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Correcting this week’s misinformation: week of July 13, 2023

Do mRNA vaccines cause blood clots?

The Claim:

The Canadian former oncologist is again making claims about the harms of vaccines. This time, he is claiming that pro-athletes, such as Deion Sanders, are suffering from blood clots and “micro clots” caused by mRNA COVID vaccines.

The Facts:

Deion Sanders experienced blood clots in 2021, which led to the amputation of two toes. If you believe the tweet, it was all due to the mRNA COVID vaccines he received months before. According to his doctors, however, those clots were due to one of the most common causes of blood clots, a prior surgery on his foot.

If you examine the tweet closely, the second image of blood clots is used to prove the blood clot risk of mRNA vaccines. Yet right there in the caption, we read that those clots were due to COVID infection itself, something he had prior to his first vaccine.
Anti-vaccine activists have used prior concerns about a particular type of blood clot associated with adenovirus vector vaccines. mRNA vaccines, like Pfizer-BioNTech and Moderna, have a minimal risk of blood clots, unlike COVID itself, which significantly increases the risk of blood clots and stroke.

Does a Canadian lawsuit prove vaccines are unsafe?

The Claim:

A 47-year-old Canadian woman has filed a lawsuit against her government and a television network, claiming that vaccines caused permanent Bell’s Palsy and other psychological harms.

The Facts:

Court cases are about settling legal disputes based on the law, not ruling on scientific facts. Scientific research uses peer-reviewed studies, clinical trials, and systematic reviews to test, analyze data, and reach consensus among the scientific community to determine the validity and reliability of our understanding.

Court cases might get people talking about medical issues, trigger more research, or even sway policy decisions, but when it comes to scientific truth, we rely on those scientists and their methods and not the courts.

Bell’s palsy is an unexplained episode of facial muscle weakness or paralysis. The cause is currently unknown, but it may be triggered by immune challenges such as infection and, on very rare occasions, vaccination.

The cases of Bell’s palsy after COVID vaccination have been watched closely and studiedObservational studies have found that the occurrence of Bell’s palsy after vaccination is not significantly higher than what would be expected in the general population without vaccination.

However, certain systemic reviews have shown a slight increase in Bell’s palsy among those who received vaccines compared to those who did not. In all cases, the risk of Bell’s palsy after COVID infection was much higher than the risk of Bell’s palsy after vaccination.

Are anecdotes more powerful evidence?

The Claim:

Departing from his days on LoveLines, a doctor/podcaster invited another doctor to opine about how anecdotes are actually case studies and that they are more meaningful than global research.

The Facts:

Anecdotes refer to personal stories or experiences shared by individuals, often based on their subjective observations or perceptions. These stories are usually not collected or analyzed systematically and may not use rigorous scientific methods. Anecdotal evidence can be convincing because it is based on personal experiences, but it’s important to know that anecdotes alone are not reliable evidence or proof of cause and effect. They can be influenced by biases like selective memory or personal beliefs and cannot be applied to larger groups of people.

Case studies involve studying specific individuals or small groups in detail. They provide a lot of information about their medical history, symptoms, tests, treatments, and outcomes.  While they can provide valuable insights and a starting point for more research, they are considered less reliable evidence because they involve a small number of cases and other factors that can affect the results.

In medical decision-making, research studies with more reliable methods are considered better than anecdotes and case studies. You can learn more about scientific studies and risk assessments by taking our free online course. Here are some examples of rigorous scientific studies:

  • Randomized Controlled Trials (RCTs): These are the best type of medical research. They randomly assign participants to different treatment groups and compare the results. RCTs have strict rules, use blinding techniques, and analyze data statistically to reduce biases and draw trustworthy conclusions.
  • Systematic Reviews and Meta-analyses: These studies combine and analyze the results of multiple research studies on a specific topic. By looking at data from many sources, systematic reviews and meta-analyses give a thorough and unbiased assessment of the evidence. They help find patterns, trends, and overall effectiveness of treatments.
  • Cohort Studies: Cohort studies follow a group of people over a period of time and look at their exposure to certain risks or treatments. These studies provide useful information about the long-term effects of treatments or the development of specific conditions.
  • Observational Studies: These studies examine the relationship between variables without directly manipulating them. They don’t establish cause and effect, but they can identify possible connections between risks and outcomes.

These research studies are generally better than anecdotes and case studies because they use rigorous methods, involve larger groups of people, and provide stronger evidence. They help prove cause and effect, assess if findings apply to a broader population, and guide medical decisions based on reliable information.

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