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Understanding Variants

Understanding Variants

Alpha, Beta, Gamma, Delta – and now Lambda: COVID-19 variants are in the news and a cause for concern. But what are variants, and will approved vaccines and other countermeasures continue to protect us?

All viruses change over time. Most of the time, these changes have little impact, but sometimes these changes affect the virus’ properties, including how easily it spreads, its severity, and how therapeutic and vaccine measures work against it.

WHO, in association with partners and international networks of experts, monitors the evolution of the SARS-CoV-2 virus (the virus that causes COVID-19).

WHO has two key classifications for variants: Variants of Interest (VOIs) and Variants of Concern (VOCs). These classifications inform ongoing local and international response to the COVID-19 pandemic. Individual national authorities may also designate variants of local concern and interest.

Public Health and Social Measures (PHSMs) have been effective in reducing COVID-19 cases, hospitalisations and deaths. Authorities continue to increase capacity so as to be able to conduct surveillance and sequence the virus to detect unusual events

SARS-CoV-2 Variants are named using letters of the Greek Alphabet.

What is a Variant of Concern?

To be classified as a variant of concern, the variant must 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
  •         Increase in virulence, or change in clinical disease presentation
  •         Decrease in effectiveness of public health and social measures, or available diagnostics, vaccines, and/or therapeutics

What are the current Variants of Concern?

Alpha (B.1.1.7) – Emerged in the United Kingdom in September 2020. It was designated a VOC on 18 December, 2020

Beta (B.1.351; B.1.351.2; B.1.351.3) – Emerged in South Africa in May 2020. It was designated a VOC on 18 December 2020

Gamma (P.1; P.1.1; P.1.2) – Emerged in Brazil in November 2020. It was designated a VOC on 11 January, 2021

Delta (B.1.617.2; AY.1; AY.2) – Emerged in India in October 2020. It was designated a VOI on 4 April, 2021. It was designated as a VOC on 11 May, 2021

What are the primary actions by WHO and Member States when a potential VOC is identified?

When a potential VOS is identified, WHO and international parties and members states engage in a series of actions to get ahead of the problem.

  •         WHO and the Technical Advisory Group on Viral Evolution compare assessment of variant characteristics and public health risks
  •         If determined to be necessary, they coordinate additional investigations with Member States and partners
  •         They communicate the new designations and findings with Members States and the public
  •         They evaluate and update WHO guidance through existing channels

When the VOC is identified WHO and international parties:

  • Submit complete genome sequences and associated metadata to a publicly available database, such as GISAID.
  • Report initial cases/clusters associated with VOC infection to WHO through the IHR mechanism.
  • Perform field investigations and laboratory assessments to improve understanding of the potential impacts of the VOC on COVID-19 epidemiology, severity, and effectiveness of PHSMs, diagnostic methods, immune responses, antibody neutralisation and other relevant characteristics.


What is a Variant of Interest (VOI)?

A SARS-Co-V-2 variant is defined when

  •         It shows genetic changes that are predicted, or known, to affect the virus’ characteristics (e.g. transmissibility, disease severity, immune escape, diagnostic or therapeutic escape
  •         Is identified to cause significant community transmission, or multiple COVID-19 clusters in multiple countries with increasing relative prevalence as well as increasing numbers of cases over time, or other apparent epidemiological impacts that suggest an emerging risk.

What are the Current VOIs?

Eta (B.1.525) – Identified in multiple countries in December 2020. Designated as a VOI on 17 March, 2021

Iota (B.1.526) – Identified in the USA in November 2020. Designated a VOI on 24 March, 2021

Kappa (B.1.617.1) – Identified in India in October 2020. Designated a VOI on 4 April, 2021

Lambda (C.37) – Identified in Peru in December 2020. Designated a VO on 14 June, 2021

What does WHO do when a VOI is identified?

  •         The identifying nation informs WHO through established channels
  •         They submit a complete genome sequence and associated metadata to publically available database, like GISAID
  •         Perform field investigations to improve the understanding of the potential impacts
  •         Perform laboratory assessments on the VOI’s impact on relevant tops

What does WHO do when a potential VOI is identified?

  •         WHO conducts a comparative assessment of variant characteristics and public health risks
  •         If necessary, laboratory investigations are coordinated with Member States and partners
  •         Global epidemiology of the VOI is reviewed
  •         The global spread of the VOI is monitored and tracked.


VOIs and VOCs may be reclassified once it is conclusively demonstrated to no longer pose a major risk to global public health. This is done by WHO in collaboration with the Technical Advisory Group on Virus Evolution using several criteria.

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