Flawed analysis by Peter McCullough and others used to promote baseless claim that brain blood clots “112,000% more likely” after COVID-19 vaccine than flu vaccine

In September 2024, a video posted on Facebook by the McCullough Foundation claimed that “brain clots […] are 112,000% more likely to occur after receiving a C-19 product than after receiving an influenza inoculation”.  At the time of writing, the video had been viewed more than 128,000 times.

The claim is based on an allegedly peer-reviewed study co-authored by cardiologist Peter McCullough in a journal named the International Journal of Innovative Research in Medical Sciences. There are indications that the journal is of dubious quality, as we will explain later on. The study initially existed as a preprint (a study that has not yet been peer-reviewed), which has been viewed more than 19,000 times.

McCullough has repeatedly propagated misinformation about COVID-19 and vaccines. He’s also chief scientific officer at the Wellness Company, which sells a supplement marketed as “spike protein detox” for people who’ve been vaccinated against COVID-19. Experts have refuted this claim, explaining that there’s no evidence the “detox” works nor is it necessary.

It’s not the first time McCullough and his colleagues published studies claiming COVID-19 vaccines are harmful.

In July 2023, they claimed that an analysis of autopsies in vaccinated people showed COVID-19 vaccines were responsible for more than 70% of the deaths. Science Feedback addressed that claim in this review, explaining that the analysis wasn’t equipped to establish a causal relationship between COVID-19 vaccination and death. It also highlighted that studies showed the mortality rate in vaccinated people isn’t higher than in unvaccinated people.

Like the autopsy study, the new study promoted in the September 2024 Facebook video also contains methodological flaws and leaps in logic that aren’t justified by the evidence. We will explain below.

Vaccine adverse event reporting rates for COVID-19 vaccines and seasonal flu vaccine were different

The study collected data on cases of blood clots in the brain (cerebral thromboembolism) from the U.S. Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) Vaccine Adverse Event Reporting System (VAERS) database from 1 January 1990 to 31 December 2023. They then compared the number of these adverse event reports after COVID-19 vaccination with those after flu vaccination.

The data they collected showed that there were 5,137 such reports in the three years after COVID-19 vaccination became available compared to 52 such reports after flu vaccination over the past 34 years. This led them to conclude that there was an “alarming breach in the safety signal threshold”, that “[a]n immediate global moratorium on the use of COVID-19 vaccines is necessary”, and that COVID-19 vaccines shouldn’t be given to women of reproductive age at all.

But the study’s interpretation of the data is erroneous. One of the reasons why vaccine adverse event reports are more numerous for COVID-19 vaccines than for other vaccines is due to the fact that COVID-19 vaccines were initially under Emergency Use Authorization (EUA).

For COVID-19 vaccines under EUA, the VAERS website states that it’s mandatory for healthcare providers to report to VAERS “serious adverse events regardless of causality” (emphasis added), including life-threatening adverse events and hospitalization. Blood clots in the brain are considered serious and potentially life-threatening, and thus qualify for mandatory reporting, even if there’s no link to vaccination.

But approved vaccines, like the flu vaccine, don’t have the same mandatory reporting requirement for serious adverse events.

The VAERS website states that “Healthcare providers are required by law to report […] any adverse event listed in the VAERS Table of Reportable Events Following Vaccination that occurs within the specified time period after vaccination”. For the flu vaccine, these events are anaphylaxis (a severe allergic reaction), shoulder injury related to vaccine administration, vasovagal syncope, Guillain-Barré Syndrome, and any acute complication or sequelae (including death) linked to these events. Events listed in the vaccine package insert as contraindications are also mandatory to report, but anaphylaxis is generally the sole contraindication listed in flu vaccines’ package inserts.

Blood clots aren’t among the reportable adverse events.

Because of this difference in adverse event reporting policy, the reporting rate for the COVID-19 vaccines is likely higher than that for the flu vaccine.

In addition, unlike the flu vaccine, the COVID-19 vaccines were subjected to intense media scrutiny surrounding potential safety concerns. Biostatistician Jeffrey Morris told FactCheck.org that the “extreme awareness, attention and concern about vaccine safety induced by the conditions of the pandemic in the past year could conceivably lead to much higher reporting than past years for other vaccines”.

Overall, this means that directly comparing the number of reports after each vaccine in itself cannot provide reliable information about a vaccine’s safety.

It’s worth noting that the study’s approach was already applied in other flawed analyses that arrived at similarly questionable conclusions, as Science Feedback and other fact-checking organizations previously reported.

Viral vector COVID-19 vaccines are linked to increased risk of blood clots, but not COVID-19 mRNA vaccines

Shortly after COVID-19 vaccines became available to the public, scientists began to observe that certain COVID-19 vaccines, specifically the viral vector COVID-19 vaccines from Johnson & Johnson and AstraZeneca, were linked to a rare blood clotting problem known as thrombosis with thrombocytopenia syndrome (TTS) or vaccine-induced immune thrombocytopenia and thrombosis (VITT)^[1-3].

Science Feedback previously reported that these cases already came to light as early as 2021 and were shortly thereafter acknowledged by public health authorities like the World Health Organization and European Medicines Agency. The relationship between viral vector COVID-19 vaccines and TTS has been well-known to the scientific community since then and prompted changes to the way these vaccines were used. For example, when this risk was identified, the U.S. Food and Drug Administration issued restrictions on the use of the Johnson & Johnson COVID-19 vaccines to mitigate this clotting risk.

However, it’s important to note that COVID-19 mRNA vaccines aren’t associated with the same risk.

Moreover, anti-vaccine narratives about the blood clot risks of COVID-19 mRNA vaccines commonly don’t acknowledge that getting COVID-19 itself is associated with a greater risk of blood clots than getting the vaccine^[4,5].

The study’s assertion that COVID-19 vaccines place women of reproductive age at particular risk of harm due to blood clots isn’t substantiated by other published studies. As we explained in previous reviews, vaccinated women don’t have a greater risk of pregnancy complications or fertility problems compared to unvaccinated women. In fact, pregnant women who get COVID-19 are at greater risk of developing complications^[6-8], and COVID-19 vaccines are associated with a lower risk of such complications^[7,9].

Journal that published the study is of dubious quality

The journal that published the study, named the International Journal of Innovative Research in Medical Sciences, claims to be published by the “Wellness Educational Association Society”, located in Madhya Pradesh, India. But we were unable to find any information demonstrating the existence of this society.

The journal’s contact page lists a “Dr. Pradeep Kumar” and a “Dr. Pankaj Soni” as part of the journal’s staff. Again, we were unable to find any information elsewhere indicating that an individual of either name was affiliated with the journal or the Wellness Educational Association Society.

A Google search of the journal’s name led us to this site. Interestingly, the editor for the journal listed on the site is named Govind Lohar, not Pradeep Kumar. Neither Kumar nor Soni’s name appear on the site.

Googling the phone number associated with the journal led us to two other journals, the International Journal of Science and Engineering Invention and the International Journal of Social Science and Economics Invention. Their pages visually resemble that of the International Journal of Innovative Research in Medical Sciences, down to the grammatical and punctuation errors (see Figure 1 below).

Even more curious is how Lohar is listed as the editor for both the International Journal of Science and Engineering Invention and the International Journal of Social Science and Economics Invention. Journal editors normally hold expertise in the specific field of science that the journal publishes articles about. It’s highly unusual for a single person to be considered an expert in fields that are so different from each other, from medicine to engineering to social science to economics.

Overall, our findings suggest that these journals are potentially part of a predatory publishing operation. The goal of predatory publishers is typically to generate revenue from article publishing or processing fees imposed on authors, attracting authors with rapid publication timelines. While there’s nothing wrong with charging authors a fee per se, these publishers commonly lack editorial and technical standards.

As such, the quality of peer review at such publishers is questionable. Hence claims by McCullough and others that the study was peer-reviewed—implying that their findings are credible or accepted by the wider scientific community—should be taken with a grain of salt.

Conclusion

The claim that blood clots in the brain are “112,000% more likely” after COVID-19 vaccination than after flu vaccination is based on a highly flawed analysis by McCullough and colleagues.

The analysis compared the number of brain blood clot reports following COVID-19 vaccination and flu vaccination. But it didn’t account for the fact that the adverse event reporting rate is likely much higher for the COVID-19 vaccines than the flu vaccines, due to adverse event reporting policies and heightened public awareness of potential side effects from COVID-19 vaccines. Hence, adverse event reports alone cannot give us sufficient information about a vaccine’s safety.

Published studies have shown that getting COVID-19 is associated with a higher risk of blood clots than getting the vaccine. Pregnant women who get COVID-19 are also at a greater risk of complications, including stillbirth and miscarriage. Getting vaccinated helps reduce these risks. Overall, the benefits of the COVID-19 vaccines outweigh their risks.

REFERENCES

• 1 – Schultz et al. (2021) Thrombosis and Thrombocytopenia after ChAdOx1 nCoV-19 Vaccination. New England Journal of Medicine.
• 2 – Greinacher et al. (2021) Thrombotic Thrombocytopenia after ChAdOx1 nCov-19 Vaccination. New England Journal of Medicine.
• 3 – Lee et al. (2021) Thrombocytopenia following Pfizer and Moderna SARS-CoV-2 vaccination. American Journal of Hematology.
• 4 – Hippisley-Cox et al. (2021) Risk of thrombocytopenia and thromboembolism after covid-19 vaccination and SARS-CoV-2 positive testing: self-controlled case series study. BMJ.
• 5 – Taquet et al. (2021) Cerebral venous thrombosis and portal vein thrombosis: A retrospective cohort study of 537,913 COVID-19 cases. eClinicalMedicine.
• 6 –  Stock et al. (2022) SARS-CoV-2 infection and COVID-19 vaccination rates in pregnant women in Scotland. Nature Medicine.
• 7 – Lindsay et al. (2023) Neonatal and maternal outcomes following SARS-CoV-2 infection and COVID-19 vaccination: a population-based matched cohort study. Nature Medicine.
• 8 – Schwartz et al. (2023) SARS-CoV-2 placentitis, stillbirth, and maternal COVID-19 vaccination: clinical–pathologic correlations. American Journal of Obstetrics and Gynecology.
• 9 – Lipkind et al. (2022) Receipt of COVID-19 Vaccine During Pregnancy and Preterm or Small-for-Gestational-Age at Birth — Eight Integrated Health Care Organizations, United States, December 15, 2020–July 22, 2021. Mortality and Morbidity Weekly Report.