Where has omicron been confirmed?

Omicron was first reported in late November, but its exact origin is still unknown. South Africa confirmed on Nov. 25 that scientists there had detected a worrying variant. Days later, other nations including the Netherlands said they had reviewed genetic sequencing data and found that the variant was already circulating within their borders at the same time as when South Africa raised the alarm. The World Health Organization soon listed it as a “variant of concern.” In South Africa, where official statistics show that more than 43 percent of the adult population is fully vaccinated, the variant spread rapidly. By Dec. 14, the positivity rate hit 34.9 percent . However, by late December, South Africa’s top infectious-disease scientist said that the country had passed the peak of new omicron cases . The first confirmed case in the United States was reported in California on Dec. 1, and within weeks, it had been detected in all 50 states . By late December, the seven-day daily average coronavirus case count in the United States had surpassed the delta-driven summer surge , Washington Post figures show. And, by the next month, the number of new daily cases had surpassed 700,000. But cases and hospitalizations have significantly declined. As of March 2, cases had dropped to about 75,000 per day, the CDC said , though data shows the virus is still circulating throughout communities in the United States.

What do we know about the variant?

Omicron’s genetic profile is unique compared with other circulating variants, meaning it represents a new lineage of the virus. It is distinct from other variants in another crucial way: There is a greater number of mutations. Omicron has more than 30 genetic changes in the spike protein, the part of the virus that binds to human cells and allows it to gain entry. Scientists were worried that those mutations would make omicron more transmissible, even among those with a natural or vaccine-acquired immune response — and they appear to have been right. Antibodies defeat the virus by targeting spike proteins, but changes that alter the structure can prevent them from binding as they usually do to neutralize the target. The omicron variant probably picked up genetic material from a virus that causes the common cold in humans, according to a preliminary study by researchers from Nference, a Cambridge, Mass.-based firm that analyzes biomedical information. Venky Soundararajan, a biological engineer who co-wrote the study, noted that as a virus evolves to become more transmissible, it generally “loses” traits that cause severe symptoms — although he said more analysis is needed. Studies have suggested that in many cases, omicron has caused less severe disease than previous variants — and may even be more likely to lead to asymptomatic infections . But because it is so contagious, the large number of infections could still result in a sizable number of severe cases, some experts have said. Although omicron appears to be more adept at evading antibodies, so far, data has suggested that the vaccines, particularly after a booster shot, still offer protection, namely against severe disease.

Why is it called omicron?

The World Health Organization named the B. 1.1.529 variant omicron in the tradition of giving variants a Greek letter name. After the most recently named variant, mu, officials chose to skip the next letters available for variants: nu and xi. “Nu is too easily confounded with ‘new,’ and Xi was not used because it is a common surname,” the WHO said in a statement to The Washington Post. The agency’s “best practices for naming new diseases suggest avoiding ‘causing offense to any cultural, social, national, regional, professional or ethnic groups,’ ” the WHO noted.

What has been done to halt the spread of omicron?

The international response initially focused on two fronts: travel restrictions and encouraging more people to get vaccinated. Within days of the discovery of the variant, several countries began curbing flights to and from South Africa and its neighbors to try to slow omicron’s advance. The United States imposed restrictions on travelers from Botswana, Eswatini, Lesotho, Malawi, Mozambique, Namibia, South Africa and Zimbabwe, though they have since been lifted . Still, all inbound international travelers to the United States age 2 and older must show a negative coronavirus test result, with the test taken no more than one day before departure, regardless of nationality or vaccination status. Those who recently had covid-19 may alternatively show documentation that they tested positive no more than 90 days before departure — and have recovered. Health experts recommend getting tested at a testing center, even pharmacies and local health departments — but not emergency departments. Not only does this clog up emergency rooms for people who need them, but it also creates a risk of exposure to covid-19 — both for the person unnecessarily visiting the ER and for others who are waiting for care, said William Schaffner, medical director of the National Foundation for Infectious Diseases. President Biden also announced that the federal mask mandate requiring travelers to wear masks on planes, buses and in transportation hubs has been extended through March 18. The CDC’s new covid-19 community levels framework does not affect travel requirements at this time, including wearing masks on public transportation, according to the CDC. U.S. public health authorities have also re-upped efforts to get shots into arms, including boosters for those who have already been fully vaccinated. The CDC recently expanded its recommendation on booster shots, stating that people 12 and older “should” get a booster five months after the initial Pfizer-BioNTech vaccine series, and those 18 and older should get boosted five months after the initial Pfizer or Moderna series or two months after the Johnson & Johnson shot. And despite the recent relaxation of mask recommendations, federal health authorities still recommend that everyone age 2 and older wear a mask in indoor public spaces in areas where the covid-19 community level is high. In addition, the CDC said people should avoid crowds and poorly ventilated areas, wash hands frequently, and, when needed, get tested and isolate to protect others.

Do we know whether vaccines are effective against omicron?

Studies are underway to examine how vaccines will hold up against the new variant, with initial findings presenting a mixed picture. Early data shows that individuals who are fully vaccinated and received a booster shot remain largely protected against severe illness and death from omicron — but officials worry about lags in getting Americans to sign up for their booster shot. More than 95 million people in the United States have gotten the extra shots, of 216 million who are fully vaccinated, according to the CDC. In the first in-depth laboratory study on omicron, scientists in South Africa found that omicron was able to elude a great deal of the protection provided by disease-fighting antibodies. But the study, a preprint that has not yet been peer-reviewed, also said that previous infection followed by vaccination or a booster shot was likely to “confer protection from severe disease in Omicron infection,” suggesting boosters could be important. One recent study showed omicron-fighting antibodies persisted for four months after a third dose of the Pfizer-BioNTech vaccine, suggesting that a fourth shot may not be immediately necessary. And a similar study found that the Moderna booster remained effective against the variant in laboratory tests for at least six months. In the event that vaccines lose some of their punch, vaccine makers say they could also adjust their formulas relatively quickly to target omicron. Nonetheless, a reformulated vaccine that’s omicron-specific is not currently planned as part of the Biden administration’s strategy, senior administration health officials and experts at vaccine companies said, adding there is no evidence a vaccine design switch is needed. Given the spread of omicron in South Africa, several experts have pointed to the need to vaccinate underserved countries to bolster the world’s protection from future, more-evasive variants. “I think vaccine equity is a really important issue,” said Linda Bauld, a professor of public health at the University of Edinburgh. She noted the low vaccination rates in many African countries and the fact that high prevalence of the virus means it can undergo many genetic changes each time it jumps between individuals. However, Bauld added, transmission of the coronavirus probably will not be eliminated even with a vaccine, as seen with the delta variant, with mutations ultimately able to “occur in any country.”

Does omicron cause severe illness, and do existing treatments work?

Current data indicates that the omicron variant causes milder cases of covid-19 than the delta variant — but scientists warn it can still be dangerous, especially to vulnerable populations, such as those who are not vaccinated. A major private study by Discovery Health, South Africa’s largest health insurer, published in December, found omicron appears to cause less severe illness than earlier coronavirus variants but is more resistant to the two-dose Pfizer-BioNTech vaccine widely. The scientists found that risk of hospital admissions among adults who developed covid-19 was 29 percent lower than in the initial pandemic wave that emerged March 2020. Two companies that have developed monoclonal antibodies, which are designed to prevent severe illness, recently announced contrasting findings on the potency of such therapies against omicron. Regeneron Pharmaceuticals said in a news release that data confirms its therapy, REGEN-COV, has “diminished potency” against omicron but remains useful against the delta variant, which is still the dominant strain in the U.S. At the same time, AstraZeneca said a lab study of Evusheld, its coronavirus antibody cocktail, found that the treatment “retained neutralizing activity” against omicron. U.S. public health officials began stockpiling a monoclonal antibody treatment called sotrovimab in December. Laboratory studies have shown that the intravenous infusion from Vir Biotechnology and GlaxoSmithKline will hold up against the new variant.

Will omicron upend plans to return to ‘normal’?

Two years into the pandemic, many people have been worried that hard-fought gains would be lost as the new variant emerged. Many have also been confused about what precautions to take amid conflicting advice and clashing guidelines coming from government, science, health, media and other institutions. “I have never before experienced such an absolutely anguished outpouring as I have around this,” said William Hanage, an associate professor of epidemiology at the Harvard T.H. Chan School of Public Health, shortly after omicron emerged in November. The response, he said, has “as much to do with humans as it does with the virus.” Stuart Ray, an infectious-disease specialist at Johns Hopkins University, said people should follow the “new wisdom” on the virus: keeping track of local infection rates to determine how vulnerable they are while using common-sense protection including vaccination, boosters, and high-quality masks such as KN95 and N95s. “This is probably not the last variant that we’ll see, so I think we should see this as part of the learning about this virus,” he said. Many plans have been scratched amid the omicron surge across the United States. Some companies have pushed back plans for their return to mandatory in-office work, and some schools have closed, forcing students back into virtual learning. Big events such as the Grammys have been indefinitely postponed. During the holidays, restaurant reservations were dwindling again. And supply and labor challenges have contributed in part to empty grocery store shelves from time to time. Few are calling for a return to the stark measures seen in the spring of 2020. A White House official recently said there is no need for lockdowns or other closures, given the tools available to fight the variant, starting with vaccines and boosters. Top federal infectious-disease expert Anthony S. Fauci recently said the United States is exiting “the full-blown pandemic phase” of the coronavirus crisis. Still, as more and more states start to relax rules such as mask mandates in schools and other public places, public health authorities say the new CDC guidance, which aims to provide individuals with an understanding of what precautions they should take based partly on the level of disease in their community, may fluctuate based on the virus. “None of us knows what the future may hold for us and for this virus,” CDC Director Rochelle Walensky said. “We need to be prepared and ready for whatever comes next. We want to give people a break from things like mask-wearing, when levels are low, and then have the ability to reach for them again, should things get worse in the future.” Joel Achenbach, Christine Armario, Lateshia Beachum, Amy Cheng, Silvia Foster-Frau, Ellen Francis, Carolyn Y. Johnson, Lesley Wroughton, Tim Bella, Sammy Westfall , William Booth and Lena H. Sun contributed to this report. Read more: Countries race to cut travel links with southern Africa, amid fears of omicron’s potential to spread Announcement of new virus variant alarms world, as stocks crash and flights are banned Dow plunges more than 900 points as new coronavirus variant sends global markets reeling

What is omicron and other questions about the new coronavirus variant identified in southern Africa

The highly transmissible omicron variant of the coronavirus remains the dominant strain in the United States.

Although covid-19 cases and hospitalizations are declining across the United States, the recent surge drove up the number of daily deaths significantly, particularly among the unvaccinated and people older than 75.

Omicron has sparked alarm both internationally and in the United States, where the variant and its mutations accounted for 100 percent of new infections during the week ending March 5, according to the most recent data from the Centers for Disease Control and Prevention. It has an unusually high number of mutations that make it significantly more contagious and capable of eluding the body’s first line of immune defenses. Omicron’s sublineage BA.1.1 currently accounts for more than 73 percent of cases in the United States while BA.2. accounts for more than 11 percent, the data shows.

Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security, previously had said omicron “is not something that can be avoided.”

“Most people are going to get infected with omicron — including those who are vaccinated, including those who are boosted,” he said during the surge. “We now have to think about covid-19 in two different ways — as a mild disease in the vaccinated and as something that is still a problem for the high-risk unvaccinated.”

With omicron, many vaccinated Americans will at some point test positive. Here’s what to do.

World leaders responded to the recent surge by placing restrictions on travel, ramping up vaccination and booster drives, increasing testing and encouraging an already pandemic-fatigued public to double down on measures including wearing masks and social distancing. Although studies indicate that omicron has been producing milder infections than other variants, the sudden swell of cases and large number of people who remain unvaccinated has still overwhelmed some strapped health-care systems.

As the number of cases have dropped, federal health authorities have started relaxing certain recommendations — namely its mask recommendations. On Feb. 25, the CDC updated its mask guidelines, which no longer recommend masking for most people in areas with low to medium levels of covid-19 community transmission and hospitalizations. However, other prevention strategies, such as vaccination, are still recommended.

How scary is omicron? Scientists are racing to find answers.

What to know about the omicron variant of the coronavirus

The recent surge is waning, but the highly transmissible omicron variant is still the dominant strain in the United States, targeting the unvaccinated and those older than 75

What to know about the omicron variant of the coronavirus

The recent surge is waning, but the highly transmissible omicron variant is still the dominant strain in the United States, targeting the unvaccinated and those older than 75

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