Two outbreaks of influenza A (H3N2) in a Japanese nursing home in the winter of 1996-1997, with differing vaccine efficacy.
Sixty of 128 (46.9%) residents of a nursing home were immunized with two doses of the trivalent split influenza vaccine. They developed 7.4-11.5-fold antibody increases, with a 69-82% protection rate, presenting good immune response rates to the influenza vaccine. Two outbreaks of influenza A (H3N2) occurred. There were no significant antigenic differences among the vaccine strain and the strains isolated from both outbreaks in haemagglutination-inhibition tests, suggesting that the second might have been a reoccurrence. There were no residents who were infected in both outbreaks. The vaccine efficacy against clinical illness in the first outbreak of typical influenza-like-illness (ILI) was 51% (relative risk: 0.49), and the febrile period was reduced significantly by vaccination. In the second outbreak, however, in which all patients had atypical ILI with a high fever but not respiratory symptoms, vaccine efficacy was not apparent for unknown reason.
Murayama
N
N
Department of Public Health, Niigata University School of Medicine, Japan.
Suzuki
H
H
Arakawa
M
M
Nerome
K
K
Mizuta
K
K
Kameyama
K
K
D000368:Aged; D000369:Aged, 80 and over; D004196:Disease Outbreaks / Q000517:prevention & control*; D005260:Female; D005334:Fever / Q000453:epidemiology; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D053122:Influenza A Virus, H3N2 Subtype; D009980:Influenza A virus / Q000276:immunology / Q000302:isolation & purification; D007252:Influenza Vaccines / Q000627:therapeutic use*; D007251:Influenza, Human / Q000453:epidemiology* / Q000517:prevention & control* / Q000821:virology; D007564:Japan / Q000453:epidemiology; D008297:Male; D011446:Prospective Studies
D007252:Influenza Vaccines