In this blog article the virus has entered the body, invaded the cells which it has been able to latch on to and is beginning to do what it does best – reproduce. But our body has an immune system which stands guard against any invaders it detects and as soon as it does, it goes into action.
The first lines of defence form part of what is known as the innate immune system and upon finding virus particles, it releases proteins called interferons. Their job is to “interfere” with the virus and try to halt it from reproducing and spreading. Additional “troops” are called on to help kill the virus in the shape of neutrophils. They are a form of white blood cell and are particularly good against bacterial infections. But remember, Covid-19 is a virus and not a bacteria.
The problem when it comes to fighting a virus is that in some cases the neutrophils don’t stop and continue to destroy the normal cells within the body. Such an event is known as a cytokine storm and is extremely serious. However, the body can call on further resources to help fight the virus such as macrophages. They have the ability to eat and clear up any virus particles they find.
If the innate immune system is not able to defeat the viral attack then the body can call on the next set of defences called the adaptive immune system. This is where antibodies are produced in vast numbers and what are termed T-killer cells attack and destroy any cells the virus particles have infected.
There are different types of antibodies and they work by understanding any new invader they detect and then producing the right type of antibody to defeat it. The antibodies remain in your blood after the virus had been defeated and they are ready to fight any new infection it recognises as the same virus. In fact, some hospitals are treating seriously ill patients with Covid-19 by transfusing the plasma from patients who have had the disease. It is hoped that these antibodies will then be able to more effectively fight the virus.
Most people who get infected with the coronavirus have mild symptoms or become asymptomatic which means they are unaware of having any symptoms. However, older people and those with certain underlying medical conditions can have weaker immune systems and can therefore be at greater risk of it developing into something more serious. The answer is to find a vaccine which is safe and effective. And that is what we shall discuss the fourth and final part of this series of articles.
John Pullen 