inclusion criteria: * acute covid-19 disease at the time of recruitment laboratory-confirmed by upper respiratory tract pcr * patient recently (0-4 days earlier) admitted to hospital due to covid-19 infection * symptom onset 10 days before recruitment (if symptom onset unknown the duration is calculated from positive pcr-test) * the day should be recorded from the duration of the covid-19 symptoms/positive test result * the dose of lmwh thromboprofylaxis should be recorded * written informed consent.

inclusion criteria: * acute covid-19 disease at the time of recruitment laboratory-confirmed by upper respiratory tract pcr * patient recently (0-4 days earlier) admitted to hospital due to covid-19 infection * symptom onset 10 days before recruitment (if symptom onset unknown the duration is calculated from positive pcr-test) * the day should be recorded from the duration of the covid-19 symptoms/positive test result * the dose of lmwh thromboprofylaxis should be recorded * written informed consent.

inclusion criteria: - acute covid-19 disease at the time of recruitment laboratory-confirmed by upper respiratory tract pcr - patient recently (0-4 days earlier) admitted to hospital due to covid-19 infection - symptom onset 10 days before recruitment (if symptom onset unknown the duration is calculated from positive pcr-test) - the day should be recorded from the duration of the covid-19 symptoms/positive test result - the dose of lmwh thromboprofylaxis should be recorded - written informed consent.

inclusion criteria: - acute covid-19 disease at the time of recruitment laboratory-confirmed by upper respiratory tract pcr - patient recently (0-4 days earlier) admitted to hospital due to covid-19 infection - symptom onset 10 days before recruitment (if symptom onset unknown the duration is calculated from positive pcr-test) - the day should be recorded from the duration of the covid-19 symptoms/positive test result - the dose of lmwh thromboprofylaxis should be recorded - written informed consent.

inclusion criteria: - acute covid-19 disease at the time of recruitment laboratory-confirmed by upper respiratory tract pcr - patient recently (0-4 days earlier) admitted to hospital due to covid-19 infection - the day should be recorded from the duration of the covid-19 symptoms/positive test result - the dose of lmwh thromboprofylaxis should be recorded - written informed consent. - availability for all visits scheduled in this study.

inclusion criteria: - acute covid-19 disease at the time of recruitment laboratory-confirmed by upper respiratory tract pcr - patient recently (0-4 days earlier) admitted to hospital due to covid-19 infection - the day should be recorded from the duration of the covid-19 symptoms/positive test result - the dose of lmwh thromboprofylaxis should be recorded - written informed consent. - availability for all visits scheduled in this study.