This report of a physician who died after receiving COVID vaccine offers a useful lesson in the importance of thinking more critically about does and what does not constitute a drug reaction.
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usatoday.com/story/news/hea…
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usatoday.com/story/news/hea…
Briefly, the MD noticed petechiae (tiny areas of bleeding into the skin, as seen in image) 3 days after vaccination. He was diagnosed with ITP (immune thrombocytopenic purpura).
People with ITP have profoundly low platelets and can bleed spontaneously as a result.
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People with ITP have profoundly low platelets and can bleed spontaneously as a result.
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The temptation to blame the vaccine is understandable: we’re hypervigilant about the safety of new drugs (especially high-profile ones employing a novel technology), and the timing seems like a slam dunk.
But step back for a moment.
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But step back for a moment.
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Let’s acknowledge two things:
First, ITP has many, many causes: autoimmune diseases, neoplasms, infections (including COVID itself, btw) and a long list of drugs.
nejm.org/doi/full/10.10…
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First, ITP has many, many causes: autoimmune diseases, neoplasms, infections (including COVID itself, btw) and a long list of drugs.
nejm.org/doi/full/10.10…
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Second—and this is a critical point—ITP doesn’t just develop overnight. It generally takes at least 5 to 7 days from first exposure, as in this example (from ref above).
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Petechiae are a sign of a profoundly low platelet count.
When they appear **3 days** after vaccination, it suggests a cause OTHER THAN the vaccine—specifically, a trigger (virus, drug, etc.) that antedated vaccination.
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When they appear **3 days** after vaccination, it suggests a cause OTHER THAN the vaccine—specifically, a trigger (virus, drug, etc.) that antedated vaccination.
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I'm not saying COVID vaccines can’t cause rare but serious side effects. They can.
Anaphylaxis is clear (~1 in 90,000 vaccinations).
Bell’s palsy is a maybe (even rarer, and generally transient.)
There will be others, perhaps even ITP.
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Anaphylaxis is clear (~1 in 90,000 vaccinations).
Bell’s palsy is a maybe (even rarer, and generally transient.)
There will be others, perhaps even ITP.
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My main point is that evaluating a possible vaccine reaction involves a lot more than “It happened after vaccination.”
It involves a thoughtful assessment of the time course, biologic plausibility, potential competing explanations, and so on.
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It involves a thoughtful assessment of the time course, biologic plausibility, potential competing explanations, and so on.
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The next time you read about something that happened after COVID vaccination, don’t assume it was *caused by* vaccination.
Causal inference just isn’t that simple.
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Causal inference just isn’t that simple.
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We're early in the post-marketing surveillance of these vaccines, but it's worth remembering that the data we have so far are actually pretty reassuring.
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https://twitter.com/DavidJuurlink/status/1346489141408788480?s=20
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