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Variants of SARS-COV-2

4 December 2021 | Q&A

What are variants of SARS-COV-2, the virus that causes COVID-19?

It is normal for viruses to change and evolve as they spread between people over time. When these changes become significantly different from the original virus, they are known as “variants.” To identify variants, scientists map the genetic material of viruses (known as sequencing) and then look for differences between them to see if they have changed.

Since the SARS-CoV-2 virus, the virus that causes COVID-19, has been spreading globally, variants have emerged and been identified in many countries around the world.

What is the difference between a variant of interest and a variant of concern?

AA variant is considered a variant of interest if it has mutations that are suspected or known to cause significant changes, and is circulating widely (e.g., known to cause many clusters of infected people, or found in many countries). There are many variants of interest that WHO is continuing to monitor in case they become variants of concern.

A variant of interest becomes a variant of concern if it is known to spread more easily, cause more severe disease, escape the body’s immune response, change clinical presentation, or decrease effectiveness of known tools – such as public health measures, diagnostics, treatments and vaccines.

How do variants of SARS-CoV-2, the virus that causes COVID-19, get their names?

For the purpose of discussing variants in the media and the public, WHO began using the Greek alphabet in May of 2021 to make it easier for people to keep track of variants without linking their names to the places where they were first identified, as variants can emerge anywhere at any time.

In accordance with WHO best practices for naming new diseases, some letters may not be used if they cause confusion in major languages or stigmatize certain groups. These WHO labels do not replace the existing scientific names of the variants, which convey important scientific information to researchers and scientists.

What is the Omicron variant?

The Omicron variant, variant B.1.1.529, was first reported to WHO on 24 November 2021 and was classified as a variant of concern by WHO on 26 November 2021. The classification was made on the advice of the Technical Advisory Group on Virus Evolution, based primarily on information from South Africa that the variant has a large number of mutations and has caused a detrimental change in COVID-19 epidemiology.

What makes the Omicron variant different from other variants?

All variants are different. The Omicron variant has a large number of mutations which may mean the virus acts differently from other variants that are circulating.

As of 1 December 2021, there is limited information about Omicron.  Studies are ongoing to determine if there is a change in how easily the virus spreads or the severity of disease it causes, and if there are any impacts on protective measures.

It will likely take time before there will be clear evidence to determine if there is any change in the transmission of Omicron compared to other variants, how the variant responds to existing therapeutics, or whether infection or re-infection with Omicron causes more or less severe disease.

WHO is working with technical partners to understand the potential impact of Omicron on vaccine effectiveness. Currently, the Delta variant is dominant worldwide and COVID-19 vaccines are highly effective at protecting you from serious illness and death, including from infection with Delta. Researchers will assess the performance of current vaccines against Omicron and will communicate these findings as soon as they become available.

See the announcement and short video on the classification of the Omicron variant.

What is being done to understand more about the Omicron variant?

WHO continues to coordinate with a large number of researchers around the world to understand more about all variants of SARS-CoV-2, the virus that causes COVID-19, including Omicron. Many studies are needed, including assessments of:

  • Transmissibility, or ease of spread from person to person, of Omicron as compared to other variants
  • Severity of infection and re-infection with Omicron
  • Performance of current COVID-19 vaccines against Omicron
  • Performance of diagnostic tests, including antigen tests, to detect infection with Omicron
  • Effectiveness of current treatments for management of patients with COVID-19 disease

WHO’s Technical Advisory Group on Virus Evolution will continue to monitor and evaluate the data as it becomes available and assess if mutations in the Omicron variant alter the behaviour of the virus.

What is the Delta variant?

The Delta variant is a variant of concern classified by WHO on May 11, 2021 and is currently the dominant variant that is circulating globally.  Delta spreads more easily than earlier strains of the virus and is responsible for more cases and deaths worldwide.  All approved COVID-19 vaccines currently in use are safe and effective in preventing severe disease and death against the Delta variant.

What can I do to protect myself from variants?

To protect yourself and others from COVID-19 variants:

  • Keep a distance of at least 1 metre from others
  • Wear a well-fitted mask over your mouth and nose
  • Open windows
  • Cough or sneeze into a bent elbow or tissue
  • Clean your hands frequently
  • Get vaccinated, as soon as it is your turn

How can we stop new variants from emerging?

As with all viruses, SARS-COV-2, the virus that causes COVID-19, will continue to evolve as long as it continues to spread. The more that the virus spreads, the more pressure there is for the virus to change. So, the best way to prevent more variants from emerging is to stop the spread of the virus.

To protect yourself and others from COVID-19:

  • Keep a distance of at least 1 metre from others
  • Wear a well-fitted mask over your mouth and nose
  • Open windows
  • Cough or sneeze into a bent elbow or tissue
  • Clean your hands frequently
  • Get vaccinated as soon as it is your turn

Are the variants more likely to cause infection, disease and death in people who are already vaccinated?

We are still learning about the ways that variants impact vaccination.

The data we currently have available show us that COVID-19 vaccines are still very effective at preventing serious illness and death against all of the current variants of concern. It is important to note that the vaccines provide different levels of protection from infection, mild disease, severe disease, hospitalization and death.

No vaccine is 100% effective. Even though COVID-19 vaccines are highly effective at protecting you against serious illness and death, some people will still get ill from COVID-19 after vaccination. You could also pass the virus on to others who are not vaccinated. This makes it very important to continue to practice protective measures, even after you have been fully vaccinated.

It is more important than ever to get vaccinated as soon as it is your turn and continue to practice protective measures after vaccination.

What is the difference between a ‘mutation’ and a ‘variant’?

Viruses are constantly evolving and changing. Every time a virus replicates (makes copies of itself), there is the potential for there to be changes in its structure. Each of these changes is a “mutation.” A virus with one or more mutations is called a “variant” of the original virus. 

Some mutations can lead to changes in important characteristics of the virus, including characteristics that affect its ability to spread and/or its ability to cause more severe illness and death.