In the case of the COVID-19 vaccines, the mRNA carries instructions for making a protein found on the surface of the SARS-CoV-2 virus — the spike protein. But here’s the thing: this protein by itself doesn’t cause disease. It’s just a small part of the virus. The mRNA vaccine doesn’t use the virus itself, just the genetic instructions to produce the spike protein.

So, when you get the vaccine, here’s what happens:

Immunity: If you later encounter the actual SARS-CoV-2 virus, your immune system already knows how to recognize and fight it because it has the antibodies and memory cells ready to attack the virus’s spike protein.

Injection: The mRNA is injected into your muscle cells (usually in the arm).

Protein production: Once inside the cell, the mRNA uses the cell’s machinery to create copies of the spike protein.

Immune response: Your immune system sees these spike proteins as “foreign” and mounts an immune response, creating antibodies that specifically target that spike protein.

Here’s how it works step by step:

1. The Spike Protein:

The first thing you need to know is that the COVID-19 virus (SARS-CoV-2) has a spike protein on its surface that it uses to invade human cells. This spike protein is what allows the virus to attach to and enter cells, leading to infection.

Now, the mRNA vaccine doesn’t contain the actual virus. Instead, it contains mRNA that encodes just the instructions for making the spike protein. This is important because your immune system needs to recognize the spike protein as foreign (not something that belongs in your body) so it can mount a defense if you get infected with the full virus.

2. How the mRNA Gets to Your Cells:

When you get the vaccine, it delivers this mRNA into your muscle cells (usually in your arm). The mRNA doesn’t stay in your body for long — it’s just there to deliver the instructions for a short period of time.

3. Protein Production:

Once inside your cells, the mRNA is taken up by ribosomes, which are the cellular machinery that makes proteins. The ribosomes read the mRNA “recipe” and begin to assemble the spike protein, just like following a cooking recipe. This process doesn’t involve the virus itself — your cells are just making a small, harmless piece of it: the spike protein.

4. Your Immune System Responds:

Once your cells start producing the spike protein, your immune system recognizes it as foreign because it doesn’t belong in your body. This triggers an immune response:

• Antibodies: Your immune system creates antibodies that specifically target the spike protein. These antibodies will help prevent the virus from entering your cells in the future.
• T-cells: Your immune system also makes memory cells (like T-cells), which “remember” how to fight the spike protein. If you’re exposed to the actual SARS-CoV-2 virus later, your immune system can quickly recognize the spike protein and mount an attack.

5. Clearing the mRNA:

Once the spike protein is made and your immune system has been activated, your cells break down and eliminate the mRNA. It doesn’t stay in your body. The mRNA is a temporary blueprint that your cells use only long enough to make the spike protein and then destroy it.

Why is This Important?

• It’s Fast: Unlike traditional vaccines, which often require growing the virus or parts of the virus in a lab, mRNA vaccines are quick to develop once scientists know the genetic sequence of the virus.
• No Risk of Getting the Disease: The mRNA vaccine doesn’t use live virus, so there’s no risk of getting COVID-19 from the vaccine. It only teaches your immune system to recognize a harmless piece of the virus.
• No Altering of DNA: The mRNA in the vaccine doesn’t interact with your DNA at all. It doesn’t change your genetic code. Once the spike protein is made and the immune response has been triggered, the mRNA is broken down and cleared from your body.

In Summary: The mRNA Vaccine Process

Injection: You get the vaccine, which delivers mRNA into your muscle cells.

Protein Production: Your cells use the mRNA instructions to make the virus’s spike protein.

Immune Response: Your immune system recognizes the spike protein as foreign and produces antibodies and T-cells to defend against it.

Memory: Your immune system “remembers” the spike protein in case it encounters the real virus in the future.

Clearance: The mRNA is broken down and cleared from your body.

No live virus: The mRNA vaccine doesn’t give you the virus or alter your DNA. It’s just a temporary set of instructions for the cells to make a protein to teach your immune system.

Fast development: mRNA technology is faster to design and produce than traditional vaccines, which often rely on growing the virus or bacterial proteins in a lab. This made it a game-changer in quickly developing a vaccine during the COVID-19 pandemic.

No integration into DNA: mRNA doesn’t stay in the body for long. Once it has been used by the cell to make the protein, it breaks down and is eliminated from the body. It never interacts with your DNA, so there’s no risk of it changing your genetic material.