The Imperative of Influenza Vaccines for Elderly Individuals—An Evolving Story

If past history is predictive, during the 2009-2010 influenza season ~1 out of every 8333 Americans will die as a result of influenza and its complications.Although influenza kills ~36,000 Americans every year, >90% of those deaths occur among individuals aged ≥65 years [1].A long-standing recommendation in the United States has been to administer influenza vaccine to those aged ≥65 years on an annual basis.Antiviral drugs also provide prophylaxis and/or treatment for this high-risk age group, but influenza A viruses (i.e., the type most likely to cause morbidity and mortality in this age group) demonstrate worrisome resistance patterns to both the class of adamantane drugs, and more recently, to oseltamivir [2].Influenza in elderly individuals also leads to substantial morbidity, diminution of the capacity to perform the usual activities of daily living, and excess medical costs.This leads to increases in influenza-related health care costs, as well as increased morbidity and mortality rates, which are of particular concern as population demographics reveal an increasingly older population.The estimated annual direct and indirect influenza-related costs in the United States are estimated at $90 billion, with almost 611,000 life-years lost annually [3].Influenza has also become a more virulent disease with rising levels of associated mortality, despite increasing rates of influenza vaccination [1].For all these reasons, serious and sustained scientific and public health policy attention must be placed on the prevention of influenza in the elderly population by use of vaccines.Unfortunately, this goal is not as simple as it may appear, because only trivalent, inactivated, influenza vaccine (TIV) is available in the United States.In other countries, MF59-adjuvanted TIV is also available for use.Although TIV provides varying levels of protection each season, depending on the match between vaccine and circulating viruses, it offers less than optimal protection [4].The only prospective, randomized, double-blind, placebo-controlled trial of TIV conducted in people aged >60 years demonstrated efficacy of 58% against serologically confirmed clinical influenza, but persons aged >70 years appeared to be less well protected [5].Thus, better vaccines for older people are clearly needed.