The Mu Covid-19 variant: What is it and why is it of interest now?
A new coronavirus variant known as “Mu” is being closely monitored, after outbreaks of the variants emerged in Colombia and Japan recently confirmed its first two cases in people arriving from abroad.
Here is more information on the variant.
What is it?
The World Health Organisation (WHO) on Tuesday (Aug 31) said it was monitoring a new Covid-19 variant known as “Mu”. Classified as a “variant of interest” (VOI), the WHO has warned that the variant has shown signs of possible resistance to vaccines and is monitoring it closely.
The Mu variant, also known scientifically as B1621, was first identified in Colombia in January this year, and has a “constellation of mutations that indicate potential properties of immune escape”, noted a WHO weekly update published on Aug 31.
Where has it emerged?
While over 4,500 sequences of the variant have emerged in at least 40 countries, the update said that its prevalence has declined. However, the variants’ prevalence in Colombia (39 per cent of cases) and Ecuador (13 per cent) has consistently increased.
Japan on Wednesday (Sept 1) confirmed its first cases of the variant in two travellers from Britain and the United Arab Emirates, said The Japan Times. According to a variant tracker by GISAID, two cases have also been found in Hong Kong, as well as more than 2,000 in the United States. Cases have also been reported in Britain and various European countries.
What is a variant of interest?
The WHO’s variant of interest designation suggests that the strain has genetic changes that may affect virus characteristics, such as increased transmissibility, disease severity, immune escape, diagnostic or therapeutic escape.
VOIs have also been identified to cause significant community transmission or multiple Covid-19 clusters in multiple countries. Other VOIs named by the WHO include Eta, Iota, Kappa and Lambda.
Is the variant more contagious? How does it fare against existing vaccines?
Preliminary data shows that Mu may more easily evade vaccine protection, similar to that seen for the Beta variant. According to The Guardian, a risk assessment released by Public Health England last month suggests the variant is at least as resistant as the Beta variant to immunity, but is unlikely to become more transmissible than the Delta variant.
However, further studies are needed to know more about the variant’s characteristics and the WHO update noted that Mu’s epidemiology will be monitored for changes.
A study published in The Lancet Infectious Diseases on Aug 13 suggests that the Mu variant has “two cases of a potential vaccine-escape” and noted that several of the spike mutations within Mu “have been reported to show reduced neutralisation by antibodies”. It added that the strain’s presence of mutations associated with vaccine escape may warrant a reclassification of Mu to a variant of concern.
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