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The U.K. Coronavirus Variant: What We Know

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A newly identified variant of the SARS-CoV-2 virus appears to be more contagious than established ones. Here’s what scientists know.

A deserted Regent Street in central London on Monday. A deserted Regent Street in central London on Monday.Credit…Andrew Testa for The New York Times Carl ZimmerBenedict Carey

  • Published Dec. 21, 2020Updated Jan. 6, 2021

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In recent days, the world has watched with curiosity and growing alarm as scientists in the U.K. have described a newly identified variant of the coronavirus that appears to be more contagious than, and genetically distinct from, more established variants. Initial studies of the new variant prompted Prime Minister Boris Johnson to tighten restrictions over Christmas, and spurred officials in the Netherlands, Germany and other European countries to ban travel from the U.K.

The new variant is now the focus of intense debate and analysis, and countries around the world are scouring their own databases to see if it is circulating within their borders. On Wednesday, health officials in Hong Kong reported that two students who returned from the U.K. this month appear to have been infected with the variant; and authorities in Italy reported a case there, with no apparent link to the U.K. Here’s some of what scientists have learned so far.

No. It’s just one variation among many that have arisen as the coronavirus SARS-CoV-2 has spread around the world. Mutations arise as the virus replicates, and this variant — known as B.1.1.7 — has acquired its own distinctive set of them.

The variant came to the attention of researchers in December, when it began to turn up more frequently in samples from parts of southern England. It turned out to have been collected from patients as early as September.

When researchers took a close look at its genome, they were struck by the relatively large number of mutations — 23, all told — that it had acquired. Most mutations that arise in the coronavirus are either harmful to the virus or have no effect one way or another. But a number of the mutations in B.1.1.7 looked as if they could potentially affect how the virus spread.

It appears so. In preliminary work, researchers in the U.K. have found that the virus is spreading quickly in parts of southern England, displacing a crowded field of other variants that have been circulating for months.

However, a virus lineage becoming more common is not proof that it spreads faster than others. It could grow more widespread simply through luck. For instance, a variant might start out in the middle of a crowded city, where transmission is easy, allowing it to make more copies of itself.

Still, the epidemiological evidence gathered so far from England does seem to suggest that this variant is very good at spreading. In places where it has become more common, the overall number of coronavirus cases is spiking. Neil Ferguson, an epidemiologist at Imperial College London, estimates that the variant has an increased transmission rate of 50 to 70 percent compared with other variants in the United Kingdom.

Spikes used to latch onto and enter human cells

Spike

protein

gene

CORONAVIRUS

CORONAVIRUS

GENOME

ORF1a

protein

ORF1b

protein

Spike

protein

Change in

RNA sequence

MUTATIONS

that led to the

B.1.1.7 variant

X

(deletion)

Change in

amino acid

Spikes used to latch onto and enter human cells

CORONAVIRUS

Spike

protein

gene

Change in

RNA sequence

Change in

amino acid

CORONAVIRUS

GENOME

N protein

M protein

E protein

Spike protein

MUTATIONS

that led to the

B.1.1.7 variant

ORF1b protein

(deletion)

ORF1a protein

Some scientists have raised the possibility that the increase in transmission is at least partly the result of how it infects children. Normally, children are less likely than teenagers or adults to get infected or pass on the virus. But the new variant may make children “as equally susceptible as adults,” said Wendy Barclay, government adviser and virologist at Imperial College London.

To confirm that the variant truly is more contagious, researchers are now running laboratory experiments on it, observing up close how it infects cells.

Researchers have already used such experiments to investigate a mutant that arose earlier in the pandemic, called 614G. That variant proved to be more transmissible than its predecessors, studies in cell culture and animals found.

But disciplined containment measures worked just as well against 614G as other variants. The same is likely true for B.1.1.7. “According to what we already know, it does not alter the effectiveness of social distancing, face masks, hand washing, hand sanitizers and ventilation,” Dr. Muge Cevik, an infectious disease specialist at the University of St. Andrews School of Medicine, said on Twitter.

Covid-19 Vaccines ›

Answers to Your Vaccine Questions

While the exact order of vaccine recipients may vary by state, most will likely put medical workers and residents of long-term care facilities first. If you want to understand how this decision is getting made, this article will help.

Life will return to normal only when society as a whole gains enough protection against the coronavirus. Once countries authorize a vaccine, they’ll only be able to vaccinate a few percent of their citizens at most in the first couple months. The unvaccinated majority will still remain vulnerable to getting infected. A growing number of coronavirus vaccines are showing robust protection against becoming sick. But it’s also possible for people to spread the virus without even knowing they’re infected because they experience only mild symptoms or none at all. Scientists don’t yet know if the vaccines also block the transmission of the coronavirus. So for the time being, even vaccinated people will need to wear masks, avoid indoor crowds, and so on. Once enough people get vaccinated, it will become very difficult for the coronavirus to find vulnerable people to infect. Depending on how quickly we as a society achieve that goal, life might start approaching something like normal by the fall 2021.

Yes, but not forever. The two vaccines that will potentially get authorized this month clearly protect people from getting sick with Covid-19. But the clinical trials that delivered these results were not designed to determine whether vaccinated people could still spread the coronavirus without developing symptoms. That remains a possibility. We know that people who are naturally infected by the coronavirus can spread it while they’re not experiencing any cough or other symptoms. Researchers will be intensely studying this question as the vaccines roll out. In the meantime, even vaccinated people will need to think of themselves as possible spreaders.

The Pfizer and BioNTech vaccine is delivered as a shot in the arm, like other typical vaccines. The injection won’t be any different from ones you’ve gotten before. Tens of thousands of people have already received the vaccines, and none of them have reported any serious health problems. But some of them have felt short-lived discomfort, including aches and flu-like symptoms that typically last a day. It’s possible that people may need to plan to take a day off work or school after the second shot. While these experiences aren’t pleasant, they are a good sign: they are the result of your own immune system encountering the vaccine and mounting a potent response that will provide long-lasting immunity.

No. The vaccines from Moderna and Pfizer use a genetic molecule to prime the immune system. That molecule, known as mRNA, is eventually destroyed by the body. The mRNA is packaged in an oily bubble that can fuse to a cell, allowing the molecule to slip in. The cell uses the mRNA to make proteins from the coronavirus, which can stimulate the immune system. At any moment, each of our cells may contain hundreds of thousands of mRNA molecules, which they produce in order to make proteins of their own. Once those proteins are made, our cells then shred the mRNA with special enzymes. The mRNA molecules our cells make can only survive a matter of minutes. The mRNA in vaccines is engineered to withstand the cell’s enzymes a bit longer, so that the cells can make extra virus proteins and prompt a stronger immune response. But the mRNA can only last for a few days at most before they are destroyed.

There is no strong evidence that it does, at least not yet. But there is reason to take the possibility seriously. In South Africa, another lineage of the coronavirus has gained one particular mutation that is also found in B.1.1.7. This variant is spreading quickly through coastal areas of South Africa. And in preliminary studies, doctors there have found that people infected with this variant carry a heightened viral load — a higher concentration of the virus in their upper respiratory tract. In many viral diseases, this is associated with more severe symptoms.

That is now a question of intense debate. One possibility is that the variant gained its array of new mutations inside a special set of hosts.

In a typical infection, people pick up the coronavirus and become infectious for a few days before showing symptoms. The virus then becomes less abundant in the body as the immune system marshals a defense. Unless patients suffer a serious case of Covid-19, they typically clear the virus completely in a few weeks at most.

But sometimes the virus infects people with weak immune systems. In their bodies, the virus can thrive for months. Case studies on these immunocompromised people have shown that the virus can accumulate a large number of mutations as it replicates in their bodies for a long period of time.

Over time, researchers have found, natural selection can favor mutant viruses that can evade the immune system. Researchers have also suggested that the evolution of the variant might have been additionally driven by medicine given to such patients. Some mutants might be able to withstand drugs such as monoclonal antibodies.

Other scientists have suggested that the virus could have gained new mutations by spreading through an animal population, like minks, before re-entering the human population. Such “animal reservoirs” have become a focus of intense interest as more animal infections have been detected.

Not yet, as far as anyone knows. But that does not mean it hasn’t already reached the United States. British scientists have established a much stronger system to monitor coronaviruses for new mutations. It’s conceivable that someone traveling from the United Kingdom has brought it with them. Now that the world knows to look for the variant, it may turn up in more countries.

No. Most experts doubt that it will have any great impact on vaccines, although it’s not yet possible to rule out any effect.

The U.S. Food and Drug Administration has authorized two vaccines, one from Moderna and the other from Pfizer and BioNTech. Both vaccines create immunity to the coronavirus by teaching our immune systems to make antibodies to a protein that sits on the surface of the virus, called spike. The spike protein latches onto cells and opens a passageway inside. Antibodies produced in response to the vaccines stick to the tip of the spike. The result: The viruses can’t get inside.

It is conceivable that a mutation to a coronavirus could change the shape of its spike proteins, making it harder for the antibodies to gain a tight grip on them. And B.1.1.7’s mutations include eight in the spike gene. But our immune systems can produce a range of antibodies against a single viral protein, making it less likely that viruses can easily escape their attack. Right now, experts don’t think that the variant will be able to evade vaccines. To confirm that, researchers at the Walter Reed Army Institute of Research are analyzing the changes to the structure of its spike protein.

Dr. Moncef Slaoui, the head scientific adviser to Operation Warp Speed, the federal effort to deliver a vaccine to the American public, said that the new variant reported in Britain was unlikely to affect the efficacy of a vaccine.

At some point — “some day, somewhere” — a variant of the virus may make the current vaccine ineffective, he said, but the chance of that happening with this vaccine is very low. Nevertheless, he said, “we have to remain absolutely vigilant.”

But Kristian Andersen, a virologist at Scripps Research Institute, thinks it is too early to dismiss the risk to vaccines. If the U.K. variant evolved to evade the immune system in immunocompromised patients, those adaptations might help it avoid vaccines. The vaccines would not become useless, but they would become less effective. Fortunately, experiments are underway to test that possibility.

“We don’t know, but we’ll know soon,” Dr. Andersen said.

Benjamin Mueller and Katie Thomas contributed reporting to this article

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