Table 1.

COVID-19 antibody prevalence among New York health care workers

Characteristic	Total		Negative for antibodies (IgG and IgM)		Positive for antibodies (IgG or IgM)
Total	474		394	83.1%	80	16.9%	(13.6%, 20.6%)
Sex—no. (%)
Male	182	38.4%	156	85.7%	26	14.3%	(9.6%, 20.2%)
Female	292	61.6%	238	81.5%	54	18.5%	(14.2%, 23.4%)
Age—mean (Std)	42.0	11.30	41.9	11.3	42.4	11.5	N/A
Race—no. (%)
Non-Hispanic White	339	71.5%	286	84.4%	53	15.6%	(11.9%, 20.0%)
Hispanic or Latino	31	6.5%	24	77.4%	7	22.6%	(9.6%, 41.1%)
African American/Black	14	3.0%	13	92.9%	1	7.1%	(0.2%, 33.9%)
Asian	87	18.4%	68	78.2%	19	21.8%	(13.7%, 32.0%)
Others/unknown	3	0.6%	3	100.0%	0	0.0%	N/A
Had a PCR test—no. (%)	65	13.7%	48	73.8%	17	26.2%	(16.0%, 38.5%)
# Days from first PCR test to antibody test (must have occurred before the antibody test)—median, IQR	15	[11, 22]	14	[9, 20]	17	[13.0, 24.0]	N/A
Symptom groups—no. (%)
Asymptomatic since 15 February 2020	244	51.5%	214	87.7%	30	12.3%	(8.5%, 17.2%)
Symptomatic, but no +PCR test prior to our AB samples	217	45.8%	178	82.0%	39	18.0%	(13.1%, 23.7%)
PCR+ test prior to our AB samples	13	2.7%	2	15.4%	11	84.6%	(54.6%, 98.1%)
# Days from symptom onset to first Ab test (n = 230) —median (IQR)	25.5	[17.0, 38.0]	24	[15.5, 39.0]	29.5	[21.0, 38.0]	N/A

Binomial exact 95% confidence intervals for proportions of positive antibodies are located in the right-most column of the table. Percentages for the total health care workers are presented as a proportion of the total (column), whereas percentages for the antibody groups are presented as proportions of the subgroup (row) Std standard deviation, PCR Polymerase chain reaction, IQR Interquartile range, Ab test Chembio COVID-19 antibody test