Table 2. Positive rates by student groups registered in Ewha Safety Campus (ESC) cohort

Group	The number of confirmed cases	The number of applications	Positive rates (%)	Ratio of positive rates (95% CI)
Complied with all quarantine policies
Yes	679	11,183	6.06	0.30 (−0.01, 0.62)
No	33	165	20	1.0 (ref)
Fully vaccinated (second dose or more)
Yes	697	11,213	6.22	0.6 (0.1, 1.1)
No	14	135	10.37	1.0 (ref)
Dormitory usage
Yes	264	7,504	3.52	0.3 (0.16, 0.45)
No	447	3,844	11.63	1.0 (ref)

Quarantine policies: wearing a facial mask, washing hands, avoiding unnecessary social gatherings, and avoiding communal facilities.