[Serological investigation on close contacts to patients with severe acute respiratory syndrome in an SARS outbreak].

OBJECTIVE: To study the evidence of severe acute respiratory syndrome (SARS) infection among close contacts to SARS patients and the level of sera IgG antibody in SARS cases.

METHODS: Specific IgG antibody against SARS-CoV in serum samples from contacts to patients, five months before an SARS outbreak in Beijing. Neutralized test, ELISA and immunity adherence test were studied. Samples were collected after clinical onset of patients or close contacts to patients, for 22 - 24 weeks. 19 close contacts and 13 cases were included in the study.

RESULTS: In close contacts, all tests were negative on three methods. All SARS cases were positive except one by immunity adherence test. The neutralized antibody levels were from 1:16 to 1:203, with medium level of 1:43.

CONCLUSION: According to our survey, there was no latent infection among close contacts. IgG antibody in sera continued to be at higher levels among SARS cases 22 - 24 weeks after onset.