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  
samples 

Attributes
Alpha United Kingdom,  
September 2020
  • ~50% increased transmission
  • Potential increased severity based on hospitalizations and case fatality rates
  • No impact on susceptibility to monoclonal antibody treatments
  • Minimal impact on neutralization by convalescent and post-vaccination sera
Beta South Africa,  
May 2020 
  • ~50% increased transmission
  • Significantly reduced susceptibility to the combination of bamlanivimab and etesevimab monoclonal antibody treatment; other EUA monoclonal antibody treatments are available
  • Reduced neutralization by convalescent and post-vaccination sera
Gamma Brazil,  
Nov 2020
  • Significantly reduced susceptibility to the combination of bamlanivimab and etesevimab monoclonal antibody treatment; other EUA monoclonal antibody treatments are available 
  • Reduced neutralization by convalescent and post-vaccination sera
Delta India,  
October 2020
  • Increased transmissibility 
  • Potential reduction in neutralization by some monoclonal antibody treatments 
  • Potential reduction in neutralization by post-vaccination sera
Omicron Multiple countries, November 2021
  • Increased transmissibility 

 

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.