COVID live updates: Australia’s first local mRNA coronavirus vaccine trials will start ‘within months’

mRNA vaccines explained

You have several articles on MRNA vaccines, but what exactly is it for laypeople?


Here’s what science reporter Belinda Smith says about how mRNA vaccines work:

Vaccines train our immune system to recognize pathogens such as bacteria and viruses and to fight them on the way.

In other words, they give our body a practice run with reality, but without causing the full blown disease.

They do this by introducing antigens to our immune system – certain parts of a pathogen that the body can use to identify the invader in later encounters.

Conventional vaccines typically inject us with antigens, such as inactivated viruses or purified molecules.

But mRNA vaccines work differently. They do not contain any antigens. Instead, they contain a blueprint for the antigen in the form of genetic material – this is the mRNA.

In the case of Pfizer and Moderna vaccines, the mRNA provides the blueprints to build the spike protein that the SARS-CoV-2 virus uses to attach to and infect our cells.

When injected into the muscle, the mRNA is taken up by cells which “read” the mRNA and form antigens over the course of a few days, after which the mRNA is broken down.

The cells push the antigens out of their membrane and wave them around, a bit like a flag, to warn the immune system that something foreign has managed to break the body’s defenses.

In response, a type of white blood cell called B cells makes and pumps out antibodies – Y-shaped molecules that create an immune “memory” for that particular antigen. (Fun fact: the word “antigen” comes from “antibody generator”.)

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