Cherry-picking: Levi’s tweet ignored multiple other published studies showing that COVID-19 vaccination isn’t associated with a higher mortality rate, heart attacks or abnormal heart rhythm, while uncritically citing studies with methodological issues that appear to support his claim.
FULL CLAIM: “The evidence is mounting and indisputable that MRNA vaccines cause serious harm including death, especially among young people. We have to stop giving them immediately!”; “They should stop because they completely failed to fulfill any of their advertised promises regarding efficacy. And more importantly, they should stop because of the mounting and indisputable evidence that they cause unprecedented levels of harm, including the death of young people and children”
In early February 2023, claims that an MIT professor and “top expert” found evidence of serious harm from the COVID-19 mRNA vaccines and called for a halt to their use went viral on social media. These claims are based on a tweet by Retsef Levi, a professor at the Operations Management Group of the Sloan School of Management at MIT.
In that tweet, he alleged that “The evidence is mounting and indisputable that MRNA vaccines cause serious harm including death, especially among young people”. To support this claim, he cited multiple studies, including one by Fraiman et al., one by Schwab et al., and another co-authored by Levi himself[1-3].
What Levi didn’t mention was that a closer reading would show these studies don’t actually provide the necessary evidence for his claim. The studies by Fraiman et al. and Schwab et al. were discussed in previous Health Feedback reviews (see here and here), which documented the various limitations in the study’s methods that prevent us from making reliable conclusions about vaccine safety. However, Levi’s uncritical citations of these studies mislead users into thinking otherwise.
Health Feedback reached out to MIT for comment regarding Levi’s claim. In an email, MIT News Office stated that “The views represented by Professor Retsef Levi are his own”, and that faculty members “are free to express their views on topics of interest to them”, adding:
“MIT’s senior leaders, MIT Sloan’s leadership, and public health professionals at MIT Medical have consistently underscored the benefits of vaccination and being up to date with all recommended Covid-19 vaccines”.
Levi’s tweet was retweeted more than 4,600 times, while several outlets also amplified his claim, such as The Epoch Times and the Western Journal. These articles, which were shared more than 3,500 times in total, also didn’t mention the limitations of the studies cited by Levi.
As the studies by Fraiman et al. and Schwab et al. were already covered at length in previous reviews (see above), this review will focus on analyzing the study by Sun et al., which Levi co-authored.
The study used population-level data, with no information on the vaccination status of people who developed heart problems
The study, published in the journal Scientific Reports in April 2022, used a dataset of calls to the Israel National Emergency Medical Services from January 2019 to June 2021. The authors examined the association between the number of cardiac arrest (CA) and acute coronary syndrome (ACS) calls for people aged 16 to 39 during this time period. This particular period was selected in order to compare calls during the pre-pandemic period, the pre-vaccine period during the pandemic, and the post-vaccine period during the pandemic.
The authors reported that they observed a correlation between the number of CA and ACS calls and the number of vaccine doses administered, but no correlation with COVID-19 cases. Based on this observation, the authors suggested that COVID-19 vaccination had caused these heart problems and called for Israel and other countries to conduct a “thorough investigation of the apparent association between COVID-19 vaccine administration and adverse cardiovascular outcomes among young adults”.
Several scientists pointed out problems with this conclusion. One of the most notable ones is that the authors didn’t have information about the vaccination status of the people who’d developed heart problems. As a first step towards evaluating a potential causal association between COVID-19 vaccination and heart problems, one first needs to see an elevation of heart problems specifically in vaccinated people that is absent in unvaccinated people. Without knowing the vaccination status of these patients, this is impossible to do.
Using population-level data to arrive at conclusions for individuals—in this case, groups of different vaccination status—is known as the ecological fallacy, and has been a feature of COVID-19 vaccine misinformation based on simplistic population-level correlations. Health Feedback documented some examples here and here.
The authors themselves were aware of this limitation, writing: “It is important to note the main limitation of this study, which is that it relies on aggregated data that do not include specific information regarding the affected patients, including hospital outcomes, underlying comorbidities as well as vaccination and COVID-19 positive status. Such related data are critical to determine the exact nature of the observed increase in CA and ACS calls in young people, and what the underlying causal factors are”.
Physician-researcher Kyle Sheldrick summed it up thus: “Sun and the other authors of this study present an inappropriate design, tacitly inviting readers to falsely conclude that Covid vaccines caused a large increase in cardiac arrests in young people (despite not having actually collected any information about whether those affected were vaccinated)”.
Levi’s tweet however made no mention of this significant issue with the study. Nor does it mention the editor’s note appended to the study on 5 May 2022, stating that “Readers are alerted that the conclusions of this article are subject to criticisms that are being considered by the Editors. A further editorial response will follow once all parties have been given an opportunity to respond in full”.
Health Feedback reached out to Scientific Reports to find out whether any editorial decision had been made since that time. In an email, Rafal Marszalek, the journal’s chief editor, stated that “This paper is still under investigation and we are carefully considering all the information and our response in line with COPE Guidelines and Springer Nature’s policies”, but that they were unable to share more details at this time.
It’s not the first time that this study was used to spread misinformation about COVID-19 vaccine safety. In fact, such misinformation dates back to May 2022, and Levi himself told Reuters that the correlation didn’t prove causality.
Epidemiologist Gideon Meyerowitz-Katz also discussed the study in a Twitter thread posted in May 2022 and highlighted some discrepancies in the analysis, such as the graphs presented. He pointed out that one of the graphs had set the y-axis (the vertical axis) for CA calls at four rather than zero, making the correlation to CA calls appear stronger than it actually was (see Figure 1), calling this practice misleading.
Figure 1. A comparison of the original graph from the study by Sun et al. (top) and a graph showing the same data but with the left y-axis set to zero rather than four (bottom). Modified from Figure 1 by Sun et al. and this graph by Gideon Meyerowitz-Katz.
Another problem with the reliability of the correlation can also be inferred through a visualization of the data for vaccine doses and COVID-19 cases in the age group being studied (16 to 39 years old), showing that these two are strongly collinear, said Meyerowitz-Katz (see Figure 2).
Figure 2. A correlation of the first vaccine doses and COVID-19 cases during the same time period. Source: Gideon Meyerowitz-Katz.
Given how both lines strongly resemble each other, the fact that the authors only detected a correlation for vaccine doses but not for COVID-19 cases—even though both vaccine doses and COVID-19 cases were part of the same model—raises questions about how meaningful the correlation detected is.
We have better-quality studies about the association between heart problems and COVID-19 vaccination
This Twitter thread by Voices for Vaccines, an organization that provides credible vaccine information, pointed out that the study by Sun et al. was actually preceded months ago by this study in Israel, which examined the safety of the COVID-19 vaccines using healthcare records as opposed to emergency medical calls. The authors detected an elevated risk of myocarditis in people who received the Pfizer-BioNTech COVID-19 vaccine (one to five events per 100,000 persons), but also found a much higher risk in people who had COVID-19 (see Figure 3).
Figure 3. The absolute excess risk of various adverse events after vaccination or SARS-CoV-2 infection. Adapted from the original figure by Barda et al. Note that the effects of vaccination and of SARS-CoV-2 infection were estimated with different cohorts: vaccinated people were compared with unvaccinated people, while those who tested positive for SARS-CoV-2 were compared with uninfected people. Thus, the risks from vaccination and that of infection cannot be directly compared.
A study in the U.S. on 6.2 million people who’d received the COVID-19 mRNA vaccines also found no association between vaccination and heart attacks or arrhythmia (abnormal heart rhythm).
It also pointed out that these studies used medical records as opposed to emergency medical calls, which are more reliable in diagnosing a person’s condition.
Another study which analyzed healthcare records of more than 10 million U.S. veterans reported that individuals who had COVID-19 were more prone to developing cardiovascular problems, and that this risk remained even 12 months after infection.
Figure 4. Risks and 12-month burdens of incident post-acute COVID-19 cardiovascular outcomes compared with people who had no evidence of SARS-CoV-2 infection. Outcomes were ascertained 30 days after the COVID-19-positive test until the end of follow-up. Hazard ratios are presented on the left. On the right, the length of the bars represents the excess burden per 1,000 persons at 12 months.
Furthermore, studies so far haven’t found that vaccinated people are more likely to die compared to unvaccinated people[7-9].
Unlike the study by Sun et al., these studies have information about vaccination status, and therefore can more reliably draw associations with vaccination.
Levi’s tweet however, made no mention of these studies.
In short, Levi’s claim that COVID-19 vaccines are responsible for deaths in young people is unsubstantiated. Although he did cite some studies as evidence, reading those studies in detail would show that none actually provide reliable evidence for his claim. His claim ignores other studies of higher quality showing that COVID-19 vaccination doesn’t increase the risk of death or heart attacks.
While COVID-19 vaccines are associated with a higher risk of myocarditis, this risk is higher in people who get COVID-19. Moreover, COVID-19 is associated with a host of health problems, of which heart problems are just one. By reducing the risk of infection and severe disease in people, COVID-19 vaccines offer many benefits that go beyond just preventing COVID-associated heart problems. As such, the vaccines’ benefit outweighs their risk.
UPDATE (13 February 2023):
This publication was updated to include a comment by MIT News Office, which can be found in the fourth paragraph.
UPDATE (10 February 2023):
This publication was updated to include a comment by Scientific Reports regarding the ongoing editorial review of the study by Sun et al., which can be found in the thirteenth paragraph.
- 1 – Fraiman et al. (2022) Serious adverse events of special interest following mRNA COVID-19 vaccination in randomized trials in adults. Vaccine.
- 2 – Schwab et al. (2022) Autopsy-based histopathological characterization of myocarditis after anti-SARS-CoV-2-vaccination. Clinical Research in Cardiology.
- 3 – Sun et al. (2021) Increased emergency cardiovascular events among under-40 population in Israel during vaccine rollout and third COVID-19 wave. Scientific Reports.
- 4 – Barda et al. (2021) Safety of the BNT162b2 mRNA Covid-19 Vaccine in a Nationwide Setting. New England Journal of Medicine.
- 5 – Klein et al. (2021) Surveillance for Adverse Events After COVID-19 mRNA Vaccination. JAMA Network.
- 6 – Xie et al. (2022) Long-term cardiovascular outcomes of COVID-19. Nature Medicine.
- 7 – Xu et al. (2021) COVID-19 Vaccination and Non–COVID-19 Mortality Risk — Seven Integrated Health Care Organizations, United States, December 14, 2020–July 31, 2021. Morbidity and Mortality Weekly Report.
- 8 – Bilinski et al. (2023) COVID-19 and Excess All-Cause Mortality in the US and 20 Comparison Countries, June 2021-March 2022. JAMA Network.
- 9 – Tu et al. (2023) SARS-CoV-2 Infection, Hospitalization, and Death in Vaccinated and Infected Individuals by Age Groups in Indiana, 2021‒2022. American Journal of Public Health.