A new strain of Covid-19 has been declared a Variant of Interest by the World Health Organisation.

The variant named Mu, or B.1.621, was first identified in Colombia earlier this year and has now been identified in South America and Europe.

What is known about the variant?

The WHO’s weekly bulletin on the pandemic explained that the variant has mutations which could make it more resistant to vaccines.

This was also the case with the Beta variant, first discovered in South Africa, but the WHO has said more studies will be needed to examine this new strain further.

The bulletin said: “Since its first identification in Colombia in January 2021, there have been a few sporadic reports of cases of the Mu variant and some larger outbreaks have been reported from other countries in South America and in Europe.

“Although the global prevalence of the Mu variant among sequenced cases has declined and is currently below 0.1 per cent, the prevalence in Colombia (39 per cent) and Ecuador (13 per cent) has consistently increased.

“The epidemiology of the Mu variant in South America, particularly with the co-circulation of the Delta variant, will be monitored for changes.”

What are variants of interest?

The Mu variant is the fifth VOI being monitored by the WHO, along with strains from Peru, the US and India.

These variants all have genetic changes that are predicted or known to affect the transmissibility of the virus, the disease severity and immunity.

The ability of these strains to spread more quickly, and potentially evade vaccines, means they pose an emerging risk to public health.

A variant is then categorised as a Variant of Concern (VOC) if it is deemed to pose a significant global health risk, meaning it is highly transmissible and public health and social measures are less effective against it.

There are four coronavirus VOCs currently being monitored by the WHO. These include:

  • The Alpha variant, first identified in Kent and now evident in 193 countries
  • The Beta, first identified in South Africa and now evident in 141 countries
  • The Gamma variant, first identified in Brazil and now evident in 91 countries
  • The Delta variant, first identified in India, and now evident in 170 countries

The emergence of the Mu strain comes after scientists warned this week that a Covid variant first identified in South Africa “could be more infectious” than all other mutations identified so far.

The C.1.2 strain was detected by scientists in South Africa in May this year and is thought to have the potential to evade coronavirus vaccines.

The variant has since been found in England, China, the Democratic Republic of the Congo, Mauritius, New Zealand, Portugal and Switzerland.

The C.1.2 strain has a mutation rate of around 41.8 mutations per year, according to experts at South Africa's National Institute for Communicable Diseases and the KwaZulu-Natal Research Innovation and Sequencing Platform.

This is almost double the current global mutation rate for any other coronavirus VOC that has been found to date.