Peter McCullough’s claim that COVID-19 vaccines might have caused rise in sudden deaths relies on flawed analysis

In a September 2024 Facebook reel, cardiologist Peter McCullough linked myocarditis from COVID-19 vaccination to sudden death. Myocarditis is an inflammation of the heart muscle that can reduce the heart’s ability to pump blood. Some cases are asymptomatic, while others can experience chest pain, shortness of breath, and abnormal heartbeat.

In the reel, McCullough argued that he had only seen two cases of myocarditis in his practice before the pandemic but now he had seen “well more than several hundred cases”. He added this was “just the tip of the iceberg”. McCullough then cited a study by Hulscher et al. that causally linked COVID-19 vaccination with deaths from myocarditis.

At the time of writing, the reel had been viewed more than 300,000 times.

McCullough is a well-known face of COVID-19 vaccine misinformation. Among other claims, he has repeatedly pushed the false narrative that COVID-19 vaccines are deadly. This new Facebook reel is just another instance of that narrative.

mRNA COVID-19 vaccines are associated with a slight increase in the risk of heart inflammation (myocarditis and pericarditis). Since its identification, public health agencies, including the U.S. Centers for Disease Control and Prevention (CDC) and the European Medicines Agency, have acknowledged this potential side effect.

The reel misled about the risk of myocarditis following COVID-19 vaccination, which, contrary to McCullough’s claim, is low and not associated with death. Furthermore, the study he cited to support this alleged link contains flaws and potential biases that call into question the validity of its conclusions. These conclusions are also at odds with the results from multiple studies showing that COVID-19 vaccination doesn’t increase the risk of death. We explain in detail below.

Study by Hulscher et al. contains methodological flaws, doesn’t support a link between COVID-19 vaccination and deaths

The “Hulscher paper” that McCullough cited in the reel might refer to two different publications by Hulscher et al., both co-authored by McCullough. Both of them analyzed published autopsy reports in which COVID-19 vaccines were considered a possible cause of death.

One of the publications is a review published in Forensic Science International in June 2024 that evaluated a potential causal link between COVID-19 vaccination and death from any cause. The review concluded that 74% of the 325 deaths analyzed were attributable to the COVID-19 vaccine.

This review was later withdrawn from the journal based on numerous concerns, including “[i]nappropriate design of methodology” and “[e]rrors, misrepresentation, and lack of factual support for the conclusions”. About a year earlier, a non-peer-reviewed version (preprint) of the study uploaded to the Social Science Research Network (SSRN)—a preprint server associated with The Lancet—was also removed from the server citing the same methodological concerns.

More likely is that McCullough referred to a review published in ESC Heart Failure in January 2024 that focused exclusively on deaths from myocarditis. Here, the authors analyzed 28 individual autopsy reports from 14 different studies and determined that all deaths “were most likely causally linked to COVID-19 vaccination”. The authors added there was “a high likelihood of a causal link between COVID-19 vaccines and death from myocarditis”, which may also apply to “sudden, unexpected deaths” following vaccination.

Among the 14 studies evaluated in this review, 12 were also included in the Forensic Science International review. This means the review on myocarditis is largely a subset of the broader review evaluating all-cause deaths. Both publications used the same methodology to establish a link between COVID-19 vaccination and death. Therefore, the methodological concerns raised for the withdrawn review apply to both. Science Feedback addressed some of these methodological flaws in earlier reviews.

The fundamental issue in both reviews is that the authors strongly relied on temporal associations to draw an alleged causal association between COVID-19 vaccination and death. In other words, because COVID-19 vaccines can cause myocarditis and the deaths occurred shortly after vaccination (most of them within the following week), the authors concluded that vaccination was the most probable cause. But this approach doesn’t rule out the possibility that factors other than vaccination, such as pre-existing medical conditions or SARS-CoV-2 infection, were the primary cause of death.

Several of the original studies included in the reviews explicitly warned about this limitation, stating that while a causal association between COVID-19 vaccination and death was “possible” in some cases, it couldn’t be definitively established^[1,2].

In some cases, Hulscher et al. even misrepresented the assessments made in the original reports. One example is the case of a 65-year-old male originally reported by Schneider et al.^[2]. Hulscher et al. attributed this death to fatal myocarditis due to COVID-19 vaccination. But according to Schneider et al., the man had “severe pre-existing cardiac changes”, including severe coronary disease and heart tissue scars generally associated with a previous heart attack, which could also have been the cause of death.

The potential risk of bias in the assessments is also a concern, considering that the physicians who evaluated causality in both reviews by Hulscher et al. are McCullough, Roger Hodkinson, and William Makis. All three authors are well-known for having previously spread misinformation about COVID-19 vaccine safety. McCullough is also chief scientific officer at The Wellness Company, which sells an unproven treatment protocol against “COVID-19 vaccine injuries”. This represents a conflict of interest whose potential influence on McCullough’s evaluations cannot be dismissed.

Science Feedback reached out to McCullough to clarify which study he referred to and to ask for further evidence supporting his claim. We will update this review if/when further information becomes available.

COVID-19 vaccines aren’t associated with an increased risk of death

Multiple studies have shown that COVID-19 vaccination doesn’t increase the risk of all-cause death, as Science Feedback explained in earlier reviews. On the contrary, they show that vaccination reduces the risk of serious illness and death from COVID-19.

Available scientific evidence also doesn’t support an association between COVID-19 vaccination and sudden cardiac death (SCD), which is a death that results from an abrupt loss of heart function (cardiac arrest). If not treated immediately, cardiac arrest is often fatal.

While SCD is a potential complication of myocarditis, current evidence indicates SCD isn’t a risk of COVID-19 vaccination.

In April 2024, a study by the CDC evaluated the risk of SCD after mRNA COVID-19 vaccination in roughly 1,300 people aged 16 to 30 who died between June 2021 and December 2022 in Oregon^[3]. The researchers identified 101 cardiac-related deaths, 40 of them among vaccinated people. Only three of these deaths (two males and one female) occurred within the 100 days following vaccination. The researchers determined they were all due to natural causes, and that two of them were also related to chronic underlying conditions. In contrast, COVID-19 was the cause of 30 deaths in the same age group. Only three of these individuals had received a COVID-19 vaccine.

Another study published in Circulation in December 2023 used autopsy records from the region of Veneto, Italy, to compare the rates of SCD in young people before the pandemic (2018 and 2019) and during the COVID-19 pandemic and the vaccination period (2020 to 2022)[4]. The causes of SCD in young people were consistent before and after the pandemic, and the study found no evidence of an association between COVID-19 vaccination and an increased risk of SCD.

In 2023, another study published in Circulation evaluated trends of SCD over a twenty-year period using data from the National Collegiate Athletic Association^[5]. The study found that SCD among athletes actually decreased between 2002 and 2022.

All these results strongly argue against a causal link between COVID-19 vaccination and SCD.

The benefits of COVID-19 vaccination outweigh the low risk of myocarditis

Population-level studies show that COVID-19 vaccination slightly increases myocarditis risk in males aged 12 to 40, particularly after the second dose. But even in this group, myocarditis following vaccination is still a rare event^[6-8]. Two large European studies evaluated this risk using data from the Nordic registry and the French national health system. They estimated that young people who received a second dose of an mRNA vaccine experienced between one and two more cases of myocarditis per 10,000 doses compared to unvaccinated people^[9].

It is also important to note that this potential side effect isn’t exclusive to mRNA COVID-19 vaccines. Rare cases of myocarditis have also been associated with traditional vaccines against other pathogens. One of the best-known examples is the smallpox vaccine.

In 2022, a review by Ling et al., published in Lancet Respiratory Medicine, analyzed data from 22 published studies to estimate the risk of myocarditis after receiving an mRNA COVID-19 vaccine and earlier vaccines^[8]. Compared to the smallpox vaccine, COVID-19 vaccines were associated with a lower risk of myocarditis.

The frequency of myocarditis following COVID-19 vaccination in the overall population wasn’t greater than after other vaccines evaluated, and was roughly 33 cases per million vaccine doses. This figure is consistent with the rates of myocarditis reported before the COVID-19 pandemic^[10-14].

Since the COVID-19 pandemic, some studies have indeed reported an increase in myocarditis cases, ranging from 150 to 4,000 cases per 100,000 individuals. This means an increase in the risk of developing myocarditis of at least 15 times compared to pre-pandemic levels^[15]. However, the available evidence indicates that, contrary to McCullough’s claim, the most likely cause for this increase is COVID-19, not vaccination.

Viral infections are a leading cause of myocarditis worldwide, and COVID-19 isn’t an exception. In fact, cardiovascular problems, including myocarditis, arrhythmia, heart attack, and blood clotting problems, were among the first complications identified in COVID-19 patients^[16,17].

However, this risk is much higher following SARS-CoV-2 infection than after vaccination. Large studies in the U.S. and in England estimated the risk at around 11 to 15 times higher after SARS-CoV-2 infection than after vaccination^[18,19]. Indeed, a study in Germany reported that myocarditis affected at least one per 1,000 hospitalized COVID-19 patients[20]. The risk was higher in young males, particularly in those with age, male sex, pneumonia, and multisystemic inflammatory COVID-19.

While complications from COVID-19 vaccine-induced myocarditis are possible, most cases tend to be mild and resolve relatively quickly^[12,21,22]. This is in contrast to cases of myocarditis from viral infection^[22] in general and SARS-CoV-2 infection in particular, which are more severe and result in greater mortality^[20,24].

Overall, the benefits of COVID-19 vaccination in reducing the risk of COVID-19 complications and death far exceed the risks. This positive benefit/risk ratio applies to all age groups, including young males^[25], who are also at the highest risk of developing myocarditis from SARS-CoV-2 infection^[26].

Conclusion

Claims like McCullough’s implying that COVID-19 mRNA vaccines cause SCD or increase the risk of death are unsubstantiated and misleading. While myocarditis is a known risk of COVID-19 vaccination in young males, most cases are mild and resolve relatively quickly with rest and medication.

The available evidence doesn’t support an association between COVID-19 vaccination and death from SCD or any other cause. On the contrary, they find that vaccination helps reduce the risks associated with COVID-19—including a much higher risk of myocarditis than after vaccination—and other complications potentially leading to hospitalization and death. These benefits clearly outweigh the low risk of myocarditis in all age groups.

REFERENCES

• 1 – Verma et al. (2021) Myocarditis after Covid-19 mRNA Vaccination. New England Journal of Medicine.
• 2 – Schneider et al. (2021) Postmortem investigation of fatalities following vaccination with COVID-19 vaccines. International Journal of Legal Medicine.
• 3 – Liko et al. (2024) Assessment of Risk for Sudden Cardiac Death Among Adolescents and Young Adults After Receipt of COVID-19 Vaccine — Oregon, June 2021–December 2022. Morbidity and Mortality Weekly Report.
• 4 – De Gaspari et al. (2023) Rate and Cause of Sudden Cardiac Death in the Young During the COVID-19 Pandemic and Vaccination. Circulation.
• 5 – Petek et al. (2023) Sudden Cardiac Death in National Collegiate Athletic Association Athletes: A 20-Year Study. Circulation.
• 6 – Straus et al. (2022) Analysis of Myocarditis Among 252 Million mRNA-1273 Recipients Worldwide. Clinical Infectious Diseases.
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• 8 – Hviid et al. (2024) Booster vaccination with SARS-CoV-2 mRNA vaccines and myocarditis in adolescents and young adults: a Nordic cohort study. European Heart Journal.
• 9 – Durand et al. (2022) Safety Monitoring of COVID-19 Vaccines: Perspective from the European Medicines Agency. Clinical Pharmacology and Therapeutics.
• 10 – Ling et al. (2022) Myopericarditis following COVID-19 vaccination and non-COVID-19 vaccination: a systematic review and meta-analysis. Lancet Respiratory Medicine.
• 11 – Kytö et al. (2014) Clinical Profile and Influences on Outcomes in Patients Hospitalized for Acute Pericarditis. Circulation.
• 12 – Diaz et al. (2021) Myocarditis and Pericarditis After Vaccination for COVID-19. JAMA.
• 13 – Roth et al. (2020) Global Burden of Cardiovascular Diseases and Risk Factors, 1990–2019: Update From the GBD 2019 Study. Journal of the American College of Cardiology.
• 14 – Fu et al. (2022) Trends in myocarditis incidence, complications and mortality in Sweden from 2000 to 2014. Scientific Reports.
• 15 – Fairweather et al. (2023) COVID-19, Myocarditis and Pericarditis. Circulation Research.
• 16 – Hendren et al. (2020) Description and Proposed Management of the Acute COVID-19 Cardiovascular Syndrome. Circulation.
• 17 – Zheng et al. (2020) COVID-19 and the cardiovascular system. Nature Reviews Cardiology.
• 18 – Boehmer et al. (2021) Association Between COVID-19 and Myocarditis Using Hospital-Based Administrative Data — United States, March 2020–January 2021. Morbidity and Mortality Weekly Report.
• 19 – Pantone et al. (2022) Risk of Myocarditis After Sequential Doses of COVID-19 Vaccine and SARS-CoV-2 Infection by Age and Sex. Circulation.
• 20 – Keller et al. (2023) Incidence and risk factors of myocarditis in hospitalized patients with COVID-19. Journal of Medical Virology.
• 21 – Montgomery et al. (2021) Myocarditis Following Immunization With mRNA COVID-19 Vaccines in Members of the US Military. JAMA Cardiology.
• 22 – Kracalik et al. (2022) Outcomes at least 90 days since onset of myocarditis after mRNA COVID-19 vaccination in adolescents and young adults in the USA: a follow-up surveillance study. Lancet Child and Adolescent Health.
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• 24 – Elizalde et al. (2024) Myocarditis and pericarditis risk with mRNA COVID-19 vaccination compared to unvaccinated individuals: A retrospective cohort study in a Spanish Tertiary Hospital. Biomedicine and Pharmacotherapy.
• 25 – Buoninfante et al. (2024) Myocarditis associated with COVID-19 vaccination. NPJ Vaccines.
• 26 – Husby et al. (2023) Clinical outcomes of myocarditis after SARS-CoV-2 mRNA vaccination in four Nordic countries: population based cohort study. BMJ Medicine.