he Mu Covid strain has been added to the World Health Organisation’s “variants of interest” list.
The strain, also known as B.1.621, was added to the WHO’s watchlist on August 30.
Here’s what we know so far…
Where has the Mu variant been detected?
The strain was added to the WHO watchlist after being found in 39 countries.
It was first discovered in Colombia in January. Since then there have been cases reported in the UK, mainland Europe, the US and Hong Kong.
Globally, it makes up less than 0.1 per cent of Covid infections.
But it appears to be gaining ground in Colombia and Ecuador where it now accounts for 39 per cent and 13 per cent of coronavirus infections respectively.
At least 32 cases of the variant have been detected in the UK.
Is the Mu strain more contagious and does it cause more severe disease?
Scientists are investigating whether the Mu variant is more transmissible or whether it causes more serious disease.
It is still far less prominent than the Delta variant, which now makes up the majority of the world’s cases.
“The epidemiology of the Mu variant in South America, particularly with the co-circulation of the Delta variant, will be monitored for changes,” a WHO bulletin states.
Can it evade vaccines?
The Mu variant “has a constellation of mutations that indicate potential properties of immune escape”, according to the WHO.
Preliminary data suggests it could evade human immune defences in a similar way to the Beta variant, which was first discovered in South Africa.
However more investigations need to be done, the WHO said.
What is Public Health England saying about the Mu variant?
PHE released a risk assessment of the Mu variant in August. It refers to it as VUI-21JUL-01.
The report highlighted laboratory analysis that suggested the variant is at least as resistant as the Beta variant to vaccines.
However, the threat the Mu strain poses is still unclear and depends on whether cases grow.
The report states: “At present, there is no evidence that VUI-21JUL-01 is outcompeting the Delta variant and it appears unlikely that it is more transmissible.”
It adds: “Immune escape may contribute to future changes in growth.”