A new coronavirus strain surging to dominance in the UK appears to spread faster despite lockdowns, prompting panic and a wave of border closures

• The UK government imposed harsher restrictions on millions of people this weekend, warning of a mutated coronavirus strain that appears to infect people more easily.
• Multiple countries also moved quickly to block travel from the UK, expressing concern over the new strain.
• The government said the new strain could increase the country's R number by 0.4 and suggested that the strain was behind 59% of new cases in eastern England and 62% of new cases in London.
• Experts say the situation is worrying and needs to be closely monitored, but they added that this strain didn't appear to be deadlier.
• They also say it's likely that vaccines will still be effective against the new strain.

The UK said it discovered a new, potentially more transmissible strain of the novel coronavirus, prompting the government to put millions of people under stricter lockdown measures for Christmas and a host of countries to block travel from the UK.

Matt Hancock, the UK's health minister, said a new variant of the virus that might be up to 70% more transmissible was "getting out of control."

UK Prime Minister Boris Johnson also announced on Saturday that about 16 million people would be put under a new, stricter lockdown across southeastern England, including London.

Soon after, a host of countries blocked travel from the UK. Some also decided to ban freight, which could seriously harm the UK supply chain.

Viruses are typically expected to mutate, and the variants aren't necessarily more harmful - they do not necessarily increase the risk to humans or threaten vaccines' effectiveness.

With this latest development, experts are urging calm and cautioning that more evidence needs to be gathered to figure out exactly what's going on and what the new risks might be.

What we know

Hancock said that this strain, named B.1.1.7, appeared to be more transmissible than other mutations of the virus and that it appeared to have spread much faster across parts of England.

Johnson also said that the new strain could increase the country's R number by 0.4. R is the average number of people who one infected person passes the virus to. An increase of 0.4 could determine whether an outbreak is contained or spreading rapidly.

The government's figures suggested the new strain was behind 59% of new cases in eastern England and 62% of the new cases in London as of December 9, compared with 28% in London three weeks earlier.

The World Health Organization said the new variant had already been seen in the Netherlands, Denmark, and Australia - meaning other countries' efforts to seal off the UK may be of little benefit.

As Insider previously reported, the new variant includes a mutation in the virus' spike protein, which is what the virus uses to invade the body's cells. This means it might be easier for the virus to infect people.

The new variant appears to have developed 23 mutations, UK health authorities said.

Previous lockdowns were insufficient

According to Science magazine, scientists believe the new strain could have emerged in a patient who was infected for a long time, allowing the virus to mutate in their body.

Susan Hopkins, the head of Public Health England, said that the strain was first found in a coronavirus patient in September but that it didn't cause alarm because mutations of the virus were expected.

But then cases rose rapidly in some areas despite lockdown measures.

This graph shows how fast cases were rising in the areas where the new strain was most prevalent, compared with the rest of the UK, as of Saturday:

Over the weekend, Johnson said he had been confused about why existing restrictions weren't slowing the virus' spread in Kent, a county in southeastern England where the new strain is thought to have emerged.

"It's not until yesterday, when we have seen this data on transmissibility, that we really got the answer that explains it," he said.

Experts are urging calm

Hancock said that while there wasn't any evidence that the strain was deadlier or more resistant to vaccines, it did seem to be "growing faster than the existing variants."

Chris Whitty, England's chief medical officer, said the strain could be 70% more transmissible - a figure given by Erik Volz from Imperial College London. Volz said that the situation needed to be monitored but that "it is really too early to tell."

Many experts are urging caution.

Christian Drosten, a virologist at Charité University Hospital in Berlin, told Science the UK government should not have cited the 70% figure. "There are too many unknowns to say something like that," Drosten said.

"The amount of evidence in the public domain is woefully inadequate to draw strong or firm opinions on whether the virus has truly increased transmission," Jonathan Ball, a virologist at the University of Nottingham, told the BBC.

Muge Cevik, a scientific advisor to the British government, noted to The New York Times that the 70% figure hadn't been confirmed in lab experiments, adding that the faster spread could be at least partially explained by people acting differently.

Alan McNally, a professor of genomics at the University of Birmingham, said in a statement to the UK's Science Media Centre that "it's too early to be worried or not by this new variant."

"It is important to keep a calm and rational perspective on the strain as this is normal virus evolution and we expect new variants to come and go and emerge over time," he said.

But some experts said that taking big steps now instead of waiting for more information is the right call in case the new strain does pose a new risk.

"Laboratory experiments are required, but do you want to wait weeks or months [to see the results and take action to limit the spread]? Probably not in these circumstances," Nick Loman, a professor with the COVID-19 Genomics UK Consortium, told the BBC.

It doesn't seem deadlier

UK officials have said there's no evidence to suggest that the new variant is deadlier, though scientists in the UK and WHO are studying it.

Experts agreed.

Wendy Barclay, the head of the Department of Infectious Disease at Imperial College London, said earlier this month - before new data about transmission came out - that "there is no evidence that the newly reported variant results in a more severe disease."

But Andrew Hayward, a professor of infectious-disease epidemiology at University College London and a member of the UK's Scientific Advisory Group for Emergencies, told The Guardian that if it has a greater ability to infect people, the virus is already deadlier.

"I think we already have enough information to know that this variant has the potential to cause a major further epidemic, worse than we had previously predicted," he said.

All viruses mutate over time, and this isn't the first discovered variant of this virus.

As the BBC noted, the virus strain now seen in most parts of the world isn't the same as the one that was first detected in Wuhan, China.

Some experts have said that more than 4,000 mutations of the novel coronavirus have emerged but that the vast majority are insignificant in terms of how they affect humans and how we can fight them.

Vaccines will likely still work

Patrick Vallance, the UK government's chief scientific advisor, said on Saturday that "our working assumption, from all of the scientists, is that the vaccine response should be adequate for this virus."

Experts also said that while this mutation is unlikely to hinder the effectiveness of vaccines, more studies are needed.

Many added that it would take years of evolution for the virus to reach a stage where vaccines aren't effective.

Jesse Bloom, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle, told The Times that "no one should worry that there is going to be a single catastrophic mutation that suddenly renders all immunity and antibodies useless."

"It is going to be a process that occurs over the time scale of multiple years and requires the accumulation of multiple viral mutations," he said. "It's not going to be like an on-off switch."

Ravi Gupta, a clinical microbiologist at the University of Cambridge, told the BBC that if the virus is allowed to keep spreading, new variants could bring it closer to the point where it has mutated too much for vaccines to work.

"If we let it add more mutations," Gupta said, "then you start worrying."