Understanding Thrombosis with Thrombocytopenia Syndrome (TTS), a Rare Effect of AstraZeneca’s Covishield Vaccine

Thrombosis with Thrombocytopenia Syndrome (TTS) is a rare condition associated with certain COVID-19 vaccines. The condition involves the formation of blood clots in unusual areas of the body, accompanied by a decrease in the number of platelets in the blood. Platelets are crucial for clotting, so a low count can be dangerous.

TTS has been observed in individuals who received adenoviral vector COVID-19 vaccines, including Vaxzevria, Covishield (AstraZeneca), and the Johnson & Johnson/Janssen COVID-19 vaccine. A lawsuit against the Serum Institute of India alleged serious harm and deaths linked to Covishield, a vaccine developed by AstraZeneca and Oxford University. Court documents indicated that in rare cases, Covishield could result in TTS.

This vaccine was widely administered in India during the COVID-19 pandemic. The CDC has categorized TTS into two tiers, with Tier 1 cases being typically more severe and posing greater risks. TTS is more prevalent among younger individuals.

Common indicators of TTS include a low platelet count (below 150,000 per microliter) and the necessity of a positive anti-PF4 ELISA test for diagnosis. The body’s immune response to the vaccine may trigger the development of TTS, as antibodies created in response to the vaccination attack a protein involved in blood clotting. Although positive anti-PF4 ELISA tests can aid in confirming the diagnosis, they are not always required.