What you need to know right now about the COVID-19 Omicron variant


An update from infectious disease expert, Rana F. Hamdy, MD, on the Omicron variant of COVID-19.

On November 26, 2021, the World Health Organization (WHO) designated the B.1.1.529 variant a variant of concern (VOC), and assigned its name the Greek letter Omicron.

The B.1.1.529 variant, which was first reported to the WHO from South Africa on November 24, 2021, with the first case reported in the United States (California) on December 1, 2021, contains around 50 mutations, of which more than 30 are in the spike protein of the SARS-CoV-2 virus. These include some of the mutations also found in the Delta and Alpha variants which have been linked to increased transmissibility. A sharp rise in cases of SARS-CoV-2 over the last 2 weeks of November 2021 in South Africa, specifically in the Gauteng province, raise concern because of 1)the rapidity with which number of daily cases is increasing is a faster rate than with any of the past 3 waves experienced in South Africa, and 2)the rapidity with which the B.1.1.529 variant took to represent the majority of SARS-CoV-2 cases (accounting for 90% of SARS-CoV-2 cases in just 2 weeks, compared to the 3 months it took for the Delta variant to become the predominant variant during the previous wave). These epidemiologic data support the concern for increased transmissibility of this variant compared to previous VOCs.

As of December 1, the Omicron variant has been detected in 20 countries around the world, including the United States. Studies are underway to understand if this variant is associated with a different severity of disease compared to other SARS-CoV-2 variants. Anecdotes from clinicians in South Africa do not suggest increased severity of disease, but additional information is needed. Studies are also underway to understand the effectiveness of current vaccines in protecting against the Omicron variant. The mutations in the B.1.1.529 variant are not impacted by the currently used PCR test, so ability to detect infection with this variant are not expected to be impacted.


1. World Health Organization, News. Accessed November 30, 2021, Available at: https://www.who.int/news/item/26-11-2021-classification-of-omicron-(b.1.1.529)-sars-cov-2-variant-of-concern

2. Nature News. 25 November 2021. Heavily mutated Omicron variant puts scientists on alert. Accessed November 30, 2021. Available at: https://www.nature.com/articles/d41586-021-03552-w

3. COVID-19 Statistics for Republic of South Africa. National Institute for Communicable Diseases. Latest Confirmed Cases of COVID-19 in South Africa (30 November 2021). Available at: https://www.nicd.ac.za/latest-confirmed-cases-of-covid-19-in-south-africa-30-november-2021/

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