The World Health Organisation (WHO) has said it is monitoring a new coronavirus variant known as “Mu”, which was first identified in Colombia in January.

Mu, known scientifically as B.1.621, has been classified as a “variant of interest”, the global health body said on August 31 in its weekly pandemic bulletin.

The WHO said the variant has mutations that indicate a risk of resistance to vaccines and stressed that further studies were needed to better understand it. “The Mu variant has a constellation of mutations that indicate potential properties of immune escape.”

All viruses, including SARS-CoV-2 which causes Covid-19, mutate over time and most mutations have little or no effect on the properties of the virus.

But certain mutations can impact the properties of a virus and influence how easily it spreads, the severity of the disease it causes, and its resistance to vaccines, drugs and other countermeasures.

After being detected in Colombia, Mu has since been reported in other South American countries and in Europe.

The WHO said its global prevalence has declined to below 0.1 per cent among sequenced cases. In Colombia, however, it is at 39 per cent.