Alexander Robertson

If you Google “COVID-19 News”, many of the results reference the new “UK strain” of the virus. What is this strain? Should we be worried? And what do new strains mean for the fight against COVID-19?

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Note: This article was written in late December when we knew very little about the emerging SARS-CoV-2 strains. Since the time of writing this article, new data has emerged characterizing the UK (B.1.1.7) strain as well as the Brazil (P.1) and South Africa (B.1.351) strains. The consensus on the threat that these strains may impose has shifted from “it will likely be fine” to “this is very worrying”.

I am leaving this blog post up as a record of how information changes with time during a pandemic. Before you take the post below at face value, please read my updated post.

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What is a “strain” of a disease?

The word “strain” does not have a technical definition; it’s a loose term used by scientists to describe when there are significant differences between multiple lineages of a pathogen. Pathogens are constantly evolving and mutating. When those mutations amount to a significant change in the way the pathogen behaves, we call it a new strain.

In this case, officials are calling the UK variant (dubbed SARS-CoV-2-B.1.1.7) a new strain due to its apparent ability to be transmitted easier than previous strains of COVID. Many outlets are reporting a 70% increase in transmissibility, but that number is still being assessed and validated by virologists and epidemiologists. There also seem to be a number of mutations in a very important protein on the surface of the virus: the spike protein. SARS-CoV-2 uses its spike protein to bind to cell surfaces, allowing it to enter a cell and start replication. These mutations in the UK variant likely make it easier for the virus to enter our cells, which is the reason why we are seeing such an increase in transmission.

It should be noted that there are a number of other strains emerging across the globe. Notably, there are strains emerging in South Africa and Nigeria. Luckily, like the UK variant, these other strains appear to be no more deadly than the original SARS-CoV-2 strain.

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Is the emergence of a new strain surprising? Not at all.

Before infecting humans, SARS-CoV-2 likely infected bats and, accordingly, was adapted for transmission between bats.  Given its sustained transmission among human populations, it’s not surprising that the virus would similarly begin to adapt to the human body and become more transmissible.

In fact, this is probably what happened during the 1918 Flu Pandemic. The influenza virus that started the 1918 pandemic was likely an animal virus that entered the human population. We don’t have the same level of genomic data for the 1918 influenza virus as we do for SARS-CoV-2, but generally as a pathogen adapts to a human host, it develops mutations that enable it to spread more freely from person to person.

Even after a pathogen has adapted to humans, it’s not uncommon for it to continue evolving into new strains. For example, influenza has circulated throughout the human population for a long time, which has led to many different strains emerging. This is one of the reasons we need to get a seasonal flu shot.

For animal species, evolution takes place over hundreds of thousands or even millions of years. For bacteria and viruses, however, evolution is much more rapid, sometimes taking as little time as a few days. This will not be the last time we see new strains of SARS-CoV-2 emerge.

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Is this all worrying? Potentially.

Am I more worried than before? Not really.

I am not worried because by all accounts, it seems that the current vaccines for COVID-19 will work against these new strains. What would be much more worrying is the emergence of a new viral serotype. 

A serotype is a variant of a pathogen that “looks” different to our immune system compared to previous strains. Think of it like a criminal wearing a fake moustache to sneak past people who have seen their face in a wanted poster. 

The emerging UK variant is, by contrast, very likely not wearing a fake moustache. If your body has had some exposure to the virus, either by infection or by vaccine, you will likely remain safe to subsequent infection of the B.1.1.7 strain.

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Does the emergence of a new strain change how we’re fighting the virus?

We already have the tools to effectively reduce transmission of SARS-CoV-2. We know that masks are incredibly effective, and we know that indoor dining greatly increases the chance of transmission. Lockdowns can be effective if done correctly but they are brutally disruptive on economies and public support for that type of intervention is low. Hopefully, the emergence of new strains will renew politicians’ concerns about the virus, but, overall, I don’t see it necessarily changing our strategies.

Scientists and epidemiologists are still working to find if there is something we should be worried about. Until we know more details about the emerging strains, keep doing what we’ve been doing – just with renewed determination.

Viruses will mutate as they spread; this is an inevitable fact. If you can help to stop the spread in some way, you are also helping to keep new strains from emerging. With the vaccines rolling out, we are closer than ever before to the end of this pandemic. Stay strong!

Have any questions about COVID-19? Diseases in general? Let me know in the comments below!

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