title: The hemagglutination inhibition antibody responses to an inactivated influenza vaccine among healthy adults: with special reference to the prevaccination antibody and its interaction with age.
abstract: The immunogenicity of the trivalent split-virus influenza vaccine was investigated among 70 healthy adults (mean age: 48.5, range: 36-68). The vaccine antigens were: A/Yamagata/32/89 (H1N1); A/Beijing/352/89 (H3N2); and B/Bangkok/163/90. Regarding the entire sample, the vaccine induced a tenfold or more rise on the average in the hemagglutination inhibition (HAI) antibody to each antigen. The response rates (greater than or equal to a fourfold rise) were about 90% or more among those with a prevaccination titer < or = 1:64 (equivalent to < or = 1:16 on the Western scale; in Japan, the HAI titers are expressed by the final, and not the initial, dilution of the serum; from hereon our findings will be expressed using the Japanese scale), whereas they were 0-50% at > or = 1:128. Thus, the prevaccination titer was negatively associated with antibody induction. The achievement rates (postvaccination titer > or = 1:128) among those with a prevaccination titer < 1:16 remained at 48-68%. Regarding the analysis of variance, a significant effect on antibody induction was indicated for the prevaccination titer (P < or = 0.002), but not for age (P > or = 0.425). The interaction between the prevaccination titer and age was significant for A/Yamagata (P = 0.030), while it was also suggestive for A/Beijing (P = 0.054): as age increased, those with no preexisting antibody (< 1:16) showed greater titer rises, in contrast to the smaller rises among those with a titer > or = 1:16. Based on the attack survey conducted separately, the vaccine efficacy on influenza-like illnesses with fever < or = 37 degrees C and > or = 37.5 degrees C was calculated to be 16% (95% confidence interval: -66% to 57%) and 37% (-55% to 74%), respectively.
authors.affiliation: Department of Public Health, Faculty of Medicine 60, Kyushu University, Fukuoka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Hirota
authors.forename: M
authors.initials: M
authors.lastname: Kaji
authors.forename: S
authors.initials: S
authors.lastname: Ide
authors.forename: S
authors.initials: S
authors.lastname: Goto
authors.forename: T
authors.initials: T
authors.lastname: Oka
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000276:immunology*; D000914:Antibodies, Viral / Q000096:biosynthesis*; D004196:Disease Outbreaks; D005260:Female; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007252:Influenza Vaccines / Q000276:immunology*; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D017186:Titrimetry; D015164:Vaccines, Inactivated / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines; D015164:Vaccines, Inactivated