What constitutes an infection?

An infection is a health problem caused by a foreign factor, like virus, bacteria or fungi, that gets into our tissues. They can enter the body internally, such as through the respiratory system or gut, or externally through areas like the eyes, broken skin and nail cuticles.

Infections occur when our immune system goes into overdrive, scrambling to protect the body. They can occur very rapidly, or gradually, depending on what is causing the infection, where it is happening and how it is recognized by the body.

What is the infection risk in older people?

People over 65 years of age are more likely to not only get an infection, but also are more likely to have more severe symptoms and account for about half of those needing to go to hospital [1].

In the case of the Covid-19 pandemic of 2019-2022, the risk of serious complications from the infection was seen to increase strongly with age all over the world. One large population study involving more than 400,000 people found that those >75 years were 4 times more likely to have life threatening symptoms, compared to <65.

Why are older people at increased risk?

There are many factors that predispose older people to getting an infection, having symptoms and complications.

• Immunity and lung health decline: In the case of colds and flu, the main health factors are that the immune system and lungs become less responsive to clearing out infections with age [2]. In fact, people over 65 make up about 30% hospital cases of lung disease, following infections. Considering that the population is also living longer, this number is likely to increase with time.
• Micronutrient status and absorption decline with age: therefore, older age groups have higher recommended intakes of important vitamins and minerals [3]. Nutrients such as vitamin D and zinc are important in helping the immune system [4] to maintain balanced and swift protective actions.
• Symptoms become more severe: because the tissues that get inflamed because of the infection take longer to recover and health properly. This is also because older people tend to have other health conditions that may complicate their recovery, such as diabetes, cardiovascular disease or lung disorders.
• Lifestyle changes: older people spend more time inside with other family members or other elderly people, such as in nursing homes [5]. This increases their risk of picking up random or seasonal viruses and bacteria. Older people are also less active, which reduces their physical ability to deal with the symptoms of infections, such as chronic cough and obstructed breathing.
• Poor lifestyle choices in earlier years: alcoholism, smoking, and poor dietary intake can have a lasting impact on your health as you age. In the case of lung infections, we know that smoking dramatically decreases the ability of your respiratory systems to handle colds and flu, by about 4 times [6] . Smoking also reduces antioxidant protection systems, promotes oxidative stress, and causes complications in the heart and blood vessels.

What can be done about it?

Starting to look after your health, nutrition, physical activity, and lifestyle choices as you approach middle age can help to minimize the chances of not just getting an infection, but getting over it. This is because changes to the immune system and the ability of tissues and organs to recover are very gradual, so a little attention earlier are useful preventative measures as an insurance policy against problems happening later in life.

References

1. https://www.cdc.gov/flu/highrisk/index.htm.
2. Lowery, E.M., et al., The aging lung. Clin Interv Aging, 2013. 8:1489-96.(doi): p. 10.2147/CIA.S51152. Epub 2013 Nov 6.
3. Das, A., et al., Associations between nutrient intakes and dietary patterns with different sarcopenia definitions in older Australian men: the concord health and ageing in men project. Public Health Nutr., 2021. 24(14): p. 4490-4505. doi: 10.1017/S1368980020003547. Epub 2020 Oct 7.
4. Maywald, M. and L. Rink, Zinc homeostasis and immunosenescence. J Trace Elem Med Biol., 2015. 29:24-30.(doi): p. 10.1016/j.jtemb.2014.06.003. Epub 2014 Jun 13.
5. https://www.health.gov.au/resources/collections/covid-19-outbreaks-in-australian-residential-aged-care-facilities.
6. Arcavi, L. and N.L. Benowitz, Cigarette smoking and infection. Arch Intern Med., 2004. 164(20): p. 2206-16. doi: 10.1001/archinte.164.20.2206.

from an Expert Author

George Thouas

BSc, MRepSc, PhD – Biomedical Scientist

George has worked as a medical researcher for 17 years in the university sector, at both Monash University health institutes, and The University of Melbourne. He spent 12 of those years in reproductive health and fertility research, in roles such as Clinical Research Associate, Clinical Embryologist, Post-graduate Demonstrator, Lecturer, and later as a Senior Research Fellow and Lab Manager. His doctoral thesis investigated the effects of mitochondrial damage in the oocyte. He also worked on improving the nutrient and growth requirements for in vitro fertilization and embryo development.

George has authored and coauthored more than 50 publications, including 1 book, 5 book chapters, 30 peer-reviewed journal reports and reviews, 6 patents, international scientific conference proceedings and health practitioner journal articles.

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