Understanding viral variants

What are viral variants?

When a virus enters the body, it invades human cells and replicates (makes more copies of itself). When a virus makes copies of itself, it sometimes changes a bit. These changes are called mutations. A virus that has mutated is referred to as a variant.1

What impact can viral variants have?

Mutations and variants are very normal for any virus. All viruses change over time – including the virus that causes COVID-19.2 Most of the time, variants don’t impact how a virus works, or its ability to cause infection and disease.1 Sometimes however, variants can:

  • make the virus spread more easily
  • affect how well a person responds to treatment for the virus
  • impact testing for the virus and how well it is picked-up
  • reduce the effect of vaccines against the virus
  • cause more severe illness from the virus.

A variant of concern is the name given to any variant of the COVID-19 virus (SARS-CoV-2) that behaves in any of the above ways.3

Some variants can also have positive public health effects such as reducing a virus’s ability to spread. Variants can also disappear over time. 

How can we protect against SARS-CoV-2 variants?

When a virus is circulating widely in a population, it will replicate more and the likelihood that variants will appear increases.1

The most effective way to stop more variants is to prevent the spread of COVID-19.1 Variants are seen more often when virus transmission levels are high, so we need to bring these levels down.

Current measures to reduce virus transmission work and will also curb the number of variants, including handwashing, good ventilation, physical distancing, mask wearing and preventative treatments, such as vaccines.

According to the World Health Organization (WHO), rolling out vaccines as quickly and widely as possible is also critical to protect people from the virus and the risk of new variants.1

What do we know about SARS-CoV-2 virus variants that cause        COVID-19?

Currently, there are four variants of concern as described by the WHO, which are labelled using letters of the Greek alphabet.4 These include the Alpha (first documented in the UK), Beta (first documented in South Africa), Gamma (first documented in Brazil) and Delta (first documented in India) variants.4 Each has mutations which are thought to make them infect people more easily than the predominant global strain of the virus. Early data also suggest that the Alpha (UK) variant is associated with an increased risk of death.3

Can vaccines protect against COVID-19 variants?

The current vaccines for COVID-19 were designed to give broad protection against the virus and offer some level of protection against different variants.1

In time, it is thought different vaccine tactics may be needed as new variants arise. This might include changing the vaccine dose, additional booster vaccinations, combination vaccines or adapting the vaccines themselves to target variants.


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1. The effect of virus variants on COVID-19 vaccines. Available at https://www.who.int/news-room/feature-stories/detail/the-effects-of-virus-variants-on-covid-19-vaccines. Last accessed May 2021.

2. SARS-CoV-2 Variant Classifications and Definitions. Available at https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/variant-surveillance/variant-info.html. Last accessed May 2021.

3. Iacobucci G. Covid-19: New UK variant may be linked to increased death rate, early data indicate. BMJ. 2021;372:n230. Available at https://doi.org/10.1136/bmj.n230. Last accessed May 2021.

4. Tracking SARS-CoV-2 variants. Available at https://www.who.int/en/activities/tracking-SARS-CoV-2-variants/. Last accessed June 2021.

Veeva ID: Z4-37097
Date of Preparation: October 2021