AstraZeneca has admitted in court documents that its Covid vaccine, Covishield and Vaxzevria, can cause Thrombosis Thrombocytopenia Syndrome (TTS) in very rare cases. This admission came in response to a lawsuit alleging that the vaccine, developed with the University of Oxford, caused death and serious injury in dozens of cases.
Despite this admission, AstraZeneca maintains that the vaccine is safe and effective. The company points to extensive clinical trial data and real-world evidence that support this claim. Regulatory agencies worldwide also continue to assert that the benefits of vaccination outweigh the risks of such extremely rare side effects.
The Serum Institute of India produced the COVID-19 vaccine named Covishield using a viral vector platform. This platform uses a modified chimpanzee adenovirus to carry the COVID-19 spike protein into human cells. This cold virus cannot infect the receiver but teaches the immune system to prepare a defense against such viruses.
The same technology was used to develop vaccines for viruses like Ebola.
In 2023, the World Health Organization (WHO) reported that TTS emerged as a new adverse event following immunization with COVID-19 non-replicant adenovirus vector-based vaccines. This refers to the AstraZeneca COVID-19 ChAdOx-1 vaccine and the Johnson & Johnson (J & J) Janssen COVID-19 Ad26.COV2-S vaccines.
The WHO issued interim emergency guidance to increase awareness about TTS and help healthcare providers assess and manage potential cases.
However, Union Health Minister Mansukh Mandaviya stated in March 2024 that the ICMR has conducted a detailed study showing that the COVID-19 vaccine is not responsible for heart attacks. He attributed such events to individual lifestyle factors such as binge drinking.