Immune response of single dose vaccination against 2009 pandemic influenza A (H1N1) in the Taiwanese elderly.
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).
Kao
Tsui Mai
TM
Department of Internal Medicine, National Taiwan University Hospital, Medical College of National Taiwan University, Taipei, Taiwan.
Hsieh
Szu Min
SM
Kung
Hsiang Chi
HC
Lee
Yi Chien
YC
Huang
Kuo Chin
KC
Huang
Li Min
LM
Chang
Feng Yee
FY
Wang
Ning Chi
NC
Liu
Yung Ching
YC
Lee
Wen Sen
WS
Liu
Hsingjin Eugene
HE
Chen
Chin I
CI
Chen
Chien-Hui
CH
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
D000914:Antibodies, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines