Response of influenza vaccines against heterovariant influenza virus strains in adults with chronic diseases.
The ability of influenza vaccination to provide cross-protection against heterovariant influenza strains was evaluated in a double-blind, randomized, trial in north-east Italy during the winter of 2005-2006. Of 238 adult subjects with underlying chronic diseases, 120 received MF59-adjuvanted subunit vaccine (Sub/MF59) and 118 received a conventional subunit vaccine (Subunit). Immunogenicity was measured for A/H3N2 and B influenza strains against both the homologous vaccine strains (A/New York/55/2004 and B/Jiangsu/10/2003), and the heterovariant strains recommended for the 2006-2007 season (A/Wisconsin/67/2005 and B/Malaysia/2506/2004). Although both vaccines conferred serological protection against the homologous vaccine strains and the 2006-2007 heterovariant A/H3N2 strain for a majority of subjects, the antibody response was highest in the Sub/MF59 vaccine group. For example, MF59-adjuvanted vaccination conferred significantly greater (P = 0.002) protection against the heterovariant A/H3N2 strain than the conventional subunit vaccine (79.2% vs. 61.0% of subjects, respectively). In conclusion, these results demonstrate that protection provided by influenza vaccination in adults affected by chronic diseases is lower against heterovariant strains than for homologous strains. However, addition of MF59 adjuvant to a subunit vaccine enhances immunogenicity against the A/H3N2 heterovariant strain, conferring broader protection than a conventional subunit vaccine in this population, who are at higher risk of influenza-related complications.
Baldo
V
V
Department of Environmental Medicine and Public Health, Institute of Hygiene, University of Padua, Padua, Italy. vincenzo.baldo@unipd.it
Baldovin
T
T
Floreani
A
A
Fragapane
E
E
Trivello
R
R
D000293:Adolescent; D000328:Adult; D002908:Chronic Disease; D004311:Double-Blind Method; D014644:Genetic Variation; D006801:Humans; D009980:Influenza A virus / Q000235:genetics / Q000276:immunology*; D009981:Influenza B virus / Q000235:genetics / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology / Q000517:prevention & control*; D008875:Middle Aged; D022223:Vaccines, Subunit / Q000008:administration & dosage / Q000276:immunology
D007252:Influenza Vaccines; D022223:Vaccines, Subunit