[Analysis of hemagglutination inhibition antibody level in patients with influenza A H1N1].
To understand the hemagglutination inhibition antibody level in patients with influenza A H1N1. Sera from 28 patients with influenza A H1N1 at different time points after illness onset were collected and measured by hemagglutination inhibition assay. The serum hemagglutination inhibition antibody titers at 1, 5, 15, 22, 37, 49 and 58 days after illness onset were 5.36, 9.39, 39.02, 57.99, 137.92, 55.19 and 57.99 respectively. The top geometric mean titer of hemagglutination inhibition antibody was 148.55. The antibody seroconversion rate and seroprotection rate were occurred in 96.4% (27/28) of patients. The patients with influenza A H1N1 have effective immune response.