Heartbeat: Immunity, antigens, pathogens and antibodies – what does it all mean?

January 25, 2022

Four key words which would rarely be mentioned outside of an outbreak meeting have suddenly become part of day to day vocabulary, mentioned on the morning news and echoed in briefings from Downing Street – but do you really know what they mean and how they affect you?

Today, we’re going to break it all down and explain how antigens and antibodies support your body to build immunity against pathogens – without the complex language that requires a doctorate to digest.

Germs and organisms are all around us, in our environment and in our bodies, and when we come across one that manages to get past our physical defences (skin and mucus) it can lead to infection, illness and sometimes death. An organism that manages to infect our bodies and cause illness is called a pathogen, these can be a virus, bacteria, fungi or parasite.

Alongside our physical barriers (skin, hair and mucus) we have our internal defences otherwise known as our immune system whose job it is to track down pathogens that have breached our defences and attack them to bring an infection under control.

Each pathogen is made up of a several subparts which are unique to that specific pathogen called antigen, dictating its behaviour and interaction with the body and the disease it causes. Our bodies immune system in response to a pathogen’s antigen creates antibodies – these are unique, only attacking the exact antigen and pathogen they were created to defend against and essentially our bodies last line of defence to infection.

It takes time for a body to produce antibodies in response to antigen, for flu and COVID-19, it’s often up to two weeks before a body has built up a fully antibody defence against a pathogen.

Once antibodies have been produced, they work alongside the rest of the immune system to destroy a pathogen and stop the disease – this immune response and natural defence is the same used during a vaccination.

Vaccines contain weakened and inactive antigen (parts of the pathogen) or more recently simply just the markers for an antigen which on their own can not cause an infection, but through their introduction to a body will trigger an immune response and begin the production of antibodies.

Some vaccines require multiple doses, given over a period of time to support the production of antibodies and memory cells, ensuring that you are able to fight that specific disease for a long period of time and boosting the response time in future infections.