Why do we have variants of the coronavirus that causes COVID-19?
And how are they different to the original virus?
Let's find out.
To understand how and why variants happen,
we need to look at the virus itself.
The structure of a virus is much simpler than that of bacteria or our own cells.
So simple, in fact, that people debate whether viruses are alive.
Viruses only need two things
an outer shell made of protein
and genetic material, either DNA or RNA.
Unlike our own cells,
viruses don't have the machinery to use their genetic code to make new proteins.
They rely on invading our cells for this.
The outer shell of the coronavirus is covered in spike proteins that it uses to infiltrate our cells.
Once inside, the virus hijacks the cell's machinery
to make copies of itself using its own genetic instructions.
For the coronavirus that causes COVID-19, this genetic material is RNA.
Whenever the RNA is copied,
there's a chance that a small change could occur.
This is called a mutation.
Mutations can be an alteration to the genetic sequence
or the deletion of a tiny part of it.
Mutations happen all the time and usually go unnoticed,
but sometimes mutations can give viruses a new advantage.
They could help the virus re-infect people, spread quicker,
evade vaccines or cause more severe symptoms.
When infection rates are high, the virus is circulating widely
and the chance of a mutation happening is higher.
We've all become aware of the coronavirus variants that cause COVID-19.
So how do we know when a new variant has emerged?
There has been a huge global effort to detect and track these variants.
Using a technique called whole genome sequencing,
scientists can find new variants by looking at the genetic code of a virus sample
taken from a diagnosed patient, and compare this to viral samples from other cases
to see if there are differences.
Before the pandemic, the UK did not have a viral genomic surveillance system in place
with the capacity to track an active pandemic.
That's why, in March 2020, the COVID-19 Genomics UK Consortium was formed.
Also known as COG-UK, it brought leading scientists together
with public health agencies and the NHS to keep track of how the virus is evolving.
So what variants have been discovered so far?
The truth is that thousands of variants have been identified and catalogued.
Thankfully, most are not worth our attention.
Newly detected variants are monitored,
but most mutations have little impact on how well a virus can spread,
evade vaccines or cause severe disease.
Variants with mutations that provide the virus an advantage are classified as ‘variants of concern’.
These mutations cause them to be different,
but still similar enough to be the same virus.
For the COVID-19 pandemic,
the World Health Organization introduced a Greek letter system
so variants could be named in a simple way
without stigmatising the countries where they were discovered.
The first to be named this way - the Alpha variant -
spread more quickly than the original virus,
causing a surge of cases across Europe in the winter of 2020.
Beta and Gamma were also more transmissible, but their spread was limited
before the more aggressive Delta variant emerged.
Delta became the dominant strain throughout the world for most of 2021
until Omicron appeared.
Compared to the original virus, Omicron has around 50 mutations,
and many are unique to this variant.
More than 30 of the mutations are in the genetic code for the spike protein,
helping Omicron to spread much faster than previous variants.
However, research suggests that Omicron causes less severe disease than previous variants.
Right now, Omicron is the dominant variant.
The question is, will there be more variants in the future?
Almost definitely.
But what impact this might have is unknown.
Despite this, we're in a much better position now than we were in the early days of the pandemic.
Vaccines have played a huge role in reducing how many people
become severely unwell and potentially die from COVID-19.
But all viruses mutate over time,
some quicker than others,
and that could cause vaccines to be less effective.
That's why people receive flu jabs on a yearly basis.
The influenza virus mutates,
meaning that vaccines need to be updated with the most prevalent strains to offer the best protection.
The future evolution of this coronavirus may be uncertain,
but now that we have COVID-19 vaccines,
there's the possibility of changing them as long as we know which variants are out there.