person in a medical lab holding a vial with the words Omicron Variant over the image

We will update this post as news comes out about Omicron variants. This post was last updated on April 20, 2022.

The COVID-19 Omicron variant, or B.1.1.529, was first identified on Nov. 24, 2021. Eight days later, the first confirmed case in the United States was reported. The U.S. Centers for Disease Control and Prevention (CDC) classified Omicron as a variant of concern.

Since then, COVID-19 Omicron sublineages (or subvariants) have emerged.

  • Omicron BA.1 subvariant – this accounted for the widespread surge in COVID-19 cases starting December 2021. BA.1 cases are now declining.
  • Omicron BA.2 subvariant – the dominant worldwide variant as of April 2022.
  • Omicron BA.3 subvariant – rare cases in isolated countries, but not in U.S.
  • Omicron XE subvariant – a recombinant variant, with reports of a handful of cases in U.S.

According to the U.S. Centers for Disease Control and Prevention (CDC), Omicron can cause more infections and spread faster than the original COVID-19 strain. It also spreads more easily than the Delta variant of COVID-19.

In general, Omicron tends to cause milder symptoms than the original COVID-19 strain, CDC says. It also tends to cause less severe symptoms than the Delta variant. Researchers believe Omicron impacts the airways more than the lungs. It replicates at a slower rate in the body, which may result in milder illness.

Some people, including those with moderate to severe asthma or COPD, may develop severe illness if infected with Omicron. They could be hospitalized or die from Omicron infection.

It remains important to protect yourself from COVID-19. Vaccinations and booster shots are widely available. These can significantly reduce your chances of severe illness, hospitalization or death due to COVID-19.

Getting vaccinated can also help reduce the chances of new variants emerging, CDC says.

What is the BA.2 “stealth” Omicron variant of COVID-19?

The Omicron BA.2 variant is the latest COVID-19 to spread rapidly around the world. It has been called a “stealth” variant because it is not easily identified through PCR tests. BA.2 lacks a certain marker that sets it apart from other variants, including Delta.

Scientists believe specific mutations within the Omicron BA.2 variant make it more easily spread than other variants.

Even though some call BA.2 the “stealth” variant, it is known to be spreading rapidly around the world, including the United States.

Is the BA.2 subvariant of the Omicron variant in the United States?

The Omicron BA.2 variant is spreading throughout the United States. As of April 2022, it accounts for 72% of all new COVID-19 cases, according to CDC.

Research continues to show that COVID-19 vaccines are effective against Omicron variants, including BA.2. The vaccines not only prevent illness but also reduce the risk of severe or life-threatening symptoms.

What are some of the symptoms of BA.2 subvariant of the Omicron variant?

Symptoms of the Omicron BA.2 variant are similar to the primary COVID-19 virus and its variants. Omicron symptoms tend to be less severe in some – but not all – people.

The most reported symptoms are:

  • Runny nose
  • Headache
  • Fatigue
  • Sore throat
  • Fever
  • Coughing and sneezing
  • Shortness of breath
  • Muscle or body aches
  • Nausea or vomiting
  • Diarrhea

Early in the COVID-19 pandemic, loss of taste and smell was commonly reported as a symptom. However, for people who get one of the Omicron variants, loss of taste and smell is not as common, researchers say.

COVID-19 tends to run its course in 1-2 weeks.

What do we know about the Omicron XE variant so far?

The Omicron XE variant is a combination of the two previous Omicron strains, BA.1 and BA.2. It’s a recombinant variant. This means it contains genetic material from both BA.1 and BA.2. Recombinant variants are not unusual — they happen with many viruses. Most die off quickly.

Scientists believe Omicron XE formed when a person had both the BA.1 and BA.2 strains at the same time. The variant quickly started to spread.

Cases of the Omicron XE variant first emerged around the world starting in January 2022. As of April, cases remain rare.

Researchers continue to study if the Omicron XE variant spreads easily. Initial reports suggest it is at least as transmissible as BA.2. The World Health Organization (WHO) issued a report on April 5 saying Omicron XE was 10% more transmissible than BA.2.

COVID-19 vaccines remain the best defense against all Omicron variants including XE. In addition, monoclonal antibody treatments Paxlovid and molnupiravir should be effective against XE.

Find public locations where COVID-19 monoclonal antibody treatments are available.
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Should we be worried about the Omicron XE variant in the United States?

Anytime a new COVID-19 variant emerges and starts spreading is cause for concern.

However, it’s too soon to be concerned about the Omicron XE variant. Researchers continue to investigate the XE variant. They are examining how easily it spreads and the severity of its symptoms.

Some variants die out quickly and never spread. But if XE starts spreading and it’s proven to be more transmissible than other variants, it could take over as the dominant variant.

You should be well protected against any COVID-19 variant if you are vaccinated against COVID-19 and received booster shots. Studies show that people who are fully vaccinated and received boosters have strong protection against hospitalization from both BA.1 and BA.2.

It also may be advisable to wear a mask when in large groups, especially in indoor public spaces.

Are there any other variants?

COVID-19 is constantly evolving. Variants are a natural progression of any virus. Similar to the flu, there will likely be more variants to emerge as we learn to live with COVID-19. Whether they are severe or not remains to be seen.

CDC is always monitoring COVID-19 variants. Most of them are not a concern. At this time, the only two listed as “Variants of Concern” are:

  • Delta (B.1.617.2 and AY lineages)
  • Omicron (B.1.1.529 and BA lineages)

CDC has monitored other variants since the start of the COVID-19 pandemic. Other variants include Alpha, Beta, Gamma, Epsilon, Iota, Kappa, Zeta and Mu. None of these variants spread as significantly as Delta and Omicron. CDC continues to monitor them but they are not considered a concern anymore.


Reviewed by:
Bradley Chipps, MD, FACAAI, is a board-certified allergist and pediatric pulmonologist with Capital Allergy and Respiratory Disease Center in Sacramento, California. He earned his medical degree from University of Texas Medical Branch in Galveston in 1972. He is Past President of the American College of Allergy, Asthma and Immunology (ACAAI).

Purvi Parikh, MD, FACAAI, is an adult and pediatric allergist and immunologist at Allergy and Asthma Associates of Murray Hill in New York City. She is on faculty as Clinical Assistant Professor in both departments of Medicine and Pediatrics at New York University School of Medicine.