title: Clinical and immunologic predictors of influenza illness among vaccinated older adults.
abstract: The diagnosis of influenza is often missed in older adults and illness presentation may be modified by prior vaccination. We evaluated the symptoms and immunologic markers predicting laboratory-confirmed influenza (LCI) among vaccinated older adults. In subjects with influenza-like illness (ILI), fever distinguished subjects with laboratory-confirmed influenza (LCI) from those with other ILI (39% vs. 12.5%, p=0.009). In LCI subjects who did not seroconvert to influenza infection, pre-infection levels of the cytolytic mediator, granzyme B, correlated with fever (r=1.000; p=0.01) and the IFN-gamma:IL-10 ratio (r=0.999; p=0.03), and increased following influenza infection in LCI vs. ILI subjects (p=0.03). The cell-mediated immune response to influenza distinguishes A/H3N2 LCI from other ILI in older adults, and suggests a link between cell-mediated immunity and influenza illness severity in vaccinated older adults.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of Connecticut Health Center, Farmington, CT, USA.
authors.forename: Zainab
authors.initials: Z
authors.lastname: Shahid
authors.forename: Alison
authors.initials: A
authors.lastname: Kleppinger
authors.forename: Beth
authors.initials: B
authors.lastname: Gentleman
authors.forename: Ann R
authors.initials: AR
authors.lastname: Falsey
authors.forename: Janet E
authors.initials: JE
authors.lastname: McElhaney
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000914:Antibodies, Viral / Q000097:blood; D002478:Cells, Cultured; D005260:Female; D005334:Fever / Q000276:immunology; D053804:Granzymes / Q000276:immunology*; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007111:Immunity, Cellular; D053122:Influenza A Virus, H3N2 Subtype; D007252:Influenza Vaccines / Q000276:immunology; D007251:Influenza, Human / Q000175:diagnosis* / Q000276:immunology; D007371:Interferon-gamma / Q000276:immunology*; D016753:Interleukin-10 / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000821:virology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011446:Prospective Studies; D012680:Sensitivity and Specificity
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines; D016753:Interleukin-10; D007371:Interferon-gamma; D053804:Granzymes