What We Know About the New Covid Variant, Omicron

Intense research into Omicron, first identified in southern Africa, has just begun. World leaders and public health experts have urged people not to panic — and to get vaccinated, if they can.,

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What is the Omicron variant?

First identified in Botswana and South Africa, this new iteration of the coronavirus has prompted concern among scientists and public health officials because of an unusually high number of mutations that have the potential to make the virus more transmissible and less susceptible to existing vaccines.

The World Health Organization has called Omicron a “variant of concern” and warned that the global risks posed by it were “very high,” despite what officials described as a multitude of uncertainties. The variant has been identified in more than three dozen countries, according to the World Health Organization, on every continent except Antarctica. At the beginning of December, a California resident who returned home from South Africa was identified as the first American infected with Omicron, and officials have since detected the variant in several states including New York, Colorado, Nebraska, Minnesota and Hawaii.

What do we know about Omicron’s presence in the U.S.?

It’s too early to say how widespread the variant will become in the United States. More than a dozen states have reported cases so far. But experts like Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, cautioned that the number is likely to markedly increase in the coming days and weeks. The first person to have tested positive for the variant returned to San Francisco from South Africa on Nov. 22 and tested positive on Nov. 29, according to the C.D.C.

The individual, who was fully vaccinated, had mild symptoms that were improving, health officials said. The nation’s top infectious disease expert, Dr. Anthony S. Fauci, said that contact tracers had identified all those who had close contact with the infected individual and that so far, all of them had tested negative for the virus.

In the second confirmed case, a man from Minnesota visited New York to attend an anime convention. He first developed mild symptoms on Nov. 22, shortly after arriving in the city. He tested positive for the virus two days later.

Health officials say the man, who had not traveled outside the country, was fully vaccinated and had received a booster shot in early November.

Should we be worried?

Omicron’s discovery has prompted considerable panic across the globe, with a number of countries banning flights from southern Africa, or — like Israel, Japan and Morocco — barring entry of foreign travelers altogether.

But public health experts have urged caution, noting that there is as yet no firm evidence that Omicron is more dangerous than previous variants like Delta, which quickly overtook its predecessors in the United States and other countries.

Although Delta turned out to be much more transmissible than prior variants — and there is some data suggesting it can cause more severe illness in the unvaccinated — there is little evidence it is more lethal or capable of outsmarting vaccines.

Much remains unknown about Omicron, including whether it is more transmissible and capable of causing more serious illness. There is some evidence the variant can reinfect people more readily.

In South Africa, where Omicron is already the dominant form of the virus, scientists reported a sudden, sharp rise last month in coronavirus cases among people who had already been infected, in a study that has not yet been peer-reviewed or published by a scientific journal. The authors noted that there was no such upswing when the Beta and Delta variants emerged.

The finding hints that Omicron may be less vulnerable to the body’s immune defenses. Researchers in South Africa also reported that the variant appears to be spreading more than twice as quickly as Delta, which had been considered the most contagious form of the virus.

There are some early signs that Omicron may cause only mild illness. But some indicators were based mainly on South Africa’s cases among younger people, who are less likely overall to become severely ill from Covid.

And a preliminary report released in early December from a hospital in Pretoria about a small number of cases noted that few of the patients in the Covid ward required supplemental oxygen and that most were admitted to the hospital for other reasons, a pattern not seen during previous waves. But the patients were also younger than during previous waves, making them less susceptible to severe disease, and it is still early in the outbreak, the report noted.

It will require more data — and more time — to determine whether the variant truly is milder, experts say.

Dr. Angelique Coetzee, who chairs the South African Medical Association, said in late November that the nation’s hospitals were not overwhelmed by patients infected with the new variant, and most of those hospitalized were not fully immunized. Moreover, most patients she had seen did not lose their sense of taste and smell, and had only a slight cough.

Early in December, Regeneron said its Covid antibody treatment might be less effective against Omicron, an indication that the popular and widely beneficial monoclonal antibody drugs may need to be updated if the new variant spreads aggressively.

That said, Omicron’s emergence is so recent that it may be a while before experts know whether it is more pathogenic. Covid hospitalizations lag new infections by two weeks or more.

Scientists expect to learn much more in the coming weeks. At the moment, they say there is no reason to believe Omicron is impervious to existing vaccines, although they may turn out to be less protective to some unknown degree.

There’s another reason to remain calm: Vaccine makers have expressed confidence they can tweak existing formulations to make the shots more effective against new variants. Also reassuring: Omicron’s distinctive mutations make it easy to quickly identify with a nasal swab and lab test.

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Staff members standing before an arrivals information board at Haneda International Airport in Tokyo. A number of countries banned flights from southern Africa or, in the case of Israel, Japan and Morocco, barring entry of foreign travelers altogether.Credit…Franck Robichon/EPA, via Shutterstock

Why are scientists so concerned about Omicron?

As the coronavirus replicates inside people, new mutations constantly arise. Most provide the virus with no new advantage, but sometimes mutations can give the pathogen a leg up by allowing it spread more readily among its human hosts or dodge the body’s immune response.

Researchers in South Africa sounded the alarm because they found more than 30 mutations in the spike protein, a component on the surface of the virus that allows it to bind to human cells and gain entry to the body. Some of the samples from Botswana shared about 50 mutations throughout the virus not previously found in combination.

The spike protein is the chief target of antibodies that the immune system produces to fight a Covid-19 infection. Having so many mutations raises concerns that Omicron’s spike might be able to somewhat evade antibodies produced by either previous infection or vaccination.

Those mutations also raise the prospect that the variant will reduce the efficacy of monoclonal antibody treatments — a fear partly confirmed late last month with Regeneron’s announcement.

Still, it is worth remembering the fate of earlier variants that stirred concern: Beta and Mu, for example, evolved the ability to partially evade the body’s immune defenses, but they never became a serious threat to the world because they proved to be poor at transmitting.

The Coronavirus Pandemic: Key Things to Know

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The Omicron variant. The latest Covid-19 variant was identified on Nov. 25 by scientists in South Africa and has since been detected in dozens of countries, including the United States. Should you be concerned? Here are answers to common questions about Omicron.

Understanding the mutation. Scientists in South Africa said that the Omicron variant appeared to spread more than twice as quickly as Delta and that past coronavirus infections give little immunity against it. In the U.S., sequencing labs are speeding up the screening of samples from travelers.

Travel restrictions and lockdowns. The U.S. is requiring international travelers to provide proof of a negative test taken no more than a day before their flights. In Europe, where Germany has already announced tough restrictions on unvaccinated people, worries of new lockdowns loom.

New York City’s new mandate. Mayor Bill de Blasio announced a sweeping vaccine mandate for all private employers in New York City to combat the spread of the Omicron variant. Eric Adams, who will succeed Mr. de Blasio as mayor in less than a month, declined to commit to enforcing the new rules.

What about vaccines?

Vaccines are expected to provide some protection against Omicron because they stimulate not only antibodies but other immune cells that attack virus-infected cells. Mutations to the spike protein do not blunt that response, which most experts believe is instrumental in preventing serious illness and death.

Citing the potential for waning immunity six months or more after vaccination, some health experts are promoting booster shots to increase antibody levels.

Dr. Fauci has urged people to get a booster shot, which he said would most likely provide additional protection against severe disease. “We’ve said it over and over again and it deserves repeating. If you’re not vaccinated, get vaccinated, get boosted if you are vaccinated, continue to use the mitigation methods, namely masks, avoiding crowds and poorly ventilated spaces,” he said on Tuesday.

Moderna, Pfizer-BioNTech and Johnson & Johnson, makers of vaccines approved for use in the United States, and AstraZeneca, which is widely used in Europe, have all said they were studying Omicron, and they expressed confidence in their ability to tailor their formulations to target the variant.

Why is it called Omicron?

When the W.H.O. began to name emerging variants of the coronavirus, they turned to the Greek alphabet — Alpha, Beta, Gamma, Delta and so on — to make them easier to describe. The first “variant of concern,” Alpha, was identified in Britain in late 2020, soon followed by Beta in South Africa.

But veterans of American sorority and fraternity life might have noticed the system has skipped the next two letters in the alphabetical order: Nu and Xi.

Officials thought Nu would be too easily confused with “new,” but the next letter, Xi, is a bit more complicated. W.H.O. officials said it was a common last name, and therefore potentially confusing. Some noted that it is also the name of China’s top leader, Xi Jinping.

A spokesman for the W.H.O. said the organization’s policy was designed to avoid “causing offense to any cultural, social, national, regional, professional, or ethnic groups.”

Next in line? Omicron. (Here’s how it’s pronounced, and here.)

I’m fully vaccinated — I’ve even had my booster. So why should I care about Omicron?

Like Delta, which was first identified in India, the rise of yet another worrisome variant in the developing world points to a more fundamental problem facing the global community more than a year-and-a-half into the pandemic.

The hoarding of vaccines by wealthy countries while poorer nations struggle to obtain them provides more opportunities for SARS CoV-2 to replicate and mutate among the unvaccinated. More mutations mean there are more chances for the virus to become more infectious, immune-resistant or lethal.

And as the rapid spread of Delta showed, a dangerous new variant is unlikely to remain in one place for very long.

The risks extend beyond public health. The resulting economic devastation from a new variant can hit affluent countries nearly as hard as those in the developing world. One academic study estimated trillions of dollars in economic loss to wealthy countries when residents of poorer countries remain largely unvaccinated.

In recent days, the cascade of travel restrictions prompted by Omicron’s emergence has triggered resentment among Africans, who believe the continent is yet again bearing the brunt of panicked policies in Western countries that have failed to deliver vaccines and the resources needed to administer them.

On Tuesday, Tedros Adhanom Ghebreyesus, head of the W.H.O., described the travel bans as unfair and counterproductive. “I well understand the concern of all countries to protect their citizens against a variant that we don’t yet fully understand,” he said.

“But I am equally concerned that several member states are introducing blunt, blanket measures that are not evidence-based or effective on their own, and which will only worsen inequities.”

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