title: Risk factors for SARS among persons without known contact with SARS patients, Beijing, China.
abstract: Most cases of severe acute respiratory syndrome (SARS) have occurred in close contacts of SARS patients. However, in Beijing, a large proportion of SARS cases occurred in persons without such contact. We conducted a case-control study in Beijing that compared exposures of 94 unlinked, probable SARS patients with those of 281 community-based controls matched for age group and sex. Case-patients were more likely than controls to have chronic medical conditions or to have visited fever clinics (clinics at which possible SARS patients were separated from other patients), eaten outside the home, or taken taxis frequently. The use of masks was strongly protective. Among 31 case-patients for whom convalescent-phase (>21 days) sera were available, 26% had immunoglobulin G to SARS-associated coronavirus. Our finding that clinical SARS was associated with visits to fever clinics supports Beijing's strategy of closing clinics with poor infection-control measures. Our finding that mask use lowered the risk for disease supports the community's use of this strategy.
authors.affiliation: Beijing Center for Disease Prevention and Control, Beijing, China.
authors.forename: Jiang
authors.initials: J
authors.lastname: Wu
authors.forename: Fujie
authors.initials: F
authors.lastname: Xu
authors.forename: Weigong
authors.initials: W
authors.lastname: Zhou
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Feikin
authors.forename: Chang-Ying
authors.initials: CY
authors.lastname: Lin
authors.forename: Xiong
authors.initials: X
authors.lastname: He
authors.forename: Zonghan
authors.initials: Z
authors.lastname: Zhu
authors.forename: Wannian
authors.initials: W
authors.lastname: Liang
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Chin
authors.forename: Anne
authors.initials: A
authors.lastname: Schuchat
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002681:China / Q000453:epidemiology; D016358:Contact Tracing; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012309:Risk-Taking; D045169:Severe Acute Respiratory Syndrome / Q000453:epidemiology / Q000209:etiology* / Q000635:transmission