The easiest way to describe the vaccines are in groups. So if you look at the Pfizer vaccine, the one about a company called Moderna, which you might hear about, and the Astra, which is the Oxford university vaccine they do roughly the same thing.

What they do is, they take a genetic message into the cell to tell the cell to produce that little spike on the Corona virus, not the whole Corona virus. I need to back up a little bit and tell you how viruses work. If you put a virus on a table, the virus doesn’t multiply, it just sits there until it loses the ability to, it’s not alive, but it basically degenerates and stops being infectious. If you put a bacterium on the table, it can multiply. So if you put one bacterium on a table, it will become two, will become four, will become eight and so on, not a virus. For a virus to survive, it’s got to get inside our bodies. Then it’s got to get inside ourselves. And what it tells ourselves to do, is tells ourselves to stop doing whatever they’re doing and start producing the actual virus. So that’s what these cells in our body do, it’s why we feel so crap, gets into their respiratory cells in our nose, in our throat, in our lungs and churns out more virus, which we then cough and sneeze and breathe over other people, and it starts the process all over again.

So what these vaccines do, these three vaccines but there’s more of them around, is that they send a genetic message to the cell. So it’s similar to what the virus does except the genetic message is not to produce the whole virus, is just to produce that little spike because that spike is what locks into our body. So if you can neutralise that spike, you stop the virus getting into our body. So the cell produces the spike, the immune system trains on that spike. So when the real virus arrives, in neutralises the spike on the Corona virus and stops attacking the body.

Now, they get the genetic message into the cell in two different ways. So the Moderna vaccine and the Pfizer vaccine do it using something called messenger RNA or MRNA. This is like a readout code. And it contains a code which is a readout for the spike protein. And what it does when it gets into the cell, it confuses the cell and tells the cell to produce this spike protein. The cell thinks it’s coming from master control, but it’s not. This is coming from this little packet of genetic information. The Astra vaccine, and in fact, the Russian vaccine that you might’ve heard, called Sputnik five, and some other vaccines, do this by taking the genetic message into the cell, using another virus.

So the Oxford vaccine uses a chimpanzee virus, and chimpanzee virus has been engineered not to cause any disease. And they engineer the genetic message onto the chimpanzee virus which is very good at infecting ourselves. So they inject the vaccine, the chimpanzee virus goes into our cells and carries with it, it’s like an Uber carrying the virus message for the coronavirus into the cell, and then the cell produces the spike protein. So the end result was the same. How do they get the message in is different.

There is a problem with the Astra vaccine and the Russian vaccine is that our body can generate antibodies to the chimpanzee virus or the cold virus that they use to transport, it’s not a chimpanzee virus by the way with the Russian vaccine, it’s another virus but our body can react to that. So you get two doses, so one dose and then you could generate antibodies, And then the second dose of the vaccine doesn’t work very well because it’s got antibodies to the Uber virus that’s coming in. So the Russian vaccine gets round this by using two different viruses. Dose one is one virus, dose two is another.

With the Astra vaccine, one of the reasons you’ve probably heard of the controversy that they got 60% effectiveness with two full doses but they got 90% effectiveness with a half dose followed by a full dose which is likely to be that the half dose didn’t generate these antibodies to the vaccine.

There are other vaccines which are more traditional where they inject part of the virus or the whole virus into the body directly. And don’t need to turn over the genetic machinery of the cell. So there’s quite a good vaccine coming out soon from a company called Novavax where they use nanotechnology, but essentially it’s part of the spike protein that they inject directly.

There’s also one of the Chinese vaccines uses the whole virus but it has been inactivated so it doesn’t cause disease. So that’s essentially the two main groups of vaccines. One, they turned over our cells to produce the spike protein. And the other is they inject the spike protein in directly to create the immune response.

Yet to be seen, which is the more effective process for generating a deep and long-lasting antibody response. But it’s likely that they’ll all perform at high levels if they work at all.

Dr Norman Swan, Physician and Journalist

 

Last Reviewed: 24/02/2021

myDr

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