Immunogenicity of influenza A(H1N1)pdm09 vaccine in patients with diabetes mellitus: with special reference to age, body mass index, and HbA1c.

Subjects with diabetes mellitus are considered to be at high risk of influenza infection and influenza-associated complications. To evaluate the immunogenicity of the influenza A(H1N1)pdm09 vaccine among these subjects, we performed a prospective cohort study and measured hemagglutination inhibition antibody titers at baseline and 3 weeks after vaccination in 49 patients. No serious adverse events were reported. We were able to perform analyses for 48 patients, after excluding one patient with suspected infection. The vaccine induced a rise of about 9-fold in the mean antibody level. The sero-response proportion was 79%, and the sero-protection proportion was 73%. Patients with older age and lower body mass index tended to show lower immune response. Multivariate analysis indicated an independent negative effect of hemoglobin A1c level on the sero-protection proportion. A single A(H1N1)pdm09 vaccination achieved a sufficient level of immunity among diabetic patients, but both clinicians and patients should be aware of the potential for reductions in immune response.