D'Arcy L. Little MD, CCFP
York Community Services, Toronto
Relenza (zanamivir), an orally-inhaled anti-viral medication effective against all known strains of the influenza virus, was approved by the Therapeutic Products Program of Health Canada on November 3, 1999.
Epidemiology
It is estimated that in Canada influenza affects between 10 to 15% of the population (between 3 and 5 million people) each year. The number of affected persons can be as high as 80% of nursing home residents. In addition, these infections result in about 75,000 hospitalizations and 7,000 deaths yearly.1 In economic terms, flu-related costs to the Canadian economy during the 1997-98 flu season were estimated to be over $1 billion.2
The Mainstay of Treatment for Influenza
The influenza vaccine has been and remains the mainstay of prophylactic protection against influenza, and is recommended for elderly and high-risk patients, their household contacts, and health-care personnel. Under ideal circumstances, in healthy, young adults, vaccine effectiveness is in the range of 70-90%, with much lower effectiveness in the elderly (30-50%).3 For optimal results, it is recommended as a single 0.5 ml IM dose to be given from October through mid-November, although it can be given from September to the end of the influenza season.
