Thrombotic thrombocytopenic purpura (TTP) after COVID-19 vaccination: A systematic review of reported cases

Introduction With the advent of COVID-19 vaccines, hospitalization rates and progression to severe COVID-19 disease have reduced drastically. Most of the adverse events reported by the vaccine recipients were minor. However, autoimmune hematological complications such as vaccine-induced immune thrombotic thrombocytopenia (VITT), immune thrombocytopenic purpura (ITP) and TTP have also been reported post-COVID-19 vaccination. Given this, we sought to reflect on the existing cases of TTP, whether de novo or relapsing, reported after COVID-19 vaccination to further gain insight into any association, if present, and outcomes. Methods We searched PubMed, Embase, and Ebsco databases for published individual case reports on the occurrence or relapse of TTP after receiving any COVID-19 vaccine. A total of 23 articles (27 patients) were included in this qualitative analysis. Results The mean age for the patients who developed de novo TTP post-COVID-19 vaccination was 51.3 years. TTP episodes were seen mostly after BNT162b2 vaccine, followed by mRNA-1273 vaccine. All patients with immune TTP except one received plasma exchange (PLEX) and steroids. One patient passed away after two days of hospitalization, likely due to a sudden cardiovascular event. Conclusion Our review underscores the importance of in-depth anamnesis before vaccination and outlines characteristics of predisposed individuals. Evaluation of post-vaccine thrombocytopenia must include the possibility of TTP given the associated fatality with this condition.