Influenza viral infection in the elderly

Abstract

Seasonal influenza with influenza types A (subtypes H1N1 and H3N2) and B cause substantial morbidity and mortality in elderly individuals, with rates increasing as the degree of frailty increases. Annual vaccination with the seasonal influenza vaccine (containing three antigens: A/H1N1, A/H3N2 and B) is effective in reducing the rates of complications of influenza in the elderly. The major debate at present is the magnitude of vaccine efficacy. However, vaccination rates worldwide are much lower than the targets set by the US CDC and the World Health Assembly. In addition, a limited number of antiviral drugs are available to treat and prevent influenza. Recent changes in viral susceptibility have almost rendered the adamantanes (e.g., amantadine and rimantadine) obsolete and have seriously compromised the clinical utility of oseltamivir, one of the two available neuraminidase inhibitors. With the emergence of the current oseltamivir-resistant type A/H1N1 virus and pandemic type A/H1N1 virus, and the spectre of avian type A/H5N1 looming in the future, the management of influenza in the elderly population will become progressively more complex. The presence of multiple influenza types may dramatically complicate outbreak management in chronic care facilities for the elderly. It is incumbent on the clinician to keep abreast of developments in this field through close communication with local, regional and/or national public health departments. Only by doing this will one be able to maximize the benefits of available vaccines and antiviral drugs in the treatment and prevention of influenza in the elderly population.