ABSTRACT
BACKGROUND: Immune thrombocytopenic purpura (ITP) relapse following vaccination remains poorly reported in the adult population. OBJECTIVES: This report details real world data from the largest single-center cohort of ITP relapse following severe acute respiratory syndrome (SARS-CoV-2) vaccination. METHODS: The vaccination status of 294 patients under active follow-up was reviewed. A total of 17 patients were identified resulting in an incidence of ITP relapse following SARS-CoV-2 vaccination in this cohort of 6.6% and an incidence of newly diagnosed ITP following SARS-CoV-2 vaccination of 1.4%. RESULTS: Patients were noted to develop marked deviation of platelet count from baseline following vaccination (P =< .0001). Fourteen patients had a prior diagnosis of ITP and median follow-up following diagnosis was 4 years (range 0-45 years). Days from vaccination to presentation ranged from 2-42 (median 14) and the follow-up period was 34 weeks. Fifteen patients (88%) presented with symptoms and all 17 patients developed symptoms during the follow-up period. Nine patients (53%) received a second dose of vaccine during the follow-up period with seven patients (78%) requiring therapeutic support to facilitate second vaccination. Decision to treat patients was multi-factorial and aimed at decreasing bleeding symptoms and obtaining a platelet count >30 × 109 /L. Sixteen patients (94%) required therapeutic intervention and at the end of the follow-up period, four patients (24%) remained unresponsive to treatment with a platelet count <30 × 109 /L. CONCLUSION: Vaccination of ITP patients continues to have important clinical benefit; however, recommendations for patients who relapse remain lacking. This report outlines the real-world patient outcomes in the era of widespread SARS-CoV-2 vaccination.