What You Need to Know about Omicron

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 most states and territories 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 still learning about how easily it spreads, the severity of illness it causes, and how well available vaccines and medications work against it.

Spread

The Omicron variant spreads more easily than the original virus that causes COVID-19 and the Delta variant. CDC expects that anyone with Omicron infection can spread the virus to others, even if they are vaccinated or don’t have symptoms.

Symptoms

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.

Severe Illness

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, the large volume of cases could overwhelm the healthcare system which is why it’s important to take steps to protect yourself.

Vaccines

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.

Scientists are still learning how effective COVID-19 vaccines are at preventing infection from Omicron. Current vaccines are expected to protect against severe illness, hospitalizations, and deaths due to infection with the Omicron variant. However, breakthrough infections in people who are vaccinated are likely to 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.

Treatments

Scientists are working to determine how well existing treatments for COVID-19 work. Some, but not all, 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

Vaccines

Getting vaccinated and staying up to date with COVID-19 vaccines is the best way to protect yourself and others against the Omicron variant.

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.

Masks

Well-fitting masks offer protection against all variants.

Wear a mask with the best fit, protection, and comfort for you.
If you are not up to date with your COVID-19 vaccines and are aged 2 or older, you should wear a mask indoors in public.
In general, people do not need to wear masks when outdoors. In areas of substantial or high transmission, people might choose to wear a mask outdoors when in sustained close contact with other people, particularly if
- They or someone they live with has a weakened immune system or is at increased risk for severe disease.
- They are not up to date on COVID-19 vaccines or live with someone who is not up to date on COVID-19 vaccines.

Testing

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 the 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

Virus Characteristics

CDC scientists are working with partners to gather data and virus samples that can be studied to answer important questions about the Omicron variant. Scientific experiments are ongoing. CDC will provide updates as new information becomes available.

Variant Surveillance

In the United States, CDC uses 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 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.

Emergence of Omicron

CDC has been using 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.

Last Updated Feb. 2, 2022

Content source: National Center for Immunization and Respiratory Diseases (NCIRD), Division of Viral Diseases