The First Omicron Case Has Been Detected in the US—Here's What to Know About the Newest COVID Variant

The World Health Organization recently announced Omicron is the latest coronavirus variant of concern, but experts stress there is still a lot we don't know, including how contagious it is.

The first case of the newly detected COVID-19 variant, Omicron, has been reported in the United States, the Centers for Disease Control and Prevention (CDC) announced Wednesday.

The individual—who returned to California from South Africa on November 22—was fully vaccinated and has mild symptoms that are improving, the CDC said in the press release. As of now, the patient is self-quarantining and their close contacts have all tested negative for COVID-19.

The news comes just days after the World Health Organization (WHO) announced Omicron, also known as the variant B.1.1.529, a "variant of concern" on November 26, quickly following its identification in South Africa. Currently, the WHO reports that at least 23 countries have identified cases of Omicron, and that number is expected to grow.

After nearly two full years of dealing with the COVID-19 pandemic, any new variant—like the now-dominant Delta strain, which is also a designated "variant of concern"—is concerning. But the truth is, there's quite a lot of information we still don't know about Omicron, and scientists are trying to figure out how the variant works in real time. Here, experts help us break down what we do know about Omicron so far, including what makes it so different from previously seen variants of concern.

The Omicron Variant: What We Know So Far
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What is the Omicron variant?

As viruses spread through a population they mutate, and sometimes those mutations result in a new variant of the virus that differs slightly from the original (in this case SARS-CoV-2). That's what Omicron is: a variant of the original virus that causes COVID-19. The variant is named Omicron after the 15th letter of the Greek alphabet, a naming system adopted by the WHO in May to make talking about the viruses less confusing, the agency said.

Omicron was first identified in South Africa and reported to the WHO on November 24. As NPR previously reported, South African officials began to sequence COVID-19 specimens following a surge in cases among university students outside the city of Pretoria, which led to the discovery of Omicron. According to a statement from the WHO, the first confirmed Omicron infection was detected in a specimen collected on November 9.

After taking a closer look, researchers noticed Omicron had unique qualities compared to previous variants such as "several mutations that may have an impact on how it behaves," according to a statemeny by the WHO, which prompted the organization to designate it a variant of concern.

"The thing that got everyone's attention was the large number of mutations—around 50—much larger than previous variants," Anthony Fauci, MD, Director of the National Institute of Allergy and Infectious Diseases and Chief Medical Adviser to the President, said in a White House COVID-19 Response Team Briefing on Tuesday. (Comparatively speaking, the highly contagious Delta variant has fewer than 20 mutations, per the CDC.)

Even more worrisome is that about 30 of Omicron's mutations are in the spike protein, or the part of the COVID-19 virus that penetrates cells, causing infections, Jennifer Lighter, MD, a hospital epidemiologist, infectious disease doctor, and associate professor in the Department of Pediatrics at NYU Grossman School of Medicine tells Health.

That spike protein is also the part of the virus that our immune system recognizes and responds to, Susan Kline, MD, MPH, an infectious disease physician and professor of medicine at the University of Minnesota Medical School tells Health. Therefore, changes in the spike protein may mean the antibodies in a person's system—whether from prior infection or the vaccine—are less effective at recognizing and containing the virus.

Is Omicron more contagious than other variants?

According to the WHO, "it is not yet clear whether Omicron is more transmissible (e.g., more easily spread from person to person) compared to other variants, including Delta." That said, there are some red flags based on preliminary data that suggest Omicron could have a higher transmissibility than variants we've previously seen.

The first red flag is the high number of mutations, some of which "have been associated with increased transmissibility and immune evasion," Dr. Fauci said during the White House briefing. But there are other mutations for which we don't have the full picture—and, it's not clear what the "combination of mutations will do together," Boghuma Kabisen Titanji, MD, PhD, an infectious-disease physician, virologist, and global-health expert at Emory University, recently told The Atlantic.

Another red flag is that Omicron appears to have quickly outcompeted the Delta variant in South Africa. NPR reported that over the past two weeks, Omicron spread to at least seven of South Africa's nine provinces, "quickly overtaking the country's outbreak."

This suggests Omicron may be more transmissible. "[Omicron] seems to be more contagious than Delta, at least in South Africa, but we don't have much data to suggest how contagious it is outside those certain regions," Dr. Lighter says, noting that only 43% of South Africa's population is fully vaccinated, according to the Republic of South Africa's Department of Health compared to almost 60% in the US, per the CDC.

Does Omicron cause more severe illness or different symptoms than other variants?

Unfortunately, much more is needed before officials can definitively say that Omicron does or does not cause more severe illness or different symptoms.

According to the WHO, preliminary data from South African suggests that there are increasing rates of hospitalization, "but this may be due to increasing overall numbers of people becoming infected, rather than a result of specific infection with Omicron," the organization says.

"We have absolutely no evidence to suggest Omicron is more dangerous," Dr. Lighter says. "Actually, anecdotal evidence suggest it is less dangerous, but we will have to wait to see what the data shows."

That anecdotal evidence comes from media reports suggesting that Omicron infections present with mild symptoms. In an interview with the BBC, Dr. Angelique Coetzee, a physician in South Africa and chairwoman of the South African Medical Association said that patients who contracted Omicron infections experienced "fatigue, head and body aches and occasional sore throats and coughs"—essentially, "extremely mild symptoms." However, the patients experiencing those mild symptoms are mostly younger, and mild symptoms are likely expected in that age group, Dr. Kline says.

"What we don't know is will [Omicron] cause a more severe disease if it infects people that we know are at a higher risk of severe complications due to COVID-19 like elderly people or those with comorbidities or chronic conditions," says Dr. Kline.

It may take several weeks for scientists and public health experts to understand the severity of Omicron, according to the WHO. But there is one thing to keep in mind here, the organization says: "All variants of COVID-19, including the Delta variant that is dominant worldwide, can cause severe disease or death, in particular for the most vulnerable people, and thus prevention is always key."

Will the vaccine work against the Omicron variant?

It's far too early to know how Omicron will respond to vaccines, and current studies underway should be give us a clearer picture in the coming weeks, says the WHO.

Given the limited data we have, there is a legitimate concern that the variant might be less susceptible to vaccines, thanks to Omircon's mutations, Dr. Kline says. However, less susceptible doesn't mean completely useless, since vaccines and boosters result in high enough antibody levels that you're protected from other variants, including Delta, Dr. Fauci said.

"The immune system actually accounts for variations, and actually has a wider immune response than just the specific targets used in the vaccine," Dr. Lighter adds.

The WHO does report, however, that there may be an increased risk of reinfection with Omicron, which means people who previously had COVID-19 but are unvaccinated, may be more likely to contract the Omicron variant. This suggests the virus might have an easier time evading the vaccine, too.

"If you have a variant that's more contagious, you will see more infections or breakthroughs," says Dr. Lighter. But, we won't know this for sure until more data is available. The good news is that the WHO says current vaccines remain effective against severe disease and death.

As research into vaccine efficacy against Omicron continues, Pfizer-BioNtech and Moderna have both announced that they're working on an Omicron-specific booster that could be ready in fewer than 100 days, reports STAT.

The CDC also strengthened its recommendations on boosters, suggesting everyone ages 18 and older get one if they're either six months out from their final dose of an mRNA (Pfizer or Moderna) vaccine, or two months out from a single-dose Johnson & Johnson/Janssen vaccine.

How could Omicron change the trajectory of the pandemic?

It's still too early to say how Omicron may or may not change the trajectory of the COVID-19 pandemic. Yet, experts do agree that there is plausible concern the latest variant causes a new wave of cases, mostly among the unvaccinated, Dr. Kline says.

"The bottom line is that anyone that is not vaccinated is at risk of getting COVID and getting severe COVID. They will get COVID there is no way around it, sooner or later it will happen," Dr. Lighter says. If vaccine hesitancy continues, "than it could a very bleak next few months," she adds.

Therefore, the best way to protect yourself is to get vaccinated if you haven't already, and to get your booster shot if you are eligible, Dr. Lighter says. Past that, the CDC recommends both vaccinated and unvaccinated people can further protect themselves by:

  • Wearing a well-fitting mask in crowded or poorly ventilated indoor spaces, especially if you are in area with high rates of transmission
  • Washing your hands frequently
  • Physically distancing yourselves from others

"We have the ammunition to shield ourselves from another surge—people need to get vaccinated," Dr. Lighter says. "We can take these measures to protect ourselves, our community, and our family."

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