Fig. 1: Study flowchart.

COVID-19 diagnosis was positive based on positive RT-PCR results (*RT-PCR+), OR specific radiological signs of COVID-19 on chest CT scan (**CT scan+). COVID-19 diagnosis was negative if RT-PCR result was negative AND (i) no specific radiological signs of COVID-19 on chest CT scan; (ii) no chest CT scan performed. A failure for COVID-19 diagnosis is reported in the absence of RT-PCR test and no evidence of COVID-19 radiological signs on chest CT scan. ± Non-exclusive reasons.