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Coronavirus USA: Where is the Mu variant from?

On 30 August the World Health Organization listed the Mu variant of covid-19 as a variant of interest. The strain was first seen in Colombia.

On 30 August the World Health Organization listed the Mu variant of covid-19 as a variant of interest. The strain was first seen in Colombia.
Denis BalibouseREUTERS

As the Delta variant continues to lead to a surge in covid-19 cases throughout the United States, the World Health Organization (WHO) has listed a new strain, Mu, as a “Variant of Interest.”

The US Centers for Disease Control and Prevention (CDC) has yet to classify Mu as a Variant of Interest within their own framework. However, as the WHO is a global organization, it typically classifying variants before other countries as they are focused on the impact variants have at a broad level not just in one specific country.

What do we know about the MU variant?

To date, very few studies have been completed to understand the Mu variant.

The WHO listed it as a Variant of Interest on 30 August after seeing that it was quickly “becoming increasingly prevalent in Colombia and Ecuador, and showed signs of possible resistance to vaccines.”

The mutations associated with the Mu variant were first identified in Colombia in January 2021, and it has now become the dominant strain in the country, with about 39% of infections related to the variant.

Since the Mu variant emerged in Colombia, the country has experienced two waves of infections, which are only now beginning to end.

Is the Mu variant more resistant to vaccines?

Read more about the covid-19 pandemic

At this point, the WHO does not know if the vaccines available are effective in preventing infection. However, the WHO did chose to list Mu as a Variant of Interest as it does have a “number of mutations that suggest it could be more resistant to vaccines.” But before it can be upgraded to the Variant of Concern status, more research into the new strain will need to be conducted.

What other countries have seen cases caused by the Mu strain?

Aside from Colombia and Ecuador where the Mu variant has or is emerging as the dominant strain, cases have been seen in the United States (2,605), Spain (473), and Mexico (357).

What are the different variant classifications for the WHO and the CDC?

Both the CDC and the WHO have two levels of variant categorization:

  • Variant of Interest relates to new strains that have mutations that could lead them to be more transmissible, resistant to treatments or vaccines, or could lead to a more severe case of covid-19. 

  •  Variant of Concern relates to statins that have been shown to have at least one of the following features, “Increase transmissibility or detrimental change in COVID-19 epidemiology; OR Increase in virulence or change in clinical disease presentation; OR Decrease ineffectiveness of public health and social measures or available diagnostics, vaccines, therapeutics.” 

The CDC also has left room for a third classification, Variant of High Consequence for those that are 
“Significantly reduced susceptibility to multiple Emergency Use Authorization (EUA) or approved therapeutics,” or are shown to evade testing and diagnostic tools, and can lead to more severe cases requiring hospitalization.

No variants have been listed under this categorization, which alarms some after seeing how quickly the Delta variant was able to rip through the United States.

For a variant to be classified as “high consequence,” a “notification to WHO under the International Health Regulations, reporting to CDC, an announcement of strategies to prevent or contain transmission, and recommendations to update treatments and vaccines,” would be required.