General information about COVID-19 variants

Please note the advice on self-isolation for close contacts has changed. Please see here for more information.

What is a ‘variant’ of COVID-19?

We know that all viruses naturally change over time, becoming slightly different ‘variants’ of the original virus. The virus that causes COVID-19 (SARS-CoV-2) is no different.

Over time, changes occur in the genetic code of the COVID-19 virus, which lead to ‘variants’ of COVID-19. Most of the time, these changes are so small that they don’t have a significant effect on the virus. However, some of these changes have the potential to make the virus more easily spread, cause more severe illness and affect protection from the COVID-19 vaccines.

Why might we be concerned about some variants of the COVID-19 virus?

Every so often a virus changes in a way that is concerning, for example, by allowing it to spread more quickly or easily from person to person.  In this instance, the variant may be called a ‘Variant of Concern (VOC)’ by the UK government, following review of the evidence by a team of specialists.

Scientists around the world have been monitoring and investigating new variants of COVID-19 closely throughout the pandemic. Most of the variants identified are not a cause for concern.

What is the difference between a Variant Under Investigation (VUI) and Variant Of Concern (VOC)?

New variants of COVID-19 are monitored closely. If variants of the COVID-19 virus are considered to be potentially concerning, for example, if it looks like they are spreading more easily, these variants are raised for formal investigation. At this stage they are called a ‘Variant Under Investigation (VUI)’ and given a code name, with a year, month, and number.  

Following expert investigation, the Variants Under Investigation (VUIs) may then be called Variants of Concern (VOC)

Total numbers and details of VUIs and VOCs detected in the UK are reported by Public Health England (PHE) and are available at:

What is the new Greek Alphabet naming system for variants recommended by the World Health Organisation?

The World Health Organization (WHO) on May 31, 2021, announced a new naming system for the COVID-19 variants.  Each variant of the virus that causes COVID-19 infection is now given a name from the Greek alphabet.  The Greek alphabet naming system of the variants of COVID-19 aims to simplify the discussion of variants and reduce the stigma around the origin country of new variants.  The existing scientific names, which convey important scientific information, will continue to be used in research.

If you have had the original strain of COVID-19 can you still catch a COVID-19?

At present we don’t know how long immunity from COVID-19 infection lasts, but it is possible to have COVID-19 infection more than once. Changes in the virus may affect the protection from previous COVID-19 infection or from the COVID-19 vaccines. Investigations are underway to find out more about the new variants. UK experts monitor ‘reinfections’ (people who have had confirmed COVID-19 twice or more) in the community, and through a large study of healthcare workers.

Do the current COVID-19 vaccines protect against variants?

Further investigation is being done to assess how variants affect the protection from the current COVID-19 vaccines. It is unlikely that variants will make the current COVID-19 vaccines not work at all, but the protection from the vaccine may be reduced. If required, future vaccines can be modified to make sure they protect against variants.

As we continue to monitor new variants remember that the best way to protect against the virus, and any variant, is to continue following the public health advice including practising social distancing, regularly washing your hands, and wearing face coverings where recommended.

If you have symptoms, self-isolate and take a test (these can be booked at, and get the COVID-19 vaccine if eligible either by booking online at or through your GP if you have received a letter from them advising you to book the COVID-19 vaccine.

Information on how variants are detected

How are ‘variants’ in the COVID-19 virus detected?

Because we know that all viruses change over time, laboratories in the UK have been set up to do extra tests to pick up changes and mutations in the genetic code of the COVID-19 virus. This is done in a similar way as for other viruses and bacteria, through a process known as ‘whole genome sequencing’. More samples are now undergoing this test than ever before.   

This test also allows us to monitor changes in the COVID-19 viruses over time, and to understand how the virus is behaving locally.  In the UK, these tests helped to identify a new variant first found in England in December 2020. 

Alerts have since been raised about other variants first seen in South Africa, Brazil, Japan, and India.  These have now been found in several other countries including the UK. More are likely to be identified in the coming months.

How are variants under investigation (VUI) or variant of concern (VOC) detected in Northern Ireland?

Samples testing positive for the virus that causes COVID-19 now undergo additional testing to check for variants in Northern Ireland.  This information allows us detect variants in Northern Ireland.

At present, people entering Northern Ireland are required to take two COVID-19 tests after arriving, even if they have no symptoms of COVID-19 (for further information on this, please see NI Direct).  A further test is done on any positive samples to check for COVID-19 variants. 

There are also currently restrictions on travel into Northern Ireland from ‘Red List’ countries (there are countries where there have been concerns in relation to new variants) in order to reduce the risk locally. People coming from ‘Red List’ countries also have to isolate in a dedicated hotel for 10 days to reduce the risk of spread, in addition to taking two COVID-19 tests. If these tests are positive, further testing is done to check for COVID-19 variants.

The ‘Red List’ for Northern Ireland is being kept under constant review and is being enforced in an effort to stop the spread of variants.  International travel advice can be found at

Advice for people who have tested positive for a variant under investigation (VUI) or variant of concern (VOC)


What happens if a variant under investigation (VUI) or variant of concern (VOC) is detected?

If testing shows that someone in Northern Ireland has a VUI or VOC, this will be followed up by the Public Health Agency (PHA).  Contact tracing is carried out by the PHA contact tracing service, including  clarifying if there is a recent travel history, and putting in place measures to reduce spread.

If I have been detected as having a variant strain of COVID-19, does my self-isolation period change?

No, if you have been confirmed as having a variant strain of COVID-19, your self-isolation period does not change. 

New variants can be passed from person to person, in the same way as the original COVID-19 virus. 

Strictly following the self-isolation advice will reduce the risk of any onward spread.

Current Variants of Concern


What do we know about the ‘alpha’ variant?

The variant now known as the ‘alpha’ variant (or VOC-20DEC-01; formerly VOC202012/01) was initially detected in December 2020.  Changes in this variant of the virus have resulted in it being able to spread more easily between people.  This was discovered after evidence showed infection rates in areas affected by this variant had increased faster than expected, despite the usual control measures being in place.  For this reason, the variant was allocated a ‘Variant of Concern’.

What do we know about the ‘beta’ variant?

The ‘beta’ variant was first identified in December 2020 and this has also been classified as a ‘variant of concern’ (also known as ‘VOC-20DEC-02’ (formerly VOC202012/02). It has been observed in a number of countries & remains a ‘variant of concern’ due to its potential to reduce the protection from previous COVID-19 infection or from the COVID-19 vaccines. The country of origin has been on NI’s ‘Red List’ & additional investigation & contact tracing is completed on anyone who is found to have this variant strain of COVID-19.

What do we know about the ‘gamma’ variant?

 The ‘gamma’ variant of concern was initially detected in January 2021  (also known as ‘VOC-21JAN-02’; formerly VOC202101/02).

This particular ‘variant of concern’ shares some of the same mutations seen in the beta variant  - ‘VOC-20DEC-02’. For this reason, additional investigations & monitoring are in place to ensure extensive follow up in all individuals who test positive for this variant. These measures may also include additional testing.

What do we know about the ‘delta’ variant?

On 1st April a variant called VUI-21APR-01 (B.1.617.1), was added as a variant under investigation (VUI).  Two similar variants were then discovered (VUI-21APR-02 and VUI-21APR-03) and these were also classified as variants under investigation on 27th April.  All of these variants remain under careful investigation.

On 6th May, the VUI-21APR-02 variant was reclassified as a Variant Of Concern (VOC) following a rise in cases and evidence of community spread in England. This variant is now known as the Delta variant (or VOC-21APR-02).  

Further research is ongoing with the aim of better understanding the impact of these variants.