Omicron Variant: What You Need to Know
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Omicron in the United States
CDC is working with state and local public health officials to monitor the spread of Omicron. As of December 20, 2021, Omicron had been detected in every U.S. state and territory and continues to be the dominant variant in the United States.
What We Know about Omicron
CDC has been collaborating with global public health and industry partners to learn about Omicron, as we continue to monitor its course. We are continuing to evaluate how easily it spreads, the severity of illness it causes, and how well available vaccines and medications work against it.
The Omicron variant, like other variants, is comprised of a number of lineages and sublineages. The three most common lineages of Omicron currently are BA.1, BA.1.1 and BA.2.
The Omicron variant spreads more easily than earlier variants of the virus that cause COVID-19, including the Delta variant. CDC expects that anyone with Omicron infection, regardless of vaccination status or whether or not they have symptoms, can spread the virus to others.
Persons infected with the Omicron variant can present with symptoms similar to previous variants. The presence and severity of symptoms can be affected by COVID-19 vaccination status, the presence of other health conditions, age, and history of prior infection.
Omicron infection generally causes less severe disease than infection with prior variants. Preliminary data suggest that Omicron may cause more mild disease, although some people may still have severe disease, need hospitalization, and could die from the infection with this variant. Even if only a small percentage of people with Omicron infection need hospitalization, a large volume of cases in a community could overwhelm the healthcare system which is why it’s important to take steps to protect yourself.
COVID-19 vaccines remain the best public health measure to protect people from COVID-19 and reduce the likelihood of new variants emerging. This includes primary series, booster shots, and additional doses for those who need them.
Current vaccines protect against severe illness, hospitalizations, and deaths due to infection with the Omicron variant. However, breakthrough infections in people who are vaccinated can occur. People who are up to date with their COVID-19 vaccines and get COVID-19 are less likely to develop serious illness than those who are unvaccinated and get COVID-19.
Scientists are working to determine how well existing treatments for COVID-19 work. Some monoclonal antibody treatments are less effective against Omicron’s BA.2 lineage, but continue to work against BA.1 and BA.1.1 lineages. Other non-monoclonal antibody treatments remain effective against Omicron. Public health agencies work with healthcare providers to ensure that effective treatments are used appropriately to treat patients.
We have the Tools to Fight Omicron
- CDC recommends that everyone 5 years and older protect themselves from COVID-19 by getting vaccinated. Everyone ages 12 years and older should stay up to date on their COVID-19 vaccines and get a booster shot when eligible.
Find a COVID-19 vaccine or booster: Search vaccines.gov, text your ZIP code to 438829, or call 1-800-232-0233 to find locations near you.
Well-fitting masks offer protection against all variants.
- In general, people do not need to wear masks when outdoors.
- If you are sick and need to be around others, or are caring for someone who has COVID-19, wear a mask.
- If the COVID-19 Community Level where you live is
- Wear a mask based on your personal preference, informed by your personal level of risk.
- If you are at risk for severe illness, talk to your healthcare provider about wearing masks indoors in public.
- If you live with or will gather with someone at risk for severe illness, wear a mask when indoors with them.
- If you are 2 or older, wear a well-fitting mask indoors in public, regardless of vaccination status or individual risk (including in K-12 schools and other community settings).
- If you are at risk for severe illness, wear a mask or respirator that provides you with greater protection.
Tests can tell you if you have COVID-19. Learn how to get tested.
- Two types of tests are used to test for current infection: nucleic acid amplification tests (NAATs) and antigen tests. NAAT and antigen tests can tell you if you have a current infection.
- Self-tests can be used at home or anywhere, are easy to use, and produce rapid results.
- If your self-test has a positive result, isolate and talk to your healthcare provider.
- If you have any questions about your self-test result, call your healthcare provider or public health department.
Individuals can use CDC’s COVID-19 Viral Testing Tool to help determine what kind of test to seek.
Your test result will only tell you if you do or do not have COVID-19. It will not tell you which variant caused your infection. Visit your state, tribal, local, or territorial health department’s website for the latest local information on testing.
It is important to use all tools available to protect yourself and others.
What CDC is Doing to Learn about Omicron
CDC scientists are working with partners to study data and virus samples that may answer important questions about the Omicron variant. CDC will provide updates as new information becomes available.
In the United States, CDC uses viral genomic surveillance to track COVID-19 variants, to more quickly identify and act upon these findings to best protect the public’s health. CDC established multiple ways to connect and share viral genomic sequence data being produced by CDC, public health laboratories, and commercial diagnostic laboratories within publicly accessible databases maintained by the National Center for Biotechnology Informationexternal icon (NCBI) and the Global Initiative on Sharing Avian Influenza Dataexternal icon (GISAID). Findings from CDC’s variant surveillance are updated on CDC’s COVID Data Tracker.
On November 24, 2021, South Africa reported the identification of a new COVID-19 variant, B.1.1.529, to the World Health Organization (WHO). B.1.1.529 was first detected in specimens collected on November 11, 2021 in Botswana and on November 14, 2021 in South Africa.
Emergence of Omicron
CDC has been using viral genomic surveillance throughout the course of the pandemic to track COVID-19 variants, and inform public health practice.
- November 24, 2021: A new variant of COVID-19, B.1.1.529, was reported to the World Health Organization (WHO). This new variant was first detected in specimens collected on November 11, 2021 in Botswana and on November 14, 2021 in South Africa.
- November 26, 2021: WHO named the B.1.1.529 Omicron and classified it as a Variant of Concern (VOC).
- November 30, 2021: The United States designated Omicron as a Variant of Concern.
- December 1, 2021: The first confirmed U.S. case of Omicron was identified.
- December 21, 2021: BA.2 was first identified in the United States from a sample collected on December 14, 2021, in New Jersey.