Table 2. Household secondary attack rate, by presence of symptoms, during a coronavirus disease outbreak in in a call center, Seoul, South Korea, 2020.

Symptom status of index patients	Exposed, no. (%)	Confirmed cases, no. (%)	Secondary attack rate, % (95% CI)
Symptomatic	210 (93.3)	34 (100.0)	16.2 (11.6–22.0)
Presymptomatic	11 (4.8)	0	0
Asymptomatic	4 (1.9)	0	0
Total	225	34	15.1 (10.8–20.6)