A widely shared article on the Express website about the safety of Pfizer’s Covid-19 vaccine is misleading in several ways.
It incorrectly claims that a recently published document about adverse events following vaccination is the first time the public have been allowed to see the clinical trial data that Pfizer submitted to the US Food and Drug Administration (FDA) for the authorisation of the vaccine. In fact, much of the data in this document does not come from Pfizer’s clinical trials, and some adverse event data from the trials has been publicly available on the FDA website at least since December 2020.
In two picture captions, the article also wrongly refers to the adverse events as “side effects”, which a correction note about a previous version of the article accepts is not accurate.
The article also lacks context, because it does not explain that a reported “adverse reaction” is not necessarily related to the vaccine at all. Indeed at one point it falsely says these are “adverse events from [Pfizer’s] vaccine”. Nor does it explain that the document itself concludes that the vaccine raises no safety concerns.
The Medicines and Healthcare products Regulatory Agency (MHRA) in the UK monitors reports of adverse events which occur after vaccination. It says, based on UK data and including reports collected after February 2021, that “the expected benefits of the vaccines in preventing Covid-19 and serious complications associated with Covid-19 far outweigh any currently known side effects in the majority of patients”.
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What is this document?
The Express told Full Fact that its article is based on a Pfizer report obtained through Freedom of Information requests by a group called Public Health and Medical Professionals for Transparency.
This report contains details of 158,893 events taken from 42,086 case reports. These reports came from a mixture of sources, including “cases of AEs [adverse events] reported spontaneously to Pfizer, cases reported by the health authorities, cases published in the medical literature, cases from Pfizer-sponsored marketing programs, non-interventional studies, and cases of serious AEs reported from clinical studies regardless of causality assessment”.
The document was prepared after Pfizer’s vaccine received emergency use authorisation in the US on 11 December 2020, and before full approval on 23 August 2021.
What did the Express say?
The article said: “When Pfizer applied for FDA approval, they were aware of almost 158,000 adverse events from their vaccine.”
It is not correct to say that these events are “from” the vaccine. The FDA defines an adverse event as: “Any untoward medical occurrence in a patient or clinical investigation subject administered a pharmaceutical product and which does not necessarily have a causal relationship with this treatment ”.
The Express article also said: “It is the first time the public are allowed to access the data Pfizer submitted to FDA from its clinical trials in support of a Covid-19 vaccine license [sic].”
This is misleading for two reasons. Firstly, the data in the document comes from a mixture of sources, many of them not clinical trials, so it isn’t just clinical trial data. Indeed, much of it was collected after the FDA gave the vaccine emergency use authorisation on 11 December 2020.
Secondly, while this document includes some more recent adverse event data which has not been previously published, this is not the first time clinical trial data which Pfizer submitted to the FDA has been released. Some of its detailed trial data on adverse reactions has been publicly available on the FDA website at least since December 2020.
Trial data, including safety data, was also published in December 2020 in the New England Journal of Medicine.
An earlier version of the Express article also referred to these adverse events as “side effects” in its headline and elsewhere—and a similar article on the Scottish Daily Express website still does, at the time of writing. This is not correct, because the adverse events in the Pfizer report were not necessarily caused by the vaccine.
The current version of the Express article, at the time of writing, contains a correction note that says: ”This article was edited on 12/03/22 to amend the use of the word 'side effects' to 'adverse events' as to be accurate with the report.”
However, the article still contains two picture captions saying “Pfizer side effects”, and it continues to lack important context, because it still does not explain that adverse events are not necessarily caused by the vaccine.
Nor does it note that the document itself concludes that “the data do not reveal any novel safety concerns or risks requiring label changes and support a favorable benefit risk profile of to the BNT162b2 vaccine [sic]”.
The Pfizer Covid vaccine is safe and effective
Reports of adverse events following vaccination against Covid have been regularly assessed by the MHRA in the UK. It says: “The expected benefits of the vaccines in preventing COVID-19 and serious complications associated with COVID-19 far outweigh any currently known side effects in the majority of patients.”
Data on adverse events from Pfizer’s clinical trials was used as evidence in the UK’s authorisation of the vaccine in December 2020.
Photo by CDC on Unsplash