SHOULD WE BE WORRIED ABOUT NEW VARIANTS?

▶ Mutations to the virus appeared in Britain, Brazil and South Africa

The world is battling new mutant variants of the coronavirus – and they are wreaking havoc.

Governments have imposed new lockdowns and introduced travel bans in response.

Three variants, first detected in Britain, Brazil and South Africa, have particular mutations – changes to the virus’s genetic material – that affect the virus’s spike protein, the structure that allows the pathogen to attach to and enter human cells.

“Flu, covid and polio throw up variants all the time,” said Prof John Oxford, professor emeritus at the University of London and co-author of Human Virology, a seminal book on the subject.

“It’s come to the fore because of molecular techniques available for the first time to analyse the genome. We’ve got a lot more detail now.”

The coronavirus, officially named Sars-CoV-2, has undergone many thousands of mutations since emerging in 2019. Most are inconsequential – and some are harmful to the virus – but the ones characterising the new variants make them more transmissible and therefore better able to survive.

“They will rise to dominate geographical areas,” said Ian Jones, a professor of virology at the University of Reading, UK.

“It is unlikely that one variant will dominate the world, as different mutations can give the same outcome, so they will end up jostling with one another.”

Variants are often referred to by the country in which they were discovered, but this is not necessarily where they originated. Some nations undertake far more genetic sequencing than others, so are more likely to identify mutations in the virus.

Dr Andrew Freedman, an infectious diseases specialist at Cardiff University in Wales, said mass vaccination could lead to variants that can be transmitted even between vaccinated people becoming dominant.

“That’s why we might have to tweak the vaccines,” he said.

So what are the variants, and what makes them stand out?

One has been traced to southeast England in September 2020 and has spread to more than 50 countries. Known by names including B.1.1.7, it is characterised by 17 mutations. One, called N501Y, involves a change in the spike protein’s receptor binding domain, the part that attaches itself to cells.

The RBD is a target for the immune system, so changes to it could potentially render vaccines less effective.

Recent research suggests this variant is 30 to 50 per cent more transmissible than most forms of the virus, not the 70 per cent first estimated. The “UK variant” has been blamed for a rise in cases in Britain and Germany, but Prof Oxford said current surges in infections could have arisen when lockdowns were eased in late December.

“Everyone had a free-for-all at Christmas. People’s behaviour has generated all these cases rather than the new mutant,” he said.

Although it spreads more easily, N501Y does not make people more ill and research has shown it is still susceptible to vaccines.

A second variant, called B.1.351, shares the N501Y mutation with the British one, although the mutations happened independently.

The earliest known samples of the variant date from October 2020 in South Africa, where it was linked to a surge in cases.

More transmissible than “regular” forms of the virus – possibly because N501Y allows it to reach higher concentrations in upper parts of the human airway – this variant has been found in more than 20 countries. The US Centres for Disease Control reported that it was the dominant variant in Zambia, for instance.

One study has suggested that an additional spike protein mutation in this variant, called E484K, may help the virus evade the body’s immune defences. But, as with the UK variant, the South African one does not make people any more sick.

Two variants first detected in Brazil have also hit the headlines, the most concerning of which, known as P.1, has been found in travellers who arrived in Japan from the country. It is thought to have emerged in December in northern Brazil and has three mutations in the RBD, including N501Y and E484K.

Officials say there is no evidence that the variant is more resistant to treatment, but Prof Jones said it could be difficult to determine whether new forms caused more harm.

“The new variants haven’t been tracked long enough yet to know if the rate of serious disease and death is lower than previously,” he said.

“It’s also confused by the fact that treatment generally improves with time, so the death rate is expected to drop anyway. How much is better clinical care and how much virus change might be hard to work out.”

Researchers are analysing whether the Brazilian variant may be better able to evade the immune response to vaccines. The CDC reported there is evidence to suggest it might be able to. If new vaccines are needed, scientists could develop them in as little as a matter of weeks.

The virus has undergone many thousands of mutations, most of little consequence, but some of them help it survive