[Covert infection of severe acute respiratory syndrome in health-care professionals and its relation to the workload and the type of work].

Objective: To study severe acute respiratory syndrome (SARS) covert infection in health-care professionals and its relation to work intensity and type of work.
Methods: Specific antibodies to SARS virus in 1 127 serum specimens from health-care professionals who had a close contact history with patients of SARS and 92 healthy persons were assayed with ELISA.
Results: The health-care professionals consisted of 287 men and 840 women, aged 21 - 55 years (mean 34 +/- 9 years). The overall positive rate of specific IgG and IgM was 2.57% (29/1 127); the positive rates in nurses, doctors and laboratory workers, and supervisors were 3.46%, 1.41%, 2.86%, respectively. 34.5% of the infected worked in the ICU, and 65.5% in the general wards. None of them presented clinical SARS. Medical examination was also carried out for 313 people who had close contact with the 29 antibody positive health care professionals, but no clinical SARS was found.
Conclusions: Covert infection can be found in the health-care professionals and it showed no contagiousness. The positive rate of specific antibodies was higher in ICU where the work intensity was higher. The positive rate in nurses was higher than in doctors.