What is a variant?
We come into contact with viruses every day. They can cause common illnesses such as the common cold, flu, and COVID-19. But did you know that viruses naturally change over time (evolve)? When that happens, they can develop new properties.
A variant describes a virus that has changed in some way from its original version. For example, a coronavirus variant is a different form of the virus to the one that was originally identified (SARS-CoV-2).
Sometimes, the term variant is used to describe a virus that has evolved to infect humans, when it previously only infected animals. Swine flu and bird flu evolved in this way.
Recently, the first human case of a strain of swine flu (H1N2) made the news. This is the first time this strain of flu has been detected in a human in the UK. Research is ongoing into how this person was infected, and to assess the potential spread of this variant.
Why do variants exist?
For a virus to survive, it needs to make copies of itself so it can spread and infect other people. The virus does this by using the cells of the person it’s infected (the host). For example, when the rhinovirus (a common cold virus), enters your body, it uses tools (structures) in your cells to copy itself.
During this process, a virus may not make exact copies of itself, and ‘mutations’ can occur. These change the genetic makeup of the virus. When at least one mutation occurs, a new variant is produced.
What’s the difference between a strain and a variant?
The terms ‘strain’ and ‘variant’ are sometimes used to describe the same thing. But they’re slightly different.
Sometimes, a new variant has properties that are very different to the virus it evolved from. These properties can help establish the variant – this means that the variant can survive and continue to infect people.
Once a variant is established, it may be referred to as a strain, rather than a variant.
Why are variants important?
All viruses mutate because it helps them to survive. Most of the time, these mutations don’t have much of an effect. But sometimes, mutations can affect the properties of the virus, such as how:
- easily it spreads
- severe the disease it causes is
- easy it is to detect
- effective treatment is
- effective vaccination is
It’s because of these changes that you might hear about variants being discussed on the news, especially variants of SARS-CoV-2. The World Health Organization (WHO) tracks and names variants of concern to help experts prioritise monitoring and research of COVID-19.
As well as changing how the disease spreads, variants may make existing vaccines less effective. Vaccines train your immune system to recognise and remove certain viruses. But if the virus has changed a lot, your body might no longer be able to recognise it. Sometimes, vaccines need to be updated to be effective against new variants.
This is why annual flu vaccinations are available – the influenza virus (which causes flu) mutates regularly, and different strains can circulate each year. The previous year’s vaccine may not protect against the strains in a new season, so flu jabs are offered yearly. Even if the strain is the same, your immunity might need to be boosted every year.
What is a variant of concern?
A variant becomes a variant of concern when its changes can impact our health and wellbeing. This means it could spread more easily, cause more severe disease, or make current vaccines less effective. These changes could affect many people, which is why they’re monitored.
Various agencies, including WHO and the UK Health Security Agency, monitor which coronavirus variants are circulating.
Five different variants of concern have previously been identified for coronavirus:
You might have heard other names in the news, such as Eris and Pirola. These are also variants of coronavirus. Although they are not currently thought to be variants of concern, they’re being monitored. These variants are most closely related to the Omicron variant of coronavirus.
If you’re at higher risk of illness from flu or COVID-19, vaccination can help protect you and limit the spread of the virus. This is particularly important when there are variants of concern circulating, and in the winter months, when flu season begins.