AstraZeneca, the manufacturer of the AZD1222 vaccine, known in India as Covishield, has revealed that its vaccine may lead to a rare but serious side effect called Thrombosis with Thrombocytopenia Syndrome (TTS). This syndrome is characterized by low platelet levels and the formation of blood clots.

The acknowledgment came to light through court documents filed in the United Kingdom, where AstraZeneca is facing lawsuits related to health claims associated with its vaccine. The company defended itself against claims but admitted to the potential link between its vaccine and TTS in very rare cases. 

The revelation by AstraZeneca surfaced in the context of a lawsuit filed by individuals who experienced adverse effects after receiving the Covishield vaccine. Notably, a case filed by Jamie Scott, who suffered a permanent brain injury after vaccination, has drawn attention to the matter.

Previous Reports and Concerns

Concerns regarding TTS have been circulating for some time. In early 2021, before the rollout of Covid-19 vaccines in India, the government issued cautionary guidelines regarding Covishield, especially for individuals with thrombocytopenia. European countries also temporarily paused AstraZeneca vaccinations due to reported cases of blood clotting.

Symptoms of TTS

TTS can manifest through various symptoms, including breathlessness, chest or limb pain, skin bruising beyond the injection site, headaches, and numbness in body parts. It poses risks of blood flow restriction, potentially leading to severe complications like stroke, heart attack, or breathing problems.

Incidents in India

In India, reports of potential thromboembolic events associated with Covishield emerged in 2021. While the government initially reported 26 such cases, more recent data from the committee on Adverse Events Following Immunization (AEFI) confirms at least 36 cases of TTS linked to Covishield. The Ministry of Health termed the risk as "minuscule" and emphasized the vaccine's overall benefits in preventing Covid-19 infections and deaths.

Comparison with Covaxin

In contrast to Covishield, India's indigenous vaccine Covaxin, manufactured by Bharat Biotech, has not reported any potential thromboembolic events. The Ministry of Health highlighted scientific literature suggesting a lower risk of blood clotting among individuals of South and Southeast Asian descent compared to those of European descent.

WHO Classification Update

In 2023, the World Health Organization (WHO) updated its classification to include vaccine-induced immune thrombotic thrombocytopenia (VITT) within the spectrum of TTS, underscoring the importance of monitoring and addressing these rare but serious vaccine-related side effects.

As the discussion around vaccine safety continues, health authorities worldwide emphasize the importance of weighing the rare risks against the substantial benefits offered by vaccination programs in combating the Covid-19 pandemic.