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21 June 2021: Editorial  

Editorial: Revised World Health Organization (WHO) Terminology for Variants of Concern and Variants of Interest of SARS-CoV-2

Dinah V. Parums

DOI: 10.12659/MSM.933622

Med Sci Monit 2021; 27:e933622



ABSTRACT: The global pandemic of coronavirus disease 2019 (COVID-19) has identified thousands of genome sequences of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). On 31st May 2021, the Virus Evolution Working Group of the World Health Organization (WHO) announced its recommendations for revised naming of SARS-CoV-2 variants of concern (VOCs) and variants of interest (VOIs). This new nomenclature system may improve infection monitoring, infection control, and sharing of research data on viral genomics and epidemiology. This Editorial aims to present an update on the current revised WHO terminology for the genomic VOCs and VOIs of SARS-CoV-2.

Keywords: COVID-19, Epidemiology, Viral Variant, nomenclature, Variant of Concern, Variant of Interest, Coronavirus Disease 2019, severe acute respiratory syndrome coronavirus 2, SARS-CoV-2, Editorial, COVID-19, Genomics, Pandemics, Phylogeny, Terminology as Topic, World Health Organization

The global pandemic of COVID-19 due to SARS-CoV-2 infection has identified thousands of genome sequences of the virus [1,2]. SARS-CoV-2 has a linear positive-sense RNA genome and continually adapts by random genome mutations as part of natural selection. Only a few SARS-CoV-2mutations may provide a selective advantage that may allow the virus to evade the host immune response or resist antiviral drugs, or increase transmissibility. In the past 18 months, there has been a lack of a coherent scheme for naming variants of concern (VOCs) and variants of interest (VOIs) of SARS-CoV-2. Three scientific nomenclature systems have been used to identify and track SARS-CoV-2 genotypes, including the Global Initiative on Sharing All Influenza Data (GISAID), Nextstrain, and Pango [3]. The most common scientific nomenclature has used the Pango virus nomenclature of active phylogenetic virus lineages based on the influenza virus naming system [3].

Since the beginning of the COVID-19 pandemic, the WHO COVID-19 Reference Laboratory Network has been tracking SARS-CoV-2 mutations, and in June 2020, the WHO Virus Evolution Working Group was established to monitor SARS-CoV-2 variants [4]. On 31st May 2021, the Virus Evolution Working Group of the World Health Organization (WHO) announced its recommendations for naming SARS-CoV-2 VOCs and VOIs [4–6].

A SARS-CoV-2 VOC shows increased transmissibility, more severe disease, a significant reduction in immune response from previous infection or vaccination, reduced treatment effectiveness, or reduced diagnostic detection (Table 1) [5,6]. A SARS-CoV-2 VOI has specific genetic markers predicted to affect viral transmission, diagnosis, treatment, or response to vaccines and may require increased public health measures (Table 2) [5]. The US Centers for Disease Control and Prevention (CDC) includes a third category of a variant of high consequence (VOHC) [7]. Although these variants await identification, a SARS-CoV-2 VOHC includes VOCS that have demonstrated diagnostic failure, reduction in vaccine effectiveness with vaccine breakthrough cases, and more severe clinical disease with increased hospitalizations [7].

The WHO continues to track new genomic variants of SARS-CoV-2 and determines when VOIs should be reclassified as VOCs [5,8]. An advantage of the new WHO nomenclature is that it is a simple and clear alternative to using geographical names that may stigmatize and are irrelevant to viral variants that are likely to become global and endemic [1,7]. A further advantage is that global surveillance monitoring and the assignment of VOCs may be improved by clarity in terminology [7,8]. Future variants will require other alphabets, as Greek letters may cause confusion when translated into other languages. Also, the WHO has now used ten of its 24 letters to describe four VOCs (Table 1) and six VOIs (Table 2), identified since December 2020 [5].


From 31st May 2021, the new system for naming and identifying more pathogenic or transmissible genomic variants of SARS-CoV-2 may benefit infection monitoring, infection control, and sharing global epidemiological research data.


1. World Health Organization (WHO): Genomic sequencing of SARS-CoV-2: a guide to implementation for maximum impact on public health January 8, 2021, Geneva, World Health Organization https://www.who.int/publications/i/item/9789240018440

2. Furuse Y, Genomic sequencing effort for SARS-CoV-2 by country during the pandemic: Int J Infect Dis, 2021; 103; 305-7

3. Rambaut A, Holmes EC, O’Toole Á, A dynamic nomenclature proposal for SARS-CoV-2 lineages to assist genomic epidemiology: Nat Microbiol, 2020; 5(11); 1403-7

4. World Health Organization (WHO): WHO announces simple, easy-to-say labels for SARS-CoV-2 Variants of Interest and Concern May 31, 2021 https://www.who.int/news/item/31-05-2021-who-announces-simple-easy-to-say-labels-for-sars-cov-2-variants-of-interest-and-concern

5. World Health Organization (WHO): Tracking SARS-CoV-2 Variants May 31, 2021 https://www.who.int/en/activities/tracking-SARS-CoV-2-variants/

6. Konings F, Perkins MD, Kuhn JH, SARS-CoV-2 Variants of Interest and Concern naming scheme conducive for global discourse: Nat Microbiol Jun 9, 2021, doi: 10.1038/s41564-021-0093-2-w [Online ahead of print]

7. Centers for Disease Control and Prevention (CDC): SARS-CoV-2 variant classifications and definitions June 10, 2021 https://www.cdc.gov/coronavirus/2019-ncov/variants/variant-info.html

8. Lauring AS, Hodcroft EB, Genetic variants of SARS-CoV-2 – What Do They Mean?: JAMA, 2021; 325(6); 529-31

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Medical Science Monitor eISSN: 1643-3750
Medical Science Monitor eISSN: 1643-3750