A group of eight older adults holding sparklers and laughing

As you age, your immune system – the body’s natural defence against infectious diseases – can start to deteriorate.

The importance of a strong immune system

A healthy immune system – made up of special organs, cells and chemicals – is needed to help fight infection from pathogens, protect against harmful substances in the environment and attack abnormal cells within our bodies (such as cancer cells). There are many ways in which the immune system offers protection, and these are generally grouped into two categories:

An icon of a shield with a tick on it

Innate immune responses


Innate (non-specific) immune responses provide immediate defence against foreign pathogens or substances – these are the immune responses we are born with. Components of the innate immune system include physical barriers (e.g., skin, eyelashes, nose hair), chemical defenses (e.g., saliva, tears, stomach acid) and some types of white blood cells.

An icon of a virus

Adaptive immune responses


Adaptive or acquired immunity is not something we are born with – our bodies have to learn this response. The adaptive immune system must learn to identify and defend against foreign pathogens, meaning the initial response takes time. After first exposure, special immune cells "remember" pathogens, allowing faster and more accurate responses to future infections from the same pathogen.

The effects of ageing

As we grow older, our adaptive and innate immune systems can stop working as well as they used to. Some of the following changes may affect the immune system:

An icon of a microscope looking at cells
  • Our immune system responds more slowly to pathogens or substances, increasing susceptibility to certain infectious diseases.
  • Immune cells reduce in numbers, which means our bodies may take longer to heal.
  • Our immune systems become less effective at detecting and correcting mutations in cells, which may increase our risk of cancer.
  • Autoimmune disorders may develop as the immune system becomes less able to distinguish self from non-self, increasing risk of damage to healthy cells.

Age-related decline in immune function may occur more rapidly after the age of 50. There are several other factors that can also contribute to decreasing immune system function, including genetics, environment, lifestyle and nutrition.


Find out more about infectious diseases, including causes, signs and symptoms, risk, treatment and prevention options.

Chickenpox (varicella)




Flu (influenza)




Meningococcal disease










Shingles (herpes zoster)




Whooping cough (pertussis)


COVID-19 is an infectious disease caused by a new virus. Early evidence suggests that older adults may be at greater risk of COVID-related illness and hospitalisation, however, evidence is still emerging. For the most up to date advice about the disease, how to stay healthy, or what to do if you have symptoms, speak to your healthcare professional, refer to your State or Territory government website or call the National Coronavirus Hotline.

NP-AU-NA-WCNT-210001 Date of GSK Approval: March 2021