There were 44 new cases of Covid-19 in the community on Friday, 41 in Auckland and three in Waikato. Video / Dean Purcell / Christine Dawson / Michael Craig
ANALYSIS:
As countries around the globe strive to reach their national Covid vaccination targets, there's unprecedented focus on the biological effects of vaccines.
While there's an enormous amount of information available online, it's increasingly difficult to discern truth from falsehood or even conspiracy.
A common myth of vaccines that has appeared in recent months is the accusation they remain active in the body for extended periods of time – a claim which has increased vaccine hesitancy in some people.
However, vaccines are cleared from your body in mere days or weeks. It's the immune response against the SARS-CoV-2 virus that appears to last for a long time.
This isn't due to the vaccines themselves remaining in the body. Instead, the vaccines stimulate our immune system and teach it how to respond if we're ever exposed to the coronavirus.
Let's explain.
Covid vaccines show your body's natural defenses how to recognize and kill the virus, then they disappear. They don't stay with you, they don't change your DNA, and serious adverse effects from vaccination are extraordinarily rare.
All vaccines, no matter the technology, have the same fundamental goal – to introduce the immune system to an infectious agent, without the risk that comes from disease.
The vaccine needs to follow a similar pathway a virus would have taken to produce an adequate immune response. Viruses enter our cells and use them to replicate themselves. So, the vaccines also need to be delivered in cells where proteins are produced, which mimics a component of the virus itself.
The Covid vaccines all do this by delivering information into our muscle cells, usually in our upper arm. They do this in different ways, such as using mRNA, like Pfizer's and Moderna's, or viral vectors, like AstraZeneca's.
Regardless of the technology, the effect is similar. Our cells use the genetic template in the vaccine to produce the coronavirus' spike protein, which is a part of the virus that helps it enter our cells. The spike protein is transported to the surface of the cell where it's detected by the immune cells nearby.
There are also other specialised immune cells nearby, which take up the spike proteins and use them to inform more immune cells – targeting them specifically against Covid.
These immune cells include B cells, which produce antibodies, and T cells, which kill virus-infected cells. They then become long-lasting memory cells, which wait and monitor for the next time it sees a spike protein.
Once they've initiated the immune response, the vaccines themselves are rapidly broken down and cleared from the body.
The mRNA vaccines consist of a fatty shell, which encapsulates a group of mRNA particles – the genetic recipe for the spike protein. Once this enters a cell, the shell is degraded to harmless fats, and the mRNA is used by the cells to produce spike proteins.
Once the mRNA has been used to produce proteins, it's broken down 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. This is why the Pfizer and Moderna vaccines have to be so carefully preserved at ultra-low temperatures.
The vector virus has all of its infectious components removed, so it's unable 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.
The viral machinery gets the genetic template into the control room of the cell, the nucleus, where it takes advantage of our normal protein building activity. The vaccine doesn't cause any alteration to our DNA.
Normally, this would cause the cell to start producing more copies of the virus, but since this was all removed, all that's produced is the spike protein.
I’m having so many conversations about the concern that vaccines interfere with cells’ genetic material but no one seems freaked out that viruses jump right in there and make our cells little virus factories
The vaccines also stimulate your immune system to produce memory immune cells. This means even once antibody levels diminish, your immune system is ready to produce more antibodies and other immune cells to tackle the virus if you're ever exposed to it.
Vasso Apostolopoulos is a professor of immunology and associate provost, research partnerships at Victoria University (Australia); Jack Feehan is a research officer - immunology and translational research at Victoria University (Aus); Maja Husaric is a senior lecturer and MD at Victoria University (Aus).
