Table 4.

Comparison of symptoms and Ct values between SARS-CoV-2 infected (PCR positive) seropositive and seronegative groups

	Seropositive group (n=19)	Seronegative group (n=1079)	Difference comparison (95% CI), p value
PCR positivity >7 days	6 (32%)	510 (47%)	−0·16 (−0·38 to 0·07), p=0·18*
Symptomatic	3 (16%)	347 (32%)	−0·16 (−0·38 to 0·05), p=0·13
N gene Ct	27·7 (7·6)	24·4 (5·5)	3·30 (0·27 to 6·33), p=0·033†
S gene Ct	26·9 (7·1)	24·3 (5·3)	2·60 (−0·58 to 5·77), p=0·11
ORF1ab Ct	28·0 (7·0)	24·0 (5·3)	3·95 (1·23 to 6·67), p=0·004

Data are n (%) or mean (SD), unless otherwise specified. Ct=cycle threshold.

^*Difference in proportion for binary variables.

^†Difference in mean for the Ct values.