The humoral response to live and inactivated influenza vaccines administered alone and in combination to young adults and elderly

Background: Vaccination is the most effective way for prevention of severe influenza infection, but the present vaccines are not very efficient in the elderly. Objective: In this study, we investigated the Ig isotype response to a cold adapted, live, attenuated influenza vaccine (LIV) and a trivalent, subunit, inactivated influenza vaccine (IIV) and the combination of both (LIV/IIV) in young and elderly men, not previously vaccinated against influenza. Study design: LIV and IIV containing the strains for 1998-1999 were used. Forty-seven 19-35 years old and forty-three 58-91 years old were divided in four groups receiving either LIV, IIV, both or placebo. All were bled before and at 4 weeks after vaccination. The hemagglutination inhibition (HAI) antibody response to homologous strains and the enzyme-linked immunosorbent assays (ELISA) IgA. IgG and IgG-subclass responses to recombinant HA proteins representing influenza A and B strains from 90 to 91, and purified virus from an A/Sydney/05/97-like strain were measured. Results: Protective HAI titers of > 40 were more frequent (P < 0.05) after IIV alone or LIV/IIV than after LIV alone; there was no difference between the young and elderly persons. The highest frequency of titer rises in ELISA was found against the H1N1 recombinant antigen. In young adults, IgG titer rises were more frequent than in elderly given LIV than IIV alone, but not when given the combination. The influenza-specific IgG subclass response after LIV consisted of IgG1 and IgG4 only in the young; after IIV it stimulated of IgG1 and IgG3 in the young and IgG1 alone in the elderly. After vaccination with the LIV/IIV combination IgG1, IgG3 and IgG4 were found in the young and IgG1, IgG3 in the elderly, Among the elderly, the IIV/LIV combination induced the same response rate of specific IgG and IgG1 as in young adults. Conclusion: The study illustrates the possibility to correct the age dependent weakening of the immune response to influenza vaccine with a combination of LIV and IIV. (C) 2002 Elsevier Science B.V. All rights reserved.