Highlights 

• COVID-19 is characterized by coagulation activation and endothelial dysfunction. Few data are available on thromboembolic complications.

• We studied symptomatic patients with laboratory-proven COVID-19 admitted to a university hospital in Milan, Italy (13.02-10.04.2020).

• Venous and arterial thromboembolic events occurred in 8% of hospitalized patients (cumulative rate 21.0%) and 50% of events were diagnosed within 24 h of hospital admission.

• Forty-four (11% of total) patients underwent VTE imaging tests; 16 were positive (36% of tests), suggesting underestimation of thromboembolic complications.

• There is an urgent need to investigate VTE diagnostic strategies and the impact of thromboprophylaxis in ambulatory COVID-19 patients.