Infectious diseases contribute significantly to morbidity, ongoing functional decline and mortality in older people. Several of these diseases are preventable by vaccination, but vaccine coverage is suboptimal for all of these. New approaches are required to improve vaccine coverage among people aged 65 years and over.
- A decline in immune function with ageing increases the impact of infectious diseases in older people.
- This immunosenescence also decreases the effectiveness of vaccines in older people.
- Older people should be provided with pneumococcal, herpes zoster and booster pertussis vaccines as well as annual influenza vaccine.
- Poor data on vaccine coverage and burden of disease have hampered efforts to increase vaccine coverage; some patients and clinicians are sceptical about the need for vaccines and their effectiveness. Better monitoring might help combat this.
- A new approach to advocacy involving a broader partnership base is required, to educate the public and deliver vaccines.
- Vaccines recommended on a scientific basis should be funded under the National Immunisation Program.
Older people undergo an age-related decline in immune responses resulting in greater susceptibility to infection and reduced responses to vaccination.1 This decline in immune function, termed immunosenescence, affects both innate and adaptive immune systems. Essential features of immunosenescence include reduced natural killer cell cytotoxicity on a per cell basis, and decreased pools of naive T and B cells. There is an accumulation of late-differentiated effector T cells, commonly associated with cytomegalovirus infection, which contributes to a decline in the capacity of the adaptive immune system to respond to novel antigens. The reduced functional capacity of T cells is the main effect of the ageing process.2 Immunosenescence is a major contributory factor to the increased frequency of morbidity and mortality among older people and the reduction in vaccine responsiveness in this age group, especially frail patients.
Infectious diseases are significant in older people not just because of their increased severity (e.g. more than 90% of influenza deaths are in people aged over 65 years) but also because of their impact on functional capacity after the illness. Data show that hospitalisation for influenza is highly likely to lead to ‘catastrophic disability’, defined as a loss of three levels of capacity for activities of daily living.3 Typically, older people who are independent at home and are hospitalised with influenza need assistance with care on discharge.
Similar data exist for people with shingles. A French study showed ongoing deficits in physical, social and psychological functioning after older people developed postherpetic neuralgia.4
Vaccines available for older people
Although not all recommended vaccines are funded for older people in Australia, GPs should ensure that every 65-year-old patient receives:
- an enhanced influenza vaccine and ongoing annual vaccination
- first-dose 23-valent polysaccharide pneumococcal vaccine, with boosters if required
- herpes zoster vaccine
- an acellular pertussis vaccine booster if this has not been given in the previous 10 years.