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Abstract

The humoral immune response generated by two commercial influenza vaccines was evaluated in a randomised, double-blind trial performed in the Public Department of Dolo Health District (North-east Italy) during the winter season 1997-1998. Ninety-eight subjects were immunised with a split virus vaccine and ninety-six with a MF59-adjuvanted subunit virus vaccine (SU/MF59). The pre- and postvaccination (approximately 30 days) antibody titres were determined by hemagglutination inhibition test (HI). After immunisation protective titre rates (> or = 1:40) were near 100% against virus A strain and 82.5% against B strain. Both vaccines caused significant rises in geometric mean antibody titres (GMTs); however, people who received SU/MF59 vaccine were found to develop a greater immune response compared to the group immunised with SVV. According to logistic regression analysis the unprotective prevaccination immune status and the use of SU/MF59 were identified as independent factors significantly increasing the response to immunisation.

Immunogenicity of Three Different Influenza Vaccines against Homologous and Heterologous Strains in Nursing Home Elderly Residents

“…Sera were stored at −20°C until laboratory determination of HI antibody titres, as described elsewhere [23]. …”

Impact of vitamin D administration on immunogenicity of trivalent inactivated influenza vaccine in previously unvaccinated children

“…20 The serum samples were tested in duplicate at an initial dilution of 1:10, and those that were negative for the antibody were assigned an arbitrary titer of 1:5. HI antibody titers were expressed as the reciprocal of the highest serum dilution that completely inhibited hemagglutination.…”