Fact Check-Pages of suspected side effects released about Pfizer’s COVID-19 vaccine ‘may not have any causal relationship’ to the jab, company says

Nine pages of adverse event reports from Pfizer-BioNTech in relation to its COVID-19 vaccine are not confirmed adverse events to the shot. They “may not have any causal relationship” to each other, the pharmaceutical company has told Reuters. The statement comes in response to claims online that the list is definitive.

The document was submitted by Pfizer as part of its Biological License Application (BLA) to the United States Federal Drug Administration (FDA) (here).

It compiled data from 63 countries such as the U.S., UK, Italy, Germany and France received between Dec. 1, 2020 and Feb. 28, 2021 – and includes nine pages of “adverse events of special interest”.

Examples of such events are difficult breathing, déjà vu and myocardial infarction, as well as 1,223 events with a fatal outcome (here).

Some people on social media have since concluded that every entry is definitively caused by Pfizer’s COVID-19 vaccine.

One post, which includes screenshots of all nine pages (here) and has been shared hundreds of times, reads: “Amongst these newly released pages are 9 PAGES OF ADVERSE SIDE-EFFECTS! The list includes auto-immune conditions, multitudinous heart issues, hemorrhaging, kidney disease, many syndromes relayed to other viruses, and even anti-sperm antibodies! Safe and effective, right...?”

Similar posts can be seen on Facebook (here, here, here, here and here)) and Twitter (here and here).

However, the list was compiled using voluntary reports through various national reporting systems, such as the U.S. Vaccine Adverse Event Reporting System (VAERS), the UK’s Yellow Card reporting scheme and the EU’s EudraVigilance database.

Reuters has produced numerous fact checks on these systems (VAERS: here and here; Yellow Card: here and here); EudraVigilance here and here) - all of which explain that reports of potential side-effects are not definitively linked to vaccines.

A Pfizer spokesperson told Reuters that reported side effects “may not have any causal relationship to the vaccine”, adding that all reports are taken “very seriously”.

“Rather, the event may be due to an underlying disease or some other factor such as past medical history or concomitant medication or the AEs (adverse events) may be coincidental,” they said.

AEs are collected for all Pfizer’s products – including its COVID-19 vaccine – to monitor safety issues that might not have been flagged in clinical studies.

The spokesperson explained that the company has “robust processes” in place to assess the potential safety risks of every product and to ensure post-authorisation responsibilities are met.

“In addition to our pharmacovigilance efforts and compliance with various regulatory requirements related to quality and safety, we also cooperate with the FDA and regulatory authorities around the world as they independently monitor the safety profile of our vaccine,” they said. 

A spokesperson for the FDA told Reuters that reports to VAERS post-vaccination “do not necessarily mean that a vaccine caused a health problem” – and anyone can submit a report, regardless of plausibility.

The FDA spokesperson added: “In fact, reviews by FDA and CDC have determined that the vast majority of the deaths reported are not directly attributable to the vaccines. FDA requires healthcare providers to report any death after COVID-19 vaccination to VAERS, even if it’s unclear whether the vaccine was the cause.”

They also explained that VAERS is an “early warning system” that is used to establish any issues with vaccines or medicines that may have been missed before they were licenced. This means, Pfizer would not have known about the suspected AEs prior to licensure.

Likewise, a spokesperson for the European Medicines Agency (EMA) told Reuters that reports of suspected side effects from COVID-19 vaccines by patients and healthcare professionals “are not necessarily related to or caused by the vaccine”.

“Spontaneous case reports of suspected adverse reactions alone are rarely sufficient to prove that a certain suspected reaction has indeed been caused by a specific medicine. This could be a symptom of another illness, or it could be associated with another medicinal product taken by the patient at the same time. Hence, a case report should be seen as a piece of a jigsaw puzzle.”

They added: “For most medicines, the vast majority of suspected side effects are not eventually confirmed as side effects.”


Missing context. The nine pages of “adverse events of special interest” are not confirmed side effects from Pfizer’s COVID-19 vaccine.

This article was produced by the Reuters Fact Check team. Read more about our fact-checking work here.