Covid-19 vaccination in patients with immune-mediated thrombotic thrombocytopenic purpura: a single-referral center experience

Cases of immune-mediated thrombotic thrombocytopenic purpura (iTTP) following the administration of vaccines have been described in literature 1-2. Recently, de novo and relapsed iTTP have been reported during SARS-Cov-2 infection3-5 and after the vaccine, mainly with adenoviral and rarely with messenger mRNA vaccines6-11. The French Reference Center for Thrombotic Microangiopathies conducted a large multicenter retrospective study to investigate the possible link between COVID-19 vaccine and the new-onset or recurrence of iTTP. Results showed that vaccination does not trigger relapse in these patients, particularly if they are regularly monitored and do not have low ADAMTS13 enzyme activity12. Similar results were described by the Vaccine Adverse Event Reporting System (VAERS), the US passive surveillance system for adverse events after immuniziation13. COVID-19 vaccine did not increase the risk of de novo or relapsed iTTP, except in individuals in hematologic remission with extremely low ADAMTS13 activity (<20%)12-13. We report here our single-center experience in 33 patients with preexisting iTTP, followed at our Institute, who received regular mRNA COVID-19 vaccination