European ADULT IMMUNISATION HUB

The clinical benefits of adult vaccination

Vaccines prevent up to 3 million deaths worldwide each year [Ehreth 2005]. The clinical (i.e. health) benefits of immunisation are clear. Vaccination success stories are well documented. Vaccines are widely regarded as an effective tool for improving health, and children in all countries are routinely immunised against major diseases [Bloom 2005]. Smallpox has been eradicated and wild poliovirus has been eliminated from most countries. Haemophilus influenzae type B (Hib) was eliminated within a few years of introduction of conjugate Hib vaccines in countries such as the UK, France and Germany [Ehreth 2005].

The benefits of vaccination extend beyond the individual patient to the wider society [Chlibek 2012] and herd protection is a well-known effect of vaccinating a significant portion of the population. However, herd protection works only if vaccination coverage is high enough to reduce the transmission to unvaccinated individuals. If the herd effect is sufficient, then the infection may be significantly reduced or even eliminated from that population.

Public authorities are also increasingly acknowledging the role of vaccination in the fight against antimicrobial resistance. Resistance to bacterial infections is a major clinical problem: these are becoming harder to treat and causing more prolonged and severe disease. This leads to reduced quality of life and higher healthcare costs [Vaccines Europe 2013]. Evidence suggests that antibiotic use can decrease in association with the initiation of immunisation programmes or increased uptake of available vaccines (e.g. pneumococcal and influenza immunisation programmes) [Coignard 2008]. Vaccination limits the development of antimicrobial resistance by decreasing the likelihood that bacteria targeted by these vaccines are exposed to antimi­crobial agents (antibiotics) [Vaccines Europe 2013].

Furthermore, several infectious diseases are often transmitted and/or acquired in healthcare settings, particularly hospitals, while patients are receiving treatment for medical or surgical conditions. These infections include bacterial pneumonia, pertussis or the secondary complications of e.g. influenza. Effective prevention of these diseases through immunisation should decrease their prevalence in healthcare settings and help drive a reduction in the use of antimicrobials [Vaccines Europe 2013].

The clinical benefits of vaccinating adults as part of life-course immunisation strategies have been shown in the following examples:

  • Cohort studies show that influenza vaccination provides substantial health benefits, including reduced hospitalisations, outpatient visits, mortality and antibiotics prescription among older people [Nichol, as cited in Chlibek 2012].
  • A vaccination programme for older people was shown to be effective at reducing cases of invasive pneumococcal disease (IPD) in the UK. Recent clinical studies also suggest vaccination with pneumococcal conjugate vaccines may provi­de a benefit in adults [Jackson, as cited in Chlibek 2012].
  • The implementation of a herpes zoster vaccination programme for older people has the potential to improve their quality of life markedly by reducing the incidence and severity of the disease. One stu­dy, based on a randomised control trial, found a reduction in disease burden in older adults of 61% and a reduction of postherpetic neuralgia by 67% [Oxman 2005, as cited in Chlibek 2012].
  • Since the initiation of widespread vaccination of infants and children, the burden of pertussis has shifted to adolescents and adults. Several countries have reported an increased incidence in older age groups. As these older age groups can transmit the disease to unprotected in­fants, there is an additional need for an effective pertussis booster vaccination programme in older age groups [De Greeff, as cited in Chlibek 2012].

For more information and references see: Adult Vaccination, A key component of healthy ageing