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Viruses, Bacteria & The Immune System

A quick introduction to pathogens and key principles of the immune system.
Electron microscopy image of an immune cell (blue).

Viruses and bacteria are microorganisms which can sometimes cause disease when they infect us.

Below, you can see an image of a bacteria called E. coli. This is an example of a bacteria which can sometimes cause disease, but which is also sometimes harmless. You can learn more about viruses and bacteria in the file at the bottom of this page.

electron microscopy image of a bacteria called E Coli, dyed green

In order to protect us, we have white blood cells which circulate around the body, often in our blood, to detect any intruders such as viruses and bacteria and kill them. These are our white blood cells make up our immune system.

To learn more about the immune system and how it works, click through to the file at the bottom of this page.

A key concept of our immune system is that it can remember pathogens it has previously encountered. Through this memory, it can respond more quickly to pathogens the second time it sees them and stop us getting sick.

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Prison Health: Vaccinations for People Working and Living in Prisons (Non-Vaccine Trained Staff)

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