Each year with the onset of the influenza “season,” we
are reminded of our inability to provide long-term protection against
the suffering and excess mortality associated with this disease.
Prevention of severe influenza requires annual vaccination of
populations at risk with hemagglutinin protein of epidemic viral
strains. Currently influenza A subtypes H1N1 and H3N2 and influenza B
are used. In recent years, vaccination of individuals > 65 years old
has increased from < 25% to as much as 70%, but as late as 1997,< 30% of high-risk individuals < 65 years old were being