Table 1.

Baseline Demographic Characteristics

Characteristic	Placebo	Hydroxychloroquine Once Weekly	Hydroxychloroquine Twice Weekly
Number randomized	494	494	495
Age, median (IQR), y	40 (34, 48)	42 (35, 49)	41 (35, 49)
Weight, median (IQR), kg	80 (68, 95)	79 (67, 93)	82 (68, 95)
Female,a n (%)	241 (48.8)	261 (52.8)	258 (52.1)
Ethnicity (all that apply), n (%)
White or Caucasian	419 (84.8)	431 (87.2)	421 (85.1)
Black or African	10 (2.0)	5 (1.0)	5 (1.0)
Asian	29 (5.9)	23 (4.7)	23 (4.6)
Native Hawaiian or Pacific Islander	1 (0.2)	0 (0.0)	1 (0.2)
Hispanic or Latino	18 (3.6)	18 (3.6)	22 (4.4)
Native American or Alaska Native	8 (1.6)	4 (0.8)	7 (1.4)
Middle Eastern	4 (0.8)	6 (1.2)	5 (1.0)
South Asian	12 (2.4)	17 (3.4)	18 (3.6)
Other	4 (0.8)	3 (0.6)	1 (0.2)
Current smoker, n (%)	13 (2.6)	17 (3.4)	21 (4.2)
Chronic health conditions, n (%)
High blood pressure	60 (12.1)	79 (16.0)	66 (13.3)
Asthma	59 (11.9)	46 (9.3)	45 (9.1)
None	336 (68.0)	311 (63.0)	335 (67.7)
Risk factors for acquisition of SARS-CoV-2 at screening
Interacted with COVID-19 patients when not wearing a mask or face shield, n (%)
Yes	62 (12.6)	69 (14.1)	85 (17.2)
No	432 (87.4)	422 (85.9)	409 (82.8)
Perform aerosol-generating procedures?, n (%)	410 (83.0)	378 (77.0)	377 (76.3)
No. of aerosol-generating procedures performed per week, mean (SD)	10 (31.4)	9 (12.2)	9 (12.5)
Setting of occupational exposure, n (%)
Emergency department	190 (38.5)	210 (42.5)	207 (40.8)
Intensive care unit	85 (17.2)	82 (16.6)	102 (20.6)
Operating room	75 (15.2)	61 (12.3)	42 (8.5)
COVID-19 ward	56 (11.3)	51 (10.3)	47 (9.5)
Ambulance	45 (9.1)	40 (8.1)	33 (6.7)
Congregate care setting	20 (4.0)	19 (3.8)	27 (5.5)

Abbreviations: COVID-19, coronavirus disease 2019; IQR, interquartile range; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; SD, standard deviation.

^aNo pregnant women were enrolled, 30 women reported breastfeeding at baseline.