Vaccination programmes in Older People

Introduction

Infectious diseases including pneumonia remain a big killer in old age, in spite of modern antibiotics. Influenza and pneumonia are responsible for around 8% of all deaths in old people, this being the 4th commonest cause of death after cancer, heart disease and stroke. Each year there is a peak incidence of deaths that coincides with the peak in influenza rates in the community. There have been influenza epidemics every 3 years or so for 400 years. Highest death rates are in the very old, the frail, those with chronic respiratory disease, and those in longstay care.

Influenza vaccination

It is difficult to diagnose influenza clinically as symptoms are a poor guide, and there are many asymptomatic infected carriers who can pass the virus on to others. Laboratory diagnosis on naso-pharyngeal swabs is specific but insensitive as well. The influenza vaccine can be inactivated, live attenuated, purified protein or DNA, but the inactivated vaccine is most common. Around 5% of subjects will have an adverse reaction to the vaccine, with upper respiratory symptoms.

The success of the vaccine depends upon seroconversion in the individual, and then the extent to which the strain in the vaccine matches the circulating viral strain. Seroconversion after vaccination occurs in 70-90% of young subjects, 60% of community-dwelling subjects around 60 years (the rate seen with the recent “swine flu” vaccine), 30% in 70-80’s, and 12% in those over 80[2]. In one study in Care Homes, seroconversion rate was 11% [3]. This reduced ability to seroconvert is attributed to immunosenescence. This has multiple elements and is difficult to measure. It includes T cell reduction from thymic involution, less effective antigen presentation through monocytes, and reduced killer cell toxicity. There are currently no reliable ways of improving responsiveness to vaccines, although higher vaccine doses and improving nutrition may be of benefit.

There is some evidence from observational studies that vaccination reduces the number of hospitalisations and deaths due to respiratory disease, in the influenza seasons [4]. In the elderly, protection against infection may be less, but immunisation

has been shown to reduce the incidence of bronchopneumonia, with a 27% reduction in hospital admissions, and 47% reduction in overall mortality [5], after adjusting for confounders in the observational studies. Confusingly, mortality from respiratory disease was unaffected, which must question the mechanism of effect. Benefits are more consistent in the 65-74 years age group, while no mortality benefit is seen in the age group above 85 years [6]. There is only one RCT of influenza vaccination in 3,000 subjects, and a recent Cochrane review concluded that it impossible to state whether the vaccine is effective in older people [7].

Other vaccines

Pneumococcal vaccine

Streptococcus pneumoniae remains the most common pathogen causing pneumonia. The 23-valent Pneumococcal polysaccharide vaccine is used in most European countries for adults aged over 60 yrs and for younger at-risk adult populations (asplenia, immunocompromised adults, chronic cardiac, renal, pulmonary or liver disease, and recipients of organ transplants). Meta-analysis has shown a 36% reduction in pneumococcal pneumonia, but no overall effect on pneumonia mortality [8]. The efficacy varies with the age of the population studied and the endpoint used: in adults aged 65-74 years, the vaccine is 70-80% effective, falling to 53-67% in 75-84 yr olds, and even further to 0-22% in the group aged 85 yrs and above [9]. However, a recent RCT from Japan showed a significant reduction in pneumonia with nursing home residents (2.8% vs 7.3% over 2 years), and pneumonia mortality rate (20.6% vs 25%) [10].

Antibody levels fall after about 5 years, and a repeated vaccine leads to a further (weaker) rise in antibody. There is no data on whether repeated vaccination confers benefit in older people.

Herpes zoster

Herpes zoster (or shingles) affects approximately 30% of the population at some point in their life. The risk of disease rises after 50 yrs, with zoster 8-10 times more likely to affect people aged 60 yrs or older (compared to younger people)[11]. About 70% of cases occur after the age of 70. It also occurs with more frequency in immunocompromised patients. Post herpetic neuralgia is the most challenging and debilitating complication, and occurs in around 20% of those between 60 and 80, and around 50% of those above 80.

A vaccine for herpes zoster was licensed in 2006 in Europe for immunocompetent adults aged 60 or over, and recommendations amended to include adults over 50 yrs in 2007.The use of herpes zoster vaccine reduced the incidence by 51 percent, incidence of post-herpetic neuralgia by 66 percent, and the overall burden of illness due to zoster by 61 percent [12]. The vaccine has uncertain duration of benefit, and the severity of post-herpetic neuralgia is greater above 70 years.

Immunisation and care homes

Influenza and pneumococcal pneumonia both take a heavy toll in Care Home residents, especially during the winter and influenza epidemics. As described above, there is limited evidence that influenza vaccination is successful in Care Homes. One study found only an 11% antibody response to a combination vaccine of influenza A and B [3]. Frailty and poor nutrition as well as extreme old age diminish the ability to respond to the vaccine. Nevertheless vaccination is generally recommended [5][13], but probably should not be given to resistive patients, or without patient consent given the equivocal benefit, or to patients with very limited life expectancy.

An alternative approach is to offer vaccination to the staff in care homes to provide herd immunity to the patients. There is RCT evidence that during an epidemic year of influenza, this approach is effective in reducing resident mortality. There is the added benefit that sick leave in the staff is likely to be reduced. This strategy appears to rely on staff uptake of the vaccine of at least 50% [14][15]. However this evidence has been criticised as a concommitant reduction in circulating influenza has not been demonstrated after staff vaccination [16].

Health policy

Trivalent (inactivated) Influenza Vaccine (serotypes H3N2, H1N1 and B) Trivalent influenza vaccine is recommended for adults aged 60 yrs and older in most European countries. The WHO has set coverage target rates of 75% or over for influenza vaccine for persons aged 60 and over, and this is also adapted by the European Parliament. The Department of Health policy on immunisation is covered by the “Green Book”, last updated in 2010 [13]. The Joint Vaccine Working Group of the European Union Geriatric Medicine Society and the International Association of Gerontology and Geriatrics (European Region) recently published recommendations for people over the age of 60 [1]. A summary of their recommendations are shown in the table appendixed below. They recommend universal coverage for those over 60 years for the annual influenza vaccine, and the pneumococcal vaccine to be given every 5 years.

The UK Joint Committee on Vaccines and Immunisation (JCVI) recommended in March 2010 [17] that a universal herpes zoster vaccination programme for adults aged 70 up to and including 79 years should be introduced provided that a licensed vaccine is available at a cost effective price.

Recommendations

The annual influenza campaign is one of the United Kingdom’s most successfully implemented public health programmes—uptake in those over 70 is estimated at 78%, the highest in Europe [18]. This combined with pneumococccal vaccination are important contributions to maintaining health and prolonging life, especially in “early” old age. The introduction of a shingles vaccine could also make a significant reduction in morbidity from post-herpetic neuralgia.

Unfortunately the body’s ability to respond effectively to vaccines diminishes with age, and this does compromise the value of immunisation in frail subjects and above the age of 80. Resources therefore need to be targeted at additional approaches. These include developing more effective vaccines and better forms of delivery for the elderly (for example, adjuvants and intradermal injections), and ensuring that more healthcare workers and carers who come into contact with vulnerable elderly people are vaccinated against influenza.