Nursing home outbreak of influenza A (H3N2): evaluation of vaccine efficacy and influenza case definitions.
OBJECTIVE
Describe an outbreak of influenza A (H3N2); provide an analysis of vaccine efficacy; measure the sensitivity, specificity, and positive predictive value of 3 clinical case definitions of influenza.


METHODS
A nursing home in Washington County, Maryland. The outbreak involved 52 residents (attack rate = 47.7%) and at least 10 of 140 employees (minimum attack rate = 7.1%).


RESULTS
Twenty-five residents exhibited a 4-fold or greater increase in titer to influenza A/Sichuan/2/87. Vaccine efficacy was measured at -7.1%, suggesting that the influenza vaccine in 1988/1989 did not offer optimal protection against influenza A infection for the institutionalized elderly.


CONCLUSIONS
The outbreak was a clear indicator of the need for rapid diagnosis. With the use of rapid diagnostic tests, influenza A could have been detected in time to use amantadine.
Taylor
J L
JL
Division of Outbreak Investigation, Maryland Department of Health and Mental Hygiene, Baltimore 21201.
Dwyer
D M
DM
Coffman
T
T
Groves
C
C
Patel
J
J
Israel
E
E
D000368:Aged; D000369:Aged, 80 and over; D000914:Antibodies, Viral / Q000302:isolation & purification; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D053122:Influenza A Virus, H3N2 Subtype; D009980:Influenza A virus / Q000276:immunology / Q000302:isolation & purification; D007252:Influenza Vaccines; D007251:Influenza, Human / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D009735:Nursing Homes; D009740:Nursing Staff; D012703:Serotyping
D000914:Antibodies, Viral; D007252:Influenza Vaccines