Influenza vaccines: Antibody responses to split virus and MF59-adjuvanted subunit virus in an adult population

The humoral immune response generated by two commercial influenza vaccines was evaluated in a randomised, double-blind trial performed in the Public D epartment of Dolo Health District (North-east Italy) during the winter seas on 1997-1998. Ninety-eight subjects were immunised with a split virus vacci ne and ninety-six with a MF59-adjuvanted subunit virus vaccine (SU/MF59). T he pre- and postvaccination (similar to 30 days) antibody titres were deter mined by hemagglutination inhibition test (HI). After immunisation protecti ve titre rates (greater than or equal to 1:40) were near 100% against virus A strain and 82.5% against B strain. Both vaccines caused significant rise s in geometric mean antibody titres (GMTs); however, people who received SU /MF59 vaccine were found to develop a greater immune response compared to t he group immunised with SVV. According to logistic regression analysis the unprotective prevaccination immune status and the use of SU/MF59 were ident ified as independent factors significantly increasing the response to immun isation.