Americans have been tired of the pandemic for nearly two years and have received a new blow during the long Thanksgiving weekend: the announcement New COVID variant Already appeared.

A variant of omicron officially named B.1.1.529 surfaced in several southern African countries in November. When South Africa’s public health officials saw it begin to compete against the previous ruling variant delta, it sounded a wake-up call on a global scale. This suggests that omicron may eventually spread widely. In fact, omicron has been reported on multiple continents, which may be due to people traveling internationally without their knowledge.

After omicron’s announcement, several countries imposed Travel ban Hope to control the virus. Whether these bans will effectively slow the spread remains unknown. Kent State University epidemiologist Tara Smith said: “As we have seen before and now, once the horse has left the stable, the travel ban will not help.”

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Scientists warn that it is too early to say whether omicron is as dangerous as delta. Other variants that seemed worrying at first have disappeared.

Now here is What we know and what we don’t know, About the omicron variant.

What is a variant?

Compared with the original strain that appeared in Wuhan, China, a variant of the virus has mutated in some way, thereby increasing its spread or severity. “RNA viruses like COVID mutate when they replicate, especially when they spread at high speeds,” said Dr. Monica Gandhi, professor of medicine at the University of California, San Francisco.

COVID is not as easy to mutate as influenza viruses, but they will mutate over time. These variants usually produce the same range of symptoms as the original strain of COVID. But these mutations may help the virus spread more effectively from person to person, or have an advantage in sneaking into natural immunity or vaccine immunity.

Which variants are already circulating in the United States?

So far, public health officials have noticed five “worrying variants” and two “interesting variants” that have not been considered worrying. So far, there has not been a variant that fits the most worrying of the three official categories—”Variants with High Impact”.

The World Health Organization’s decision earlier this year to name these variants in Greek letters was both to simplify the discussion and to limit the stigma of variants named after a country.

For most of this year, the first four “variables of concern”—alpha, beta, gamma, and delta—have been popular in the United States. But the most important variant is delta, because it can spread from person to person faster than other variants.For months, delta has accounted for more than 99% of COVID infections in the United States

As of noon on November 29, there were no confirmed cases of omicron in the United States, but experts warned that it was only a matter of time. It may already be in the United States, but it has not been discovered.

How did Omicron appear?

Although scientists are unsure of the exact location where omicron first appeared, it is likely to occur in southern African countries.

Experts say that the low vaccination rate in that part of the world may have played a role in creating an enabling environment. For mutations that produce omicron. (It can be pronounced as AH-mi-crahn or OH-mi-crahn.)

“The immunity of the population in many countries in Africa is very low-about 30% of people in South Africa are vaccinated,” Smith said. “In people with basically no immunity, the virus can swept through, and every newly infected person has a chance to mutate the virus.”

Why did public health officials make such an urgent response to Omicron?

This concern stems from the scope and nature of mutations in the new variant. According to a report in New York magazine, South African health officials pointed out 50 significant mutations, 30 of which occurred in the spike protein, which is a key structure of the virus. This is more than the previous variant.

Aris Katzourakis, an evolutionary biologist at Oxford University, said in an interview with “Science” magazine: “If we are looking for mutations that do affect infectiousness, it will find all of them.”

Nevertheless, it is not yet certain how these mutations will work together effectively to create variants that can consistently outperform delta.

How much do we know about Omicron’s infectivity?

The omicron variant is so new that scientists are just beginning to understand its properties. Therefore, experts urge caution when drawing conclusions, especially based on anecdotal evidence.

Nevertheless, the scientists said that if omicron becomes as easy to spread as delta, they will not be shocked.

Dr. William Schaffner, a professor of preventive medicine at Vanderbilt University School of Medicine, said: “Of course, the answer is uncertain, but it seems to be at least as infectious as delta.”

A complicating factor, Schaffner said, is that the area with the fastest spread is the area where young people and university students in Johannesburg live, and their vaccination rates tend to be lower. The vulnerability of these groups to infection may exaggerate the speed at which omicron appears to spread.

How much do we know about whether Omicron will make the patient’s condition worse?

Early evidence is somewhat contradictory, but there are signs that omicron’s symptoms may not be more severe than previous variants. The President of the South African Medical Association, Dr. Angelie Couche, said that the early cases found in the unvaccinated population are mild.

However, it remains to be seen whether elderly and unhealthy patients will also experience milder symptoms. Another warning is that it may be too early to see severely advanced cases in the spread of omicron.

Are existing vaccines effective against Omicron variants?

Scientists are cautiously optimistic that the existing vaccines will also be effective against omicron, just like they are against delta, at least able to prevent diseases that are serious enough to require hospitalization.

“Scientists in South Africa and Israel have also discovered this mutation, and they said that they have not found serious diseases in the vaccinated population,” Gandhi said.

Gandhi added that the immunity-providing B cells produced by the vaccine have been shown to produce antibodies against variants, while the T cells that can prevent serious diseases are very immune and should not be at risk of the mutations found in omicron. She said These vaccines also produce polyclonal antibodies that can fight against multiple parts of the spike protein. Finally, booster injections have been shown to be effective in quickly enhancing immunity.

“Most scientists believe that we should still prevent serious diseases through vaccination, and vaccination is still the main means of control,” Gandhi said.

Bottom line: If you have not been vaccinated, especially if you are not sick yet, get vaccinated. If you have already been vaccinated, get a booster.

How long will it take us to better respond to threats from Omicron?

Moderna, Pfizer-BioNTech, and Johnson & Johnson have all tested the effectiveness of their existing vaccines against omicron in the laboratory based on a variant analysis protocol developed at the beginning of this year. These results should be available within a week or two.

Other questions—including whether omicron makes you sick and whether it spreads more easily—will take longer to answer because they require careful contact tracing and accurate diagnosis of infected persons.

In order to better answer these questions, Smith said: “I think it will take at least a month to obtain some preliminary data, and it will probably take longer to truly understand a more comprehensive situation. We do not know the real world experience. In the vaccine breakthrough before that.”

Can we expect to develop specific new boosters for Omicron?

I don’t know if the omicron variant requires a reformulated booster. Delta does not need a booster for the new formula, because the researchers are sure that the existing formula is still valid.

In other words, vaccine manufacturers can quickly add new boosters when necessary.

A Pfizer spokesperson told the Washington Post that if such a variant occurs, Pfizer and BioNTech “expect to be able to develop and produce a customized vaccine for the variant within 100 days,” pending regulatory approval.

Dr. Matthew Lawrence, an expert on pediatric infectious diseases at the University of Maryland School of Medicine, said he believes that boosters can be quickly developed and tested if needed, “maybe within a few months.”

What happened to the other variants?

In May 2021, delta was named a variant of attention. By November 2021, omicron was given the same label, and the other two variants were promoted to a lower “variant of attention” status: lambda and lambda from Peru Mu from Colombia. Other variants, such as a variant called “delta-plus” found in Nepal, also attracted people’s attention during this period. But none of these beat deltas in a consistent way in the competition, so they have never been promoted as “variants of concern.”

This is the most promising result of Europe and America. Gandhi said that the other variants “all had similar concerns about them, but they did not expand to any significant extent after the initial report.”

Is it reasonable to think that the United States is in a better position to deal with Omicron than Delta?

Experts generally believe that the United States should be better prepared to fight omicron than when delta appeared earlier this year.

Gandhi said: “We are in a better position because we have a higher vaccination rate, boosters are available to everyone over 18 years old, and the qualification for the vaccine can be as low as 5 years old.” “Due to the delta variant. Since the spread since July 2021, our natural immunity rate in this country is also higher. And we are about to launch oral antiviral therapy. So we have the tools to fight this new variant.”

Schaffner said the challenge will be to ensure that Americans continue to vaccinate and strengthen vaccinations, and use testing and maintain public safety behavior.

“All these tools are available,” he said. “The biggest question is how the public tends to use these tools.”

Will COVID last forever like the flu?

Experts now believe that the new coronavirus is unlikely to be eradicated from the world like smallpox, even in the United States, because polio is after the near-universal vaccination. The combination of rapid mutations and low vaccination rates makes it very likely that COVID-19 will not be submitted after smallpox and polio.

“This is more likely to be a flu model, and we have to track mutations every year and change the boosters accordingly,” Schaffner said. He said that, in fact, the joint COVID-flu vaccine effort is already underway.