Omicron Variant is here: What You Need to Know

Emergence of Omicron

On November 24, 2021, a new variant of SARS-CoV-2, B.1.1.529, was reported to the World Health Organization (WHO). This new variant was first detected in samples collected in Botswana on November 11, 2021, and in South Africa on November 14, 2021.

On November 26, 2021, WHO designated B.1.1.529 Omicron and classified it as a variant of concern (VOC). On November 30, 2021, the United States designated Omicron as a variant of concern, and on December 1, 2021, the first confirmed case of Omicron was detected in the United States.

CDC has been working with public health and industry partners around the world to learn more about Omicron and continue to track its progression. CDC has used genomic surveillance throughout the course of the pandemic to track variants of SARS-CoV-2, the virus that causes COVID-19, and to inform public health practice. We do not yet know how easily the virus spreads, how severe the disease it causes is, or how well available vaccines and drugs work against it.

Despite the increased attention to Omicron, Delta remains the main variant circulating in the United States.

Where was Omicron discovered in the United States?

CDC is working with state and local health departments to monitor the spread of Omicron. This map shows the states where at least one case of COVID-19 disease caused by the Omicron variant has been detected. Omicron will be included in variant surveillance data on CDC’s COVID Data Tracker as soon as incidence can be reliably estimated.

What we know about Omicron

Infection and spread

How easily does Omicron spread? The Omicron variant is likely to spread more easily than the original SARS-CoV-2 virus, and it is not yet known how easily Omicron spreads compared to Delta. The CDC assumes that anyone infected with Omicron can spread the virus to others, even if they are vaccinated or have no symptoms.
Will Omicron cause more severe illness? More data are needed to know whether Omicron infections, especially reinfections and breakthrough infections in people who are fully vaccinated, cause more severe illness or death than infections with other variants.
Are vaccines effective against Omicron? Current vaccines are expected to protect against severe illness, hospitalization, and death due to infections with the Omicron variant. However, breakthrough infections are likely in people who are fully vaccinated. For other variants, such as Delta, vaccines have been effective in preventing severe illness, hospitalizations, and deaths. The recent emergence of Omicron further underscores the importance of vaccination and boosters.
Will treatments work against Omicron? Scientists are working to determine how well existing treatments work against COVID-19. Because of Omicron’s altered genetic makeup, it is likely that some treatments will remain effective, while others may be less effective.

We have the tools to fight Omicron.

Vaccines remain the best public health measure to protect people from COVID-19, slow transmission, and reduce the likelihood of new variants emerging. COVID-19 vaccines are highly effective in preventing serious illness, hospitalizations, and deaths. Scientists are currently studying Omicron, including how well vaccinated people are protected from infections, hospitalizations, and deaths. CDC recommends that all persons 5 years of age and older protect themselves from COVID-19 by being fully vaccinated. CDC recommends that all persons 18 years of age and older receive a booster vaccination at least two months after receiving the first J&J/Janssen vaccine or six months after completing the first COVID-19 vaccination series from Pfizer-BioNTech or Moderna.

Masks provide protection against all variants. CDC continues to recommend wearing a mask indoors in public areas with significant or high community transmission, regardless of vaccination status. CDC offers advice on masks for individuals who want to learn more about what type of mask is right for them based on their circumstances.

Tests can be used to determine if you are currently infected with COVID-19. Two types of tests are used to detect current infection: Nucleic acid amplification tests (NAATs) and antigen tests. NAATs and antigen tests only tell you if you have a current infection. Individuals can use the COVID-19 virus testing tool to find out which type of test they should have. Additional testing is needed to determine if your infection is caused by Omicron. Visit your state, tribal, municipal, or territorial website for the latest local information on testing.

Self-tests can be done at home or any other location, are easy to use, and provide quick results. If your self-test shows a positive result, stay home or isolate yourself for 10 days, wear a mask if you have contact with others, and call your health care provider. If you have questions about your self-test result, contact your health care provider or the health department.

Until we know more about the risk of Omicron, it is important to use all available resources to protect yourself and others.

What CDC is doing to learn more about Omicron
Characteristics of the virus

CDC scientists are working with partners to collect data and virus samples that can be studied to answer important questions about the Omicron variant. Scientific experiments have already begun. CDC will provide updates as soon as possible.

Variant Surveillance

In the United States, CDC is using genomic surveillance to track variants of SARS-CoV-2, the virus that causes COVID-19, to more quickly identify and respond to these findings to best protect public health. CDC has created several opportunities to link and share genomic sequence data produced by CDC, public health laboratories, and commercial diagnostic laboratories with publicly available databases maintained by the National Center for Biotechnology Informationexternal symbol (NCBI) and the Global Initiative on Sharing Avian Influenza Dataexternal symbol (GISAID). CDC’s national genomic surveillance can detect a variant circulating at a frequency of 0.1% with 99% statistical confidence.

Last updated December 4, 2021Content source: National Center for Immunization and Respiratory Diseases (NCIRD), Division of Viral Diseases.