In its weekly epidemiological bulletin on the evolution of the epidemic, the World Health Organization said that the variant – B.1621 according to the scientific nomenclature – has so far been classified as a “variable to follow”.

The World Health Organization specifies that the variant has mutations that could indicate a risk of “immune escape” (vaccine resistance), and stresses that more studies are needed to better understand its properties.

All viruses, including SARS-CoV-2 responsible for COVID-19, change over time. Most mutations have little or no effect on the characteristics of the virus.

However, some mutations can affect the characteristics and influence of the virus, for example, how easily it spreads, the severity of the disease it causes, or the effectiveness of vaccines, medicines, diagnostic tools or other social and public health measures.

The emergence of variables, at the end of 2020, increased risks to global public health, led the World Health Organization to characterize the variables to be monitored and the variables of importance, in order to prioritize surveillance and research activities at the global level.

The World Health Organization decided to name the variants that should be followed or interest in using the letters of the Greek alphabet, in order to avoid any stigma for a particular country and to make it easier for the general public to pronounce the names.

Currently, the World Health Organization considers four variables of concern, including alpha variables, present in 193 countries, and delta ones, present in 170 countries, while five other variables (including Mu) should be monitored.

The Mu type was first discovered in Colombia in January. It has since been reported in other South American countries and Europe.

“Although the global prevalence of the mu variant among the sequenced cases has decreased and is currently less than 0.1%, its prevalence in Colombia (39%) and Ecuador (13%) has increased steadily,” the WHO explained.