Emergence of Omicron
CDC is working with state and local public health officials to monitor the spread of Omicron. As of December 20, 2021, Omicron has been detected in most states and territories and is rapidly increasing the proportion of COVID-19 cases it is causing.
CDC has been using genomic surveillance throughout the course of the pandemic to track variants of SARS-CoV-2, the virus that causes COVID-19, and inform public health practice.
- 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 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.
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 at preventing severe illness, hospitalizations, and death.
- Scientists are currently investigating Omicron, including how protected fully vaccinated people will be against infection, hospitalization, and death.
- CDC recommends that everyone 5 years and older protect themselves from COVID-19 by getting fully vaccinated.
- CDC recommends that everyone ages 18 years and older should get a booster shot at least two months after their initial J&J/Janssen vaccine or six months after completing their primary COVID-19 vaccination series of Pfizer-BioNTech or Moderna.