New Delhi: Pharma company AstraZeneca has admitted for the first time in UK high court documents that its COVID-19 vaccine, Covishield, may cause Thrombotic Thrombocytopenic Syndrome (TTS), a rare but serious condition.
TTS is a condition where blood clots (thrombosis) are formed in the brain (cerebral venous sinus thrombosis) or abdomen combined with low levels of platelets (thrombocytopenia), which are necessary for blood clotting.
The British-Swedish multinational pharmaceutical company, which is now contesting more than 50 court cases in the UK high court, has admitted in papers submitted to the court that the vaccine may cause the rare disease.
Severe or persistent headaches, blurred vision, shortness of breath, chest pain, swelling in the legs, abdominal pain, easy bruising or tiny blood spots under the skin are the symptoms of TTS.
However, the Centre for Disease Control and Prevention (CDC) classifies TTS into two tiers based on severity and symptoms. In tier 1, which is more severe and riskier and more common in young people, there are rare blood clots, like in the brain or gut, sometimes alongside more typical ones in the legs or lungs, low platelet count (below 150,000 per microliter) and positive anti-PF4 ELISA tests can help confirm diagnosis but aren’t always needed. In tier 2, the blood clots are in the legs or lungs, the platelet count is below 150,000 per microliter and a positive anti-PF4 ELISA test is necessary for diagnosis.
Experts say early diagnosis and treatment of TTS is crucial to protection from the life-threatening condition.
“TTS, or thrombosis with thrombocytopenia syndrome, involves blood clots in the brain or other parts of the body, along with a low platelet count. It’s a rare occurrence following specific types of vaccines and other causes. According to the WHO, adenovirus vector vaccines, in particular, have been rarely associated with this condition,” Dr Jayadevan, Co-Chairman of the National Indian Medical Association (IMA) Covid Task Force in Kerala told ANI.
Last year, the World Health Organization (WHO) reported that Thrombosis with Thrombocytopenia Syndrome (TTS) emerged as a new adverse event in people immunized with COVID-19 non-replicant adenovirus vector-based vaccines. This includes the AstraZeneca COVID-19 ChAdOx-1 vaccine and the Johnson & Johnson (J&J) Janssen COVID-19 Ad26.COV2-S vaccines.
The COVID-19 vaccine developed by the company along with the University of Oxford was sold in India as Covishield and in Europe as Vaxzevria. The viral vector vaccine is developed using the modified chimpanzee adenovirus ChAdOx1.
In India, it was marketed in partnership with Serum Institute of India (SII).
More than 50 cases have been lodged against the company in the UK High Court.
The first case was lodged in 2023 by Jamie Scott, who was left with a permanent brain injury after developing a blood clot and a bleed on the brain, since April 2021 when he received the vaccine, Indian Express reported.
