Antivirals for influenza: what is their role in the older patient?

Influenza infection is a cause of high morbidity and mortality in the elderly living in the community or in long-term care facilities. Yearly immunisation is the most important means for prevention of infection. However, protection by vaccination in the elderly is incomplete, and influenza infections and outbreaks in long-term care facilities still occur. Symptoms of influenza include fever, chills, headache, myalgia and respiratory symptoms. These clinical features overlap considerably with other co-circulating respiratory viruses such as respiratory syncytial virus and parainfluenza virus. Elderly and debilitated patients with influenza may present with less prominent respiratory symptoms and may present only with fever, lassitude and confusion. Antiviral prophylaxis and treatment with amantadine and rimantadine have been given in the past but adverse effects and early development of drug resistance have limited their use. The newer antivirals zanamivir and oseltamivir are equally effective and have the advantage of being well tolerated and active against both influenza A and B without the development of resistance. However, they are costly. Early identification and diagnosis of influenza illnesses are crucial since treatment with antiviral agents should be started within 48 hours of the beginning of illness.