The Pfizer and Moderna vaccines are set to become the mainstay of Australia’s COVID-19 vaccine rollout as the year progresses, according to the latest government projections released this week.

From September, up to an average 1.3m doses of the Pfizer vaccine plus another 125,000 doses of the yet-to-be approved Moderna vaccine are expected to be available per week. These figures are set to rise from October, as use of the AstraZeneca vaccine drops.

Both the Pfizer and Moderna vaccines are mRNA vaccines, which contain tiny fragments of the genetic material known as “messenger ribonucleic acid”. And if social media is anything to go by, some people are concerned these vaccines can affect their genetic code.

Here’s why the chances of that happening are next to zero and some pointers to how the myth came about.

Remind me, how do mRNA vaccines work?

The technology used in the Pfizer and Moderna vaccines is a way of giving your cells temporary instructions to make the coronavirus spike protein. This protein is found on the surface of SARS-CoV-2, the virus that causes COVID-19. The vaccines teach your immune system to protect you if you ever encounter the virus.

The mRNA in the vaccine is taken up by the cells in your body, ending up in the liquid inside each cell known as the cytoplasm. Our cells naturally make thousands of our own mRNAs all the time (to code for a range of other proteins). So the vaccine mRNA is just another one. Once the vaccine mRNA is in the cytoplasm it’s used to make the SARS-CoV-2 spike protein.

The vaccine mRNA is short-lived and is rapidly broken down after it’s done its job, as happens with all your other mRNA.

Typical mammalian cell, showing different parts, such as nucleus and cytoplasm

Vaccine mRNA is in the cytoplasm and once it’s done its job, it’s broken down. www.shutterstock.com
Here’s why the mRNA can’t insert into your genetic code

Here’s why the mRNA can’t insert into your genetic code

Your genetic code is made up of a different, but related, molecule to the vaccine mRNA, known as DNA, or deoxyribonucleic acid. And mRNA can’t insert itself into your DNA for two reasons.

One, both molecules have a different chemistry. If mRNAs could routinely insert themselves into your DNA at random, this would play havoc with how you produce proteins. It would also scramble your genome, which is passed on to future cells and generations. Life forms that do this would not survive. That’s why life has evolved for this not to happen.

The second reason is vaccine mRNA and DNA are in two different parts of the cell. Our DNA stays in the nucleus. But vaccine mRNA goes straight to the cytoplasm, never entering the nucleus. There are no transporter molecules we know of that carry mRNA into the nucleus….

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