AstraZeneca Covishield Controversy

AstraZeneca Covishield Controversy

• Controversy: AstraZeneca's Oxford-AstraZeneca vaccine (Covishield in India) has faced controversy due to rare side effects, specifically Thrombosis with Thrombocytopenia Syndrome (TTS).

• TTS (Vaccine-Induced Prothrombotic Immune Thrombocytopenia): A rare immune reaction triggered by adenovirus vectors leading to blood clots (thrombosis) and low platelet count (thrombocytopenia).

• Prevalence: TTS is more common in healthy young women (~30 years old), occurring at a rate of approximately 1-2 cases per 100,000. At the population level, it's estimated at 2-3 cases per million vaccinated individuals.

• India's Use: India administered nearly 1.75 billion doses of Covishield, vaccinating approximately 80% of its vaccinated population.

• Temporary Suspensions: Several European countries, the UK, USA, and Australia temporarily paused Covishield use due to reported TTS cases, although benefits were deemed to outweigh risks.

• WHO Classification: In 2023, the WHO classified Vaccine-induced immune thrombotic thrombocytopenia (VITT) as a type of TTS.

• India's Response - Concerns: Pre-vaccine rollout, India issued guidelines cautioning against Covishield use in individuals with low platelet counts. In May 2021, 26 potential blood clot cases were reported, (0.61 cases per million doses).

• India's Response - Position: India's government maintained the vaccine's positive benefit-risk profile and that the risk is low. Comparatively, no such reports were seen for indigenous vaccine Covaxin. The risk of blood clots is also noted to be lower in South and Southeast Asians as compared to Europeans.

Oxford-AstraZeneca Vaccine

• Development: Developed by a collaboration between Oxford University and AstraZeneca using a modified chimpanzee adenovirus (ChAdOx1).

• Vaccine Type: Viral vector vaccine containing the SARS-CoV-2 spike protein.

• Components: Contains full-length, codon-optimized SARS-CoV-2 spike protein coding sequence along with a tissue plasminogen activator (tPA) leader sequence.

• Collaboration Partners: Oxford University's Jenner Institute, Vaccitech, Oxford Sciences Innovation, Google Ventures, Sequoia Capital, and others.

• First approvals and Use: The UK issued the first emergency use approval for the vaccine. The first vaccination outside clinical trials occurred on January 4, 2021.

• Company: AstraZeneca, British-Swedish, headquartered in Cambridge.

• Other Reported Side Effects:

  • Cerebral venous sinus thrombosis (CVST) - Blood clots in the brain
  • Guillain-Barré syndrome - Immune system disorder affecting nerves
  • Myocarditis and pericarditis - Inflammation of heart tissue

AstraZeneca: The Company

• History: Founded in 1999 through the merger of Astra AB (Sweden) and Zeneca Group (UK). Zeneca was itself formed from the pharmaceutical operations of Imperial Chemical Industries.

• Leadership: Michel Dame is Chairman and Pascal Soriot is CEO.