Virus World

HANOI, Vietnam (AP) — Vietnam has discovered a new coronavirus variant that’s a hybrid of strains first found in India and the U.K., the Vietnamese health minister said Saturday. Nguyen Thanh Long said scientists examined the genetic makeup of the virus that had infected some recent patients, and found the new version of the virus.  Viruses often develop small genetic changes as they reproduce, and new variants of the coronavirus have been seen almost since it was first detected in China in late 2019. The World Health Organization has listed four global “variants of concern” – the two first found in the U.K. and India, plus ones identified in South Africa and Brazil. Long says the new variant could be responsible for a recent surge in Vietnam, which has spread to 30 of the country’s 63 municipalities and provinces. 

Vietnam was initially a standout success in battling the virus — in early May, it had recorded just over 3,100 confirmed cases and 35 deaths since the start of the pandemic. But in the last few weeks, Vietnam has confirmed more than 3,500 new cases and 12 deaths, increasing the country’s total death toll to 47. Most of the new transmissions were found in Bac Ninh and Bac Giang, two provinces dense with industrial zones where hundreds of thousands of people work for major companies including Samsung, Canon and Luxshare, a partner in assembling Apple products. Despite strict health regulations, a company in Bac Giang discovered that one fifth of its 4,800 workers had tested positive for the virus. In Ho Chi Minh City, the country’s largest metropolis and home to 9 million, at least 85 people have tested positive as part of a cluster at a Protestant church, the Health Ministry said. Worshippers sang and chanted while sitting close together without wearing proper masks or taking other precautions. Vietnam has since ordered a nationwide ban on all religious events. In major cities, authorities have banned large gatherings, closed public parks and non-essential business including in-person restaurants, bars, clubs and spas. Vietnam so far has vaccinated 1 million people with AstraZeneca shots. Last week, it sealed a deal with Pfizer for 30 million doses, which are scheduled to be delivered in the third and fourth quarters of this year. It is also in talks with Moderna that would give it enough shots to fully vaccine 80% of its 96 million people.

The first detailed studies of the so-called P.1 variant show how it devastated a Brazilian city. Now scientists want to know what it will do elsewhere.  In just a matter of weeks, two variants of the coronavirus have become so familiar that you can hear their inscrutable alphanumeric names regularly uttered on television news. B.1.1.7, first identified in Britain, has demonstrated the power to spread far and fast. In South Africa, a mutant called B.1.351 can dodge human antibodies, blunting the effectiveness of some vaccines. Scientists have also had their eye on a third concerning variant that arose in Brazil, called P.1. Research had been slower on P.1 since its discovery in late December, leaving scientists unsure of just how much to worry about it. “I’ve been holding my breath,” said Bronwyn MacInnis, an epidemiologist at the Broad Institute. Now three studies offer a sobering history of P.1’s meteoric rise in the Amazonian city of Manaus. It most likely arose there in November and then fueled a record-breaking spike of coronavirus cases. It came to dominate the city partly because of an increased contagiousness, the research found.  But it also gained the ability to infect some people who had immunity from previous bouts of Covid-19. And laboratory experiments suggest that P.1 could weaken the protective effect of a Chinese vaccine now in use in Brazil.  The new studies have yet to be published in scientific journals. Their authors caution that findings on cells in laboratories do not always translate to the real world, and they’ve only begun to understand P.1’s behavior. “The findings apply to Manaus, but I don’t know if they apply to other places,” said Nuno Faria, a virologist at Imperial College London who helped lead much of the new research.

A new coronavirus variant with three mutations "of biological significance" has been detected in 11 countries, according to a new academic report. This new variant, B.1.525, has been found on several continents, academics at the University of Edinburgh noted in an assessment of the variant published on Monday.

Here are countries where it has been found:

• United States
• Canada
• Denmark
• United Kingdom
• France
• Belgium
• Spain
• Nigeria
• Ghana
• Jordan
• Australia

medRxiv - The PrexThe new SARS-CoV-2 variant B.1.1.7 was identified in December 2020 in the South-East of England, and rapidly increased in frequency and geographic spread. While there is some evidence for increased transmissibility of this variant, it is not known if the new variant presents with variation in symptoms or disease course, or if previously infected individuals may become reinfected with the new variant. Using longitudinal symptom and test reports of 36,920 users of the Covid Symptom Study app testing positive for COVID-19 between 28 September and 27 December 2020, we examined the association between the regional proportion of B.1.1.7 and reported symptoms, disease course, rates of reinfection, and transmissibility. We found no evidence for changes in reported symptoms, disease severity and disease duration associated with B.1.1.7. We found a likely reinfection rate of around 0.7% (95% CI 0.6-0.8), but no evidence that this was higher compared to older strains. We found an increase in R(t) by a factor of 1.35 (95% CI 1.02-1.69). Despite this, we found that regional and national lockdowns have reduced R(t) below 1 in regions with very high proportions of B.1.1.7.

Available in medRxiv (Jan. 29, 2021):

 https://doi.org/10.1101/2021.01.28.21250680 

At the heart of each coronavirus is its genome, a twisted strand of nearly 30,000 “letters” of RNA. These genetic instructions force infected human cells to assemble up to 29 kinds of proteins that help the coronavirus multiply and spread.  As viruses replicate, small copying errors known as mutations naturally arise in their genomes. A lineage of coronaviruses will typically accumulate one or two random mutations each month. Some mutations have no effect on the coronavirus proteins made by the infected cell. Other mutations might alter a protein’s shape by changing or deleting one of its amino acids, the building blocks that link together to form the protein. Through the process of natural selection, neutral or slightly beneficial mutations may be passed down from generation to generation, while harmful mutations are more likely to die out....

South African scientists and health officials announced on Friday the discovery of a new lineage of the coronavirus that has quickly come to dominate samples of virus tested in the country. Scientists are examining this particular variant closely because it includes several changes in the part of the virus that allows it to attach to human cells, which is a key target for antibody therapies and vaccines The variant, named 501.V2, has also been associated in a preliminary analysis with faster spread and a higher load of virus found in swabs. It has not yet been linked to any difference in disease severity, and the findings have not yet been reviewed by other scientists or published in a journal. “There is reason for concern that we have a virus that seems to be spreading rapidly,” Dr. Salim Abdool Karim, co-chair of the country’s ministerial advisory committee on Covid-19, said at a national news conference. He emphasized that public behavior was a major factor in driving the uptick in cases.

It is normal for viruses to collect tiny changes in their genetic sequences as they move through populations. Typically these changes, known as mutations, have little significance, and certain lineages can become more common by chance. But scientists across the world track them to assess whether they affect characteristics such as transmissibility, disease severity and the response to treatments and vaccines. The new South African lineage now accounts for 90 percent of sequences analyzed in the country, an effort led by the Kwazulu-Natal Research Innovation and Sequencing Platform in Durban. “Clearly there’s still a lot of work to be done ahead,” Dr. John Nkengasong, director of the Africa Centers for Disease Control and Prevention, said at the news conference.

A presentation describing the South African variant available (Dec. 18, 2020): 

https://www.scribd.com/document/488618010/Full-Presentation-by-SSAK-18-Dec

Experts reaction to South African variant:

https://www.sciencemediacentre.org/expert-reaction-to-south-african-variant-of-sars-cov-2-as-mentioned-by-matt-hancock-at-the-downing-street-press-briefing/

European countries impose travel bans as scientists probe whether new strain spreads faster or causes more severe COVID-19.  On 8 December, during a regular Tuesday meeting about the spread of the pandemic coronavirus in the United Kingdom, scientists and public health experts saw a diagram that made them sit up straight. Kent, in the southeast of England, was experiencing a surge in cases, and a phylogenetic tree showing viral sequences from the county looked very strange, says Nick Loman, a microbial genomicist at the University of Birmingham. Not only were half the cases caused by one specific variant of SARS-CoV-2, but that variant was sitting on a branch of the tree that literally stuck out from the rest of the data. “I've not seen a part of the tree that looks like this before,” Loman says. Less than 2 weeks later, that variant is causing mayhem in the United Kingdom and elsewhere in Europe. Yesterday, U.K. Prime Minister Boris Johnson announced stricter lockdown measures, saying the strain, which goes by the name B.1.1.7, appears to be better at spreading between people. The news led many Londoners to leave the city today, before the new rules take effect, causing overcrowded railway stations. The Netherlands, Belgium, and Italy announced they were temporarily halting passenger flights from the United Kingdom. The Eurostar train between Brussels and London will stop running tonight at midnight, for at least 24 hours. Scientists, meanwhile, are hard at work trying to figure out whether B.1.1.7 is really more adept at human-to-human transmission—not everyone is convinced yet—and if so, why. They’re also wondering how it evolved so fast. B.1.1.7 has acquired 17 mutations all at once, a feat never seen before. “There's now a frantic push to try and characterize some of these mutations in the lab,” says Andrew Rambaut, a molecular evolutionary biologist at the University of Edinburgh.

Too many unknowns

Researchers have watched SARS-CoV-2 evolve in real time more closely than any other virus in history. So far, it has accumulated mutations at a rate of about one to two changes per month. That means many of the genomes sequenced today differ at about 20 points from the earliest genomes sequenced in China in January, but many variants with fewer changes are also circulating. “Because we have very dense surveillance of genomes, you can almost see every step,” Loman says. But scientists have never seen the virus acquire more than a dozen mutations seemingly at once. They think it happened during a long infection of a single patient that allowed SARS-CoV-2 to go through an extended period of fast evolution, with multiple variants competing for advantage.  One reason to be concerned, Rambaut says, is that among the 17  utations are eight in the gene that encodes the spike protein on the viral surface, two of which are particularly worrisome. One, called N501Y, has previously been shown to increase how tightly the protein binds to the angiotensin-converting enzyme 2 receptor, its entry point into human cells. The other, named 69-70del, leads to the loss of two amino acids in the spike protein and has been found in viruses that eluded the immune response in some immunocompromised patients.  A fortunate coincidence helped show that B.1.1.7 (also called VUI-202012/01, for the first “variant under investigation” in December 2020), appears to be spreading faster than other variants in the United Kingdom. One of the polymerase chain reaction (PCR) tests used widely in the country, called TaqPath, normally detects pieces of three genes. But viruses with 69-70del lead to a negative signal for the gene encoding the spike gene; instead only two genes show up. That means PCR tests, which the United Kingdom conducts by the hundreds of thousands daily and which are far quicker and cheaper than sequencing the entire virus, can help keep track of B.1.1.7.

In a press conference on Saturday, chief science adviser Patrick Vallance said that B.1.1.7, which first appeared in a virus isolated on 20 September, accounted for about 26% of cases in mid-November. “By the week commencing the ninth of December, these figures were much higher,” he said. “So, in London, over 60% of all the cases were the new variant.” Johnson added that the slew of mutations may have increased the virus’s transmissibility by 70%.  Christian Drosten, a virologist at Charité University Hospital in Berlin, says that was premature. “There are too many unknowns to say something like that,” he says. For one thing, the rapid spread of B.1.1.7 might be down to chance. Scientists previously worried that a variant that spread rapidly from Spain to the rest of Europe—confusingly called B.1.177—might be more transmissible, but today they think it is not; it just happened to be carried all over Europe by travelers who spent their holidays in Spain. Something similar might be happening with B.1.1.7, says Angela Rasmussen, a virologist at Georgetown University. Drosten notes that the new mutant also carries a deletion in another viral gene, ORF8, that previous studies suggest might reduce the virus’ ability to spread. But further reason for concern comes from South Africa, where scientists have sequenced genomes in three provinces where cases are soaring: Eastern Cape, Western Cape, and KwaZulu Natal. They identified a lineage separate from the U.K. variant that also has a N501Y mutation in the spike gene. “We found that this lineage seems to be spreading much faster,” says Tulio de Oliveira, a virologist at the University of KwaZulu-Natal whose work first alerted U.K. scientists to the importance of N501Y. (A preprint of their results on the strain, which they are calling 501Y.V2, will be released on Monday, de Oliveira says.) Another worry is B.1.1.7 could cause more severe disease. There is anecdotal evidence that the South African variant may be doing that in young people and those who are otherwise healthy, says John Nkengasong, director of the Africa Centres for Disease Control and Prevention. “It’s concerning, but we really need more data to be sure.” The African Task Force for Coronavirus will convene an emergency meeting to discuss the issue on Monday, Nkengasong says....

Preliminary characterization of the new variant available in Virological (Dec. 18, 2020): https://virological.org/t/preliminary-genomic-characterisation-of-an-emergent-sars-cov-2-lineage-in-the-uk-defined-by-a-novel-set-of-spike-mutations/563

See also ICOG Report (Dec.19, 2020): https://www.cogconsortium.uk/wp-content/uploads/2020/12/Report-1_COG-UK_19-December-2020_SARS-CoV-2-Mutations.pdf

CDC Comments on UK's variant (Dec. 22, 2020):

https://www.cdc.gov/coronavirus/2019-ncov/more/scientific-brief-emerging-variant.html

The emergence of SARS-CoV-2 variants with enhanced transmissibility, pathogenesis and resistance to vaccines presents urgent challenges for curbing the COVID-19 pandemic. While Spike mutations that enhance virus infectivity may drive the emergence of these novel variants, studies documenting a critical a role for interferon responses in the early control of SARS-CoV-2 infection, combined with the presence of viral genes that limit these responses, suggest that interferons may also influence SARS-CoV-2 evolution. Here, we compared the potency of 17 different human interferons against 5 viral lineages sampled during the course of the global outbreak that included ancestral and emerging variants. Our data revealed increased interferon resistance in emerging SARS-CoV-2 variants, indicating that evasion of innate immunity is a significant driving force for SARS-CoV-2 evolution. These findings have implications for the increased lethality of emerging variants and highlight the interferon subtypes that may be most successful in the treatment of early infections.

Posted in bioRxiv (March 21, 2021):

 https://doi.org/10.1101/2021.03.20.436257 

Two separate teams of researchers have found a worrying new coronavirus variant in New York City that carries mutations that help it evade the body's natural immune response -- as well as the effects of monoclonal antibody treatments.  Genomics researchers have named the variant B.1.526. It appears in people affected in diverse neighborhoods of New York City, they said, and is "scattered in the Northeast." One of the mutations in this variant is the same concerning change found in the variant first seen in South Africa and known as B.1.351. It appears to evade, somewhat, the body's response to vaccines, as well. And it's becoming more common. "We observed a steady increase in the detection rate from late December to mid-February, with an alarming rise to 12.7% in the past two weeks," one team, at Columbia University Medical Center, write in a report that has yet to be published, although it is scheduled to appear in pre-print version this week.  It's the latest of a growing number of viral variants that have arisen in the US, which has had more coronavirus cases -- 28 million -- than any other country and where spread is still intense. It's "home grown, presumably in New York," Dr. David Ho, Director of the Aaron Diamond AIDS Research Center at Columbia, who led the study team, said by email.  Viruses mutate all the time. The more people who are infected, and the longer they are infected, the more chance the viruses have to change. A patient's body will be loaded with billions of copies of a virus, and may will be slightly changed, or mutated. Most will come and go. But sometimes a mutation or pattern of mutations takes hold and gets passed along. If viruses with such patterns become more common, they're called variants. Again, it's not unusual for variants to arise but if they give the virus worrying properties, such as better transmissibility or the ability to evade treatments and vaccines, that's when doctors start to worry.

SARS-CoV-2 has been mutating since it was first sequenced in early January 2020. Here, we analyze 45,494 complete SARS-CoV-2 geneome sequences in the world to understand their mutations. Among them, 12,754 sequences are from the United States. Our analysis suggests the presence of four substrains and eleven top mutations in the United States. These eleven top mutations belong to 3 disconnected groups. The first and second groups consisting of 5 and 8 concurrent mutations are prevailing, while the other group with three concurrent mutations gradually fades out. Moreover, we reveal that female immune systems are more active than those of males in responding to SARS-CoV-2 infections. One of the top mutations, 27964C > T-(S24L) on ORF8, has an unusually strong gender dependence. Based on the analysis of all mutations on the spike protein, we uncover that two of four SASR-CoV-2 substrains in the United States become potentially more infectious. Rui Wang et al. report a comprehensive analysis of nearly 13,000 SARS-CoV-2 genome sequences isolated from patients in the United States, comprising more than 7000 single mutations. They show that SARS-CoV-2 genomes cluster into four distinct groups and that two of these groups are potentially more infectious, underlining the urgent need for viral control strategies in the US.

Findings Published in Communications Biology (Feb. 15, 2021):

https://www.nature.com/articles/s42003-021-01754-6

Health authorities identified the first U.S. cases of a fast-spreading form of the coronavirus initially seen in South Africa.  Neither person has a history of travel to countries where the variant has been confirmed, and there is no connection between the two people, South Carolina health officials said Thursday. That indicates there has been some local spread of the variant after it arrived in the United States. One case was found in South Carolina’s Pee Dee region, and one in the Lowcountry.  The announcement Thursday means that three coronavirus variants that appear to be more contagious and have emerged in recent months have all been documented in the United States. But in a way, the news was no surprise to experts. They had for weeks said the variant that first cropped up in South Africa, called B.1.351, was likely already in the U.S., but this country’s limited system of surveillance for different iterations of the coronavirus meant the variant likely went unnoticed once it was imported via a traveler and could have even been spreading. Earlier this week, Minnesota health officials confirmed the first Covid-19 case caused by P.1, a variant first identified in Brazil. There have been a few hundred U.S. cases of the B.1.1.7 variant, which initially appeared in the United Kingdom. All three variants are thought to be more transmissible than earlier forms of the coronavirus and, if left unchecked, could lead to more cases overall by infecting more people faster. The Centers for Disease Control and Prevention has estimated that B.1.1.7 could become the dominant form of the coronavirus in the United States by March.

“It’s critical that we all continue to do our part by taking small actions that make a big difference,” Brannon Traxler, South Carolina’s interim public health director, said in a statement. “These include wearing our masks, staying at least six feet apart from others, avoiding large crowds, washing our hands, getting tested often, and when we can, getting vaccinated. These are the best tools for preventing the spread of the virus, no matter the strain.” The three variants evolved independently — all viruses mutate and occasionally pick up alterations that give them a transmission advantage — but happen to share some of the same mutations.  B.1.351 and P.1 in particular have raised a different set of alarms than B.1.1.7. Studies have shown that mutations that appear in both variants can help the virus partially evade the human immune response, perhaps making it more likely the variants could reinfect people who had an initial case of Covid-19. Such studies resulted in concerns that existing Covid-19 vaccines — which were designed based on earlier iterations of the virus — might not be as effective against the variants. On Thursday, for example, Novavax said its experimental Covid-19 vaccine was 90% effective in one trial in the U.K., but that in a separate trial in South Africa, it was 49% effective. Of the cases that occurred in the South Africa trial for which there was sequencing data, 93% were caused by B.1.351. Other vaccines made in different ways may see less of a drop in efficacy, though more studies are ongoing. With the mRNA vaccines from Pfizer-BioNTech and Moderna, it seems like the shots do lose some of their neutralizing potency against some of the mutations seen in both P.1 and B.1.351, but that the immune response elicited by the vaccines is so overwhelmingly powerful that the shots can withstand a loss of some of their oomph while still protecting people from getting sick with Covid-19.

On Monday, Moderna said its shot should still be effective against B.1.351 despite the fact that the neutralizing antibodies generated by the vaccine do not recognize the form of the virus as well as other forms. Essentially, the antibody response induced by the shot should still be sufficient to help people ward off Covid-19. There is a question, however, of whether the immune response from the vaccines will last as long against the variants as earlier viral iterations. So far, the studies investigating the impact of variants on the Pfizer and Moderna vaccines have largely focused on neutralizing antibodies, but experts note the shots also rally other parts of the immune system — including T cells, B cells, and other types of antibodies — providing additional reasons that the current vaccines should still broadly work against the variants.  Still, experts do think the coronavirus could one day pick up a certain suite of mutations that does threaten the shots’ overall effectiveness, so, they say, vaccine makers and regulators should start considering what will be required to update the immunizations to better match circulating forms of SARS-CoV-2, the scientific name of the coronavirus causes Covid-19.

Moderna and Novavax have said they are studying booster shots designed specifically against B.1.351. For now, the most pressing concern about the variants, experts stress, remains their infectiousness. The World Health Organization, for example, warned on Thursday that B.1.351 was driving a surge in cases as it spread out of South Africa into other African nations, with Matshidiso Moeti, the WHO’s regional director, saying the continent “is at a crossroads.” Cases in the United States remain sky-high, but they are coming down from peaks earlier this month. If any of the variants take off, the country could see yet another spike. It will also take a greater portion of the population to be immune to the virus to slow the spread of more contagious variants, adding even more pressure to the U.S. vaccine campaign.  In the past week, scientists in the U.K. have been reporting that the variant first seen there, B.1.1.7, may also be deadlier than other forms of the virus, though they are still parsing through national data. Generally, experts actually fear a more transmissible virus more than one that is correspondingly more lethal; more infectious variants could lead to more deaths overall even if they’re not deadlier just because they result in that many more cases. But with B.1.1.7, “unfortunately, it looks as if this virus might be both,” said John Edmunds of the London School of Hygiene & Tropical Medicine.

DENVER (AP) — The first reported U.S. case of the COVID-19 variant that’s been seen in the United Kingdom has been discovered in Colorado, Gov. Jared Polis announced Tuesday, adding urgency to efforts to vaccinate Americans. The variant was found in a man in his 20s who is in isolation southeast of Denver in Elbert County and has no travel history, state health officials said. Elbert County is a mainly rural area of rolling plains at the far edge of the Denver metro area that includes a portion of Interstate 70, the state’s main east-west highway. Colorado Politics reported there is a second suspected case of the variant in the state according to Dwayne Smith, director of public health for Elbert County. Both of the people were working in the Elbert County community of Simla. Neither of them are residents of that county — expanding the possibility of the variant’s spread throughout the state. The Colorado State Laboratory confirmed the virus variant, and the Centers for Disease Control and Prevention was notified. Scientists in the U.K. believe the variant is more contagious than previously identified strains. The vaccines being given now are thought to be effective against the variant, Colorado health officials said in a news release.

For the moment, the variant is likely still rare in the U.S., but the lack of travel history in the first case means it is spreading, probably seeded by travelers from Britain in November or December, said scientist Trevor Bedford, who studies the spread of COVID-19 at Fred Hutchinson Cancer Research Center in Seattle. “Now I’m worried there will be another spring wave due to the variant,” Bedford said. “It’s a race with the vaccine, but now the virus has just gotten a little bit faster.” Public health officials are investigating other potential cases and performing contact tracing to determine the spread of the variant throughout the state. “There is a lot we don’t know about this new COVID-19 variant, but scientists in the United Kingdom are warning the world that it is significantly more contagious. The health and safety of Coloradans is our top priority, and we will closely monitor this case, as well as all COVID-19 indicators, very closely,” Polis said. Polis and state health officials are expected hold a news conference Wednesday. The discovery of the new variant led the CDC to issue new rules on Christmas Day for travelers arriving to the U.S. from the U.K., requiring they show proof of a negative COVID-19 test. Worry has been growing about the variant since the weekend before Christmas, when Britain’s prime minister said a new strain of the coronavirus seemed to spread more easily than earlier ones and was moving rapidly through England. The nation’s first variant case was identified in southeast England. Dozens of countries barred flights from the U.K., and southern England was placed under strict lockdown measures. Scientists say there is reason for concern but the new strains should not cause alarm.

Japan announced Monday it would bar entry of all nonresident foreign nationals as a precaution against the new strain. New variants of the coronavirus have been seen almost since the virus was first detected in China nearly a year ago. It is common for viruses to undergo minor changes as they reproduce and move through a population. The slight modifications are how scientists track the spread of a virus from one place to another. But if the virus has significant mutations, one concern is that current vaccines might no longer offer the same protections. Although that’s a possibility to watch for over time with the coronavirus, experts say they don’t believe it will be the case with the latest variant. The U.K. variant, known as B.1.1.7, has also been found in Canada, Italy, India and the United Arab Emirates. South Africa has also discovered a highly contagious COVID-19 variant that is driving the country’s latest spike of confirmed cases, hospitalizations and deaths. The variant, known as 501.V2, is dominant among the newly confirmed infections in South Africa, according to health officials and scientists leading the country’s virus strategy.

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

Is the U.K. variant some kind of new supervirus?

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.

What is unusual about it?

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. 

Is it more contagious than other viruses?

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.  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 strain 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.

Does it cause more severe disease?

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...