Years-Old List of Alleged Pfizer COVID-19 Vaccine ‘Side Effects’ Is Misleading

In January 2025, Snopes readers asked us about the authenticity of a long list (archived) circulating on the internet of what were claimed to be “side effects” of the Pfizer BioNTech COVID-19 vaccine. 

PFIZER JUST RELEASED ITS LIST OF SIDE EFFECTS OF ITS “COVID VACCINE”

The list of some side effects of the Pfizer-Biontech Covid-19 Vaccine. 

Blood thrombosis.

Acute kidney injury,

Acute flaccid myelitis,

Positive antisperm antibodies,

Brainstem embolism,

Brainstem thrombosis,

Cardiac arrest (hundreds of cases),

Heart failure,

Cardiac ventricular thrombosis,

Cardiogenic shock,

Central nervous system vasculitis,

Neonatal death,

Deep vein thrombosis,

Brainstem encephalitis,

Hemorrhagic encephalitis,

Frontal lobe epilepsy,

Foaming at the mouth,

Epileptic psychosis,

Facial paralysis,

Fetal distress syndrome,

Gastrointestinal amyloidosis,

Generalized tonic-clonic seizure,

Hashimoto’s encephalopathy,

Hepatic vascular thrombosis,

Herpes zoster reactivation,

Hepatitis Immune-mediated,

Interstitial lung disease,

Jugular vein embolism,

Juvenile myoclonic epilepsy,

Liver damage,

Low birth weight,

Multisystem inflammatory syndrome in children,

Myocarditis,

Neonatal seizure,

Pancreatitis,

Pneumonia,

Stillbirth,

Tachycardia,

Temporal lobe epilepsy,

Testicular autoimmunity,

Thrombotic stroke,

Type 1 diabetes mellitus,

Neonatal venous thrombosis,

Vertebral artery thrombosis,

Pericarditis,

Sudden death…

Remember this it was supposed to be harmless too

The post appeared on Facebook, as seen above, as well as X (archived) and Instagram (archived).

This post is a copypasta — a copied-and-pasted text shared online — that goes back to at least (archived) March 2022. Previous fact checks carried out by Science Feedback, The Dispatch and Reuters found that the list stemmed from a document released by the pharmaceutical company Pfizer in March 2022. 

Adverse Events Aren’t the Same as Side Effects

The Pfizer document comprises “adverse event reports” submitted on behalf of subjects who received the Comirnaty BNT162B2 vaccine produced by Pfizer-BioNTech. However, adverse events are not the same thing as side effects. Pfizer wrote in its report that: “an accumulation of adverse event reports (AERs) does not necessarily indicate that a particular AE was caused by the drug.” In fact, only two of the conditions on the lengthy list could be found on Pfizer-BioNTech’s list of actual side effects as of 2024. Therefore, we rate this claim as mostly false.

Public Health and Medical Professionals for Transparency, a group that publishes data used by the U.S. Food and Drug Administration to license COVID-19 vaccines, obtained the 38-page document that was the source of the copypasta list in March 2022, according to Science Feedback. A Freedom of Information Act request filed in August 2021 led to the release of the document, titled “5.3.6 CUMULATIVE ANALYSIS OF POST-AUTHORIZATION ADVERSE EVENT REPORTS OF PF-07302048 (BNT162B2) RECEIVED THROUGH 28-FEB-2021.” 

Soon thereafter, false claims that it was Pfizer’s list of the “side effects” of its COVID-19 vaccine appeared on social media.

Pfizer’s actual report covers adverse events from Dec. 1, 2020, to Feb. 28, 2021. During this time, Pfizer received 42,086 case reports, mainly from the U.S., the U.K., Italy, Germany, France, Portugal and Spain, according to the report. A nine-page appendix at the end of the report lists the various reported adverse events.

All but two of the conditions listed in the January 2025 claims — “Blood thrombosis” and “Positive antisperm antibodies” — also appeared in Pfizer’s report. However, Pfizer specifically said in the report that adverse events were not always caused by the drug being tested:

An accumulation of adverse event reports (AERs) does not necessarily indicate that a particular AE was caused by the drug; rather, the event may be due to an underlying disease or some other factor(s) such as past medical history or concomitant medication.

The FDA also distinguishes between a side effect and an adverse event. In the FAQ section for the FDA Adverse Events Reporting System Public Dashboard, a tool that gathers adverse events submitted to the agency, the administration wrote:

Pfizer Website Lists Up-to-Date Side Effects of COVID-19 Vaccine

According to the patient package insert distributed with the Pfizer-BioNTech Comirnaty vaccine in 2024, the listed side effects are:

Severe allergic reactions

Non-severe allergic reactions such as rash, itching, hives, or swelling of the face

Myocarditis (inflammation of the heart muscle)

Pericarditis (inflammation of the lining outside the heart)

Injection site reactions: pain, swelling, redness, arm pain

General side effects: tiredness, headache, muscle pain, chills, joint pain, fever, nausea, feeling unwell, swollen lymph nodes (lymphadenopathy), decreased appetite, diarrhea, vomiting, dizziness

Fainting in association with injection of the vaccine

Two of these side effects — myocarditis and pericarditis — also appear in the copypasta list. However, the claim as a whole is still mostly false, as it attempts to pass off adverse event reports as side effects.

The U.S. Centers for Disease Control and Prevention recommends COVID-19 vaccinations for people 6 months and older. The CDC extended the emergency use authorization for the Pfizer-BioNTech Comirnaty vaccine in August 2024 to include the current 2024-25 formula. 

Snopes has collected a series of COVID-19 fact checks of claims from the “infodemic” that accompanied the pandemic in 2020.

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