You've heard of Alpha, Delta, and possibly even Lamda but this week a new covid variant is on the list of ones to watch - Mu.

The coronavirus strain, also known as B.1.621, has been classified as a variant of interest by the World Health Organisation. Here's why:

With most coronavirus restrictions now lifted and pupils returning to the classroom for the start of a new school year the number of covid cases being reported in England is being watched very closely as we move towards the autumn and winter.

But also being monitored, alongside the spread of currently our most prevalent Delta strain, is other variants of coronavirus that may pose a risk to both us and the success of the vaccination programme.

Earlier this week scientists at the WHO, within their latest report, confirmed that after a round of assessments it had taken the decision to watch strain B.1.621 more closely while also giving it the new WHO label name of Mu.

Why are scientists concerned?

According to the WHO report the Mu variant has a 'constellation of mutations that indicate potential properties of immune escape'.

This means that this particular Covid-19 strain may have the ability to infect someone who has already built up an immune response, either through receiving their coronavirus vaccines or as a result of already having had the virus.

The report added that further studies were now needed to better understand how resistant this strain is to vaccines or antibodies generated by a previous infection. The concerns are similar to those surrounding the Beta variant, which is also thought to have the ability to infect someone already carrying some element of protection against coronavirus.

Where did it originate?

Mu was first identified in Colombia in January of this year. Since then more than 4,000 cases have been reported across 39 countries worldwide.

While the numbers of cases connected to the Mu strain remain low globally, infection rates are gathering pace in South America says the WHO.

The prevalence of the strain in both Colombia and Equador is at the moment on the increase, says the report and scientists are now watching it closely, alongside it's 'co-circulation' with the highly transmissible Delta variant.

Is it in the UK?

There have been just under 50 cases of Mu recorded in the UK up until the end of August according to the latest figures from Public Health England. The majority of these are in England with just one or two scattered between Scotland, Wales and Northern Ireland. It is not clear whether those infected with the Mu variant picked up the virus as a result of international travel.

Is there cause for concern?

It is important to remember that all viruses over time mutate, something we have already seen with the emergence of the more contagious Delta coronavirus variant since late last year. And the number of cases of Mu currently remain low in this country.

But certain mutations can change the severity of the disease or its resistence to drugs or vaccines, and this is what experts want to monitor.

Mu is currently listed as a variant of interest but if it were to continue to cause concern for those monitoring the spread of the pandemic it would be elevated to a VOC or variant of concern like both the Alpha and Delta strains - with Delta currently the UK's most prevalent strain of coronavirus.

A list of variants being watched by Public Health England, and the number of cases being reported by each strain, is available to read here.

The government is also being encouraged to move ahead with a Covid booster campaign ahead of winter. Read the latest on that here.

For the latest coronavirus news and advice, click here.

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