Prevalence of subclinical infection by the SARS coronavirus among general practitioners in Hong Kong.

Yu, Wai Cho; Tsang, Thomas Ho Fai; Tong, Wing Lok; Ng, Tak Keung; Lim, Wilina; Yeung, Henry Chiu Fat; To, Wing Kin; Lam, Bosco; Tsang, Dominic Ngai Chong; Ho, Thomas Ock Ling; Lai, Sik To; Tong, Kwok Lung

Eight general practitioners had severe acute respiratory distress syndrome (SARS) in Hong Kong during the epidemic, and others may have been infected by the SARS coronavirus without developing the full syndrome. We conducted a serological and questionnaire survey to determine the prevalence of subclinical infection by SARS coronavirus among general practitioners in Hong Kong. Participants had to be doctors actively practising in family medicine and who did not have SARS. Approximately 3200 general practitioners were invited to participate and the results of 574 were eligible for analysis. 29 samples were tested positive by enzyme-linked immunosorbent assay, but all these samples had titre < 25 by immunoflorescence assay. The prevalence for seropositivity was thus 0% (95% CI, 0.0%-0.6%). This finding documents the lack of subclinical infection by SARS coronavirus in an at-risk group in the community.