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As requested by the awesome @sindivanzyl - here’s a SUPER beginner’s guide to the immune system (to help you understand vaccines).
Thread
(For this thread, pathogen = bacteria, virus, parasite
or anything else the body deems ‘foreign’)
/1
Thread
(For this thread, pathogen = bacteria, virus, parasite
or anything else the body deems ‘foreign’)/1
The immune system is very complex, and you don’t need to know it all to understand vaccines. 
But we all have an army inside of us, working 24/7 to keep us safe.
Without it, we would die within a few weeks. 
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But we all have an army inside of us, working 24/7 to keep us safe.
Without it, we would die within a few weeks. /2
We are exposed to hundreds of pathogens daily, but only rarely get sick. This is because our immune system works beautifully to protect us (it’s amazing!).
There are 2 main components: ‘innate’ and ‘adaptive’. /3
There are 2 main components: ‘innate’ and ‘adaptive’. /3
The innate (or ‘non-specific’) has a few roles, some of which are:
- Prevent infections getting in (skin, mucous membranes, healthy bacteria)
- Identify & kill pathogens (neutrophils, N killer cells, macrophages)
and
Present them to the adaptive (dendritic cells, macrophages) /4
- Prevent infections getting in (skin, mucous membranes, healthy bacteria)
- Identify & kill pathogens (neutrophils, N killer cells, macrophages)
and
Present them to the adaptive (dendritic cells, macrophages) /4
The innate system is NON-SPECIFIC and therefore relatively INEFFICIENT.
It does not differentiate between different bugs and does not remember pathogens.
It has NO MEMORY.
But it’s a good first line of defence. /4
It does not differentiate between different bugs and does not remember pathogens.
It has NO MEMORY.
But it’s a good first line of defence. /4
The ‘adaptive’ side, when presented with a pathogen by the ‘innate’ side has the ability to form T cells to directly kill the pathogen, or stimulate B cells to make antibodies.
Antibodies bind to pathogens and signal to the rest of the immune system to kill what they’re on. /5
Antibodies bind to pathogens and signal to the rest of the immune system to kill what they’re on. /5
The adaptive immune system, because it directly targets individual pathogens, is much more efficient than the innate system.
But more importantly, it has the ability to REMEMBER pathogens it has seen before. This is the KEY POINT!
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But more importantly, it has the ability to REMEMBER pathogens it has seen before. This is the KEY POINT!
/6
Both the B and T cells can form ‘memory cells’ which lie in the background...
... and if a pathogen is identified in the body again, they spring into action and either make more antibodies or tell the T cells to attack
immediately. /7
which lie in the background...... and if a pathogen is identified in the body again, they spring into action and either make more antibodies or tell the T cells to attack
immediately. /7
Vaccines exploit this aspect of the immune system by getting the body to develop an ‘adaptive’ response to a pathogen WITHOUT requiring a full blown infection first 
.
This results in development of cells (B and/or T) ready to fight a certain pathogen when they next see it. /8
.This results in development of cells (B and/or T) ready to fight a certain pathogen when they next see it. /8
If you can wrap your head around this (and it’s complicated!), then vaccines become easy!
Please note, I am not an immunologist, and if I have made any errors, I apologize. This was meant to be a beginner’s guide, not a definitive reference. I hope it helped. /9
Please note, I am not an immunologist, and if I have made any errors, I apologize. This was meant to be a beginner’s guide, not a definitive reference. I hope it helped. /9
Tomorrow, with this in mind, I’ll do a thread on HOW exactly vaccines get the immune system to develop a response and where Covid vaccines fit into all of this.
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PS- for those who are interested and would like to know more, this is a helpful video that is still understandable for those without medical training.
