Inclusion Criteria:  non-critically ill young adults' patients with COVID-19 admitted to our hospital will have confirmed unusual thrombotic events and accept recruitment to this study.  After that, we will focus only on previously healthy patients without pre-existing prothrombotic factors and presented with COVID-19 related unusual thrombotic events  Exclusion Criteria:  COVID-19 patients below 18 years and above 40 years COVID-19 patients diagnosed as critically ill COVID-19 COVID-19 patients with pre-existing diabetes mellitus (DM), hypertension, ischemic heart disease (IHD), valvular heart disease, cardiomyopathy and chronic arrhythmia, dyslipidemia, metabolic syndrome, chronic kidney disease, liver disease, nephrotic syndrome, previous autoimmune disease, and malignancy COVID-19 patients with chronic lung disease or immune compromise COVID-19 pregnant women COVID-19 patient with history of thrombosis/ psychiatric disorders/ drug abuse COVID-19 patient previously diagnosis with congenital thrombophilia COVID-19 patient with drug history could induce thrombosis.  COVID-19 patient unwilling to be followed up.  Patients are previously diagnosed with one or more risk factors of thrombosis