Vaccines are not usually a common topic of conversation around the holiday table. But as we keep being reminded, this is a year like no other.
With new COVID-19 vaccines being rolled out across the world, and soon to reach Australia, vaccination has become a hot topic.
We know that vaccines act as a primer for our immune system. They give our body a preview of a pathogen (such as a virus or bacteria), allowing us to make antibodies so when we meet the real thing our immune system is able to quickly neutralise it.
But what is actually in a vaccine that makes it work? The first essential part of a vaccine is an antigen. This is the part of a vaccine that stimulates your immune system.
Most vaccines use either inactivated or killed pathogen, or a key part of that pathogen, such as a specific protein or toxin.
The COVID-19 vaccines are a bit different - they are messenger RNA (or mRNA) vaccines. mRNA is a type of genetic material.
In our cells, our DNA is copied into mRNA, which is then used as a template to make proteins. With an mRNA vaccine, mRNA that has the instructions to make part of a viral protein is introduced to our cells. Our cells use that mRNA as a template to make that viral protein, allowing our immune system to be primed to recognise and fight that pathogen should it encounter it in the future. While mRNA is genetic material, it only remains intact within your cells for a short time, and doesn't become part of your own DNA.
Alongside an antigen, many vaccines also contain something called an adjuvant. These compounds (often aluminium salts) trick our immune system into thinking there is a large infection, and therefore mounting a stronger immune response. Adjuvants that stimulate a better immune response lead to longer lasting protection.
The antigen and any adjuvants are the active parts of a vaccine - the things that make it work. But vaccines need to be kept stable for transport and delivery. So they can also contain stabilising compounds, things like sugar or proteins, as well as surfactants, which help keep all of the vaccine components from clumping together or separating from the mixture.
Vaccines against diseases like whooping cough, diphtheria, polio, measles, mumps and influenza have saved hundreds of millions of lives. It's nice to think we'll soon add COVID-19 to that list.
