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  • Writer's pictureSinead Mackintosh

Herd Immunity

If you are like me, your nation’s lockdown has been extended. Maybe you also can’t help but look at other countries where they have either never had lockdown (we are looking at you Sweden) or are starting to ease on the lockdown restrictions. Sweden is implementing a herd immunity tactic, and this has caused some disputes across the world among medical professionals, national leaders, and just ordinary people. So, what exactly is herd immunity?

Very basically, herd immunity is when enough people in a community become immune to a disease that it stops the virus from spreading. This can be achieved in two ways: 1. A significant number of people get the disease in time and develop a natural immunity to it. 2. A considerable amount of people are vaccinated against the disease and are after that immune.

Okay, so what is the magic “significant number”? Well, it is dependent on the infectious disease. For some diseases, it’s 40%, but generally, 80-95% of the community needs to be immune. If we look at measles, 19/20 people must have had the measles vaccine for herd immunity to work. Therefore, if a child gets measles, then the vast majority of the people around them would be immune and not get sick. This is sort of like a broken telephone. If people are resistant, they won’t spread the disease from person to person. This then helps people who are not vaccinated or who are vulnerable to infection, such as the elderly, babies, pregnant women, and people with weakened immune systems.  

You are probably wondering about Corona/COVID-19/SARS-CoV-2 or whatever you prefer to call it. Well, we all know that there is no available vaccine for it, so we can’t develop herd immunity that way. Additionally, researchers are not sure if a person can get the virus more than once. This is concerning because then herd immunity won’t be as effective as it would be for something like chickenpox. It is also suggested that based on what we know about Corona so far, we would need about 70% of the population to be immune for herd immunity to work. Researchers are also trying to figure out why some people are more severely affected by the virus, besides the predisposing stuff. Still, there is more to the story than that.

The answer is most likely closely related to genetics, because we see this a lot in other diseases. Genetics are involved in your immune system development as well as your risk of getting other health complications such as heart disease. This will need further investigation, and I am sure that over the coming years, we will be uncovering a lot more about Corona. Until then, get the seasonal flu jab if you can, wash your hands and stay safe! 

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