[Primary investigation on the changing mode of plasma specific IgG antibody in SARS patients and their physicians and nurses].

OBJECTIVES: To primarily investigate the changing mode of anti-SARS coronavirus IgG antibody in clinically diagnosed SARS patients and the possibility of subclinical infection in physicians and nurses through close association with SARS patients.
METHODS: The plasma levels of anti-SARS coronavirus IgG antibody of 57 normal subjects, 127 physicians and nurses worked in SARS wards for one month and 73 SARS patients with different course of SARS were measured by enzyme linked immunosorbent assay.
RESULTS: Plasma anti-SARS coronavirus IgG antibody was not detected in normal subjects and the clinical personnel. After 0-7 days, 8-10 days, 11-14 days, 15-20 days of onset of disease, the positive rates were 0.33%, 52%, 86% respectively, and the general positive rate was 61%.
CONCLUSION: The specificity and sensitivity of ELISA to detect plasma anti-SARS IgG antibody were satisfactory. Cases with positive reaction could be diagnosed as patients already infected by the virus. The specific IgG antibody didn't emerge in some patients in the early stage of the disease, and the negative results didn't indicate that they were not infected. And follow-up investigation should be made in those patients. Unlike common epidemic infectious diseases, SARS probably hadn't the potentiality of subclinical infection.