A Summary
The AstraZeneca vaccine, also known as AZD1222 or Covishield in India, is a viral vector vaccine designed to protect against the SARS-CoV-2 virus, the causative agent of Covid-19. It utilizes a weakened version of a common cold virus found in chimpanzees, modified to carry the gene for a protein from the SARS-CoV-2 virus. Upon injection, the vaccine prompts the human immune system to produce antibodies and activate T-cells to fight off the virus if exposed.
The vaccine was developed through a collaboration between the University of Oxford and the British-Swedish pharmaceutical company AstraZeneca. The Pune-based pharma firm Serum Institute of India (SII) partnered with them in January 2021 to manufacture the Covishield vaccine for India and other low- and middle-income countries.
As of April 30, 2024, over 1.7 billion doses of Covishield were administered in India as part of the world's largest vaccination program. The vaccine has played a crucial role in vaccination campaigns worldwide, including India's efforts to curb the spread of Covid-19 and achieve herd immunity.
However, the vaccine faced scrutiny and bans in several countries following reports of blood clots in vaccinated individuals. In February 2023, AstraZeneca acknowledged in court documents that the vaccine can cause a rare side effect known as Thrombosis with Thrombocytopenia Syndrome (TTS). However, the company also stated that TTS can occur even without vaccination and that expert testimony is required to determine causation in individual cases.
AstraZeneca now faces a class-action lawsuit claiming that its vaccine caused serious injuries and fatalities.
Understanding TTS
Thrombosis with Thrombocytopenia Syndrome (TTS) is a rare but serious condition associated with certain Covid-19 vaccines, particularly adenovirus vector vaccines like AstraZeneca and Johnson & Johnson's Janssen vaccine. It involves the formation of blood clots in combination with low platelet levels (thrombocytopenia).
TTS typically presents with blood clots in unusual locations, such as the brain (cerebral venous sinus thrombosis) or abdomen, along with low platelet counts. Symptoms include severe headache, blurred vision, difficulty speaking, chest pain, abdominal pain, shortness of breath, and leg swelling.
TTS is thought to result from an immune response triggered by the adenovirus vector used in the vaccines, which activates platelets and forms blood clots.