title: Immune response of single dose vaccination against 2009 pandemic influenza A (H1N1) in the Taiwanese elderly.
abstract: We conducted a multi-center, randomized and laboratory-blinded clinical trial with subgroup analyses, involving adults aged greater than 60 years old (range 61-86 years old), to investigate the immunogenicity and the potential factors affecting the immune response of a monovalent, unadjuvanted, inactivated, split-virus vaccine. A total of 107 subjects were randomized to receive 15 and 30 microg of hemagglutinin antigen in a 1:1 ratio. The immunogenicity was detected through hemagglutination inhibition (HAI) test of serum obtained before and 3 weeks after vaccination. By 3 weeks after vaccination, HAI titer >or=1:40 was observed in 75.5% and 81.1% of participants receiving 15 and 30 microg of hemagglutinin antigen, respectively. Positive seroconversion was observed in 71.7% and 81.1% of recipients of the 15 and the 30 microg, respectively. The GMTs increased by a factor of 10.7 and 17.4 in the groups of 15 and 30 microg, respectively. This study indicated that one dose of 15 microg hemagglutinin antigen without adjuvant induced protective immune response in the majority of elderly. Multivariate logistic regression analyses showed that gender, age and diabetes were statistically significant factors affecting the seroprotection rate (p=0.04, 0.01 and 0.01, respectively) and seroconversion rate (p=0.01, 0.01 and 0.01, respectively).
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, Medical College of National Taiwan University, Taipei, Taiwan.
authors.forename: Tsui Mai
authors.initials: TM
authors.lastname: Kao
authors.forename: Szu Min
authors.initials: SM
authors.lastname: Hsieh
authors.forename: Hsiang Chi
authors.initials: HC
authors.lastname: Kung
authors.forename: Yi Chien
authors.initials: YC
authors.lastname: Lee
authors.forename: Kuo Chin
authors.initials: KC
authors.lastname: Huang
authors.forename: Li Min
authors.initials: LM
authors.lastname: Huang
authors.forename: Feng Yee
authors.initials: FY
authors.lastname: Chang
authors.forename: Ning Chi
authors.initials: NC
authors.lastname: Wang
authors.forename: Yung Ching
authors.initials: YC
authors.lastname: Liu
authors.forename: Wen Sen
authors.initials: WS
authors.lastname: Lee
authors.forename: Hsingjin Eugene
authors.initials: HE
authors.lastname: Liu
authors.forename: Chin I
authors.initials: CI
authors.lastname: Chen
authors.forename: Chien-Hui
authors.initials: CH
authors.lastname: Chen
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000914:Antibodies, Viral / Q000097:blood; D000917:Antibody Formation; D003920:Diabetes Mellitus; D005260:Female; D006385:Hemagglutination Inhibition Tests; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000276:immunology*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology / Q000517:prevention & control*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012737:Sex Factors; D016037:Single-Blind Method; D013624:Taiwan
chemical_list: D000914:Antibodies, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines