Study Regarding the Incidence of Anti-platelet Factor 4-antibodies in Patients Aged 18 to 60 Years With Spontaneous or Infection- or Vaccine-associated or Recurrent Venous and/or Arterial Thrombosis

Inclusion Criteria: * Age between 18-60 years * Written informed consent of the patient * Spontaneous arterial and/or venous thrombosis * infection-associated arterial and/or venous thrombosis within 30 days of infection * Vaccine-associated arterial and/or venous thrombosis within 30 days of vaccination * Recurrent arterial or venous thrombosis despite anticoagulant therapy Exclusion Criteria: * Lack of consent of the patient * Risk-associated venous thromboses (e.g. following surgery, immobilization, plaster cast, fractures or sprains) * Risk-associated arterial thromboses (in the presence of vascular risk factors such e.g. diabetes mellitus, hypercholesterolemia, hypertension, nicotine abuse) * Thromboses more than 120 days old at the time of blood sampling