What are COVID-19 variants, where do they come from, and why do they matter?

April 12, 2021

You may have seen headlines warning about new variants of COVID-19 emerging in the UK, South Africa and elsewhere. But how do COVID-19 variants develop? Why do they matter? And what do they mean for the future course of the pandemic and the effectiveness of vaccines?

How do COVID-19 variants arise?

COVID-19 is caused by the SARS-CoV-2 coronavirus - a tiny particle that is little more than a length of genetic code (RNA) wrapped in a spiky molecular coat.

When SARS-CoV-2 infects a human cell, it makes thousands of copies of itself, which then spread out into the world in search of new hosts. Viral replication is quick and messy, so every time the virus replicates, there is the potential for a mistake in its genetic code. 

Most of the time, these changes, known as mutations, are small and irrelevant, while others put the virus at a disadvantage. 

Since COVID-19 was first identified in 2019, scientists have identified thousands of SARS-CoV-2 variants, most of which we haven’t heard about because they don’t affect the behaviour of the virus or our defences against it.

But sometimes a chance mutation gives the virus an advantage, like making it better at infecting people or helping it evade our immune systems. 

High infection rates increase the chance of this happening. To put it simply, more virus equals more variants.

Why are COVID variants a problem?

Once an advantageous genetic change appears, viruses with the advantage quickly become the dominant strain. This is what happened with the B.1.1.7 variant (also known as the Kent or UK variant),  which has a cluster of mutations affecting its spike protein that helps it spread more easily. 

What’s more, growing immunity rates provide evolutionary pressure for the virus to keep changes that help it evade immune responses, for example, by escaping antibodies acquired during a previous infection.  

We saw this in Manaus, Brazil, where around 75% of the population had been infected with the virus by October 2020. New variants emerged that were less affected by pre-existing antibodies, causing a surge of re-infections

COVID-19 variants with advantages that make them harder to contain or fight have been called ‘Variants of Concern’ (VOC). Several variants of concern have now been identified, including the B.1.1.7 (Kent), B.1.351 (South African) and P.1 (Brazil) variants. 

How do we detect variants?

Researchers all over the world are monitoring the emergence of new COVID-19 variants by analysing the genetic code of viral samples and looking out for any changes - an approach known as genomic surveillance.

The UK is a leader in genomic surveillance thanks to the nationwide COVID-19 Genomics UK Consortium (COG-UK) programme, which is why the B.1.1.7  variant was identified so quickly. 

COG-UK identifies variants by extracting viral DNA from COVID test swabs, sequencing it, and comparing the sequences with other known variants. They aim to sequence as many positive test swabs as possible, analysing up to around 10,000 per week across the UK. 

How do variants affect COVID symptoms?

Our research suggests that COVID-19 caused by the B.1.1.7 variant has the same symptoms as COVID-19 caused by other variants in the UK.  

However, recent research linked this variant with more severe disease and higher death rates from COVID-19, though the overall risk of dying from the virus is still low, particularly in younger age groups. 

Currently, there is no evidence that the South African or Brazil variants cause different symptoms or more severe disease, but more research is needed.

Will vaccines work on COVID variants? 

Well, it’s a little early to say. Because COVID-19 vaccines train our immune system to respond to the spike proteins on the surface of the virus, there is concern that new variants with changes to the spike protein that help them evade immune responses may also render vaccines ineffective. 

Fortunately, research has shown that the Oxford AstraZeneca vaccine is working well against the B.1.1.7 variant. However, initial research suggests that it is less protective against mild and moderate disease caused by the South African variant. 

However, because the trial mainly included young people who don’t tend to get seriously ill from COVID-19, it wasn’t possible to investigate the vaccine’s effect on rates of severe disease. 

Laboratory studies suggest that the Pfizer and Oxford AstraZeneca vaccines offer some protection against the Brazil variant, but more work is needed to confirm this.

What will COVID variants mean for the future of the pandemic?

As COVID-19 continues to spread in many places, new variants will continue to emerge, especially in areas where rates of infection remain high. We don’t know for sure, but experts think future variants could help the virus avoid immune recognition, meaning that we will need new vaccines. 

To prepare for this, scientists are investigating the likely impact of potential future mutations in the laboratory.  And several vaccine producers, including Pfizer and AstraZeneca, are already working on updated versions of the vaccines that protect against new variants. The UK is already preparing to offer boosters to over 70s, care workers and health workers from September to help combat the current crop of new variants. If the virus continues to change, it may well be the case that regular boosters are needed in the future, similar to the current situation with the flu jab

How can you stay safe from COVID variants?

SARS-CoV-2 variants are more likely to arise where there are lots of cases of COVID-19, so it’s vital we all take steps to stop the spread and bring the numbers down as much as possible.

Vaccines play an important part, and the UK vaccine rollout is going well. However, slower progress in many other countries presents a risk that new variants could be brought in by travellers visiting or returning to the UK.

Even if you’ve been vaccinated, you should still follow public health measures such as social distancing, covering your face, regular hand washing and keeping indoor spaces well ventilated.

It’s also essential to know the 20+ symptoms of COVID-19 and get tested as soon as you feel unwell, so you can self-isolate to protect your loved ones and the wider community.

To help keep tabs on the emergence of new variants and the effectiveness of the vaccines, make sure you download, use and share the ZOE COVID Study  app

You are our early warning system for tracking COVID infections, and the more people get involved, the more accurate our data is, so we need as many people logging their symptoms in the app as possible.

Stay safe and keep logging.

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