Variants of the Virus that Causes COVID-19


Top 5 Things You Should Know about Variants 

  1. On November 26, 2021, the World Health Organization (WHO) designated the variant B.1.1.529 a variant of concern and named it Omicron. On November 30, it was declared a variant of concern in the United States. Omicron is different from other variants because it has so many mutations. Some of these are concerning and may be associated with the ability to escape the immune system’s protection from vaccination or infection, and may allow the virus to spread faster from person to person. There is a lot that we do not yet know about Omicron. Researchers around the world are conducting studies to better understand many aspects of Omicron and will be sharing their findings as they become available. We will learn more information in the coming days and weeks.
  2. The most commonly identified variant in Virginia is the Delta variant. Since early October 2021, of the positive samples that have been tested to identify the variant, more than 99% have been Delta. Delta is much more contagious than previous variants and might be associated with more severe illness.
  3. COVID-19 vaccines available in the United States are effective at protecting people from severe illness, hospitalization and death from circulating variants of the COVID-19 virus. Boosters are now recommended for U.S. adults to maintain a high level of protection.
  4. Variants are expected. The more the COVID-19 virus circulates, the greater the chances that new mutations or variants can develop. Variants have been identified in Virginia throughout the course of the pandemic and are more common in our communities than the reported number of cases suggest. The best way to slow the emergence of new variants is to follow public health recommendations proven to reduce the spread of COVID-19.
  5. Public health recommendations to slow the spread of the virus that causes COVID-19 will also work to protect us from variants. Keep yourself and others safer by: 
    • Getting the COVID-19 vaccine if you are not yet vaccinated and getting a booster dose if you are eligible
      • Find your free COVID-19 vaccine and learn more at or call 877-VAX-IN-VA (877-829-4682)
    • Wearing a mask that covers your nose and mouth when you are around people not in your own household, both indoors and in crowded outdoor settings
    • Staying at least 6 feet apart from other people when possible 
    • Keeping away from large crowds and poorly ventilated spaces
    • Washing your hands often
    • Delaying travel if you are not fully vaccinated

About Viruses

COVID-19 is caused by a virus called SARS-CoV-2, which stands for Severe Acute Respiratory Syndrome Coronavirus 2. Viruses are unable to survive and produce more viral copies (replicate) on their own. They survive by infecting a new host that is able to be infected. After a new host is exposed to a virus, the virus infects the host’s cells. Once inside the host cells,  the virus takes over the cell’s machinery to produce more copies of the virus. This process of making new copies of a virus within a host cell is called viral replication. 

As these copies are made, mistakes can happen that cause the new copies of the virus to not be exact copies of the “parent” virus. These mistakes are called mutations. Mutations happen all the time and usually don’t result in big changes to the virus. Sometimes, mutations can happen that change the virus in such a way that they change how the virus functions, such as changes to how infectious the virus is (how easy it is to spread the virus to others), the type of illness it causes, or how our immune systems respond to the virus.

What are variants?

Viruses constantly change through mutation and new variants of a virus, that arise from these mutations, are expected to occur over time. Multiple variants of the virus that causes COVID-19 have been documented in the United States and globally during this pandemic. Sometimes new variants emerge and disappear. Occasionally, new variants emerge that can pass more easily from one person (or host) to another.

Learn more about what causes a virus to change in this World Health Organization (WHO) video:

As more people have been infected during the COVID-19 pandemic, more variants have been documented. Scientists continually monitor the virus that causes COVID-19 to look for changes to the virus over time. This helps us better understand how the virus is changing and if these changes might affect how the virus spreads (transmissibility), how sick you could get (disease severity), and how well viral tests, treatments, and vaccines might work on different versions (variants) of the virus. 

The best way to stop variants from developing in the first place is to stop the spread of the virus.


Variant Names

Variants have names so that scientists can communicate with one another about trends they see with certain viral lineages. These names can be pretty technical and specific and work well for scientific communications. In May 2021, a group of scientists and experts in communications met to discuss the names we use when communicating with non-scientific audiences about certain variants. They developed a naming system, using letters of the Greek Alphabet (such as Alpha, Beta, Gamma) that are considered to be easier to pronounce and reduce stigma that can develop when a variant is referred to by the country in which it was first identified. Not all variants have a Greek letter name, but ones that the World Health Organization is monitoring closely do. On this page, we mainly refer to variants by their Greek letter name (but we kept the scientific names too because some people find those helpful).

Why are some variants concerning?

A variant of the virus that causes COVID-19 is considered to be concerning when it increases the risk to human health. The risk to human health could be increased because a variant is able to: 

  • Spread more easily
  • Cause more severe illness
  • Escape the immune protection provided by available COVID-19 vaccines or by natural infection with the virus that causes COVID-19
  • Make viral tests less accurate
  • Make some treatments less effective

Scientists have a system to categorize variants based on how concerning they are to the U.S. population. 

  • Variants being monitored are variants for which there is evidence that they might be of concern, but they are either no longer detected or are circulating at very low levels in the U.S., and as such, they do not pose a significant risk to public health in the United States. There are currently ten variants being monitored. These are B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), B.1.427 and B.1.429 (Epsilon), B.1.525 (Eta), B.1.526 (Iota), B.1.617.1 (Kappa), B.1.617.3 (no WHO label), P.2 (Zeta), and B.1.621 and B.1.621.1 (Mu).
  • Variants of interest show some evidence that they might be of concern. There are currently no variants of interest for the United States. 
  • Variants of concern show evidence of being concerning. There are currently two variants of concern for the United States. These are Delta (B.1.617.2) and its sublineages and the newly recognized Omicron (B.1.1.529) variant. Both are discussed in more detail below
    • The World Health Organization (WHO) may classify certain variants in different categories because of the  impacts they are having in other countries. Because the importance of variants can differ by location, the U.S. classifications may differ from those of the WHO. 
  • Variants of high consequence show clear evidence of making our disease prevention measures or medical countermeasures less effective. This may include demonstrated failure of diagnostic tests, more severe clinical disease, and increased hospitalizations. There are currently no SARS-CoV-2 variants of high consequence.

For more information on these categories and variants in each category, visit CDC SARS-CoV-2 Variant Classifications and Definitions.

Why should you care?

Everyone should care about variants of concern because if they continue to spread in the United States, there could be another surge (large growth) in cases that could overwhelm our health care systems. This also means that the pandemic could go on longer and might require stronger public health measures to slow the spread. With more COVID-19 cases, there would also be more people who get severely ill and die. Severe infections caused by variants might also be harder for healthcare providers to treat. 

At this time, the evidence shows that available COVID-19 vaccines remain effective in protecting the American public from getting severely sick, being hospitalized, or dying from currently circulating variant strains of the virus that causes COVID-19. Every time a person is infected with the virus that causes COVID-19, there is a chance that the virus can mutate and a new variant can develop. There is a concern that with another variant, the COVID-19 vaccines might not work as well to prevent people from getting sick with COVID-19.

About Delta

The Delta variant is currently the only variant of concern in the United States.

WHO/CDC Label Name Pango Lineage Name Where First Detected Impact on Viral Spread Impact on Disease Severity Impact on Immune Protection  Impact on Antibody Therapy Impact on Diagnostic Tests
Delta B.1.617.2 India This variant spreads more easily and quickly than other variants. Delta is more than 2x as contagious as previous variants. 

Delta is, by far, the most common variant of SARS-CoV-2 in the U.S. and in Virginia.

Might be associated with an increased risk of serious illness or death Potential reduction of immune protection  offered by vaccination or natural infection, but this is being monitored.

Some “vaccine breakthrough infections,” meaning infections in fully vaccinated people occur, but most of these are mild.

Potential impact on some, but not all, monoclonal antibody therapies No real impact


About Omicron

On November 26, 2021, WHO designated the variant Omicron (B.1.1.529) a variant of concern and on November 30, 2021, Omicron was designated a variant of concern for the United States. Omicron has been identified in the United States, but has not yet been identified in Virginia. Omicron is different from previous variants because it has both a high number of mutations and an unusual combination of mutations. Some of these are concerning because they change the viral spike protein, a key part of the virus that our immune systems respond to. This could mean a decrease in the effectiveness of COVID-19 vaccines and certain monoclonal antibody treatments as well as a decrease in the protection provided after natural infection with previous variants. There is also a concern that Omicron may spread even more easily from person to person than the highly-transmissible Delta variant. There is a lot of information that we do not yet know about Omicron and its key features. Researchers around the world are conducting studies to better understand many aspects of Omicron and will continue to share the findings of these studies as they become available. We will learn more information in the coming days and weeks. 

Learn more from the WHO and the CDC about Omicron.

More About Variants

To see how commonly SARS-CoV-2 variants are being identified in the U.S. and where these variants are being identified, visit CDC’s COVID Data Tracker. To see where these variants are being identified in Virginia, visit VDH’s Variants Dashboard. To learn more about the Delta variant, visit the CDC’s Delta Variant: What We Know About the Science.

At this time, available diagnostic tests (that help us know if a person has the virus that causes COVID-19) are expected to detect existing viral variants. It is very likely that these variants are more common in our communities than the number of reported cases suggest. This is because not all COVID-19 positive samples are tested to see what variant type they are. It is important now, more than ever, that we all continue following public health recommendations to prevent the spread of COVID-19. Public health recommendations for stopping the spread of COVID-19 will work for all COVID-19 variants.

What are we doing in response to these variants?

  • Working with CDC and our laboratory partners to actively monitor for changes in the genetic material of the virus that causes COVID-19.
  • Tracking what is happening with the spread of these variants globally, within the U.S., and in Virginia.
  • Monitoring for any concerning changes in the epidemiologic pattern of the virus that causes COVID-19 in Virginia. 
  • Sharing information with healthcare providers and the public about variants.

How can you protect yourself and others?

Public health recommendations for stopping the spread of COVID-19 will work for all variants. For more information on how to protect yourself and others, visit our Prevention webpage.

Learn more about stopping the spread of COVID-19 variants in this WHO video:

For more information:

Page last updated: December 1, 2021