Vaccine-Induced Strokes: Myth Or Reality?

There have been reports of people experiencing strokes after receiving a COVID-19 vaccine. However, the link between COVID-19 vaccines and strokes is uncertain.

Some sources claim that the COVID-19 vaccines had an over 1,000-fold increased risk of blood clots in the brain compared to the flu vaccine and more than a 200-fold increased risk compared to all other vaccines. Blood clots in the brain are difficult to treat and can leave patients with devastating disabilities.

However, other sources claim that there is no evidence that the Pfizer bivalent vaccine is associated with an increased hazard of ischemic stroke compared to the monovalent or Moderna bivalent vaccines.

The most common form of stroke, where blood clots occur in arteries supplying blood to the brain, has not been previously described as the presenting feature of thrombosis following administration of the Oxford-AstraZeneca vaccine.

COVID-19 vaccines can cause unusual blood clots

The COVID-19 pandemic has had devastating impacts on people's lives globally. As of April 2021, the number of infected cases and disease severity continued to rise, causing an unprecedented crisis for many countries' public health systems. It is now well-known that patients with certain underlying diseases are at a greater risk of death if infected with COVID-19.

COVID-19 Vaccines

COVID-19 vaccines are a game-changer in minimizing the risk of infection, reducing disease severity, and increasing survival rates. They are particularly effective for patients with co-morbidities. However, it is important to note that some vaccines can cause rare side effects related to unusual blood clots.

Blood Clots and COVID-19 Vaccines

COVID-19 vaccines have been associated with serious side effects related to blood clots, leading to the temporary discontinuation of certain vaccines in some countries. Blood clots in the veins, including the brain, thigh, and lower leg, have been reported. In rare cases, blood clots can travel to the lungs, causing pulmonary embolism.

The cause of these unusual blood clots or thrombosis involves the activation of the immune system, which acts against platelets, resulting in low platelet levels and unwanted blood clot formation. This is not a new adverse reaction, as it is also a possible complication during the treatment of cardiovascular diseases.

Stroke-like Side Effects

Additionally, undesired stroke-like side effects have been reported in some countries, such as Thailand. These symptoms are typically temporary and mild to moderate in severity, with a lower chance of causing long-term disability. However, further clinical studies are needed to monitor long-term effectiveness and safety.

While COVID-19 vaccines are crucial in the fight against the pandemic, it is important to be aware of potential side effects, such as unusual blood clots, and to ensure their safe administration.

COVID-19 vaccines have been linked to an increased risk of stroke in older adults

There is a growing body of evidence that suggests a link between COVID-19 vaccines and an increased risk of stroke in older adults. While the exact mechanism is still under investigation, several reports and studies have indicated a potential association between the two. Here are some key findings and insights on this topic:

Case Reports and Studies:

• Ischemic Stroke: Ischemic stroke, which is caused by blood clots blocking blood flow to the brain, has been reported in a few cases following COVID-19 vaccination. This type of stroke is the most common form and accounts for about 87% of all strokes. The cases described in these reports involved young adults and older individuals who received the Oxford-AstraZeneca vaccine. The patients experienced symptoms such as headaches, weakness, confusion, and vision loss. Some of these cases resulted in severe outcomes, including death.
• Cerebral Venous Sinus Thrombosis (CVST): CVST is a rare form of stroke that typically affects younger patients, especially women. It has been reported in association with COVID-19 vaccination, particularly with the Oxford-AstraZeneca and Johnson & Johnson vaccines. CVST can lead to increased intracranial pressure and, in some cases, hemorrhagic stroke. The clinical course of CVST following COVID-19 vaccination may be more severe than CVST not associated with the vaccine.
• Vaccine-Induced Thrombotic Thrombocytopenia (VITT): VITT is a condition characterized by blood clots and low platelet counts. It has been observed in some individuals following COVID-19 vaccination, particularly with the Oxford-AstraZeneca vaccine. VITT can lead to both ischemic and hemorrhagic stroke. The management of VITT-associated stroke is challenging and may differ from standard stroke treatment.
• Increased Risk in Older Adults: A study published in npj Vaccines compared the risk of ischemic stroke in older adults aged 65 and over who received the Pfizer bivalent COVID-19 booster vaccine with those who received the monovalent or Moderna bivalent boosters. The results showed a reduced hazard of ischemic stroke in the Pfizer bivalent cohort compared to the other cohorts, suggesting that the bivalent boosters might provide stronger protection against severe COVID-19 infection and hospitalization.
• Gender Disparity: Women, especially those of reproductive age, appear to be at a higher risk of certain types of blood clots in the brain, such as cerebral venous thrombosis. This disparity has raised concerns, and some experts have called for further investigation and caution in vaccine recommendations for women.
• Underreporting and Data Limitations: It is important to note that the reported cases and studies may not capture the full scope of the issue due to underreporting in adverse event databases like VAERS. Additionally, the data available may not represent a random sampling of the entire population, and there are challenges in processing and analyzing the large volume of reports.

Mechanisms and Pathophysiology:

The exact mechanisms underlying the potential link between COVID-19 vaccines and stroke are not yet fully elucidated. However, some proposed mechanisms include:

• Immune Response: The COVID-19 vaccines are designed to stimulate an immune response against the SARS-CoV-2 virus. In some individuals, this immune activation may lead to the production of antibodies that act against platelets, resulting in low platelet counts (thrombocytopenia) and the formation of blood clots (thrombosis). This phenomenon is known as vaccine-induced immune thrombotic thrombocytopenia (VITT).
• Spike Protein: The SARS-CoV-2 spike protein, which is targeted by the vaccines, may also play a role. The spike protein in both the virus and the vaccine could potentially contribute to blood clotting issues. However, more research is needed to understand the exact mechanisms involved.

Recommendations and Future Directions:

The available evidence suggests that COVID-19 vaccines may be associated with an increased risk of stroke in older adults, particularly in certain subgroups such as women of reproductive age. However, it is important to note that the overall benefits of COVID-19 vaccination in preventing severe disease and reducing mortality may still outweigh the risks. Here are some key considerations and recommendations:

• Surveillance and Monitoring: Continued surveillance and monitoring of adverse events following COVID-19 vaccination are crucial. This includes reporting suspected cases to relevant authorities and databases to improve data collection and understanding of the potential risks.
• Individual Risk Assessment: Healthcare providers and individuals should carefully consider the benefits and risks of COVID-19 vaccination, especially for those with underlying health conditions or specific risk factors for stroke. Personalized risk assessments can help guide vaccination decisions.
• Prompt Diagnosis and Treatment: Clinicians should be vigilant in recognizing and managing stroke symptoms, especially in individuals who have recently received a COVID-19 vaccine. Prompt diagnosis and appropriate treatment are essential for improving outcomes.
• Further Research: More research is needed to fully understand the mechanisms underlying the potential link between COVID-19 vaccines and stroke. Additionally, long-term studies can help elucidate the long-term effects and safety profiles of the vaccines.
• Vaccine Development and Alternatives: The development of safer and more effective COVID-19 vaccines remains a priority. Additionally, exploring alternative prevention and treatment strategies, such as antiviral medications and improved therapeutics, can help provide additional options to combat the pandemic.

COVID-19 vaccines can cause blood clots in the brain

Overview

It has been found that the COVID-19 vaccines carry a much higher risk of blood clots in the brain compared with other vaccines. Blood clots that block blood flow to the brain account for about 87% of all strokes. These clots in the brain are difficult to treat and often leave patients with devastating disabilities.

Study Findings

A study by Dr. Peter McCullough and colleagues found that the COVID-19 vaccines had an over 1,000-fold increased risk of blood clots in the brain compared to the flu vaccine and more than a 200-fold increased risk compared to all other vaccines. In the three years since the COVID-19 vaccine rollout, they found 5,137 reports of a brain blood clot event in those who received one or more COVID-19 shots. Meanwhile, VAERS data showed only 52 reports since 1990 of a brain blood clot event following a flu vaccine and 282 since 1990 following all other vaccinations.

COVID-19 Vaccines and Blood Clots

The spike protein in both the SARS-CoV-2 virus and the COVID-19 vaccine can cause serious blood clotting. The COVID-19 vaccines may trigger stroke with thrombotic thrombocytopenia with or without the presence of anti-platelet factor 4 antibody (anti-PF4 antibody). This association between thrombosis and thrombocytopenia rarely occurs in other conditions such as thrombotic thrombocytopenic purpura, heparin-induced thrombocytopenia (HIT), and disseminated intravascular coagulation (DIC).

Management and Treatment

The management of COVID-19 vaccine-associated blood clots in the brain is challenging and complex. The use of non-heparin anticoagulants and intravenous immunoglobulin (IVIg) can be related to a low probability of death or dependency at the end of hospital admission. IVIg prevents platelet activation by PF4 antibodies and rapidly restores the platelet count. However, clinicians should avoid all forms of heparin in the treatment of COVID-19 vaccine-associated blood clots in the brain.

COVID-19 vaccines can cause cerebral venous sinus thrombosis

CVST has been reported in patients following the Oxford-AstraZeneca, Johnson & Johnson, and Moderna vaccines. The most common clinical symptom of CVST seen after COVID-19 vaccination was headache. The clinical course of CVST after COVID-19 vaccination may be more severe than CVST not associated with COVID vaccination.

CVST after COVID-19 vaccination is associated with vaccine-induced immune thrombotic thrombocytopenia (VITT), a rare and serious condition. VITT is characterised by the presence of anti-platelet factor 4 (anti-PF4) antibodies, which are typically detected in heparin-induced thrombocytopenia (HIT). However, anti-PF4 antibodies in VITT are thought to be produced as a result of molecular mimicry between viral proteins and platelet antigens, or as a result of cross-reactivity with antibodies produced against viral spike proteins.

The diagnosis of VITT is challenging due to its diverse clinical manifestations. It is recommended that patients presenting with symptoms suggestive of thrombotic events after COVID-19 vaccination are urgently evaluated for VITT using comprehensive diagnostic criteria. This includes laboratory tests such as a complete blood count, PF4-ELISA, fibrinogen level, and imaging for thrombosis.

The management of CVST following COVID-19 vaccination is complex and may differ from the standard treatment of CVST. Low molecular weight heparin is commonly used in the treatment of CVST but may worsen outcomes in CVST associated with VITT. Non-heparin anticoagulants and intravenous immunoglobulin have been recommended with various success rates.

COVID-19 vaccines can cause arterial thrombosis

Arterial thrombosis has been observed following the administration of the Oxford-AstraZeneca COVID-19 vaccine, with several cases reported in young adults. In these cases, patients experienced symptoms such as intermittent headaches, drowsiness, weakness in the face, arms and legs, and confusion. In some instances, patients also presented with venous thrombosis, extremely low platelet counts, and antibodies to platelet factor 4 (PF4).

While the exact mechanism underlying the development of arterial thrombosis following COVID-19 vaccination is not yet fully understood, it is believed to be associated with an abnormal immune response. This abnormal response may involve the production of antibodies that act against platelets, leading to low platelet counts and the formation of blood clots.

The risk of developing arterial thrombosis after receiving a COVID-19 vaccine is very low, and it is important to note that the benefits of vaccination far outweigh the risks. However, it is crucial to be aware of this potential side effect and seek urgent medical attention if any symptoms suggestive of thrombotic events occur after vaccination.

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