What affects health more: germs and viruses, or the environment?

When we think about the determinants of health, it is important to remember that there is no single factor which causes people to be healthy or not.

Not everyone gets the flu when exposed to a flu virus in the air. People do not stay healthy only because they are physically active. And they do not get sick only because they inherited specific genes from their ancestors. The reasons that people get sick or stay healthy are more complicated than this. Any or all of these and other determinants can interact to influence health.

What effect do other determinants have?

For example, pollution affects the quality of our water and air, which in turn affects our health. Also, the way people feel and behave affects their biology. And the environments that people live in – social, physical and even cultural – influence both their behaviour and their biology, and in turn their health. This means that things like

• whether you grow up poor,
• how much support you get from family and friends, or
• how much control you have over your work
• can all influence your life choices, your body’s responses, and of course, your overall health and well-being.

All of this seems to follow a biological pathway. For children, we see how early childhood experiences influence brain development and mental and physical health. In adults, feelings such as fear, loneliness, depression, powerlessness and frustration are translated by complex body systems – like the nervous system and the immune system – into chemicals and hormones that flow throughout the body. Strong negative emotions can trigger floods of stress hormones (the "fight or flight" phenomenon). This in turn hinders the body’s ability to defend itself against disease.

Therefore, while germs, viruses and the environment can all affect health, our health is also determined by a complex relationship of factors, across the entire lifespan.