SARS transmission in Vietnam outside of the health-care setting

SUMMARY To evaluate the risk of transmission of SARS coronavirus outside of the health-care setting, close household and community contacts of laboratory-confirmed SARS cases were identified and followed up for clinical and laboratory evidence of SARS infection. Individual- and household-level risk factors for transmission were investigated. Nine persons with serological evidence of SARS infection were identified amongst 212 close contacts of 45 laboratoryconfirmed SARS cases (secondary attack rate 4 . 2 %, 95% CI 1 . 5–7). In this cohort, the average number of secondary infections caused by a single infectious case was 0 . 2. Two community contacts with laboratory evidence of SARS coronavirus infection had mild or sub-clinical infection, representing 3% (2/65) of Vietnamese SARS cases. There was no evidence of transmission of infection before symptom onset. Physically caring for a symptomatic laboratoryconfirmed SARS case was the only independent risk factor for SARS transmission (OR 5 . 78, 95 % CI 1 . 23–24 . 24).