AstraZeneca has recognized the clotting risk associated with its vaccine. Here’s why Covishield recipients in India shouldn’t panic.

Global pharmaceutical giant AstraZeneca has acknowledged a rare side effect of its Covid-19 vaccine, developed in collaboration with researchers from Oxford University, which can lead to blood clotting and low platelet count post-immunization. In India, the same vaccine, known as Covishield and manufactured by the Serum Institute of India based in Pune, has been administered through 1.75 billion doses. Naturally, this raises concerns about the safety of the vaccine that many of us have received.

The company admitted to this side effect, known as Thrombosis with Thrombocytopenia Syndrome (TTS), during legal proceedings as it faces a lawsuit alleging severe harm and deaths caused by the vaccine, according to The Daily Telegraph. While this might be the company’s first acknowledgment in court, TTS has been well-documented and recognized in scientific literature. Cases of TTS emerged within months of vaccination campaigns commencing in Europe, prompting some countries to temporarily halt the use of the AstraZeneca vaccine.

The Government committee on Adverse Events Following Immunization (AEFI) reviewed at least 36 cases of TTS and confirmed 18 deaths from it in 2021, the initial year of Covid-19 vaccination in the country. However, it’s improbable that affected Indian patients can participate in the British petition due to legal obstacles such as approvals from different regulators and the vaccine being manufactured by an Indian company, which falls under Indian jurisdiction and laws.

Experts state that while TTS was reported early in the pandemic by European countries, it was very rare in India. A senior health ministry official, involved in discussions on the vaccination drive, mentioned, “TTS is an extremely rare side effect, even rarer among Indians and South Asians compared to Europeans. However, there is sufficient evidence to demonstrate that vaccination has saved lives — the benefits outweigh the risks.” Furthermore, the risk is not only rare but also higher only in the initial few weeks after the first vaccination. Most Indians have already received three shots, and a considerable amount of time has elapsed. Dr. Gagandeep Kang, Director of Global Health at the Bill and Melinda Gates Foundation, emphasized, “It’s crucial to reassure people that the risk of TTS occurs shortly after vaccination. We are well beyond the vaccination phase now.” Dr. Anurag Agarwal, Dean of Biosciences and Health Research at the Trivedi School of Biosciences of Ashoka University, stated, “The rare side effect was well-documented and scientifically accepted even during the vaccination campaigns. The benefits of vaccination during the peak of the pandemic outweighed the risk.” Additionally, the package insert for Covishield always included a warning about the rare condition.

A study published in Lancet Global Health in 2022 found that AstraZeneca reported rates of 8.1 TTS cases per million for the first dose and 2.3 TTS cases per million for the second dose. The study also highlighted geographical variations in TTS reporting, with the highest cases reported in Nordic countries (17.6 per million doses) and the lowest in Asian countries (0.2 per million doses).

Dr. Agarwal suggests that immunization is unnecessary for most people at present. “The antibody levels in the Indian population are currently very high despite the circulation of the virus. There is no need for vaccination unless someone is extremely immunocompromised. Even then, they should opt for newer vaccines that can protect against later variants like Omicron,” he advises. He also suggests considering other vaccines for younger women who were at a lower risk of severe disease at the time.

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