All About Pfizer Covid-19 Bivalent Vaccine And Stroke Risk

Credit: Guido Hofmann/Unsplash

The Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA) announced on January 13 that there may be a “safety signal” for the Pfizer-BioNTech Covid-19 bivalent booster vaccine, as reported by Forbes.

High levels of panic 

Unsurprisingly, the conversation has been scattered, much like the 2020 film I’m Thinking of Ending Things. That is understandable given that throughout the epidemic, Pfizer-BioNTech Covid-19 vaccine communications have been subpar, earning an F. There has been far too much use of the F-word and Pfizer press releases, which has led to unnecessarily high levels of panic.

So let’s consider the recent announcement from the CDC and FDA in its correct context. There shouldn’t be any need for concern. When a larger-than-expected proportion of persons experience a negative event, this is referred to as a “safety signal.” In this instance, the CDC discovered in its Vaccine Safety Datalink (VSD) surveillance system that among those 65 and older, more ischemic strokes occurred within 21 days (as opposed to 22 to 44 days) after receiving the Pfizer-BioNTech Covid-19 bivalent vaccine. Other Covid-19 vaccines, such as the Moderna bivalent booster, did not exhibit the same type of signal, the researchers found.

Just because there has been an increase in ischemic strokes does not necessarily mean anything. To infer in any manner that the Pfizer-BioNTech Covid-19 bivalent vaccine contributed to those extra strokes is insufficient. That would be like claiming that the California mudslides, which have been happening recently, are somehow related to Donald Trump’s introduction of his digital trading card non-fungible tokens (NFTs), just because the latter occurred after the former. It doesn’t necessarily follow that events that occurred around the same period were connected in any manner. The increase in ischemic strokes may have simply been a coincidence.


The CDC and FDA cannot, however, ignore such a safety signal. They must approach it with the same level of caution that they would use when entering their parent’s bedroom in the middle of the night. You can never be sure what you’ll find. Furthermore, an ischemic stroke is not something that should be taken lightly. You don’t normally announce, “I’m having an ischemic stroke and I’m going to be late for our date.” Order the appetisers now; I’ll be there shortly. Because a blood clot in a head artery has cut off blood flow to certain areas of your brain, an ischemic stroke is a medical emergency. Because it deprives your brain tissue of oxygen, it is known as an ischemic condition. Your brain tissue will quickly perish without oxygen. Furthermore, brain tissue is not comparable to breadsticks from the Olive Garden. You can’t just demand more. Once gone, anything is permanently lost.

A firm conclusion 

In order to determine whether a safety signal can truly be confirmed, additional data and research need to be examined once it is discovered. It’s comparable to learning that one of your buddies has undergone some sort of, eh, cosmetic surgery. You don’t just say, “This is Harry and he has some huge news for all of you,” or, “This is Lori and she has something she wants to get off her chest that’s now on her chest,” when introducing your friend to others. Instead, you might make further observations and even do some studies before doing so. New of them might be indirect questions such as, “Would these jeans need to be larger when you say you need to buy some pants?” or “Is it a stretch to state your sweaters have stretched.” There may be more direct methods. The fact is that you wouldn’t draw judgements based just on what you had heard. The CDC and FDA would similarly need to perform a variety of analyses on various data sources in order to get a more firm conclusion.

And that’s what they’ve been doing. So far, the original safety signal has not been supported by other data sources. For example, the CDC did mention that they have already looked at the following data sources and have not found any increased risk of ischemic stroke:

  • A large study of updated (bivalent) vaccines (from Pfizer-BioNTech and Moderna) using the Centers for Medicare and Medicaid Services database
  • A preliminary study using the Veterans Affairs database
  • The Vaccine Adverse Event Reporting System (VAERS) managed by CDC and FDA
  • Pfizer-BioNTech’s global safety database

Also highlighted by the CDC was the fact that “other nations have not reported a higher risk for ischemic stroke with updated (bivalent) immunisations.” That demonstrates how crucial it is for nations to cooperate and exchange data.

Changing vaccination policies 

It shouldn’t be possible to change vaccination policies based only on a single unconfirmed safety signal found in a single database. That’s assuming the unpleasant reaction isn’t more obviously related to the vaccination. It’s not like the moment individuals received the immunisations, their heads started to fall off. Because of this, the CDC is not currently changing any of its Covid-19 guidelines.

They will nevertheless advise “that everyone aged 6 months and older stay up to date with COVID-19 vaccination, including persons who are currently eligible to get an updated (bivalent) vaccine” until further notice. This is a reasonable strategy because the advantages of vaccinations still vastly outweigh the disadvantages. Regardless of what some politicians and TV celebrities may claim, the Covid-19 pandemic is still ongoing.

Does this mean that the most recent safety signal has come to an end? Not yet, it shouldn’t. The remaining members of the scientific community should have enough time to examine all of the information and analyses. It is critical that the FDA, CDC, and Pfizer operate with the greatest amount of openness. Further study and debate will be possible at the Vaccines and Related Biological Products Advisory Committee meeting on January 26. The FDA, CDC, public health specialists, and other scientists should continue to gather information about and assess the effectiveness and safety of the Covid-19 vaccines in the meantime. And the government ought to pressure Pfizer to make all of its Covid-19 vaccination data public.

Vaccine’s emergency use authorization (EUA)

Pfizer and Moderna’s decision to disseminate press releases on the outcomes of the Covid-19 vaccine clinical trial before properly sharing all of their data with the larger scientific community has been a major problem for much of the pandemic. The U.S. government cannot enable pharmaceutical companies to influence health policies in this way, either directly or indirectly, or at least not give the impression that they are permitting it. Instead, the evidence should be examined by unbiased experts who then present their interpretations to the public and the government.

The idea that the bivalent boosters were rushed out to the public is only strengthened by this safety signal notice. People have questioned why the bivalent vaccine gained emergency use authorization (EUA) from the FDA rather than undergoing equivalent levels of human testing as earlier versions of the vaccines did in 2020 and 2021, as I reported for Forbes on September 12, 2022. The ensuing optics haven’t been all that fantastic, but this doesn’t necessarily imply that the bivalent boosters aren’t secure and efficient. All of this has further heightened the scepticism that anti-vaxxers like septic tanks have been trying to sow over the Covid-19 vaccinations. It has also demonstrated how adopting shortcuts for instant gratification isn’t always wise in the long run—a mistake both the Trump and Biden administrations have made. Is it really shocking, given everything, that just 15.9% of those aged five and older have received the Covid-19 bivalent boosters?

This safety signal news shouldn’t be a deterrent at this moment from purchasing the Covid-19 bivalent booster. In the end, there’s a good likelihood that this signal will turn out to be a serendipitous finding and sort of a nothing burger based on the information that is now known. The risks of contracting Covid-19 if you are not up to date on your vaccinations, however, are not the same.

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Source: Forbes