Tue. May 17th, 2022

As Australia strives to achieve its national COVID vaccination targets, there is unprecedented focus on the biological effects of vaccines.

Although there is a huge amount of information available online, it is increasingly difficult to distinguish the truth from lies or even conspiracy.

A common myth about vaccines that has emerged in recent months is the accusation that they remain active in the body for extended periods of time – a claim that has increased vaccination doubts in some people.

However, vaccines are removed from your body in just days or weeks. It is the immune response to the SARS-CoV-2 virus that appears to last for a long time.

This is not because the vaccines themselves remain in the body. Instead, the vaccines stimulate our immune system and teach it to respond if we are ever exposed to coronavirus.

Let us explain.

How do vaccines work?

All vaccines, regardless of technology, have the same basic goal – to introduce the immune system to an infectious drug without the risk of disease.

The vaccine must follow a similar path that a virus would have taken to produce an adequate immune response. Viruses enter our cells and use them to replicate themselves. So the vaccinations must also be delivered in cells where proteins are produced, which mimics a component of the virus itself.

The COVID vaccines do all this by providing information to our muscle cells, usually in our upper arm. They do this in different ways, e.g. Using mRNA, like Pfizers and Moderna’s, or viral vectors, like AstraZenecas.

Healthcare professional holds a vial of Moderna COVID-19 vaccine
Vaccines break down quickly and are removed from our bodies. But the COVID-bursting cells that our immune system creates persist.
Mick Tsikas / AAP

Regardless of the technology, the effect is the same. Our cells use the genetic template in the vaccine to produce the coronavirus’ spike protein, which is part of the virus that helps it enter our cells. The spike protein is transported to the surface of the cell, where it is detected by the nearby immune cells.

There are also other specialized immune cells nearby that take up spike proteins and use them to inform more immune cells – targeting them specifically to COVID.

These immune cells include B cells that produce antibodies and T cells that kill virus-infected cells. They then become long-lasting memory cells, which wait and monitor the next time they see a spike protein.

If you are exposed to the virus, these B and T cells of memory allow a faster and greater immune response that destroys the virus before it can cause disease.

Read more: Revealed: the protein ‘pig’ that lets 2019-nCoV coronavirus pierce and invade human cells

So what happens to the vaccine?

Once they have started the immune response, the vaccines themselves are rapidly broken down and removed from the body.

The MRNA vaccines consist of a fatty shell that encapsulates a group of mRNA particles – the genetic recipe for the spike protein. When this enters a cell, the shell is broken down into harmless fats and mRNA is used by the cells to produce spike proteins.

Once the mRNA has been used to produce proteins, it is degraded and cleared from the cell along with the rest of the mRNAs produced by the normal function of the cell.

In fact, mRNA is very fragile, with the most long-lasting only able to survive for a few days. That is why Pfizer and Moderna vaccines need to be maintained so carefully at ultra-low temperatures.

The vector vaccines (AstraZeneca and Johnson and Johnson) use an adenovirus, which is harmless in humans, as a vector to deliver a genetic template for the spike protein to the cells.

The vector virus has all its infectious components removed so that it is not able to multiply or cause disease. Then, a genetic template for the spike protein is inserted into the vector.

Once the vaccine is injected, the vector virus binds to your cells and inserts its genetic components before the shell breaks down and is removed.

Read more: How long does immunity last after COVID vaccination? Do we need booster shots? 2 immunology experts explain

The viral machinery gets the genetic template into the control space of the cell, the nucleus, where it benefits from our normal protein-building activity. The vaccine does not cause any changes in our DNA.

Normally this would cause the cell to start producing more copies of the virus, but since all of this was removed, all that is produced is the spike protein.

Again, after making a large amount of the spike, the genetic templates degrade in a matter of days or weeks.

What about the spike protein?

While the vaccines themselves are quickly removed, what happens to all the spike proteins produced as a result?

They are identified as foreign by the immune system and destroyed – and teach the cells to recognize coronavirus in the process.

The spike proteins are completely cleared out of the body after a few weeks. At this point, they do not appear to be leaving the vaccination site (usually your upper arm).

However, antibodies specifically targeted to the spike protein produced by your immune system remain in the body for many months after vaccination.

The vaccines also stimulate your immune system to produce memory immune cells. This means that even when antibody levels drop, your immune system is ready to produce more antibodies and other immune cells to tackle the virus if you are ever exposed to it.

Read more: How long does immunity last after COVID vaccination? Do we need booster shots? 2 immunology experts explain

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