COVID-19 variants
All viruses change over time. Most changes have minimal or no impact on the properties of a virus. Some changes, however, may affect the ease of transmission of virus or the severity of the disease it causes, or the performance of vaccines, therapeutics, diagnostics or other public health and social measures.
During late 2020, the emergence of variants of SARS-CoV-2 that posed an increased risk to global public health prompted the characterisation of specific Variants of Interest (VOIs) and Variants of Concern (VOCs). These have been used prioritise global monitoring and research, and to inform the ongoing response to the COVID-19 pandemic.
As of 31 May 2021, the World Health Organisation (WHO) proposed labels for global SARS-CoV-2 Variants of Concern and Variants of Interest to be used alongside the scientific nomenclature.
Variants of Concern (VOC)
The WHO’s working definition:
A SARS-CoV-2 variant that meets the definition of a Variant of Interest (see below) and, through a comparative assessment, has been demonstrated to be associated with one or more of the following changes at a degree of global public health significance:
- Increase in transmissibility or detrimental change in COVID-19 epidemiology; or
- Increase in virulence or change in clinical disease presentation; or
- Decrease in effectiveness of public health and social measures or available diagnostics, vaccines, therapeutics.
Currently designated Variants of Concern:
WHO label |
Earliest documented |
Attributes |
Alpha | United Kingdom, September 2020 |
|
Beta | South Africa, May 2020 |
|
Gamma | Brazil, Nov 2020 |
|
Delta | India, October 2020 |
|
Omicron | Multiple countries, November 2021 |
|
Variants of Interest (VOI), and other variants
The WHO’s working definition:
A SARS-CoV-2 variant :
- with genetic changes that are predicted or known to affect virus characteristics such as transmissibility, disease severity, immune escape, diagnostic or therapeutic escape; AND
- Identified to cause significant community transmission or multiple COVID-19 clusters, in multiple countries with increasing relative prevalence alongside increasing number of cases over time, or other apparent epidemiological impacts to suggest an emerging risk to global public health.