The first Covid-19 vaccine to be approved in Malaysia was the Pfizer-BioNTech vaccine, also called Comirnaty. As at March 11, 250,000 people have been given the first dose of this vaccine. Globally, millions have already received either the first shot, or even both shots of the vaccine.

Nevertheless, there is still quite a lot of concern on whether this vaccine, and others from the similar group of mRNA vaccines could prove to be harmful to individuals in the long run. The reason? These mRNA vaccines could modify your DNA and cause disastrous effects – with cancer being one of them.

The Covid-19 vaccines consist of a few types; with the two using the newest technology being mRNA vaccines and viral vector vaccines. In this instalment, mRNA vaccines are explained in length.

Before going into the workings of mRNA vaccines, it is perhaps better to revisit some concepts in biology.

First, let’s explain what DNA and RNA is. Deoxyribonucleic acid (DNA) and Ribonucleic Acid (RNA) are both polymers consisting of sugars, phosphates and nitrogenous bases. While DNA consists of two strands (entwined in the classic double helix) RNA is single-stranded.

DNA replicates and stores genetic information for an entire being and is found inside the nucleus of every cell. Think of DNA as an SD card with a lot of information. Each being has their own individual DNA containing their genetic information.

RNA is formed in the nucleolus (centre of the nucleus) and converts genetic information within DNA to a form that can be used to signal the building of proteins. Think of RNA like an SD card reader that is used to decode or read the information contained within DNA so that it can be recalled on a computer. Besides carrying instructions for making proteins, RNAs help to turn genes on and off, help in chemical reactions, modify other RNAs and even build proteins. Three main types of RNAs are:

• mRNA or messenger RNA which copies genetic code from DNA and carries it to ribosomes (factories within the cell that makes proteins).
• tRNA or transfer RNA which brings amino acids to the ribosomes in response to instructions from the mRNA.
• rRNA or ribosomal RNA which makes up the ribosome itself.

Together, DNA and RNA make proteins which are used by cells. The DNA sends information via mRNA and the mRNA’s information is subsequently made into proteins in the ribosome.

Second, let’s see how DNA and RNA are used by viruses. While complex beings such as humans use DNA and RNA in this sequential manner to make proteins, simple organisms such as viruses (including the Covid-19 virus) have only RNA – with all their genetic info contained within it.

When the Covid-19 virus infects a living human cell, it injects its RNA directly into it. This RNA then takes over the host’s protein production, making viral proteins including new virus cells which then burst out of the host cell and go on to infect other cells.

With all our biology refresher classes completed, we can now unwrap the ideas behind mRNA vaccines and how they work. Quite a bunch of smart people have studied the concept of mRNAs and how to use it to treat diseases since the 1990s, with RNA-based therapies being used since then.

One of the main areas in which RNA-therapies have been focused in recent years is in cancer – where RNA is being used to induce immune responses against cancer cells by the body itself.

Interestingly, BioNTech was a firm researching RNA technology in cancer which was subsequently quickly adapted for the purpose of an mRNA vaccine for Covid-19, in which they partnered with Pfizer.

Although these Covid-19 vaccines are the first mRNA vaccines to be approved, there has been a number of mRNA-based vaccines developed for the purpose of infectious diseases, even from 1993. So while the technology seems “new” and many are worried about it for this reason, in actuality, it’s been around for a while.

The current Pfizer-BioNTech mRNA vaccine works like this. The vaccine contains instructions for the injected human muscle cells (the vaccine is injected into the muscles of the upper arm) to make a protein. Remember, this is what mRNA’s do.

The protein our muscle cells make in response to this viral mRNA is a harmless piece of the Covid-19 virus called the spike protein. Once the mRNA has delivered its message it is broken down by the muscle cell itself (like any other RNA).

The spike protein is deemed harmless because it is not alive and cannot replicate to make new viral cells. On the other hand, when the spike protein is made, it “sticks” to the surface of the muscle cell into which the mRNA was originally injected and is recognised by our immune system as something “alien”.

The immune system begins building an immune response to this alien invasion exactly as though our body was infected by actual Covid-19 virus cells. This includes making antibodies. In time, the muscle cell with the spike protein is destroyed.

Why are two doses required of the vaccine if our immune system has already been prepared by the first dose and production of the spike protein? Well, in the initial testing period for these mRNA vaccines, it was found that the immune response generated by the body was weak after the first dose (not enough antibodies were produced).

After a suitable period (about 21 days after the first dose), when a second dose was given, there was a much stronger response – something like a jump start for a car. At these strong immune response levels, our body has a much reduced risk of being infected.

This is how mRNA vaccines work and once you realise how they work, it’s simple to refute the myth that they can transform your DNA. mRNA vaccines are a clever way of replicating the way viruses infect our body and turning that knowledge into our advantage to create this vaccine that works against them.

If you would like to get caught up on previous topics covered under this series, they are available as per the links below:

INFOVAX is a community education and awareness series on Covid-19 vaccines brought to you by the Malaysian Medical Association Public Health Society (MMA PHS). Feel free to ask questions and clear your doubts about Covid-19 vaccines by putting them to us at [email protected]. Your questions and answers will be collated and answered in the following sessions.