Mu Covid-19 Variant: 10 Things That We Know About The Latest WHO ‘Variant Of Interest’

WHO says the Mu variant could be more vaccine-resistant. No Covid case of the Mu variant has been detected in India yet

New Delhi: The World Health Organization (WHO) has identified yet another ‘variant of interest’ — Mu or B.1.621. This was first detected in South America’s Colombia in January 2021, and it currently has the highest prevalence in Colombia, according to reports.

According to the WHO, a ‘variant of interest’ is one that has genetic changes that affect the characteristics of the virus — transmissibility, disease severity, immune escape etc for example. 

A ‘variant of interest’ is also identified as one that causes significant community transmission in multiple countries “with increasing relative prevalence alongside an increasing number of cases over time” suggesting an emerging risk to global public health, the WHO says.  

A ‘variant of interest’ is different from a ‘variant of concern’ that is more alarming in nature. WHO has four designated ‘variants of concern’ as of now — Alpha, Beta, Gamma, and Delta.

Mu was designated as a ‘variant of interest’ on August 30, after it was detected in 39 countries, the WHO said in its weekly bulletin.

There have been “sporadic reports” of cases and also some larger outbreaks in South America and Europe since January 2021, when it was first detected, the UN health agency said.

The US now has the most cases as far as absolute numbers are concerned. Dr Anthony Fauci, White House chief medical adviser, however, has said it is not an immediate threat.

Here is what we know about the Mu variant so far.

1. The global prevalence of Mu is below 0.1%, but its prevalence has “consistently increased” in Colombia and Ecuador, the WHO said. The Mu variant is now responsible for around 39% and 13% of the infections, respectively, in the two countries. 

2. The scientific name of Mu is B.1.621.

3. Fifth variant of interest to be monitored by WHO since March, Mu has a number of mutations that suggest it could be more resistant to vaccines. The WHO, however, said this needs to be confirmed with further research.

4. According to WHO, preliminary data show reduced effectiveness of vaccines on the Mu variant, “similar to that seen for the Beta variant”. 

5. The WHO assessment said the Mu variant was found to possess a “constellation of mutations that indicate potential properties of immune escape”.

6. As of 29 August, over 4,500 genome sequences have been designated as Mu in the past four weeks. Most of these cases have been reported in the US (2,065), followed by Colombia (852), Mexico (357), and Spain (473).

7. Mu cases have also been reported in the UK, Europe, and Hong Kong.

8. Public Health England added the Mu variant to its list of variants under investigation in July.

9. No Covid case of the Mu variant has been detected in India yet.

10. WHO said the epidemiology of the Mu variant in South America, particularly with the co-circulation of Delta, will be monitored to understand its characteristics.