261018 – Pfizer COVID Vaccine Side Effects List

October 18, 2026 Leave a comment

The Pfizer “Side Effects” List: What It Is, What It Isn’t, and What Remains Unsettled

· @Thomas Lee Abshier, ND

The post

A post circulating on X claims Pfizer has “just published” a list of possible side effects of its COVID vaccine. Below that headline sit forty-nine conditions, from blood clots to sudden infant death syndrome, and the verdict “It is a crime.”

The post is wrong about what the list is. It is not new; Pfizer did not just publish it. It contains a long list of side effects. VAERS has reported many conditions, and some of them may have been on that list. My point is not to confirm or deny whether the vaccine causes any of the above. Rather, I want to counsel on how to view such lists. This list gives no provenance or sourcing. I can say the post is correct that the vaccine carries real risks acknowledged by Pfizer. In particular, the list includes inflammation of the heart, which is now written into the vaccine’s own label.

Because the list includes both confirmed and less-verified reports, the post deserves a careful answer rather than dismissal. A reader who believes the whole list may be correct about the concern. This essay aims to leave the reader with the true proportions: what the document is, how to read it, what has actually been established, and what remains honestly disputed.

Where the list comes from

The list traces to a Pfizer report titled 5.3.6 Cumulative Analysis of Post-authorization Adverse Event Reports. It covers the first three months of public use, December 1, 2020 through February 28, 2021. The FDA released it in 2022 under a Freedom of Information Act lawsuit brought by a group of physicians and scientists seeking the vaccine’s licensing records.

The report summarizes the reports Pfizer received during that period: about 42,000 case reports, including 1,223 with a fatal outcome. Those numbers are counts of reports, not counts of vaccine injuries. The report states that its database holds cases “regardless of causality assessment” (FactCheck.org).

The report ends with Appendix 1, a nine-page alphabetical list of 1,291 “adverse events of special interest.” That appendix is the source of every viral version of this post since 2022. The present version picks about fifty items from it, adds some of its own, and presents them as fresh news. Fact-checkers documented the same recycling in 2022 and again in 2025.

Three terms that are not the same

The whole confusion rests on three phrases that sound alike and mean very different things.

An adverse event is anything bad that happens to a person after he receives a drug or vaccine, whether or not the product caused it. If a man is vaccinated on Monday and breaks his leg on Wednesday, he can report the broken leg as an adverse event. The category is deliberately broad because it aims to catch problems no one predicted.

A side effect (in labeling language, an adverse reaction) is an adverse event for which there is good evidence that the product caused it. Establishing that takes more than a report. It takes a comparison: does the condition occur more often in vaccinated people than in similar unvaccinated people, more often than its normal background rate, within a plausible time window, and with a plausible mechanism?

An adverse event of special interest is neither of these. It is a condition placed on a watch list before the data come in because it has been linked to vaccines in general, to the disease being prevented, or to the technology involved. Regulators ask manufacturers to watch for these conditions specifically. Being on the list means “look here carefully,” not “this was found” (PolitiFact).

An analogy helps. A building inspector carries a checklist: cracked foundation, faulty wiring, mold, roof leaks, asbestos. Publishing the checklist does not mean every house has asbestos. The checklist tells you what the inspector looks for. The inspection report tells you what he found. Appendix 1 is the checklist.

That is why the list contains items no one could seriously call vaccine side effects. For example, it includes ordinary viral infections such as metapneumovirus infection, which a safety program must monitor for because vaccinated people may respond differently to infection (AAP FactCheck).

What the post gets wrong

The post makes four errors, and each is checkable.

  1. It calls a watch list a list of side effects. This is the central error, explained above. After reviewing the reports by organ system, Pfizer’s own report concluded that the data did not reveal new safety concerns beyond those already being tracked (FactCheck.org). One may doubt that conclusion. One cannot honestly cite the same document as proof of the opposite. FactCheck.org’s validity is another point of research. A single source of truth may be biased; multiple sources, each with different loyalties to the government, pharma, or political agendas, are preferable. Such research takes time, effort, and specialized knowledge, which most casual consumers of headlines and news generally lack.
  2. It says Pfizer “just published” the list. The document is from early 2021 and was made public in 2022. The “just published” framing has been attached to it repeatedly since then (Science Feedback).
  3. It adds items that are not medical terms. “Turbo cancer” is a phrase coined on social media, not a diagnosis, and no regulatory list uses it. The post’s commentary, such as “hundreds of cases” of cardiac arrest, is likewise the poster’s addition, not the document’s.
  4. It was not checked. The numbering repeats items 17 and 18 and skips item 33. That is a small thing, but it tells the reader how much care went into the claim.

None of these errors require a medical degree to see. They require only reading the source the post claims to report.

What has actually been established

Of the forty-nine items in the post, two are established side effects: myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the sac around the heart). These are not suppressed findings. They have been in the vaccine’s labeling since 2021 (FDA), and the current Comirnaty label states that post-marketing analyses have shown increased risks of both, usually within the first week after a dose (Comirnaty prescribing information).

The risk is concentrated in young males and is highest after the second dose of the primary series. The best-known U.S. analysis, by Oster and colleagues at CDC, counted 1,626 confirmed cases among roughly 354 million mRNA doses from December 2020 to August 2021 (JAMA, 2022).

Group Cases per million doses Source and period
Males 16–17, second Pfizer dose 105.9 Oster et al., JAMA, 2020–21 primary series
Males 12–15, second Pfizer dose 70.7 Oster et al., JAMA, 2020–21 primary series
Males 18–24, second Pfizer dose 52.4 Oster et al., JAMA, 2020–21 primary series
Males 12–24, any dose about 27 FDA label update, 2023–24 formula
Everyone 6 months–64 years about 8 FDA label update, 2023–24 formula

Two cautions keep these numbers in proportion. First, in the Oster series, most patients recovered quickly, and none of the verified cases required a heart transplant or mechanical heart support (Physician’s Weekly summary). Second, the label itself says that information on long-term effects is not yet available, and in the CDC follow-up, more than 70 percent of young patients had abnormal cardiac MRI findings (AuntMinnie). Rare and usually mild is not the same as trivial, especially for a teenage boy at low risk from COVID itself.

The label also lists severe allergic reactions and fainting at the time of injection, along with the familiar short-lived reactions: sore arm, fatigue, headache, chills, and fever for a day or two. That is the documented list. It is far shorter than forty-nine items, and it includes one serious risk that deserves attention.

What remains honestly disputed

Correcting the post does not settle every question about these vaccines. Several serious questions remain open, and readers deserve to know them.

How much the reporting systems miss. The U.S. Vaccine Adverse Event Reporting System (VAERS) accepts reports from anyone, so it overcounts events the vaccine did not cause. It also undercounts because most doctors and patients never file reports. A federally funded 2010 study at Harvard Pilgrim Health Care estimated that only a small fraction of vaccine adverse events reach VAERS. Both errors are real. That is why passive reporting raises signals, and why researchers must then test them in controlled comparisons before anyone claims a cause in either direction.

Whether the benefit outweighs the risk for every group. In 2021, the CDC concluded that benefits outweighed risks for all age and sex groups. Critics argued that this calculation was weakest for healthy young males, especially those already immune from prior infection. Several Nordic countries restricted one mRNA vaccine for young people in late 2021. In 2025, U.S. policy itself moved toward the critics’ position: the FDA approved that season’s formula for people 65 and older and for younger people with underlying conditions, and the label now singles out males 12 to 24 as the group at highest risk. Where the line should fall remains a fair point of contention.

Whether the public was told the truth in proportion. Some argue that early public messaging emphasized “safe and effective” while the myocarditis signal was still being assessed, and that this cost public trust. Others argue that officials disclosed the signal within months, added it to the label in 2021, and acted as fast as the data allowed. The record supports parts of both views, and readers can weigh it for themselves.

Long-term outcomes. The label states that long-term effects of vaccine myocarditis are not yet known. Follow-up studies are ongoing. Until they mature, honest writers on both sides should say “we do not yet know” rather than “there are none” or “they are devastating.”

Why proportion matters

A claim can be false without inventing a single word. This post shows how: take a real document, misstate what kind of document it is, and let the reader’s fear do the rest. That kind of exaggeration is a lie told by proportion.

It also harms the people it claims to defend. Young men who developed myocarditis after vaccination have a real injury and a real grievance about how their risk was communicated. When their case is buried among forty-seven conditions with no established link, the strongest criticism of the vaccine program looks like the weakest. Every careless post makes it easier to dismiss the careful critic.

The remedy is not to stop asking questions about vaccines. It is to ask them well. Before sharing a claim like this, a reader can ask three questions:

  1. What is the source document, and what kind of document is it? A watch list, a report count, and a confirmed finding are three different things.
  2. Was a comparison made? You show cause by comparing rates in exposed and unexposed people, not by listing things that happened afterward.
  3. Does the official label say it? The prescribing information must list established risks. If a claimed side effect is absent there, either the evidence has not reached that standard or the claim is wrong. Both are worth knowing.

Measured by those questions, the post fails, and myocarditis passes. That is the true proportion, and it is the one readers should carry away.

References

Note: the Harvard Pilgrim (2010) under-reporting study and the 2021 Nordic restrictions are cited from general knowledge and should be given direct links. U.S. vaccine recommendations have changed several times since 2025; if you plan to quote this article, please confirm the current statistics.

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