaccines and adverse events of special interest: A multinational Global Vaccine Data Network (GVDN) cohort study of 99 million vaccinated individuals](https://www.sciencedirect.com/science/article/pii/S0264410X24001270) [^2]: [COVID-19 vaccines and adverse events of special interest: A multinational Global Vaccine Data Network (GVDN) cohort study of 99 million vaccinated individuals - PubMed](https://pubmed.ncbi.nlm.nih.gov/38350768) [^3]: [99 Million People Included in Largest Global Vaccine ...](https://brightoncollaboration.org/press-release-gvdn-largest-global-vaccine-safety-study) [^4]: [Study Largely Confirms Known, Rare COVID-19 Vaccine Side Effects](https://www.factcheck.org/2024/02/study-largely-confirms-known-rare-covid-19-vaccine-side-effects) [^5]: [No studies show COVID-19 vaccine skyrockets heart risk | Fact check](https://www.usatoday.com/story/news/factcheck/2024/12/06/covid-19-vaccine-heart-attack-risk-fact-check/76771143007) ### 8. The risk of heart attack increased by 286% after the second COVID-19 vaccine dose. — 5% Model: Kimi K2.6 · Checked on: 18/08/2026 · Detail: /claim/OH81EFX74bIDcBuB64Q8 - The 286 % figure appears to come from a single 2025 Bayesian meta-analysis (Karimi et al., *International Journal of Preventive Medicine*), which reported an odds ratio of 3.86 for myocardial infarction after the second vaccine dose in a subgroup analysis[^1]. - That same paper’s overall analysis concluded that **no** significant increase in heart attack risk was observed post‑vaccination, and the abstract notes a “protective effect” on myocardial infarction after the third dose; the article contains contradictory statements[^1]. - This finding is directly refuted by a UK cohort study of **45.7 million adults**, which found second doses were associated with a **lower** risk of arterial thrombotic events (including heart attacks), with adjusted hazard ratios of 0.73 (AstraZeneca) and 0.80 (Pfizer)—a 20–27 % reduction, not an increase[^2]. - Other research confirms that COVID‑19 infection itself poses a substantially higher heart‑attack risk than vaccination[^3]. - The claim cherry‑picks a single, inconsistent subgroup result from a low‑citation meta‑analysis and presents it as a general fact, while ignoring far larger, high‑quality studies that show the opposite effect. **Overall validity**: 5% [^1]: [COVID-19 Vaccination and Cardiovascular Events - PMC - NIH](https://pmc.ncbi.nlm.nih.gov/articles/PMC11970839) [^2]: [Risk of heart attack, stroke drops after COVID vaccination ...](https://www.cidrap.umn.edu/covid-19/risk-heart-attack-stroke-drops-after-covid-vaccination-data-show) [^3]: [COVID-19 Infection Linked to Higher Heart Attack Risk Than Vaccination, New Study Finds](https://www.pharmacytimes.com/view/covid-19-infection-linked-to-higher-heart-attack-risk-than-vaccination-new-study-finds) ### 9. The risk of stroke increased by 240% after the first dose of a COVID‑19 vaccine. — 0% Model: Kimi K2.6 · Checked on: 18/08/2026 · Detail: /claim/Uds4gUrvjrz7P0JtVlLe - The claim that stroke risk increased by 240% after a first COVID-19 vaccine dose appears to stem from a single 2025 meta-analysis (Karimi et al., *Int J Prev Med*) that is deeply problematic: it reports an impossible confidence interval for that finding (1.98–1.98), contradicts itself by also stating “no significant relationship was detected between vaccination and stroke,” and its PubMed abstract explicitly says “No increased risk of heart attack, arrhythmia, or stroke was observed post-COVID-19 vaccination”[^1][^2][^3]. - Anti-vaccine blogs have cherry-picked the subgroup odds ratio (OR 3.40) from that flawed paper while ignoring its overall conclusion, presenting the 240% increase as established fact[^4]. - Large, high-quality population studies contradict the figure. A self-controlled case series of more than 32 million people in the UK found only a small, specific increase in hemorrhagic stroke after BNT162b2 (IRR 1.38, i.e., \~38% higher, not 240%) and no association with ChAdOx1[^5]. - An NCBI Bookshelf evidence review of multiple large cohorts (including \>9.5 million people in England) found no significantly increased risk of ischemic stroke after first-dose mRNA or Ad26.COV2.S vaccines[^6]. - A separate 2025 systematic review and meta-analysis found a pooled risk ratio for stroke of 1.13 (95% CI: 0.87–1.47), indicating no statistically significant association[^7]. **Overall validity**: 0% [^1]: [COVID-19 Vaccination and Cardiovascular Events: A... : International Journal of Preventive Medicine](https://journals.lww.com/ijom/_layouts/15/oaks.journals/downloadpdf.aspx?an=01439446-202503210-00006) [^2]: [COVID-19 Vaccination and Cardiovascular Events: A Systematic Review and Bayesian Multivariate Meta-Analysis of Preventive Benefits and Risks - PubMed](https://pubmed.ncbi.nlm.nih.gov/40191438) [^3]: [COVID-19 Vaccination and Cardiovascular Events - PMC - NIH](https://pmc.ncbi.nlm.nih.gov/articles/PMC11970839) [^4]: [Increased Risk of Heart Attack, Stroke, and Arrhythmia Following COVID Shots](https://www.parkallergy.com/increased-risk-of-heart-attack-stroke-and-arrhythmia-following-covid-shots) [^5]: [Neurological complications after first dose of COVID-19 vaccines and SARS-CoV-2 infection](https://doi.org/10.1038/s41591-021-01556-7) [^6]: [Vascular Conditions and COVID-19 Vaccines: Myocardial Infarction, Stroke, Pulmonary Embolism, Deep Vein Thrombosis, and Venous Thromboembolism - Evidence Review of the Adverse Effects of COVID-19 Vaccination and Intramuscular Vaccine Administration - NCBI Bookshelf](https://www.ncbi.nlm.nih.gov/books/NBK607380) [^7]: [COVID-19 vaccination and stroke risk: A systematic review ...](https://www.sciencedirect.com/science/article/pii/S1876034125003703) ### 10. The risk of brain clots increased by 223% after the first dose of a COVID‑19 vaccine. — 10% Model: Kimi K2.6 · Checked on: 18/08/2026 · Detail: /claim/MdINity2E8e270Osu5Xd - The 223 % figure appears to originate from a large 2024 Global Vaccine Data Network (GVDN) study of 99 million people, which reported an **observed‑to‑expected (O/E) ratio of 3.23** for cerebral venous sinus thrombosis (CVST) after the **first dose of the ChAdOx1 (AstraZeneca) viral‑vector vaccine**—not after “a COVID‑19 vaccine” generally[^1][^2][^3]. - The same study found **no comparable safety signal for CVST after mRNA vaccines** (Pfizer or Moderna), and the absolute risk was extremely rare: **69 events observed versus 21 expected across roughly 23 million ChAdOx1 doses**[^3]. - Multiple large independent analyses confirm that the risk of brain clots is **far higher after COVID‑19 infection than after vaccination** (about 8–10 times higher than after the AstraZeneca vaccine and 28–32 times higher than after mRNA vaccines)[^4][^5]. - The claim generalizes a rare, vaccine‑specific finding to all COVID‑19 vaccines, mislabels an O/E ratio as a blanket individual risk increase, and omits the context that infection itself is a much greater clotting risk. **Overall validity**: 10% [^1]: [Evaluation of The Global COVID Vaccine Safety Project](https://www.contagionlive.com/view/evaluation-of-the-global-covid-vaccine-safety-project) [^2]: [COVID-19 vaccines and adverse events of special interest: A multinational Global Vaccine Data Network (GVDN) cohort study of 99 million vaccinated individuals](https://www.sciencedirect.com/science/article/pii/S0264410X24001270?amp%3Bfr=RR-2&%3Brr=914f31984c2d608f) [^3]: [\[PDF\] A multinational Global Vaccine Data Network (GVDN) cohort study of 99](https://downloads.regulations.gov/CDC-2026-0199-2422/attachment_13.pdf) [^4]: [Risk Of Brain Blood Clots 'Significantly Higher' After Covid ...](https://www.forbes.com/sites/roberthart/2022/03/18/risk-of-brain-blood-clots-significantly-higher-after-covid-infection-than-pfizer-moderna-shots-study-finds) [^5]: [Risk of rare blood clotting higher for COVID-19 than for vaccines](https://www.ox.ac.uk/news/2021-04-15-risk-rare-blood-clotting-higher-covid-19-vaccines) ### 11. The risk of brain inflammation increased by 278% after the first dose of a COVID‑19 vaccine. — 5% Model: Kimi K2.6 · Checked on: 18/08/2026 · Detail: /claim/aBkgFnrcny23qzUSxICW - The 278 % figure matches the observed-to-expected (O/E) ratio of 3.78 reported in the multinational Global Vaccine Data Network (GVDN) study for acute disseminated encephalomyelitis (ADEM) after the first dose of the Moderna (mRNA‑1273) vaccine—mathematically a 278 % increase over expected background cases[^1]. - The GVDN study itself treated this as a potential safety signal requiring further investigation, and follow-up analyses by the same network and other large observational studies in the UK, Australia, and the US did not replicate the finding[^2][^3]. - The signal is specific to ADEM (a rare inflammatory demyelinating condition of the brain and spinal cord) and to the Moderna vaccine; it does not apply to brain inflammation broadly or to other COVID‑19 vaccines such as Pfizer‑BioNTech or AstraZeneca[^4][^5]. - The absolute risk is extremely low: the estimated rate is roughly 1 case per 1.75 million first Moderna doses, and the vaccine‑attributable risk is about 0.39 per million doses[^6][^4]. - Other large population‑based studies found the overall incidence of encephalitis after COVID‑19 vaccination is approximately 1.9 per million doses, and one primary‑care cohort found a standardized incidence ratio of 0.79 (below the expected background rate) for encephalitis after the Pfizer‑BioNTech vaccine[^7]. - Because the claim overgeneralizes a rare, non‑replicated signal for one specific vaccine and condition to all COVID‑19 vaccines and “brain inflammation,” it is highly misleading and largely inaccurate. **Overall validity**: 5% [^1]: [COVID-19 vaccines and adverse events of special interest](https://www.sciencedirect.com/science/article/pii/S0264410X24001270) [^2]: [Despite Sensational Reports, COVID-19 Vaccine Safety Outweighs Risks - Health Policy Watch](https://healthpolicy-watch.news/despite-sensational-reports-covid-19-vaccine-safety-outweighs-risks) [^3]: [From discovery through emergency use to the present: Safety evaluation of the COVID-19 mRNA-1273 (Moderna) vaccine](https://pmc.ncbi.nlm.nih.gov/articles/PMC13108353) [^4]: \[The risk of acute disseminated encephalomyelitis (ADEM) following covid-19 vaccination in England: A self-controlled case-series analysis - UK Health Security Agency\](https://researchportal.ukhsa.gov.uk/en/publications/the-risk-of-acute-disseminated-encephalomyelitis-adem-following-c) [^5]: [Neurological complications after first dose of COVID-19 vaccines and SARS-CoV-2 infection | Nature Medicine](https://www.nature.com/articles/s41591-021-01556-7) [^6]: [Study Largely Confirms Known, Rare COVID-19 Vaccine Side Effects](https://www.factcheck.org/2024/02/study-largely-confirms-known-rare-covid-19-vaccine-side-effects) [^7]: [COVID‑19 vaccines increase the risk of autoimmune encephalitis by 79 times compared with flu shots](/claim/rXVaiJVVqHz7gZ2BbOYP) ### 12. The risk of myocarditis increased by 510% after the second COVID‑19 vaccine dose. — 40% Model: Kimi K2.6 · Checked on: 18/08/2026 · Detail: /claim/REkC5nA9bG5HXxOYl6Mo - The 510 % figure accurately reflects the observed-to-expected (OE) ratio of 6.10 (95 % CI: 5.52–6.72) for myocarditis reported in the Global Vaccine Data Network (GVDN) cohort study after a second dose of the Moderna (mRNA‑1273) vaccine[^1]. - The GVDN study explicitly identifies this as the highest OE ratio among the vaccines examined, meaning other COVID‑19 vaccines (e.g., Pfizer‑BioNTech BNT162b2) showed smaller increases[^1]. - The claim omits that the absolute risk remains very low; large studies estimate only about ten extra myocarditis events per million second doses of mRNA‑1273[^2]. - Because the claim presents a product‑specific statistic as a blanket statement about all COVID‑19 vaccines and omits the rarity of the event, it is misleading. **Overall validity**: 40% [^1]: [\[PDF\] A multinational Global Vaccine Data Network (GVDN) cohort study of 99](https://downloads.regulations.gov/CDC-2026-0199-2422/attachment_13.pdf) [^2]: [Risks of myocarditis, pericarditis, and cardiac arrhythmias associated with COVID-19 vaccination or SARS-CoV-2 infection | Nature Medicine](https://www.nature.com/articles/s41591-021-01630-0) ### 13. The risk of coronary artery disease increased by 244% after the second COVID vaccine dose. — 5% Model: Kimi K2.6 · Checked on: 18/08/2026 · Detail: /claim/ZNfT44o2v7iv4ENj0N8m - The 244% figure comes from a single meta-analysis (Karimi et al., 2025) published in the *International Journal of Preventive Medicine*, which reports an odds ratio (OR) of 3.44 for coronary artery disease (CAD) after the second vaccine dose[^1]. - However, this study has significant methodological problems: the CAD definition included acute myocardial infarction codes (I21, I22) that overlap with the study’s separate MI outcome, creating potential double-counting or misclassification[^1]. - The study’s results are internally inconsistent and biologically implausible, such as reporting a 99.7% risk reduction for myocardial infarction after the third dose (OR 0.003), which suggests model or data errors[^1]. - Most of the CAD data came from Asian studies comparing BNT162b2 to inactivated vaccines (e.g., Sinovac/CoronaVac), not to unvaccinated controls. An OR of 3.44 in that context reflects relative differences between vaccine types, not an absolute 244% increase in population risk from vaccination[^1]. - Large, high-quality studies contradict this finding. A 2021 *Nature Medicine* study of tens of millions of people found that COVID-19 infection itself carries far higher cardiovascular risk than vaccination, and identified no signal for CAD[^2]. A 2025 study in *Frontiers in Public Health* found vaccination was protective against coronary heart disease[^3]. - The American Heart Association has explicitly warned that misinformation incorrectly linking COVID-19 vaccines to heart defects is spreading[^4]. **Overall validity**: 5% [^1]: [COVID-19 Vaccination and Cardiovascular Events - PMC - NIH](https://pmc.ncbi.nlm.nih.gov/articles/PMC11970839) [^2]: [Risks of myocarditis, pericarditis, and cardiac arrhythmias associated with COVID-19 vaccination or SARS-CoV-2 infection](https://doi.org/10.1038/s41591-021-01630-0) [^3]: [Association between COVID-19 vaccination and coronary ...](https://www.frontiersin.org/journals/public-health/articles/10.3389/fpubh.2025.1641156/full) [^4]: [Beware: Myths incorrectly connecting COVID vaccine to heart defects may be spreading | American Heart Association](https://newsroom.heart.org/news/beware-myths-incorrectly-connecting-covid-vaccine-to-heart-defects-may-be-spreading) ### 14. The risk of cardiac arrhythmia increased by 199% after the first COVID‑19 vaccine dose. — 0% Model: Kimi K2.6 · Checked on: 18/08/2026 · Detail: /claim/cN3QMVEfc4kRT9Wck5RJ - The claim appears to trace to a single Bayesian meta-analysis that reported an odds ratio (OR) of 2.99 for arrhythmia after the first dose in a subgroup table[^1]. Anti-vaccine websites convert this OR into “199% increased risk”[^2]. - However, the **same study’s abstract and conclusion explicitly state** that “no increased risk of … arrhythmia was observed post-COVID-19 vaccination” and that “no significant relationship was detected between vaccination and … arrhythmia”[^1]. - Large, high-quality population-based studies directly contradict this subgroup finding. A **Nature Medicine** self-controlled case series of millions of people in England found a **decreased** risk of cardiac arrhythmia after the first dose of ChAdOx1 (IRR 0.94) and BNT162b2 (IRR 0.89), with an increased risk only after the second dose of mRNA-1273 (IRR 1.46)[^3]. - A subsequent England cohort study of 40.4 million adults found **no elevated incidence of cardiac arrhythmia** within 28 days of the first dose for any vaccine type or age group[^4]. - The “199% increased risk” framing epidemiologically misrepresents an odds ratio as a relative risk increase; ORs do not translate directly to percentage risk increases, especially for rare outcomes. - The claim is a **cherry-picked misinterpretation** of a single, limited meta-analysis that is contradicted by the study’s own authors and by much larger, robust epidemiological data. **Overall validity**: 0% [^1]: [COVID-19 Vaccination and Cardiovascular Events - PMC - NIH](https://pmc.ncbi.nlm.nih.gov/articles/PMC11970839) [^2]: [Increased Risk of Heart Attack, Stroke, and Arrhythmia Following COVID Shots](https://www.parkallergy.com/increased-risk-of-heart-attack-stroke-and-arrhythmia-following-covid-shots) [^3]: [Risks of myocarditis, pericarditis, and cardiac arrhythmias associated with COVID-19 vaccination or SARS-CoV-2 infection](https://doi.org/10.1038/s41591-021-01630-0) [^4]: [Risk of cardiac arrhythmia and cardiac arrest after primary and booster COVID-19 vaccination in England: A self-controlled case series analysis - PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC10714224) ### 15. The risk of Guillain‑Barré syndrome increased by 149% after the first dose of a COVID‑19 vaccine in the two largest COVID vaccine safety studies involving 184 million people. — 0% Model: Kimi K2.6 · Checked on: 18/08/2026 · Detail: /claim/U4mEPe53fw0zFe1VLbWs - The claim is based on a social-media distortion of the large multi-country Global Vaccine Data Network (GVDN) study by Faksova et al. (2024), which included **99 million vaccinated individuals**, not 184 million people, and analysed **183.5 million doses** of the Pfizer/BioNTech vaccine, not participants[^1][^2]. - In that study, the **observed-to-expected ratio for Guillain–Barré syndrome was 2.49** (a 149 % increase) **only after the first dose of the ChAdOx1 (AstraZeneca) adenoviral-vector vaccine**, not after “a COVID-19 vaccine” generally[^2]. The same study did **not** find a significant GBS signal for the mRNA vaccines. - The post conflates the GVDN study with a separate **Karimi et al. meta-analysis of cardiovascular events** that reviewed data on roughly 85 million people; that paper does **not** report GBS findings at all[^3][^4]. - Therefore, the claim misrepresents the number of studies, the number of participants, the vaccine types involved, and the outcome being measured. **Overall validity**: 0% [^1]: [Study Largely Confirms Known, Rare COVID-19 Vaccine Side Effects](https://www.factcheck.org/2024/02/study-largely-confirms-known-rare-covid-19-vaccine-side-effects) [^2]: [COVID-19 vaccines and adverse events of special interest](https://pubmed.ncbi.nlm.nih.gov/38350768) [^3]: [Increased Risk of Heart Attack, Stroke, and Arrhythmia Following COVID Shots](https://www.parkallergy.com/increased-risk-of-heart-attack-stroke-and-arrhythmia-following-covid-shots) [^4]: [COVID-19 Vaccination and Cardiovascular Events](https://pubmed.ncbi.nlm.nih.gov/40191438)