-
As the pandemic continues - variants
have become the latest concern
-
with notable examples detected in South Africa,
Brazil and the UK.
-
But variants are complicated. Each one is
made up of a collection of mutations,
-
all of which have the potential to change the
SARS-CoV-2 virus in unexpected ways.
-
So what do scientists mean when they talk
about variants
-
and what might this mean for the future of the pandemic?
-
Viruses multiply by copying their genomes
over and over.
-
But like an old photocopier, these copies aren’t always perfect.
-
Each of these imperfect copies is a variant.
-
Normally the imperfections or mutations don’t
change how the virus behaves
-
and they can often make it less successful
than the original strain.
-
But very rarely mutations can change the virus
in some important ways.
-
It could become more infectious,
or more able to avoid the immune system.
-
The more a virus is allowed to replicate unchecked,
-
the more chance it has to accumulate these rare beneficial mutations.
-
That can occur when viruses are allowed
to spread quickly through a population,
-
or if they encounter a host that’s less able to fight them,
-
such as people with compromised immune systems
from medical treatment or those who are HIV+.
-
If a particular set of mutations makes a variant
more successful, it might become more prominent than others
-
and that’s when it gets noticed.
-
Epidemiologists may even decide to label it
a ‘variant of concern’,
-
like the examples identified in Brazil, South Africa and the UK.
-
For months, scientists have been striving
to work out what’s changed in these variants,
-
and what those changes mean.
-
Because a variant spreading doesn’t necessarily
mean that it has an advantageous mutation.
-
For example a small number of people could,
by chance, move a variant from one region
-
to another, like tourists travelling back
from popular vacation spots.
-
This could cause that variant to start
spreading in a new location
-
even though there may be no significant
change to the biology of the virus.
-
This is called
the Founder Effect.
-
Understanding why a variant has emerged requires
a combination of studies.
-
Epidemiology can help detect and trace new variants and flag
new or worrying patterns of infection.
-
Meanwhile lab studies can start to pinpoint how the
mutations are changing the properties of the virus.
-
And studies like these are starting to identify
mutations that have given the virus an upper hand.
-
Some variants are faster spreading,
and there are hints that certain mutations
-
could start to weaken or even evade natural
and vaccine derived immunity.
-
For example, the D614G mutation, known to
virologists as Doug, spread widely in the
-
early days of the pandemic and can be seen
in almost all variants.
-
It affects the spike protein that coronavirus
particles use to penetrate cells. A mutation
-
in the genome changes one amino acid for another,
-
and makes the new variant more infectious than the original virus.
-
N501Y also known as Nelly, is another spike protein mutation
which appears to be associated with increased transmissibility.
-
This mutation has been detected in the B.1.1.7,
B.1.351 and P.1 strains - all variants of concern.
-
The worry of so-called ‘immune escape’ has also been hinted at with another spike protein mutation, E484K or Eek.
-
Eek has been spotted in B.1.351 and P.1, the
variants detected in South Africa and Brazil.
-
Lab studies in early in 2021 showed that the
variant could evade some virus-blocking antibodies,
-
while trials in South Africa suggested that
the variant reduced the efficacy of several vaccines.
-
Despite these worries, the coronavirus is
actually mutating very slowly compared to
-
something like influenza and it seems like
the vaccines developed so far will remain at least partly effective.
-
But scientists are still taking the threat
posed by variants seriously.
-
And there are several things that
can be done to help tackle it.
-
Firstly, to do anything researchers need data
-
- it’s very important to monitor and trace the emergence of
variants and that isn’t always simple to do.
-
Organisations like the COVID-19 Genomics UK
consortium, or COG-UK,
-
have stepped up their efforts to combine
fast sequencing with efficient data sharing.
-
COG-UK has already sequenced over 400,000 SARS-CoV-2 genomes.
-
Next, researchers need to look forward to
how these mutated viruses could affect global
-
vaccination efforts. Existing vaccines can be redesigned and
combinations of vaccines are also being tested
-
but it could be difficult to perform reliable
clinical trials amid the ongoing vaccination programmes.
-
Right now though, work needs to continue at
a national level.
-
Public health policies such as track and trace, social distancing and vaccine roll-outs
-
are powerful tools to interrupt transmission and keep tabs on new variants.
-
After all, every time the virus is prevented
from spreading,
-
it's also prevented from mutating,
-
nipping new variants in the bud
before they even have a chance to develop.