Table 2.

PCR-positive infections and time at risk by baseline antibody status

	Participants, n	Time at risk, months	PCR-positive infections, n (%)	Rate of PCR-positive infections per month at risk
Residents
All	682	1809	97 (14%)	0·054
Antibody-negative at baseline	456	1203	93 (20%)	0·077
Antibody-positive at baseline	226	606	4 (2%)	0·007
Staff
All	1429	3749	121 (8%)	0·032
Antibody-negative at baseline	1021	2663	111 (11%)	0·042
Antibody-positive at baseline	408	1086	10 (2%)	0·009