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The new variant, called B 1.1.7 was first identified in Britain, where it rapidly became the primary source of infections, accounting for as many 60 percent of new cases diagnosed in London and surrounding areas.

Covid cases and deaths have broken record after record across the country, with a peak number of deaths, 4,400, announced on Tuesday. At least 3,973 new deaths and 238,390 new cases were reported on Thursday, and the nation is nearing a milestone of 400,000 deaths.

“I want to stress that we are deeply concerned that this strain is more transmissible and can accelerate outbreaks in the U.S.

In the new report, C.D.C. scientists modeled how quickly the variant might spread in the United States, assuming about 10 percent to 30 percent of people have pre-existing immunity to the virus, and another 1 million people will be vaccinated each week beginning this month.

It’s not yet clear what makes the new variants more contagious. They share at least one mutation, called N501Y, that is thought to be involved. One possibility, researchers said, is that the mutation may increase the amount of virus in the nose but not in the lungs — potentially explaining why it is more contagious, but not more deadly.A higher amount of virus in the nose means anyone infected would expel more virus while talking, singing, coughing or even breathing, said Trevor Bedford, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle

Federal health officials sounded the alarm Friday about a fast spreading, far more contagious variant of the coronavirus that is projected to become the dominant source of infection in the country by March, potentially fueling another wrenching surge of cases and deaths.

The variant is not known to be more deadly or to cause more severe disease. But the dire warning — hedged by limited data about just how prevalent the variant first identified in Britain has become — landed in a week where the nation’s nascent vaccination campaign was hampered by confusion and limited supplies as demand grew among growing numbers of eligible people

Only 76 cases of the variant have been identified so far in the U.S., but the actual number is believed to be higher and is expected to spiral upward in the next few weeks, officials said.

But spikes in cases threaten to cripple already overwhelmed hospitals and nursing homes in many parts of the country. Some are at or near capacity. Others have faced troubling rates of infection among their staff, causing shortages and increasing patient loads.

One in 860 Americans have died of Covid-19 in the last year, according to new figures released by the C.D.C. But the burden of deaths has not fallen equally across racial, ethnic lines and geographic regions, and there is concern that vaccines will not reach the hardest hit communities, where access to health services is limited and distrust is rampant. Editors’ PicksFor Pro Athlete Leading Social Justice Push, a Victory and UncertaintyJames Comey’s View of Justice — and How It Differs From Donald Trump’sHow ‘Orwellian’ Became an All-Purpose InsultAdvertisementContinue reading the main storyImage

If the variant is about 50 percent more contagious, as suggested by data from Britain, it will become the predominant source of all infections in the United States by March, the model showed. A slow rollout of vaccinations will hasten that fate.

Several states in the Northeast also have among the country’s worst outbreaks now. Connecticut, New Jersey and Pennsylvania, among others, are all experiencing marked rises in case counts, and labs have identified both the B.1.1.7 variant and large shares of another variant, B.1.526.

The B.1.526 variant, which first appeared in New York City in samples from November, appears in two forms: one with a mutation that may help the virus evade antibodies and another that may help it bind more tightly to human cells.

The outbreak in the Northeast is currently much worse than it is in California, but California faces a variant of its own that makes up a large share of cases.

Studies have indicated the variant first discovered in California, B.1.427/B.1.429, may also be more transmissible than earlier forms of the virus, but it does not appear to spread as quickly as B.1.1.7.

Like the variant first discovered in New York City, the B.1.427/B.1.429 variant has also been seen in high levels in neighboring states, including Arizona, but does not yet make up a significant number of cases outside the region.

In Michigan, Covid-19 hospitalizations are already more than three times higher than they were a month ago. Other states with rising cases are also seeing significant increases in hospitalized Covid-19 patients.

The vaccine rollout continues to speed up, and recent studies confirm that vaccines are effective against the coronavirus in the real world, giving experts hope that an end may be in sight. But with increased transmission, they say, comes a renewed need for caution in the immediate term.

“I think we’ve got to hang on just a little bit longer, being conservative and getting more people vaccinated,” Dr. Martin said. “I’d hate to see us having another hospital surge when we’re getting so close to being done with this. I’m definitely worried about it.”

Dr. Brannon Traxler, the department's interim public health director, said that the variant's arrival is an important reminder that the fight against COVID-19 is far from over.

Noting the limited supply of vaccines, she added, "Every one of us must recommit to the fight by recognizing that we are all on the front lines now. We are all in this together."

But the one first seen in South Africa has more mutations in its spike protein than the one from the United Kingdom. Several of its mutations are also present in a variant that was first identified in Brazil.

Earlier this week, Moderna said its COVID-19 vaccine offers protection against new variants of the coronavirus — but that the vaccine is more effective against the strain first identified in the U.K. than the one found in South Africa.

The company said that when its vaccine was used against the variant from South Africa, the vaccine produced levels of virus-fighting antibody titers that were around six times less than when it's used against other variants.

As a result, Moderna said it will test booster doses of its vaccine, including one that would be tailored to fight strains that have recently emerged.

The coronavirus variants have alarmed public health experts in recent months, posing a new challenge even as vaccines from Moderna and Pfizer-BioNTech have raised hopes in the fight against the COVID-19 pandemic.

Researchers have found growing evidence that both of the variants circulating in South Africa and Brazil may be capable of evading the body's immune system, heightening the risk of reinfection, as NPR's Michaeleen Doucleff recently reported.

The first U.S. case of the strain from Brazil was identified earlier this week in the Minneapolis metro are

Experts think the UK or "Kent" strain emerged in September and may be up to 70% more transmissible or infectious, although latest research by Public Health England puts it between 30% and 50%.

The South Africa variant emerged in October, and it has more potentially important changes in the spike protein than the UK variant. It has one of the same mutations as the UK one, plus two more that scientists think may interfere more with vaccine effectiveness. One of these may help the virus evade parts of the immune system called antibodies.The UK has imposed a ban on direct flights from South Africa and restrictions on flights to the country.

The Brazil variant emerged in July and has three key mutations in the spike protein that make it similar to the South Africa one.

The current vaccines were designed around earlier variants, but scientists are confident that they should still work against the new ones, although perhaps not quite as well.

Vaccines train the body to attack several parts of the virus, however, not just these sections of the spike protein. Variants could emerge in the future that are more different again.Even in the worst case scenario, the vaccines could be redesigned and tweaked to be a better match - in a matter or weeks or months, if necessary,

As with flu vaccines, where a new shot is given each year to account for any changes in circulating flu viruses, something similar could happen for coronavirus.

There is currently no evidence to suggest that any of them cause more serious illness.Measures such as washing your hands, keeping your distance from other people and wearing a face covering will still help prevent infections, and because the new variants spread more easily it is important to be extra vigilant.

Scientists around the world are on the look-out and any new variants will be closely studied and monitored. Researchers at the Kenya Medical Research Institute say they are analysing a new variant that is different to the UK and South Africa strains, for example. The UK's vaccine development minster Nadhim Zahawi says measures have already been put in place to produce another wave of vaccines if needed.

Other European countries put a premium on opening schools in September and have worked to keep them open, though the variant already has forced some to close.

If community prevalence rises to unmanageable levels — a likely proposition, given the surge in most states — even elementary schools may be forced to close.

In the United States, the variant has only been spotted in a handful of states, and still accounts for less than 0.5 percent of infections.

Over all, though, the variant was more contagious in each age group than previous versions of the virus.

In France, where the new variant has not resulted in a surge of infections so far, schools reopened earlier this month after the winter break.

Adolescents and teenagers between ages 10 and 19 were more likely than younger children to spread the variant, but not as likely as adults.

“When we look at what’s happened in the U.K. and think about this new variant, and we see all the case numbers going up, we have to remember it in the context of schools being open with virtually no modification at all,” Dr. Jenkins said. “I would like to see a real-life example of that kind of country or state or location, which has managed to control things in schools.”

The school Dr. Bromage’s children attend took additional precautions. For example, administrators closed the school a few days before Thanksgiving to lower the risk at family gatherings, and operated remotely the week following the holiday.Officials tested the nearly 300 students and staff at the end of that week, found only two cases, and decided to reopen.

The researchers found several genetic variants at different locations in the genome that were unusually common in the Inuit, compared with people in Europe or China. Several of these variations occurred within a cluster of genes that direct construction of enzymes called fatty acid desaturases. (The genes are called FADS, for short.)

This discovery was particularly tantalizing, because the scientists knew that these enzymes helped regulate the different fats in our bodies, including omega-3 fatty acids.

one of these gene variants was present in almost every Inuit in the study. It is much less common in other populations: About a quarter of Chinese people have it, compared with just 2 percent of Europeans.

Natural selection is the only known way this gene variant could have become so common in the Inuit. Dr. Nielsen said this adaptation might have arisen as long ago as 20,000 years, when the ancestors of the Inuit were living in the Beringia region, which straddles Alaska and Siberia

To uncover the effect of this variant gene, the scientists compared the Inuit in their study with others with more European ancestry. Some had inherited a European version of the variant. People with two copies of the Inuit gene had different blood levels of fatty acids than people without them, the researchers found.

The adaptation did more than just change blood levels of fatty acids, the scientists found. Inuit who carried two copies of the variant gene were on average an inch shorter and 10 pounds lighter than those without a copy.“That’s quite extreme,” said Dr. Nielsen.

Indeed, it’s rare to find a single gene that can influence height and weight so drastically. In recent years, scientists have run a number of large studies pinpointing hundreds of genes that affect height and weight, but each one played a minuscule role in the variation from person to person.

Those studies missed this influential gene variant because they focused mostly on people of European ancestry. So Dr. Nielsen and his colleagues also investigated how it affects Europeans. As it turns out, the gene variant is linked to a drastic drop in height and weight in that population, too.

natural selection might not have favored the FADS variant but a neighboring, as yet unknown piece of DNA that conferred evolutionary advantages.As that gene spread through the Inuit population, the FADS variant might simply have been passed down with it.

Dr. Nielsen and his colleagues are planning to investigate the long-term health effects of the gene variants they’ve found. They may help explain why some of us metabolize fats more effectively than others, and why omega-3s haven’t been the heart panacea once hoped.

The variant was detected in about one-quarter of samples analyzed by the two academic groups in mid-February, one led by a group at Caltech, the other by researchers at Columbia University.

Dr. Anthony West, a computational biologist at Caltech, said in an interview on Wednesday that his ongoing research also showed that the B.1.526 variant was “increasing at a considerable pace in New York City” but that it remained “fairly localized” in the area.

“What we’ve seen in Europe when we hit that 50 percent mark, you’ll see cases surge,” said Dr. Michael Osterholm, director of the University of Minnesota’s Center for Infectious Disease Research and Policy, on NBC’s “Meet the Press” on Sunday. He urged the public not to let up on health measures and to get vaccinated as quickly as possible.

“It’s anybody’s guess, given the vaccine, the competition among the variants and everything we are trying to do to keep the virus low,” he said.

And variants of the virus that appear to be more transmissible are turning up more frequently, according to the US Centers for Disease Control and Prevention, which warns they could worsen the already raging spread of the virus.

experts including Fauci are optimistic that current vaccines will largely protect against known variants, though they warn the more the virus spreads, the greater chance mutations could defeat current vaccines.

Health experts had warned that the November-December holidays, with boosts in travel and indoor gatherings, would send Covid-19 cases soaring.

And the country has reported fewer than 200,000 new cases a day for 10 straight days -- the longest such stretch since before Thanksgiving.

Experts have said movements in the volume of deaths can lag weeks behind case and hospitalization numbers, because those who succumb to the disease can first be sick for weeks.

That includes one first identified in the UK (B.1.1.7), one first seen in Brazil (P.1) and one seen in South Africa (B.1.351).

Researchers also are eying a variant found in California, Fauci said Monday, though it is unclear if it is more transmissible.

Moderna said it would develop a potential booster shot against this variant, just to be safe.

Biden said Monday he hoped to eventually increase the pace to 1.5 million shots a day. The time frame also would shrink if some people get one-dose vaccines, such as the candidate from Johnson & Johnson, which is expected to reports result of its Phase 3 trials soon.

The World Health Organization, meanwhile, has stressed that rich nations need to do more to ensure vaccines are available worldwide.

Biden last week signed an executive order requiring masks in federal buildings and on federal lands, and asked Americans to wear masks for his first 100 days in office.

“We do know how to dial down the transmission of the virus by a lot with our behavior,” said Carl T. Bergstrom, an evolutionary biologist at the University of Washington in Seattle. “We’ve got a lot of agency there.”

The vaccine alone will not be enough to get ahead of the virus: It will take years to inoculate enough people to limit its evolution. In the meantime, social distancing, mask-wearing and hand-washing — coupled with aggressive testing, tracking and tracing — might buy some time and avert devastating spikes in hospitalizations and deaths along the way. These strategies could still turn the tide against the virus, experts said.

“It’s a race against time,” said Marion Koopmans, a Dutch virologist and a member of a World Health Organization working group on coronavirus adaptations.

experts had warned from the start that it would only be a matter of time before the virus became an even more formidable adversary.

The spread of the variant lashing Britain has left some countries vulnerable at a time when they seemed on the brink of scientific salvation.A case in point: Israel. The country, which had launched a remarkably successful vaccine rollout, tightened its lockdown on Friday after having discovered cases of the variant. About 8,000 new infections have been detected daily in recent days, and the rate of spread in ultra-Orthodox communities has increased drastically.

Yet in the course of the pandemic, governments have often proven reluctant or unable to galvanize support for those basic defenses. Many countries have all but given up on tracking and tracing. Mask-wearing remains politically charged in the United States, despite clear evidence of its efficacy.

“Every situation we have studied in depth, where a virus has jumped into a new species, it has become more contagious over time,” said Andrew Read, an evolutionary microbiologist at Penn State University. “It evolves because of natural selection to get better, and that’s what’s happening here.”

Experts say that countries should focus instead on ramping up vaccinations, particularly among essential workers who face a high risk with few resources to protect themselves. The longer the virus spreads among the unvaccinated, the more mutations it might collect that can undercut the vaccines’ effectiveness.

The variants that have emerged in South Africa and Brazil are a particular threat to immunization efforts, because both contain a mutation associated with a drop in the efficacy of vaccines. In one experiment, designed to identify the worst-case scenario, Dr. Bloom’s team analyzed 4,000 mutations, looking for those that would render vaccines useless. The mutation present in the variants from both Brazil and South Africa proved to have the biggest impact.

Still, every sample of serum in the study neutralized the virus, regardless of its mutations, Dr. Bloom said, adding that it would take a few more years before the vaccines need to be tweaked.“There should be plenty of time where we can be prospective, identify these mutations, and probably update the vaccines in time.”

Dr. Rambaut and colleagues released a paper on the variant discovered in Britain on Dec. 19 — the same day that British officials announced new measures. The variant had apparently been circulating undetected as early as September. Dr. Rambaut has since credited the South Africa team with the tip that led to the discovery of the variant surging in Britain.

Public health officials have formally recommended that type of swift genetic surveillance and information-sharing as one of the keys to staying on top of the ever-changing virus. But they have been calling for such routine surveillance for years, with mixed results.

Britain has one of the most aggressive surveillance regimens, analyzing up to 10 percent of samples that test positive for the virus. But few countries have such robust systems in place. The United States sequences less than 1 percent of its positive samples. And others cannot hope to afford the equipment or build such networks in time for this pandemic.

If vaccines are the ultimate way out from this global pandemic, Brazil has a long way to go to seeing this through. As of Friday, less than 10 million people in the country of about 220 million had received at least one dose,

Only 1.57% of the population had been fully vaccinated.

That is the result of a slow rollout program that has been plagued by delays. During the announcement of its distribution plan in early February, the government promised some 46 million vaccine doses to be available in March. It's been repeatedly forced to lower that number, now estimating only 26 million by month's end.

In-country production of what the governments says will eventually be hundreds of millions of doses of the Oxford-AstraZeneca vaccine only just got off the ground. The first 500,000 doses were delivered and celebrated by top Ministry of Health officials in Rio de Janeiro this week, despite being months behind schedule.

If vaccines are to remain in short supply for the foreseeable future, the only remaining ways to control the epidemic's exponential growth in Brazil are the methods the world has heard ad nauseam -- social distancing, no large crowds, restricted movements and good hygiene.

But in many places throughout Brazil, that is just not happening. In bustling Rio de Janeiro, it is easy to find maskless crowds walking the streets, conversing in close quarters. Though the city's famed beaches are closed this weekend, restaurants and bars can still be open until 9 p.m., many likely to be filled to capacity.

Many states have imposed much harsher restrictions including nighttime curfews, but local leaders are fighting against federal leadership, or a lack thereof, determined to keep things open.

President Jair Bolsonaro, a Covid-19 skeptic who has mocked the efficacy of vaccines and hasn't publicly taken one himself, announced Thursday that he would be taking legal action against certain states in the country's Supreme Court, claiming the only person who can decree curfews is him -- something he has promised never to do.Despite thousands of people dying from the virus each day, he claims the real threat is from the economic harm virus-prompted restrictions can impose.

Millions of his supporters are following his lead, openly flaunting local regulations of social distancing and mask wearing.All of this would be concerning enough on its own, but it is exacerbated by a deeply concerning reality -- the spread of Covid-19 variants.

The P.1 variant was first discovered in Japan. Health authorities detected the viral mutation in multiple travelers that were returning from Amazonas state, an isolated region in Brazil's north replete with rainforest.

Nearly two months later, more and more research points to the P.1 variant as a crucial factor not only in the Manaus outbreak but in the nationwide crisis Brazil faces today.A study from Brazil's top medical research foundation, Fiocruz, from early March found that of eight Brazilian states studied, Covid-19 variants including P.1 were prevalent in at least 50% of new cases.

The variant is widely agreed to be more easily transmissible, up to 2.2 times so according to a recent study. That is more transmissible than the widely discussed B.1.1.7 variant first identified in the United Kingdom, which is up to 1.7 times more transmissible, according to a December study.That same study also found that people are 25% to 65% more likely to evade existing protective immunity from previous non-P.1 infections.

Finally, there remain concerns the different vaccines might not be as effective against the P.1 variant. Though a recent study from the UK did find that the "existing vaccines may protect against the Brazilian coronavirus variant," CNN spoke to several epidemiologists who remain concerned.

Amidst Brazil's unmitigated viral spread lies two additional, distinct threats. One, the easier export of the existing P.1 variant abroad. It's already in at least two dozen countries and counting and international travel to and from Brazil is still open to for most countries.Two, if the P.1 variant was created here, so can others.

Under the laws of viral evolution, new variants are created to try and allow the virus to spread more easily. Along the way, more dangerous iterations can be created.

With a lack of a vaccines and a government unwilling to take the steps necessary to prevent that from happening, it is unclear how things get better in Brazil anytime soon.

Researchers who have studied the E484K mutation say it may make the existing Covid-19 vaccines less effective against the new variant, but is unlikely to be totally resistant to the shots.

Laboratory experiments have shown that the E484K mutation can make the virus resistant to some important antibodies the body uses to fight off Covid-19.

“The challenge like here in [South Africa] is in knowing whether reinfection is more likely with these variants,” said Richard Lessells, an infectious-disease specialist at the KwaZulu-Natal Research Innovation and Sequencing Platform, “or whether they are just seeing reinfection with these variants because they are the viruses circulating at the moment and immune responses from first episodes have waned.”

South Africa expects to get its first one million doses of a vaccine developed by the University of Oxford and AstraZeneca PLC this month, with the second shipment of 500,000 doses due in February.

The problem echoes the country’s catastrophic stumbles early in the pandemic, when a lack of testing allowed the virus to spread widely. Currently, only a tiny fraction of all positive coronavirus tests in the United States are forwarded for further sequencing.

t if scientists don’t know what strains are moving through the population, the mutations that matter may pop up undetected.

For months, scientists have been sounding alarms and trying to ramp up genetic sequencing of test samples, but the effort has been plagued by a lack of funding, political will and federal coordination

Centers for Disease Control and Prevention Director Rochelle Walensky said Friday that the government is increasing the level of sequencing nationwide.“We have scaled up surveillance dramatically just in the last 10 days, in fact. But our plans for scaling up surveillance are even more than what we’ve done so far,”

Ultimately, the country needs real-time data — similar to the dashboards now used to track daily cases, hospitalizations and deaths — to track variants and their prevalence across the country

“None of that exists right now. We’re incredibly behind compared to other countries,”

The U.S. effort is so underdeveloped that it’s impossible to say exactly how many virus cases are sequenced daily.

The CDC has warned that the variant found in the United Kingdom — which British scientists said could be up to 70 percent more transmissible — could become dominant in the United States by March.

It also recently contracted with four private companies — Quest, Labcorp, Illumina and Helix — to conduct more sequencing. By mid-February, those contracts should hit full capacity, analyzing 6,000 samples per week, CDC officials said.

Illumina estimates that the country needs to sequence 5 percent of its coronavirus cases to detect a new variant when the variant represents about 0.1 percent to 1.0 percent of the country’s case

However, the United States so far has only sequenced about 0.32 percent of its total cases

the country ranks 38th out of 130 countries reporting whole-genome sequencing data.

The United States has sequenced 84,177 samples out of 25.7 million cases as of Friday, according to a Washington Post analysis. By comparison, the United Kingdom, in ninth place, has sequenced 214,000 genomes — almost 6 percent — of the country’s 3.7 million cases.

Unlike the United States, the U.K. invested in genetic sequencing early on in the pandemic, launching its genomics consortium in March with a $27 million investment and a multimillion-dollar boost late last year.

Even before the emergence of mutations such as the variants first discovered in South Africa and the United Kingdom, U.S. experts had been warning for months about the need for a national standard for genetic surveillance.

In May, the CDC launched a surveillance program for the coronavirus called SPHERES (SARS-CoV-2 Sequencing for Public Health Emergency Response, Epidemiology, and Surveillance). But, in practice, the program relied on a haphazard patchwork of academic labs contributing genetic sequencing on a volunteer basis.

A July report by the National Academies of Science said that “poor funding, coordination, and capacity” had led to a “patchy, typically passive, and reactive” U.S. sequencing effort.

Two important factors seem to be playing a role in Brazil’s resurgence. The first is that, after a COVID-19 infection, the natural immunity that our bodies develop seems to vary in strength and permanence. Protection wanes after infection with most respiratory viruses, including coronaviruses

The solution, then, depends on vaccination. The immune response that the vaccines create is generally more robust than the immune response we get after being infected by a virus, and should buy a population more protected time than would a surge in exposure to the virus

it at least has a capacity to infect people who have already recovered from COVID-19, even if their defenses protect them against other versions of the virus.

The mutations that help the virus spread and evade immune responses have arisen independently in multiple places. Combined with waning immunity, these factors underscore the challenge before the world: Populations may still be vulnerable to disaster scenarios just when things seem to be getting better.

the virus’s capacity to cause such a deadly second surge in Brazil suggests a dangerous evolutionary potential.

New, dangerous variants are all but inevitable when there are extremely high levels of transmission of the virus. As more people gain immunity, the selective pressure on the virus will favor the variants that can most effectively evade immune responses

the basic nature of evolutionary biology means that the virus should be expected to evolve in ways that circumvent defense mechanisms. Evidence that it is already doing so has been clear in the latest vaccine trial data.

the variant in Brazil, known as the P.1 (or B.1.1.248) lineage, has a potent combination of mutations. Not only does this variant seem to be more transmissible; its lineage carries mutations that help it escape the antibodies that we develop in response to older lineages of the coronavirus.

Wealthy countries have time to avoid a fate like Brazil’s through immediate, efficient vaccination.

In most places, however, this is not close to happening. And as of last week, only one of the world’s 29 poorest countries had vaccinated anyone at all. A study in the journal BMJ estimated that vaccines will not be available to more than a fifth of the world’s population until 2022.

The coronavirus’s constantly evolving nature is a stark reminder that the entire world is in this crisis together.

Vaccine distribution is more than just an issue of justice or morality

Ensuring that every human is vaccinated is in everyone’s interest, as global distribution of vaccines is the most effective way to drive down the virus’s capacity to replicate and evolve.

The key will be bringing down the global rates of transmission as quickly as possible—not getting any single country to 100 percent vaccination while dozens of countries roil.

“It is truly confounding that wealthier nations think that hoarding vaccines is the way to protect their citizens from a global pandemic that doesn’t respect borders,”

As the virus currently surges across Africa, some 2.5 million health-care workers are unvaccinated. “Clearly, the failure to address vaccine allocation based on health and epidemiological needs, rather than national interest, is now promising to have a dire impact on the world’s ability to achieve rapid, global control of COVID,”

Certain countries will approach herd immunity by vaccinating almost every citizen. Other countries could see mass casualties and catastrophic waves of reinfection—potentially with variants that evolved in response to the immunity conferred by the very vaccines to which these populations do not have access. In the process, these hot spots themselves will facilitate rapid evolution, giving rise to even more variants that could make the vaccinated populations susceptible to disease once again

The countries that hoard the vaccine without a plan to help others do so at their own peril.

Mr. Graham, the chairman of the Judiciary Committee, and the 40 other Republican senators backing the resolution are taking their cues from a grievance-filled president.

“He keeps telling us he did nothing wrong.”

He thanked them in a tweet for being “tough, smart, and understanding in detail the greatest Witch Hunt in American History.”

high-profile public hearings that could begin as early as mid-November and feature hours of testimony damaging to the president.

the next stage:

William B. Taylor Jr., the top American diplomat in Ukraine, who testified in excruciating detail about a quid pro quo in which Mr. Trump and his allies held up security aid and a White House meeting in exchange for an investigation into former Vice President Joseph R. Biden Jr. and his son Hunter Biden.

lie in state in the Capitol.

campaign to pressure Ukraine for his own political gain.

White House aides are planning to add communications aides dedicated to impeachment

On Wednesday he called Mr. Taylor, who has a 50-year-long résumé of public service, a “Never Trumper.”

He has repeatedly demanded information about the identity of the whistle-blower whose complaint about the president’s call with the president of Ukraine and the handling of foreign aid kicked off the impeachment inquiry.

a majority of the public now supports the impeachment inquiry — if not the president’s removal.

What Impeachment Is: Impeachment is charging a holder of public office with misconduct. Here are answers to look into former Vice President Joseph R. Biden Jr., a potential Democratic opponent in the 2020 election. a reconstructed transcript of Mr. Trump’s call to President Volodymyr Zelensky of Ukraine. A Visual Timeline: Here are Here are 8 takeaways from the complaint. How Trump Responds: The president said the impeachment battle would be “repeatedly referred to the whistle-blower as “crooked” and condemned the news media reporting on the complaint. At the beginning of October, Mr. Trump publicly called on China to examine Mr. Biden as well.

he B.1.351 variant has already spread beyond South Africa to neighboring countries, the United States and Britain. Scientists believe one of its mutations may make it harder for antibodies to grab onto the virus and keep it from entering cells.Among scientists’ worries is that the variant first detected in Britain has acquired the same mutation, known as E484K, in some cases.

Because the trial participants in South Africa were relatively young and unlikely to become severely ill, it was impossible for the scientists to determine if the vaccine protected people from hospitalization or death. Immune responses detected in blood samples from vaccinated people suggest it could.

Like many developing countries, South Africa was relying on the relatively cheap and easy-to-store AstraZeneca shot — “the people’s vaccine,” as Ms. Taylor put it — to tamp down new outbreaks. When airport workers rolled vaccine crates out of the belly of an airplane last week, President Cyril Ramaphosa watched from the rain-soaked tarmac.

Given the proven safety of the AstraZeneca vaccine and the hope that it might yet prevent hospitalizations and deaths from the new variant, Professor Venter said that health officials should consider offering it to anyone who wanted it.

cases involving the U.K. variant are growing exponentially in Denmark. British studies have estimated that the strain is 30 to 70 percent more contagious than the original.

he British variant is spreading so quickly that Danish authorities project it will be the dominant strain of the virus in their country as early as mid-February.

Danish officials, crunching similar data slightly differently, estimate that it is about 20 to 50 percent more contagious than the original in their country, although they say their numbers are still so small that estimates may be inexact.

Danish officials say that at this stage, they are in a race to vaccinate as many people as possible before the British variant takes hold.

the available vaccines slash the odds that infected people will spread the virus onward by at least half and likely more. In the rare cases that the virus breaks through, infections are generally milder, shorter, and lower in viral load.

Worryingly, a recent study documented several cases during India’s spring surge in which health-care workers who were fully vaccinated with AstraZeneca’s vaccine were infected by Delta and passed it on.

If other vaccines have similar vulnerabilities, vaccinated people might have to keep wearing masks indoors to avoid slingshotting the virus into unvaccinated communities

2. The variants are pummeling unvaccinated people.

Vaccinated people are safer than ever despite the variants. But unvaccinated people are in more danger than ever because of the variants.

richer nations would be wrong to think that the variants will spare them, because ...3. The longer Principle No. 2 continues, the less likely No. 1 will hold.

Many nations that excelled at protecting their citizens are now facing a triple threat: They controlled COVID-19 so well that they have little natural immunity; they don’t have access to vaccines; and they’re besieged by Delta.

While America worries about the fate of states where around 40 percent of people are fully vaccinated, barely 10 percent of the world’s population has achieved that status, including just 1 percent of Africa’s.

it’s how we might eventually face variants that can truly infect even vaccinated people.

“We have to assume that’s going to happen,” Gupta told me. “The more infections are permitted, the more probable immune escape becomes.”

We’re unlikely to be as vulnerable as we were at the beginning of the pandemic. The vaccines induce a variety of protective antibodies and immune cells, so it’s hard for a variant virus to evade them all. These defenses also vary from person to person, so even if a virus eludes one person’s set, it might be stymied when it jumps into a new host.

“I don’t think there’ll suddenly be a variant that pops up and evades everything, and suddenly our vaccines are useless,” Gupta told me. “It’ll be incremental: With every stepwise change in the virus, a chunk of protection is lost in individuals. And people on the edges—the vulnerable who haven’t mounted a full response—will end up bearing the cost.”

The discussion about vaccine-beating variants echoes the early debates about whether SARS-CoV-2 would go pandemic. “We don’t think too well as a society about low-probability events that have far-reaching consequences,”

even highly vaccinated nations should continue investing in other measures that can control COVID-19 but have been inadequately used—improved ventilation, widespread rapid tests, smarter contact tracing, better masks, places in which sick people can isolate, and policies like paid sick leave.

bly originated in the South East region of England in Septembe

The World Health Organization says the new variant is responsible for more than half of new infections in the U.K.

And the new version of the virus is already mutating — 17 mutations have been spotted

"In the vast majority of cases, these mistakes are harmless or they even weaken the virus," Doucleff said. "But in rare instances, mutations can help the virus — they can give it this little boost, or advantage, over the other versions."

The good news is that the new variant doesn't appear to be more deadly. But it is much more contagious — researchers are still trying to determine exactly how much more, but many have estimated it could be 50% more transmissible than the original strain

"Contacts of people with B.1.1.7 would get sicker at higher rates."

Plus there's evidence people infected with the B.1.1.7 variant have what's known as a higher viral load -- they have more virus reproducing in their bodies. That makes sense if the variant infects cells more easily, because viruses hijack the cells they infect, turning them into virus factories. More infected cells equal more virus.

Biologist Michael Worobey of the University of Arizona said he's found evidence B.1.1.7 was imported at least five separate times to the US, and likely many more. "It is striking that this lineage may already have been established in the US for some 5-6 weeks before B.1.1.7 was first identified as a variant of concern in the UK in mid-December,"

That should reassure people, Nussenzweig said. The human immune system adapts very well to viral mutations, he said, and produces hundreds of different antibodies that can attack coronavirus.

Finally, there's a new variant seen in California. "We don't know yet what the significance of that one is," said Armstrong. It also has a mutation in the receptor binding domain of the spike protein. The new California variant is called L425R and while it's being found commonly, it's not yet clear if it's more transmissible.

some South African scientists have pointed out that the travel ban may also be hampering the race to learn more about Omicron by blocking supplies of the reagents they need to study it.

Partly because of this South Africa was, until recently, recording less than one-tenth as many daily covid cases as Britain. “It boggles the mind that people in the United Kingdom can pile into a full football stadium and in the United States it appears as though it’s business as usual, but as soon as something happens on African soil, those countries go into a hysterical tailspin,”

The new travel restrictions will wallop the region’s tourism industry, just as hotels, game reserves and wine estates were preparing for their busiest months of the year

Because of the drop in tourism and the imposition of lockdowns the economy shrank by about 6% last year. Thousands of small businesses collapsed

The ripples may spread far beyond southern Africa to countries such as Kenya and Uganda that do not yet face travel restrictions.

South Africa’s health workers are gearing up for another December of mayhem as covid’s fourth wave washes over the country.

The emergence of Omicron, which seems to spread easily, will probably upset those estimates. “It looks like it's spreading quickly but there’s so much that’s unknown, specifically if it will evade the vaccines and its severity,”