London CNN  — 

The United Kingdom has identified a new, more contagious coronavirus variant linked to a recent surge in cases in England.

The new mutation is being called VUI-202012/01 – the first “Variant Under Investigation” in the UK in December 2020. While scientists hunt for more information about the variant, its impact is already being felt, with dozens of countries imposing restrictions on travelers from the UK.

Here’s what you need to know.

What is a variant and why are officials concerned about this one?

A variant occurs when the genetic structure of a virus changes. All viruses mutate over time and new variants are common, including for the novel coronavirus.

Like other variants, this one carries a genetic fingerprint that makes it easy to track, and it happens to be one that is now widespread in southeast England. That alone does not necessarily mean a variant is more contagious or dangerous.

But scientists advising the UK government have estimated that this variant could be up to 70% more effective at spreading than others. Peter Horby, chair of the New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG), said Wednesday that scientists were “confident” the new variant is “spreading faster than other virus variants.”

Speaking at an emergency meeting of the UK Parliament Science and Technology Committee, Horby explained that the new variant has “some kind of biological advantage to make it spread faster.”

Scientists still don’t have a complete picture as to why, he said, but that there were a few different scenarios they were investigating.

There is preliminary evidence to suggest that the new strain results in a person holding a higher viral load, which means the virus is easier to pass on, Horby said.

Another possibility is that people are becoming infected more quickly after exposure, he said. It’s also possible, he added, that people are infectious for longer.

All of these potential explanations, however, lead to the same conclusion: The virus is spreading faster.

England’s chief medical officer, Chris Whitty, has said the variant contains 23 changes, including 17 key “non-synonymous” mutations.

“These [17] are ones that change the protein sequence of one of the viral genes,” said Jeffrey Barrett, lead Covid-19 statistical geneticist at the UK’s Wellcome Sanger Institute, according to the Science Media Centre.

The World Health Organization said Tuesday that these mutations “may influence the transmissibility of the virus in humans,” though it added that further laboratory investigations were needed.

Scientist Neil Ferguson, a member of NERVTAG, said Monday that the variant may be more infectious for children. “There is a hint is that [the variant] … has a higher propensity to infect children,” he told a press briefing organized by the Science Media Centre (SMC), though he cautioned that more data was needed. Severe illness due to Covid-19 is still relatively rare for children.

The findings have immediate implications for virus control. More cases could place an even greater strain on hospitals and health care staff just as they enter an already particularly difficult winter period, and ultimately lead to more deaths.

Where did the variant originate and how has it taken hold?

The new variant is believed to have originated in southeast England, according to the WHO. Public Health England (PHE) says backwards tracing, using genetic evidence, suggests the variant first emerged in England in September. It then circulated in very low levels until mid-November.

“The increase in cases linked to the new variant first came to light in late November when PHE was investigating why infection rates in Kent [in southeast England] were not falling despite national restrictions. We then discovered a cluster linked to this variant spreading rapidly into London and Essex,” PHE said.

But Sharon Peacock, professor of public health and microbiology at the University of Cambridge, said scientists did not know whether the mutation had originated in southeast England or whether it was introduced there from elsewhere.

Speaking at a press briefing on Tuesday, Peacock also praised the strength of the UK’s genetic surveillance operation. “If you’re going to find [a variant] anywhere, you’re going to find it probably here first,” she said. “And if this occurs in places that don’t have any sequencing, you’re not going to find it at all unless you’re using [other methods.]”

Whitty said Saturday the variant was responsible for 60% of new infections in London, which have nearly doubled in the last week alone. On Wednesday, Northern Ireland’s Health Minister Robin Swann said the variant was detected in its borders.