Their reaction time when performing simple tasks may fall by 20-40 per cent, a deterioration comparable with that caused by alcohol ingestion or working at night. In the US, influenza and pneumonia are the fifth and sixth most common causes of death, with up to 40,000 excess deaths occurring during an epidemic season. Pregnant women may be at higher risk of dying than non-pregnant women, and 4 per cent of children admitted to hospital for influenza related pneumonia die 4 . Since they feel so ill, people with influenza often seek medical advice from their primary care physician or pharmacist. Generally, about 42 per cent of patients with influenza consult a doctor and about three per cent are admitted to hospital.
Attack rates vary with the virus strain and degree of contact between people.
For example, the elderly make up one fifth of the US population but, in years when an influenza epidemic occurs, account for at least half of all hospital admissions and three quarters of extra deaths are attributable to influenza. Once admitted, older people tend to stay in hospital for considerably longer than younger people. In one study, patients aged 15-44 years stayed for an average of eight days, while patients over 65 stayed for 12 days. In children, influenza also leads to an increase in hospital admissions. The total costs of influenza are made up of direct costs and indirect costs.