Inactivated COVID-19 vaccine CoronaVac associated with TTP

A study published in the journal Frontiers of Medicine has found an association between the inactivated COVID-19 vaccine CoronaVac from Sinovac Biotech and immune thrombotic thrombocytopenic purpura (TTP). The study presents two cases of TTP occurring after the administration of the vaccine, highlighting the potential association between this type of vaccine and TTP. The article also provides an analysis of TTP incidence in the Nanjing area of China, suggesting a possible correlation between COVID-19 vaccination and the occurrence of TTP. 

The first case details a 23-year-old female who developed symptoms of TTP three days after receiving her second dose of CoronaVac. Initially presenting with dizziness and weakness, her condition progressed to include thrombocytopenia, anaemia, elevated lactate dehydrogenase (LDH), and α-hydroxybutyrate dehydrogenase (α-HBDH) levels, with further deterioration indicated by decreased platelet count, haemoglobin levels, and the presence of schistocytes in peripheral blood smears. Her condition improved following the introduction of glucocorticoids, plasma exchange, and rituximab, with a gradual return to normal values for ADAMTS13 antigen and inhibitory antibodies. 

The second case involves a 45-year-old female who experienced fever and muscle soreness five days after her second dose of CoronaVac. She presented with high fever, haematological abnormalities, acute renal failure, and thrombocytopenia. She was finally diagnosed with TTP based on the presence of schistocytes in peripheral blood smears and significantly low ADAMTS13 levels. Treatment with plasma exchange and glucocorticoids led to her recovery.

The study also examines a series of TTP cases from 14 hospitals in the Nanjing area, showing an increase in TTP incidence from 2019 to 2022 that may be related to COVID-19 vaccination. The data suggests that while TTP is rare — about one new case per million — the incidence rates increased in years following the initiation of COVID-19 vaccination campaigns. It is hypothesised that the increase in TTP cases could be associated with the vaccines, although a direct causal link is not established.

The report delves into the potential mechanisms by which COVID-19 vaccines could trigger TTP, focusing on the autoimmune response that may cross-react with ADAMTS13, leading to its deficiency and subsequent TTP development. The report emphasises the importance of accurate and timely diagnosis of TTP, as misdiagnosis can lead to inappropriate treatment, which may exacerbate the condition. Furthermore, it underscores the critical nature of plasma exchange and immunosuppression in the treatment of TTP, as evidenced by the successful management of the reported cases.