Epidemiological and genetic correlates of severe acute respiratory syndrome coronavirus infection in the hospital with the highest nosocomial infection rate in Taiwan in 2003

Abstract

Taiwan experienced a series of outbreaks of nosocomial severe acute respiratory syndrome (SARS) infections in 2003. Two months after the final outbreak, we recruited 658 employees from the hospital that suffered the first and most severe SARS infections to help us investigate epidemiological and genetic factors associated with the SARS coronavirus (SARS-CoV). SARS-CoV infections were detected by using enzyme immunoassays and confirmed by a combination of Western blot assays, neutralizing antibody tests, and commercial SARS tests. Risk factors were analyzed via questionnaire responses and sequence-specific oligonucleotide probes of human leukocyte antigen (HLA) alleles. Our results indicate that 3% (20/658) of the study participants were seropositive, with one female nurse identified as a subclinical case. Identified SARS-CoV infection risk factors include working in the same building as the hospital's emergency room and infection ward, providing direct care to SARS patients, and carrying a Cw*0801 HLA allele. The odds ratio for contracting a SARS-CoV infection among persons with either a homozygous or a heterozygous Cw*0801 genotype was 4.4 (95% confidence interval, 1.5 to 12.9; P = 0.007).

FIG. 1.

Results from EIA (upper panel) and NA (lower panel) tests for 19 anti-SARS-CoV antibody-positive cases. The EIA cutoff value equaled the mean optic density of normal controls plus 3 standard deviations. The lowest NA test titer was 2. First and second blood samples were collected 2 and 8 months after the outbreak, respectively. HP613 was a subclinical case. OD, optical density.