Viruses and Immunity
This chapter focuses on the immune responses to viruses after infection has happened. Viruses need a host in order to replicate, and when a person is infected by a virus, their immune system is responsible for fighting the infection off (Nie and Wang, 2013).
What is the immune system?
The immune system is a defence system which protects us against harmful invaders that come from outside our body or harmful changes that happen inside us. It is vital for our survival.
There are two sides to the immune system:
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Innate immune system: it is immediate and fights harmful substances that want to enter our bodies using both physical barriers such as skin and immune cells such as phagocytes. It is non-specific and we are born with it (Bal and Rath, 1998).
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Adaptive immune system: it is slower than the innate system but consists of specialised cells that make antibodies after an initial contact with a pathogen (any agent that can cause disease). Antibodies are capable of fighting off repeat infections from the same pathogen. It is specific and develops after we are born (Alberts, 2002).
If it is the first time the virus infects a person, the innate immune system alone may not be able to fight it off, so the person will start to get sick. At the same time the adaptive immune system has started to produce antibodies against the virus and eventually you will recover and have immunity against future infections (Immune responses to viruses, 2020).
If it is not the first time the virus infects a person, antibodies against it already will exist. They will bind to the virus before it has a change to infect a cell, neutralise it and ultimately eliminate it, therefore avoiding the development of an illness (Immune responses to viruses, 2020).
Vaccines are created using the adaptive immune system in order to create immunity against a virus.
how does the immune system fight virus infections?
When a virus infects a person our immune system reacts in different ways.
Vaccines
Vaccines help develop immunity to a virus by taking advantage of the adaptive immune system. A vaccine imitates an infection, one that does not cause an illness but is enough for the immune system to produce antibodies against the virus (Understanding How Vaccines Work, 2018).
​Once this “infection” leaves the body, it will now have antibodies against that specific virus and will fight off any future infections (Understanding How Vaccines Work, 2018).