Most studies have demonstrated that between eighty to ninety percent of influenza-related deaths occur in persons older than 65 years. This is tragic because many of these deaths could have been avoided since the influenza vaccine is at least 60 percent effective for those at risk. Influenza vaccine is widely available at this time of year. As the protection afforded by the vaccine tends to diminish with time, it is recommended that the flu vaccine be obtained from the middle of October until mid-December. The vaccine becomes effective about two weeks after administration, and influenza epidemics generally do not occur in the United States before the middle of December.
Influenza is an illness that is caused by one of several different viruses.
These viruses mutate or change over time. As a result, a vaccine against influenza must be specific for the strains likely to be seen in a given year. In the United States, the composition of each year's flu vaccine is determined by the U.S. Public Health Service. Unfortunately, last year's vaccine is unlikely to offer protection against the current year's epidemic. The influenza vaccine is indicated for individuals older than 6 months of age who are at increased risk for complications.