The AstraZeneca COVID-19 vaccine has been associated with a rare but serious side effect known as vaccine-induced immune thrombotic thrombocytopenia (VITT). This condition involves the formation of blood clots, which can lead to severe complications, including death. The occurrence of VITT is extremely rare, with reports of 73 deaths out of nearly 50 million doses administered in the UK alone. Despite its rarity, the condition has been linked to a high mortality rate, particularly among young and healthy individuals.
VITT is characterized by the onset of symptoms 5 to 30 days after vaccination, a low platelet count, and the presence of a blood clot. The condition has been observed to affect individuals regardless of their age or health status, with no specific risk factors identified 4. The risk of death associated with VITT is significant, with a 73% mortality rate in patients who also experience very low platelet counts and brain bleeds following blood clots in the brain.
The European Medicines Agency (EMA) has emphasized that the benefits of the AstraZeneca vaccine far outweigh its risks, including the rare occurrence of VITT. However, the potential for devastating or fatal outcomes, such as brain blood clots, has led some regulators and segments of the public to consider the risk unacceptable, even if it is extremely rare.
Research from Germany and Norway has identified unusual antibodies in individuals who developed serious and sometimes fatal blood disorders after receiving the AstraZeneca vaccine. These antibodies activate platelets, a blood component involved in clotting. Younger individuals appear more susceptible to these reactions, but no pre-existing health conditions are known to predispose people to the rare reaction.
Based on these findings, the Joint Committee on Vaccination and Immunisation (JCVI) recommended offering an alternative to the AstraZeneca vaccine for individuals under the age of 40, where possible, while infection rates remain low. This recommendation reflects the ongoing efforts to mitigate the risk associated with VITT and to ensure the safety and efficacy of COVID-19 vaccines.
Can The VITT Condition Be Prevented Or Treated?
Vaccine-induced Immune Thrombotic Thrombocytopenia (VITT) is a rare but serious condition that can occur following vaccination, particularly with the AstraZeneca/Johnson & Johnson adenoviral vaccines. The condition is characterized by the development of blood clots and a low platelet count, which can lead to severe complications, including death. Given the rarity of VITT, prevention strategies are not straightforward, but understanding the condition and its management is crucial for healthcare providers and patients.
Diagnosis and Management
Diagnosis: A definitive diagnosis of VITT requires meeting all five criteria, which include the presence of any venous or arterial thrombosis (often cerebral or abdominal), severe headache, visual changes, abdominal pain, nausea and vomiting, back pain, shortness of breath, leg pain or swelling, petechiae, easy bruising, or bleeding within 4 to 42 days after vaccination.
Urgent Evaluation: If any of the symptoms mentioned above develop after vaccination, urgent medical evaluation is indicated. This includes a complete blood count (CBC) with platelet count and peripheral smear, imaging for thrombosis based on signs/symptoms, and PF4-ELISA (HIT assay) to draw blood prior to any therapies.
Treatment: The treatment of VITT is primarily focused on managing the symptoms and complications associated with the condition. This may involve the use of anticoagulants to prevent further blood clotting, platelet transfusions in cases of life-threatening bleeding, and supportive care to manage any complications such as brain bleeds or other organ damage.
Avoidance of Heparin: It is recommended to avoid the use of heparin until VITT has been ruled out or until an alternative other plausible diagnosis has been made. This is because heparin can interfere with the diagnosis and treatment of VITT.
Referral to Tertiary Care Center: If VITT is confirmed, it is advised to consider referral to a tertiary care center for further management and monitoring.
Prevention and Risk Management
While there is no direct prevention for VITT, the risk of developing the condition can be minimized by ensuring that individuals are evaluated promptly if they experience symptoms that could indicate VITT. Healthcare providers should be vigilant for these symptoms and recommend immediate evaluation if they occur within the specified timeframe after vaccination. Additionally, the ongoing research and updates on VITT will provide further insights into the condition and potential prevention strategies.
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References
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9538855/
- https://www.hematology.org/covid-19/vaccine-induced-immune-thrombotic-thrombocytopenia
- https://www.acc.org/Latest-in-Cardiology/Articles/2021/04/01/01/42/Vaccine-induced-Thrombotic-Thrombocytopenia-VITT-and-COVID-19-Vaccines
