Pfizer Vaccine And Stroke: Is There A Link?

In January 2023, the US Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) announced a possible link between the Pfizer-BioNTech Covid-19 bivalent booster vaccine and ischemic stroke in people aged 65 and above. However, the CDC and FDA emphasised that the data did not prove causation and that further investigation was needed.

Following the announcement, some social media users claimed that the Pfizer Covid-19 bivalent vaccine caused strokes. However, this claim is unsupported and has been deemed misleading by health authorities. While the Vaccine Safety Datalink (VSD) surveillance system found a higher number of ischemic strokes in people aged 65 and above who received the Pfizer bivalent vaccine, this finding has not been replicated in other databases, clinical studies, or other countries.

It is important to note that vaccine safety monitoring systems are designed to be sensitive, and occasional false alarms can occur. As of January 2023, the CDC and FDA concluded that the data suggested it was very unlikely that the Pfizer bivalent vaccine increased the risk of ischemic stroke.

The Pfizer vaccine and risk of ischemic stroke in the elderly

The Pfizer-BioNTech COVID-19 bivalent vaccine has been associated with a possible "safety signal" by the Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA). This safety signal indicates a higher-than-expected number of ischemic strokes in individuals aged 65 and above who received the vaccine. However, it is important to note that this observed increase does not prove a causal relationship between the vaccine and the strokes.

An ischemic stroke occurs when a blood clot blocks an artery in the head, obstructing blood flow to parts of the brain. This interruption in blood supply can quickly lead to brain tissue death as the brain is deprived of oxygen. Due to the urgency of this condition, an ischemic stroke is considered a medical emergency.

Following the identification of the safety signal, the CDC and FDA conducted further investigations to assess the potential link between the Pfizer vaccine and ischemic strokes in the elderly. They analyzed data from various sources, including the Centers for Medicare and Medicaid Services database, the Veterans Affairs database, and the Vaccine Adverse Event Reporting System (VAERS) managed by both agencies.

The results of these investigations found no evidence of an increased risk of ischemic stroke among people aged 65 and older who received the Pfizer bivalent booster. A large study using the Centers for Medicare and Medicaid Services database revealed no elevated risk, and the VAERS system also showed no increase in reports of ischemic strokes following the updated vaccine. Additionally, the CDC emphasized that other countries using the updated bivalent vaccines had not observed a heightened risk for ischemic stroke.

While the investigations did not find a direct link between the Pfizer vaccine and ischemic strokes in the elderly, it is important to recognize that vaccines, like any medical intervention, can have side effects. The short-term outcomes of COVID-19 vaccination are generally promising, but some individuals may experience adverse events, especially concerning the nervous system. These side effects can include both mild and severe neurological complications, such as weakness, numbness, headache, dizziness, and in rare cases, more severe conditions like Bell's palsy, Guillain-Barre syndrome, and stroke.

In conclusion, while there was a preliminary safety signal suggesting a potential association between the Pfizer-BioNTech COVID-19 bivalent vaccine and ischemic strokes in individuals aged 65 and above, subsequent investigations by the CDC and FDA found no evidence of an increased risk. The benefits of COVID-19 vaccination continue to far outweigh the risks, and health authorities continue to recommend that everyone over the age of 6 months stays up to date with their COVID-19 vaccinations.

Vaccine-induced immune thrombotic thrombocytopenia

The pathogenesis of VITT is not yet fully understood, but it is believed to involve the production of antibodies against platelet factor 4 (PF4), a protein involved in coagulation. These antibodies are thought to activate platelets and trigger the coagulation cascade, leading to thrombosis. In addition, the destruction of activated and antibody-coated platelets by the reticuloendothelial system may contribute to thrombocytopenia. The incidence of VITT is estimated to be 3 to 15 cases per million initial vaccinations, with a higher incidence in those receiving adenovirus vector-based vaccines compared to mRNA-based vaccines such as those from Pfizer-BioNTech and Moderna.

The clinical presentation of VITT typically includes severe headache, abdominal pain, neurological symptoms, and leg pain or swelling, occurring 4 to 30 days after vaccination. Thrombocytopenia is almost universal by the time of presentation, and elevated D-dimer levels and reduced fibrinogen levels are commonly observed. Imaging studies often reveal thrombosis in the cerebral venous sinus, splanchnic venous system, pulmonary embolism, or arterial thrombosis.

The treatment of VITT includes intravenous immunoglobulin (IVIG) to inhibit platelet activation, corticosteroids, and non-heparin anticoagulants to combat the hypercoagulable state. Early screening and identification of VITT are crucial, as prompt treatment can significantly improve outcomes and reduce mortality.

Pfizer vaccine and stroke risk in younger people

The Pfizer vaccine has been associated with a slight increase in the risk of stroke, according to some studies. However, it is important to note that the link between the vaccine and stroke is not yet conclusive, and more research is needed to establish a direct causal relationship. While some individuals have reported experiencing strokes after receiving the Pfizer vaccine, the exact cause is often unclear, and other factors may be involved.

In one case, a 36-year-old Melbourne man named Peter Lee suffered a stroke two days after receiving his second Pfizer vaccine dose. Lee, who was previously "fit and healthy", experienced a "massive headache" shortly after vaccination and later collapsed while walking with his family. He was diagnosed with a stroke on his right brain capsule due to blood clots and spent two weeks in the hospital and rehab. Despite reporting the incident to Australia's medicines regulator, the Therapeutic Goods Administration (TGA), and other agencies, Lee was told that stroke is "not a recognised adverse event" of the Pfizer vaccine.

While the TGA does not currently recognise stroke as a known side effect of the Pfizer vaccine, a large study from the UK in August 2021 found an increased risk of stroke associated with the vaccine. The study, published in the British Medical Journal, examined records of over 29 million people who received a first dose of a Covid-19 vaccine and looked for complications up to 28 days after vaccination. The results showed that for every 10 million people vaccinated with Pfizer, an extra 143 strokes would be observed, equivalent to a rate of 1.43 per 100,000 people. However, it is important to note that the risk of stroke was still far higher after contracting Covid-19 compared to receiving the vaccine.

Another study from the Food and Drug Administration (FDA) investigated the risk of stroke in people aged 85 and older who received the Covid-19 vaccine and a high-dose flu shot together. The results suggested a slightly elevated risk of stroke in this age group, with three extra cases of transient ischemic attack (TIA) or "mini-stroke" per 100,000 immunizations. However, experts agree that more research is needed for clinical certainty, and the benefits of both vaccines still outweigh the risks.

It is worth noting that the overall risk of experiencing a stroke after receiving the Pfizer vaccine is relatively low, and the vaccine has been deemed safe and effective by regulatory agencies. Additionally, the benefits of vaccination in protecting against Covid-19 and its potentially severe complications far outweigh the potential risks associated with the vaccine. While the link between the Pfizer vaccine and stroke risk in younger people is not yet fully understood, individuals are advised to weigh the risks and benefits before making a decision regarding vaccination.

The role of the spike protein in impairing blood zeta potential

The SARS-CoV-2 spike protein is a major virulence factor that can cause harm through several mechanisms, including vascular damage. The spike protein can bind to the ACE2 receptor on platelets, leading to their activation and causing fibrinogen-resistant blood clots.

The zeta potential is the electrical charge difference between the second layer of ions surrounding a suspended particle and the bulk water surrounding it. A negative zeta potential is required to maintain colloidal stability.

The SARS-CoV-2 spike protein is positively charged and can disrupt the zeta potential, causing blood cells to clump together. This clumping, or "blood sludging", can lead to microstrokes throughout the body, which may underlie many chronic diseases.

Vaccines, particularly those that use the SARS-CoV-2 spike protein, can trigger microstrokes by impairing the zeta potential. The spike protein's positive charge is remarkably effective at clumping fluids together.

The SARS-CoV-2 spike protein is also highly disruptive to the glycocalyx, a network of negatively charged glycoproteins that protectively coat the endothelium. The endothelium has a high concentration of ACE-2 receptors, to which the spike protein binds.

In addition to the three recognized types of strokes (embolic, hemorrhagic, and thrombogenic), there is also a condition known as a transient ischemic attack (TIA), which may indicate dangerous impairments to the microcirculation. These microstrokes are too small to be seen with current imaging technologies and are therefore not believed to exist.

However, the SARS-CoV-2 spike protein is remarkably effective at causing all three recognized types of strokes, as well as TIAs. This is due to its specific positive charge, which attracts it to the negatively charged glycocalyx and endothelium.

By impairing the zeta potential and causing blood cells to clump together, the SARS-CoV-2 spike protein can lead to microcirculation issues and blood stagnation, resulting in a wide range of diseases.

The Pfizer vaccine and the risk of stroke compared to Moderna

In January 2023, the Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA) announced a possible "safety signal" for the Pfizer-BioNTech Covid-19 bivalent booster vaccine, indicating a potential increased risk of ischemic stroke in seniors aged 65 and older within 21 days of receiving the vaccine. However, it is important to note that this observed bump in ischemic strokes does not prove a causal relationship, and further investigations are needed to confirm or refute this association.

The CDC and FDA's announcement was based on data from the Vaccine Safety Datalink (VSD) surveillance system, which detected a higher-than-expected number of ischemic strokes within the specified timeframe. This safety signal has not been observed with other COVID-19 vaccines, such as the Moderna bivalent booster, or in other surveillance systems, analyses, or studies. Federal officials have advised that the safety signal likely does not indicate a "true clinical risk", and there have been no changes to the current vaccine recommendations.

While the link between the Pfizer booster and stroke risk is considered "very unlikely", the CDC is conducting further investigations to determine if there is a definitive association or if there are other explanations for the data. Experts agree that the potential benefits of the vaccine still far outweigh any possible risks, and there is no reason to delay or avoid getting the updated booster.

In a separate study, researchers found a slightly increased risk of stroke in adults aged 65 and older who received a high-dose flu shot, with an absolute risk of 1-2 strokes per 100,000 doses. This risk was even smaller when considering COVID-19 and influenza vaccinations together, with approximately 3 strokes or transient ischemic attacks per 100,000 doses. The study also found an elevated risk of strokes caused by blood clots in seniors aged 85 and older who received Pfizer vaccines, but not in those who received Moderna shots. However, the study was observational and could only show associations, not prove causation.

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