Multicenter retrospective and prospective observational study based on the collection of sequential anonymized data from principal Italian ITP centers, to describe the clinical course of ITP patients becoming infected by SARS-CoV-2 and of COVID-19 patients developing de novo ITP.

Multicenter retrospective and prospective observational study based on the collection - through pre-piloted electronic CRFs - of sequential anonymized data from principal Italian ITP centers representative of national geographical distribution, to evaluate, during a 2-years study period, both the cumulative incidence COVID-19 occurring in patients with prior or ongoing ITP (COVID-19 in ITP) and the cumulative incidence of de novo ITP manifesting during COVID-19 (ITP in COVID-19). Data will be collected to describe the clinical course of patients in the two groups. The enrolment period will last 24 months or terminate at the last day of 1-month-COVID-19 free in Italy, whichever comes first. Each patient will be followed up to the first visit scheduled as per common center practice, including at least six months after hospital discharge or end of quarantine home confinement.

Inclusion Criteria:

• Age ≥ 18 years
• Confirmed diagnosed of ITP (ITP could be past, ongoing, persistent >3 months, chronic >12 months) in patients that are in regular follow-up (at least once a year) and who have been diagnosed with COVID-19
• All patients who develop de novo ITP from 1st January 2020 to the end of study after a diagnosis of COVID-19 or during the first 6 months after COVID-19 recovery
• Signed informed consent

Exclusion Criteria:

• All subjects not fitting inclusion criteria

Adult patients with ITP becoming infected by SARS-CoV-2 and adult patients with COVID-19 developing de novo ITP, during a study period of two years, starting from 1st January 2020