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Influenza and older people

The World Health Organization (1) and the Ministry of Health (2) recommend annual influenza vaccination for all adults aged 65 years or older. Annual influenza vaccination with AFLURIA QUAD is funded for all eligible adults aged 65 years or older.

Influenza vaccination supports healthy ageing and maintenance of independence for older people

Influenza vaccination provides older people with low to modest protection against influenza infection (3-6) but can also reduce influenza disease severity (7,8) and complications (7,9,10) in older people who have been vaccinated but subsequently get influenza. Influenza- related death, (4,11) hospitalisation,(4,11,12) and increases in disability or frailty (13,14) are lower in older people who receive influenza vaccination compared with those who do not.

Influenza vaccine efficacy for the prevention of acute myocardial infarction (AMI) following influenza is between 19% and 45%,(9) which is similar to the effect of other measures to lower cardiovascular disease risk factors such as smoking cessation, use of statins and treatment of hypertension. (9)  Repeated annual influenza vaccination has a positive cumulative effect of greater protection against influenza complications and hospitalisation compared with only ever being vaccinated against influenza once. (7,15-20)

Aging and the serious impact of influenza infection

The natural decline in immune function associated with ageing can increase an older person’s vulnerability to both the risk of infectious disease and serious complications. This is known as immunosenescence. (21-24) 

Disease complications in older people with influenza include pneumonia, (25-29) secondary bacterial infection (30,31), acute coronary syndrome (18,19) (including AMI) (9,32,17,33), heart failure (34), ischaemic stroke (14,15,35), haemorrhagic stroke (36), exacerbation of asthma (37) and increased frailty.(29,38) Influenza may also exacerbate chronic underlying conditions(26-28,30), including cardiovascular disease(34,39), ischaemic heart disease (IHD)(40), heart failure(17,35,41), diabetes and chronic obstructive pulmonary disease (COPD).(42)

Influenza increases the risk of mortality

Mortality is significantly higher in older people with influenza (1,28,43,44) than younger healthy adults with influenza. (44) The risk of influenza-related death increases with advancing age, the presence of chronic conditions, or increasing levels of frailty.(26,28)

Influenza increases the risk of hospitalisation

The risk of influenza-related hospitalisation is greater for older people compared with healthy adults aged under 65 years.(26-29,45,54) Increasing levels of frailty(29,46,47,54) and the presence of chronic conditions such as diabetes or heart, kidney, neurological or respiratory diseases(27-29,44,54) add to the risk of influenza-related hospitalisation.

Influenza increases the risks of disability and frailty

Older people have lower physiological reserves to aid a return to pre-illness function.(13) Periods of restricted activity or hospitalisation related to illness or injury in older people living in the community are significant causes of ongoing inability to perform activities of daily living (ADLs). (46,29)

Following hospitalisation of older people living in the community with an illness such as influenza, inability to perform ADLs was substantially higher in those who required admission to an intensive care unit (ICU) than those who did not.(13) In a review, 10–63% of older people admitted to an ICU experienced new or worsened disability with ADLs during the year after discharge. The disability persisted beyond the first year in 22–37% of these people.(13)

Admission of older adults to an ICU has been shown to be related to a two-fold increase in outcomes such as polypharmacy, urinary incontinence, depression, immobility, faecal incontinence and cognitive impairment in the subsequent 12 months.(48) The survival rate of older people has also been shown to be reduced following discharge from an ICU, ranging from two-thirds at 6 months (49) to around half at 12 months (48) (66% and 49%).(48,49)

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