The Vaccine : Explained

While it may seem to be coming to an end, the world is still fighting COVID – 19. Today, I will take you through a basic biological explanation of the vaccines, and help you understand how innovative this new technology is.

Today we will take a look at the mRNA vaccines that the CDC recommends.

The main thing I want to address here is neither Moderna, Pfizer nor any other mRNA vaccine will ever alter, change or manipulate your DNA or genes. This is a fatal misconception that I want to help dissipate with this blog post.

Before we dive into how vaccines work, we need to understand some basics.

Our body is made up of cells, and cells are the primary unit of life. These cells are then grouped with other cells that share functions, into tissues. Tissues are then grouped into organs, and organs are grouped into organ systems. This right here, is the way our bodies are structured from the cell upwards.

Within each and every single one of our cells, we have a central unit known as the nucleus. The nucleus can be thought of as the brain of the cell. Here, we have our DNA, which stores coded information of various biological molecules and is also how animals transmit genetic inheritance to offspring. Arguably, the most important job that DNA has is coding for proteins, which are critical for the cell’s and the body’s daily work. Certain types of proteins are known as enzymes (heard of this before?) that help with our body’s chemical reactions. The nucleus is guarded by something known as the nuclear envelope, which is a membrane covering with certain pores. Another critical part of the cell are organelles, which have different purposes. Here is a labelled picture to help you to visualize all of this.

credit: national geographic

As you can see, we have the nucleus and nuclear envelope, as well as some other organelles that are useful for the cell’s daily work.

Remember how I said that DNA codes for various proteins? Well how does this coded information go to form actual proteins? That process, is known as gene expression.

When we need a certain protein, we have to look at the DNA to find instructions for that protein. To explain this concept, I am going to use an analogy.

Let’s say that you and I are chefs working in a restaurant. In the center of this restaurant, we have a giant cookbook filled with age old recipes for everything that is on the menu. If we want to cook a specific meal, we will need to find the instructions for that meal in our cookbook. After flipping to the right page, we confirm that this is in fact the recipe that we need. Instead of taking the entire cook book to the kitchen area, we make the more sensible decision of photocopying the recipe page. This is to make sure that should anything disastrous happen (water spill, accidental crumple), we will always have the original copy in perfect form.

This is exactly how it works with DNA. Think of DNA as our master cookbook, but instead of taking a photocopy of a page from a cookbook, we convert a specific part of this DNA (called a gene) into another special “photocopy” molecule, known as mRNA or messenger RNA. This mRNA strand only has copied information for that specific protein, and ventures outside our nucleus and nuclear envelop to an special place in the cell known as a ribosome. Here, the ribosome will read the mRNA strand and make the protein through a process known as translation. After the protein is made and the mRNA is no longer needed, the mRNA gets degraded and is never used again.

credit: campbells biology

Congrats! You now understand how DNA works, and how it helps us create proteins!

Now lets look at how this complicated process related to the vaccines and viruses. What happens when a COVID virus comes into our body? The best way to think of it is that the virus is hacking gene expression, the process explained above. Most viruses have certain spike proteins that allow it to interact with a body cell. COVID is no exception. If a receptor is able to make contact with this cell, COVID-19 will deposit its own RNA into the cell. (Keep in mind, a virus is not living, rather is only made up of a protein shell and genetic material). Once the virus deposits its own genetic material into the cell, this RNA travels to a ribosome just like any other mRNA in gene expression. However, this RNA has not been taken from the cell’s DNA, and does not code for proteins useful to the cell. Instead, it codes for the virus’s own spike proteins. Here, the virus controls the cell, effectively turning it into a “protein printer” for its own destruction. These spike proteins will then go on to form more viral structures, infect more cells, and the process will continue.

Once the body detects that these spike proteins are floating around, it knows that they are foreign particles. Critical to the battle against the virus are white blood cells. The immune system is made up of various types of white blood cells. These are most commonly separated by their role in the immune response. One of the first responders, known as a macrophage (“big eater”) will consume any cells that have been hacked by the virus. It then takes the spike proteins that have been created by that hacked cell, and displays them on their outer membrane. This then alerts the second group of immune cells. Two of these cells, are in a family of white blood cells known as t cells. Both of these cells are alerted by the macrophage’s presentation of these spike proteins. Helper t cells will go on to mitigate viral attacking of the bodies immune cells (it helps our cells), and cytotoxic t cells will kill infected cells (it destroys infected cells).

credit: trends in biochemical sciences

Another type of white blood cell, B cells, work to mitigate the virus itself. (note: t cells are working with the infected and body cells, b cells are working with the virus itself.) Plasma b cells make antibodies, and “shoot” these at the virus. These anti bodies are literally proteins that block the spike proteins of the virus from touching the cell’s receptors, therefore preventing any “hacking”. While the plasma cells “shoot” at the virus in the current, memory B cells store similar anti bodies on their outer membrane.

Activation Of B-cell Leukocytes Stock Vector - Illustration of killer,  cells: 103194897
credit: dreamstime

These memory B cells are how we get long term resistance to a virus. When the virus comes around again, these memory b cells are already floating around the body with the anti bodies ready to go, and can stop the virus from hacking cells with a higher level of efficiency and speed.

14 Lymphocytes ideas | immunology, b cell, microbiology

A vaccine wants to get this sweet resistance and then some, without the entire painful process of undergoing the entire immune response with a real virus. Usually, this is done by creating a “deadened” virus and inserting that into the body, lessening the immune response but still getting that resistance. For COVID, we have now seen innovative technology come into the market in the form of mRNA vaccines.

As you now know, viruses insert their RNA into the cell, which starts the immune response. With mRNA vaccines, scientists have genetically modified RNA to be less severe and more effective, while keeping the original instructions for the COVID spike proteins. We then insert this RNA into the cell, as it undergoes the same process as the virus, but with less severe effects and higher efficacy. After this, memory b cells floating around the cell will provide resistance to the COVID -19 virus.

In essence, the mRNA vaccine does not make direct contact with DNA, and just replicates how a virus infects our cells, but with more efficiency then the normal deadened virus method. This method isn’t necessarily experimental either, production and study of this technology has been going on for years, even if it wasn’t directly in the hands of patients.

If you want to learn some more on the immune system, I highly recommend this video/channel :

If you have any questions throw them into a comment below and I will get back to you. Please consider following me and sharing this post. Get vaccinated and help us protect against the delta variant!


  1. Reece, J., & Campbell, N. (2021). Campbell’s Biology (12th ed.). Pearson. (Original work published 2002)

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