Question: How do you make a vaccine

Ciarán O'Brien answered on 13 Nov 2014:

Making a vaccine is much harder than it sounds.

First of all, you need to know what causes the disease. This can be tricky as bacteria and viruses are tiny and hard to find, and even harder to grow in large enough numbers to study properly. If it’s not caused by bacteria or viruses, you’re out of luck, a vaccine won’t help.

then you have to figure out HOW the bacteria or virus causes the disease. This means finding out almost everything about it, whether it invades your body’s cells or makes toxins that damage them, what individual proteins it puts on the outside of its cell, what it does in different environments, how it responds to temperature, acid, heat/cold, too much sugar, too little sugar, and a hundred other things.

You then have to work out how it provokes your body to fight it. Is it a protein on the outside of the cell? Is it the toxin? Is it a combination of things?

Then you have to figure out a way to trick your body into thinking it’s being invaded by the bug, while not actually causing any damage. This is probably the hardest part of all, and sometimes the only part of a bacteria or virus that causes the body to respond is the very thing that’s also killing it! Biochemists could take a toxin and try to modify it so it’s not dangerous but still gets a response out of your body. Sometimes if it’s the proteins on the surface of a cell, it’s enough to kill those cells and inject them, so the body learns to fight them but they can’t fight back.

Once you have something in the lab that works, you have to figure out a safe way of getting it inside a person’s body. A lot of vaccines only stay fresh for a very short time so you have to add preservatives, but some of those might make the vaccine useless or dangerous.

Then, unfortunately, you have to test it. This usually means giving the vaccine to an animal and then infecting it with the disease. If it works, great, but if it doesn’t, it probably kills the animal 🙁 Health organisations won’t let anyone take a vaccine though unless scientists can first prove that it works on animals. Once they’re satisfied it’s not dangerous, they’ll start testing on humans. All this testing takes years and years, because everyone wants to make sure that it’s absolutely safe.

Then, finally, if it works, health organisations will approve it and it can be given to the public by doctors, and nobody has to worry about that disease again! 🙂