The preliminary data shows it may evade immune defences in a similar way to the Beta variant first discovered in South Africa, the UN agency said, adding that this needs to be confirmed by further work.

“More studies are required to understand the phenotypic and clinical characteristics of this variant, it said, adding that the epidemiology of the Mu variant in South America, particularly with the co-circulation of the Delta variant, will be monitored for changes.

As of August 29, over 4,500 sequences (3,794 B.1.621 sequences and 856 B.1.621.1 sequences), genome sequences, analysed samples of the virus taken from patients, have been designated as Mu in the past four weeks. The sequences are used to track how it moves through the population, on an open-source genome repository, known as GISAID.

Most of these have been reported in the U.S (2,065) and Colombia (852), Mexico (357) and Spain (473).

Meanwhile, South African scientists are closely monitoring the development of another new variant there.

Scientists from National Institute for Communicable Diseases (NICD) and the KwaZulu-Natal Research Innovation and Sequencing Platform (KRISP) in South Africa said the potential variant of interest, C.1.2, was first detected in the country in May this year.