Dose-dependent antibody response to influenza H1N1 vaccine component in elderly nursing home patients

The effects of an increased antigen dose on HI, IgG, IgA, and IgM antibody responses to influenza A/Taiwan/1/86 (H1N1) were investigated in 92 elderly nursing-home residents (mean age 81 years) and 104 young subjects (mean ag e 20 years). At a standard 10-mu g dose, HI and IgG titer rises were lower in the elderly. HI titers did not improve at higher vaccine dosages. By con trast, influenza-specific IgG and IgA antibody responses were dose dependen t in elderly subjects, but not in young. In the young subjects, IgM antibod y responses were dose dependent. The improved antibody responses in the eld erly as observed in IgG and IgA were not reflected in the HI response. Ther efore, the evaluation of antibody production by HI only may lead to an unde restimate of the immune response in elderly people. (C) 1999 Elsevier Scien ce Inc. All rights reserved.