COVID Dictionary: What’s the Difference Between Strain & Variant?

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The emergence of coronavirus variants, first in the United Kingdom and later in South Africa, has renewed COVID-19 restrictions across the globe.

But here’s the big question – should we worry about the new variants?

What does a variant even mean? Are mutations among viruses normal?

Let’s understand the basic definitions.

What is a virus strain?

The term strain can only really be used when we are talking about Sars-Cov-2 – the main virus causing COVID.

This because that is a strain of the larger family of coronaviruses – like Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) .

These are all different strains belonging to the same virus family, which all have very different yet similar effects and severities.

So, again: SARS-COV-2 is the strain, and these new mutations – like the one in UK – are variants of that strain.  

What is a virus mutation?

The word mutation can sound scary and ‘unnatural’. Think X-men and all the ways we use the word in pop culture. But in reality, it’s a normal and expected process by which a strain takes on new variants.

There is a simple rule for understanding new variants: Ask whether the behaviour of the virus has changed.

In the majority of the cases, viral mutations hardly have any impact on the way the virus affects individuals. In fact, in many cases, the mutation could actually make a virus less potent, as FIT had earlier explained.

But in certain instances, a mutation could offer the virus an advantage - which may be what is happening in the United Kingdom. This would ensure that the viruses that do have these mutations (or combinations of mutations) would increase in number by natural selection, given the right epidemiological environment, as described in an article published in The Conversation.

“Many mutations mean nothing at all, or at least are more successful for reasons we don’t know. For instance a different strain may be more transmissible, but cause less disease. Bottom line is that we need to monitor, but at present, there is no evidence that the new strain in UK is more transmissible nor severe nor resistant to treatment or vaccination.”

Dr Marc-Alain Widdowson, Director of Institute of Tropical Medicine, Antwerp, told <i>The Indian Express </i>

What is virus variant?

Notably, many of the mutations observed in the UK variant have been seen earlier during the pandemic. Yet, the UK variant is defined by an unusual number and combination of mutations.

According to a BBC report, three factors are causing concern over the new variant of COVID-19:

• It is said to spread faster than the other versions – 70 percent more infectious
• It is the most common version of the virus in the UK
• There have been changes to the spike protein of the virus, which plays a key role in unlocking the doorway to the body's cells

Dr Gagandeep Kang, Professor at Christian Medical College, Vellore, was quoted by The Indian Express as saying, “It is the coronavirus spike protein that binds to a human protein to initiate the process of infection. So, changes here could possibly affect how the virus behaves in terms of its ability to infect, or cause severe disease, or escape the immune response made by vaccines — but these are theoretical concerns at the moment.”

What is genome sequence?

Genome sequencing is the process of figuring out the complete DNA sequence of an organism's genome at a single time.

This is how scientists can figure out the order of DNA nucleotides, or bases, in a genome that make up that organisms DNA.

(This was first published on FIT.)