How do Inactivated Vaccines Work?

An inactivated vaccine is made up of disease causing microorganisms that have been killed, usually by heat treatment, so that they can be safely administered to the human body without the risk of a an actual infection. Inactivated vaccines are used to treat diverse conditions including polio, cholera, and typhoid fever, and in this article we look at how these vaccinations confer immunity against virulent and dangerous diseases.

How do inactivated vaccines make us immune to diseases?

The basic principle behind vaccination is to get your body’s defensive mechanisms to respond to a particular disease causing organism. These defences, dubbed the immune system, are highly adaptable and are able to ‘learn’ how to respond to specific viruses and bacteria, preventing their harmful effects. This ‘learning’ process requires an initial exposure during which the immune system usually takes some time to mount an adequate defence. It is this initial exposure which a vaccine mimics, getting your defences familiar with a particular pathogen (disease causing micro-organism) but in a manner safer than being exposed to the actual, live pathogen.

Some diseases can be extremely dangerous, overwhelming the immune system before it can defend against the causative pathogen. These are usually highly contagious conditions that vaccines are developed for. By priming the immune system, a vaccination gives us a chance to properly defend itself against what would otherwise be a dangerous infection.

After the vaccine has been injected, your body will respond against it as if it were any normal pathogen, developing cells and molecules called antibodies that specifically target the vaccine. Once the vaccine has been cleared from your system, your body retains a number of appropriately named memory cells which remain in circulation for long periods of time, ready to respond to any further exposure to the disease. That means that if you were to be exposed to the actual infection, these memory cells would mount a rapid defence, protecting you from serious illness.

An inactivated vaccine is composed of dead pathogens, however these still possess the characteristics which mark them as harmful invaders. Your immune system is able to recognise and respond against the inactivated vaccine, treating it like the actual infection. However, because the injected pathogens are dead, your body does not face the risk of serious illness, making this technology an effective method of immunising people of all ages.

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