How Do Vaccines Work?

By Katie Pain

In our current climate, many people are taking the steps to be vaccinated in order protect themselves from COVID-19, as well as many other illnesses… but what is in a vaccination, and how can it protect us from disease.


Before we can understand how vaccines work we need to understand how our bodies fight illness. When a pathogen (disease causing organism) enters your body, it can infect and cause disease which makes you ill. The symptoms you get as a result are often the visible signs of your body trying to fight the illness - for example coughing. However your body is also fighting from the inside. The pathogens contain antigens, which cause the production of antibodies. Antibodies and antigens fit together like puzzle pieces. The antigens are unique to different pathogens, and so different antibodies are necessary to fight different diseases.

They latch onto the antigen and work together with the body's immune system to kill the pathogen and fight the disease. Although the antibodies are specific to individual illnesses, when they are produced, they are remembered by ‘memory cells’ so that if you come in contact with that pathogen again, the antibodies can be produced quickly and will fight the disease quicker than before. Although this method works for less deadly diseases, like the common cold, when you come in contact with a deadly pathogen, within the time it takes for your body to produce the antibodies, and to fight the disease, you can get very ill.


A vaccination is a dead or weakened form of the pathogen. When injected into your body, it allows your immune system to create the necessary antibodies to fight the antigens and allows the memory cells to store them, without actually making you ill. This means that when you come in contact with the actual pathogen, your immune system immediately starts to combat it, and can produce antibodies at a much faster rate than before.

As well as helping you to get better quickly, and stopping you from feeling unwell, the vaccine helps to reduce your viral load, meaning that you don’t spread the disease as easily to others, which reduces the infection rate. When a lot of people are vaccinated, this creates Herd Immunity. This means that because a lot of people have reduced viral loads and don’t get very bad symptoms (for instance coughing, which can easily spread pathogens), it is more difficult for the disease to circulate and spread around a community, meaning that less people come in contact with the disease. Over time, because less people are getting infected, this reduces the spread and slowly works towards abolishing the disease completely.

History has proved that by vaccinating, and creating herd immunity, we can eradicate diseases completely over time. For instance, Polio, tetanus, and the measles, (and many more) were all a massive threat in the past, but since the use of vaccinations, we have almost completely expelled any risk of these illnesses. Polio in particular, was a worldwide disease in the early 1900s, which was highly infectious. It invaded the brain and spinal cord, causing paralysis. While it used to be a huge threat and widely spread, the use of vaccinations has led to us completely eradicating it.

If we continue to vaccinate against coronavirus, we will stop the spread of the virus. We can create herd immunity, and hopefully completely eradicate the disease.