Long-term immunogenicity of influenza vaccine among the elderly: Risk factors for poor immune response and persistence.
The elderly have been considered as the priority group for influenza vaccination, but their influenza vaccine-induced antibody was believed to decline more rapidly. Long-term immunogenicity of the influenza vaccine among the elderly was evaluated as compared to young adults. Serum hemagglutinin inhibition (HI) titers were determined at pre- and post-vaccination periods (at 1, 6, and 12 months after vaccination). Of the 1018 subjects, 716 (70.3%) were followed up during a 12-month period. Seroprotection rates at 1 month post-vaccination ranged from 70.1% to 90.3% depending on the age group and influenza vaccine virus strain. At 6 months post-vaccination, seroprotection rates for all three strains had declined significantly in adults >or=65 years (P<0.01), but still met the EMEA criteria. Low pre-vaccination HI titer (<1:40) and advanced age were associated with early decline of HI titers, falling below seroprotective levels around 6 months after vaccination.
Song
Joon Young
JY
Division of Infectious Diseases, Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea.
Cheong
Hee Jin
HJ
Hwang
In Sook
IS
Choi
Won Suk
WS
Jo
Yu Mi
YM
Park
Dae Won
DW
Cho
Geum Joo
GJ
Hwang
Taik Gun
TG
Kim
Woo Joo
WJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D000914:Antibodies, Viral / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology; D007252:Influenza Vaccines / Q000276:immunology*; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D056910:Republic of Korea / Q000453:epidemiology; D012307:Risk Factors; D055815:Young Adult
D000914:Antibodies, Viral; D007252:Influenza Vaccines