- 4 years ago
- Wedding: October 2013 - Dalhousie Castle
After reading a lot of comments on this thread on the vaccination question thread I realised there seems to be a little knowledge gap about how the immune system works and what all the scary sounding ingredients in a vaccine are for. I’m a biochemist so I thought maybe I could give a brief explanation of some stuff. I wrote this in the thread but it got a bit buried and I spent ages writing it so I’m posting in it’s own thread. Hopefully its pitched at the right level and not too simple or too sciency….here goes…
1. Immune system. This is a complicated system that involves several different organs and a lot of different cell types and lots of message molecules all working together to protect your body for infections from bacteria, fungi, viruses and parasites.
The part of the immune system that vaccines act on are the cells and processes that produce antibiodies. Antibodies are molecules grab onto parts of the invading pathogen and render it inert/mark it for destruction. They are very specific and each type of antibody should only bind to one thing (usually part of a surface protein). Think of it like a lock and key. The key looks generally the same, but the end of each one is different, meaning it only works in one specific lock.
The business end of the antibody is produced randomly by some fancy gene rearrangements that occur when each of these cells is forming. That means each cell only knows how to produce a single type of antibody. Before you encounter a disease, all these cells are speeding around in your blood waiting to be activated and many never will be because their key will never find the right lock, but they are there, just in case. That means, until you are exposed to a disease, the body doesn’t know which cells to use and which to keep dormant…..you can probably see where this is going.
When an invader enders the body the cell with the right antibodies, that bind to that invader, will be activated. It will first divide (a LOT) so now you have an army of cells that have the right antibody and that are making tons of it to fight the infection. This responce is slow because a lot of things have to happen to get the army ready. This is a what is known as a primary infection. While all this is going on, you will be suffereing from the symptomes of the disease. If you cannot get the responce going quick enough, you might be overwhelmed and suffer permanent damage or die. Yikes!
Anyway, some of these cells that were activated then mature and migrate into the bone marrow where they hang out and wait for the same invader to stop by (secondary infection). If it does, the body is ready for them. No lag time, the army is ready to roll! This infection will be a lot less severe and often you will not even know you have been invaded because you body clears it out so fast. Yay!
2. Vaccines: The principle of vaccines is to mimic the primary infection without actually making you suffer through a potentially deadly disease. That way, you get the immunity without the danger.
Vaccines do this by using putting bits of the pathogen, dead pathogen, or what’s known as live attenuated (changed so they can’t actually harm you) pathogen into your body so you can activate the right cells and get the army ready. It sounds scary to put live pathogen in the body so why do this?
The actions of the live pathogen help to put your immune system on high alert and basically help it to take your vaccination as a serious threat (even though it’s not). This gives you a better immune responce and usually means your more ready should the real bad guy come along.
Most of what sounds like scary chemicals in the vaccine are there for two reasons. The first is to preserve the vaccine. Remember the lock and key? Well if your lock changes shape, then the key can no longer fit and the cell with the right key won’t be activiated. We need to stop that from happening. Second, is to spur the immune system into action, just like the live pathogen, some of the chemicals help to get the response going and make it last longer.
Not only will vaccination protect the individual that has been treated, it will also protect others around them who are not immune. Because vaccinated people can clear an infection so quickly the chances they will spread the infection to others is reduce dramatically. If enough people are vaccinated (needs to be roughly 85% of the population, but varies from disease to disease) we will get herd immunity. This means that there is so little chance for the infection to spread to a new host before it’s cleared that it drops to a very low or none existant level in the population. This means that individuals that are not immune and cannot be vaccinated for whatever reason are also protected.
Also, because the infection has little chance to thrive, the chances that it will mutate (change) enough so it’s lock is now too different for the protective keys to work is vastly reduced. This is very important. If vaccination uptake drops below a certain level, we are all at risk from new strains of an infection. Our previous vaccinations (eg like flu, that changes easily because of its genetic structure) will not protect us against these and we will all be in danger until a new vaccination can be made.
In summary. Please vaccinate if you can. You protect not only yourself, your children, but also your community and large. It’s one of the easiest things you can do to help humankind in general!