Study of the Protective Effect of an Injectable Influenza Vaccine Against Influenza Illness in Adults Under 50 y.o.

• Incidence of culture confirmed influenza-like illness due to virus strains matching the vaccine during the interval from November to April following treatment.
  

• Incidence of culture and/or serologically-confirmed influenza-like illness during the interval from November to April following treatment;
  
• Rate of solicited local and systemic common reactions in days 0 to 3 post-treatment;
  
• Rate of other adverse events through approximately 135 days post-treatment;
  
• Rate of four-fold rises in influenza specific antibody titers 21 days after treatment;
  
• Rate of influenza-specific antibody titers equal to, or greater than, 40 at 21 days after treatment;
  
• Geometric mean influenza-specific antibody titers at 21 days after treatment.
  

Yearly influenza (flu) epidemics cause a large burden of lost work and school time among younger persons and excess hospitalizations and deaths among the elderly. Injectable flu vaccines are generally believed to be effective, but formal studies using modern culture methods to prove this are limited. This study will compare the rate of respiratory illnesses associated with positive influenza virus cultures in healthy younger adults (a group at low risk for serious influenza complications) who have received Fluviral (an injectable flu vaccine) with the rate of such illnesses in healthy younger adults who have received an injection of saline (salt water). The rate of local vaccine reactions and other symptoms will be compared between the vaccine and salt water groups, and the immune responses to the vaccine measured.