Another side effect linked with AstraZeneca COVID vaccine: All about VITT

Amidst concerns around TTS or Thrombotic Thrombocytopenia Syndrome, the side effect the drug maker has admitted in court documents, one more side effect has come to the fore in connection with AstraZeneca's COVID vaccine.

As per a report, AstraZeneca's COVID vaccine can also cause VITT or Vaccine-Induced Immune Thrombocytopenia and Thrombosis, a blood clotting disorder.

According to the American Society of Hematology, signs of VITT develop 4 to 42 days after vaccination. The key signs are severe headache, visual changes, abdominal pain, nausea and vomiting, back pain, shortness of breath, leg pain or swelling and easy bruising.

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A 2022 study published in the Journal of Family Medicine and Primary Care, highlights the occurrence of VITT. "Vaccination is supposed to be the most reliable means to end the COVID 19 pandemic, but recently there have been reports of thrombosis and thrombocytopenia in patients receiving the vaccine especially ChAdOx1 nCoV-19 (AstraZeneca University of Oxford and Serum Institute of India). This has been termed as vaccine-induced immune thrombotic thrombocytopenia (VITT), thrombosis with thrombocytopenia syndrome (TTS) and vaccine-induced prothrombotic immune thrombocytopenia (VIPIT)," it says. "The incidence of VITT ranges widely from one case per 26,000 to one case per 127,000 doses of AstraZeneca/COVISHIELD administered in countries like Norway and Denmark reporting the highest rates," the report by researchers from the Department of Medicine, Tata Main Hospital, Bistupur, Jamshedpur, Jharkhand, India adds.

Development of symptoms 4–42 days after exposure to COVID vaccine.

Venous or arterial thrombosis at any site.

Thrombocytopenia (platelet count <150 × 109/L).

Positive platelet-factor 4 heparin-induced thrombocytopenia (PF4 HIT) by ELISA.

D-dimer elevated at least four times the upper limit of normal.

In VITT, individuals make antibodies that stick to one of the body’s own proteins called the PF4 or the platelet factor 4. This results in the formation of large structures called immune complexes. A Conversation report explains: These complexes bind to and activate small cells called platelets that are vital for blood clotting. Normally, platelets float around in the blood in an inactive state, but once activated they spread out, get very sticky, and spew out hundreds of different chemicals. In VITT, platelets are strongly activated and this causes blood clots. The blood clots commonly affect the veins surrounding the brain, which is a very unusual and rare site for clots. Many people with VITT reported excruciating headaches, which continue to affect survivors.