19 Table 1 Characteristics of the study population. Age (years) Male gender Clinical status Time between onset of symptoms and inclusion (days) Mean ± SD t p- n (%) p-value Asymptomatic URTI LRTI p-value Mean ± SD t p-value value Hydroxychloroquine treated patients 51.2 ± 18.7 9 (45.0) 2 (10.0) 12 (60.0) 6 (30.0) 4.1 ± 2.6 (N=20) -1.95 0.06 0.65 0.30 -0.15 0.88 Control patients 37.3 ± 24.0 6 (37.5) 4 (25.0) 10 (62.5) 2 (12.5) 3.9 ± 2.8 (N=16) All patients (36) 45.1 ± 22.0 15 6 (16.7) 22 (61.1) 8 (22.2) 4.0 ± 2.6 (41.7) URTI: upper tract respiratory infection, LRTI: lower tract respiratory infection