Humoral and secretory antibody responses to immunization with low and high dosage split influenza virus vaccine

Tri (n-butyl) phosphate (TNBP)-split vaccine containing 6400 CCA units of influenza virus A/Aichi/68 (H3N2) was given intramuscularly to a group of volunteers. The changes in serum haemagglutination-inhibiting (HI) and nasal wash neutralizing antibody were measured, and the results compared with that of volunteers given a TNBP-split vaccine containing 400 CCA of the same virus. More volunteers given the high-dose vaccine developed a fourfold rise in serum HI antibody, and there was a greater increase in geometric mean titre in this group. In addition, more volunteers given the high-dose vaccine developed detectable nasal wash neutralizing and anti-neuraminidase antibodies. Following low-dose vaccine, the production of nasal wash antibody was not related to the serum antibody response. For both groups given vaccine, antibody was detected most frequently in nasal washings with relatively high levels of protein and IgA; the concentration of IgA was also directly related to the protein concentration.