The simple intervention that could boost your health in old age

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Vaccines have transformed children's lives by protecting them against debilitating and life-threatening illnesses. But they could have a similarly transformative impact on healthy ageing, experts say.

Writing in Science Translational Medicine this week, an international group of scientists outlined how vaccines could be used to improve the health and well-being of older people - as well as the challenges that must be addressed to unlock their full potential.

"Progress in immunology suggests that adult vaccines, if well deployed, have substantial potential to promote healthy ageing."

Aurelia Nguyen, Gavi's Chief Programme Officer and a contributor to the study

"Healthy ageing aims at slowing the process through which health tends to decline with advancing age at both the individual and societal level," said Aurelia Nguyen, Gavi's Chief Programme Officer and a contributor to the study. "Progress in immunology suggests that adult vaccines, if well deployed, have substantial potential to promote healthy ageing and are a key tool to promote improved health and the social and economic well-being of an ageing population."

Ageing populations

The number of people aged 65 and older is projected to grow to 2.1 billion over the next three decades - nearly doubling the current proportion of the global population falling into this age group and tripling the number of people aged 80 and older. 

The recent development of effective vaccines against shingles, respiratory syncytial virus (RSV), hepatitis B virus and human papillomavirus, as well as therapeutic vaccines for certain cancers, demonstrate the potential of vaccines to prevent diseases in older adults.

While increased lifespans are largely cause for celebration, there are concerns about the additional pressures that large numbers of people who are frail and need dedicated medical care may place on health care systems - particularly in low- and middle-income countries, where 77% of the global population aged 65 years and older is expected to be living by 2050.

The recent development of effective vaccines against shingles, respiratory syncytial virus (RSV), hepatitis B virus and human papillomavirus (which protects against liver and cervical cancer), as well as therapeutic vaccines for certain cancers, such as melanoma, demonstrate the potential of vaccines to prevent diseases in older adults.

Yet, to fully harness their potential, researchers must take better advantage of existing knowledge and technologies, and expand their knowledge about vaccination in older age. Also needed are strategies to boost uptake of vaccines by older individuals, the authors said.

Boosting knowledge

Immunising older populations can be challenging because of age-related declines in people's immune responses. This not only makes them more susceptible to infections, but it can make vaccines less effective. Scientists have already developed some strategies to overcome this issue, such as increasing the amount of antigen (the part of the vaccine that triggers an immune response) in each dose and identifying adjuvants (a substance that enhances the body's immune response to an antigen) that generate more robust and enduring immunity among older adults. Even so, more research into how ageing impairs the immune response is needed, which could provide further strategies to boost responses to vaccination.

Longevity is also associated with chronic health conditions, such as cardiovascular diseases, type 2 diabetes and cancer. Clinical trials of therapeutic and preventive cancer vaccines are ongoing, with recent clinical evidence showing the efficacy of mRNA-based vaccines in combination with monoclonal antibody therapy reinforcing the idea that cancer vaccines are possible.

This data raises the possibility of applying the same approach to other cancer types or other chronic diseases such as cardiovascular disease or rheumatoid arthritis - or to infectious agents that increase the risk of developing chronic diseases, such as proposed links between RSV and asthma, or Epstein-Barr virus and multiple sclerosis.

"Even partially efficacious vaccines to prevent or immunotherapies to treat such diseases could have an important impact," the study authors said.

Further scientific research is needed to make such approaches widely available, together with regulatory pathways for clinical validation and licensure.

Improved adherence and access

As more vaccines for older people become available, major shifts in immunisation programmes will be required. Even though older adults are often at high risk of illness or death from many infectious and non-infectious diseases, vaccine hesitancy could be an issue.

Lessons could be learned from the field of dentistry, where messaging about the need for regular prevention visits to avoid future problems is ingrained. Public confidence in the safety of air travel has also been boosted by using 'black box' investigative teams to determine the cause of airplane crashes. "Publicising vaccine safety surveillance systems and their operation would likely increase public confidence in vaccines," said the study authors.

Given the importance of surveillance, current practices for monitoring routine childhood vaccines will need to be adapted and expanded.

A proactive approach to adult vaccination that addresses the evolving demographic landscape of low- and middle-income countries, as well as overcoming obstacles such as a lack of data on the burden of vaccine-preventable diseases in adults, or the absence of policies and appropriate delivery systems for adult immunisation initiatives, is also needed.

Nguyen said: "We've seen that outbreak-prone diseases can strike in every age group - and the transmission can be driven by varying age groups - and so having a strong health system that can deliver vaccines to different time points is important."

Economic impact

The economic impact of these vaccination programmes, which is often used to justify spending on them, may be hard to quantify.

Older adults contribute to the global economy through employment as well as through activities that enrich society, such as caring for grandchildren or volunteering in the community - but the latter are not traditionally included in national income calculations such as gross domestic product (GDP).

Productivity and the benefits of vaccination in different age groups also need to take regional differences, particularly between high- and low-income countries, into account.

There are further potential benefits: "Older adult vaccination at scale may bring additional aggregate economic gains through reductions in healthcare payer costs, which in turn would lower insurance premiums (private payer) or taxes (social healthcare)," said the study authors. "Older adult vaccination also provides secondary protection for older adults who may not otherwise be eligible for certain vaccines."

Adult vaccination offers a golden opportunity to improve the health, social and economic well-being of ageing populations. Achieving this goal will take work, but it is surely worth it.