The World Health Organisation says it is monitoring a new COVID-19 “variant of interest” named Mu (also known by its scientific name as B.1.621).
In its weekly epidemiological update, published on Tuesday, WHO warned that the variant was becoming increasingly prevalent in Colombia and Ecuador, showing signs of possible vaccine resistance.
Mu was first identified in Colombia in January 2021, and since then, there had been “sporadic reports” of cases and outbreaks in South America and Europe, WHO said.
While the global prevalence of Mu among sequenced COVID-19 cases is below 0.1 per cent, its prevalence has consistently increased in Colombia and Ecuador, where it is now responsible for around 39 per cent and 13 per cent of infections, respectively.
Reports on the variant’s prevalence should be interpreted with due consideration given to the low sequencing capacity of most countries, the agency said.
Mu is the fifth variant of interest to be monitored by the WHO since March.
The health agency warned that Mu had several mutations suggesting it could be more resistant to vaccines, stressing further research to confirm the position.
Preliminary data showed reduced effectiveness of vaccines “similar to that seen for the Beta variant.”
The WHO explained that it would be monitoring “the epidemiology of the Mu variant in South America, particularly with the co-circulation of the Delta variant 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, had been designated as Mu in the past four weeks.
Meanwhile, according to a WHO report on Wednesday, the novel coronavirus pandemic has killed at least 124,811 people in Colombia.
More than 4,905,258 confirmed cases have been officially diagnosed across the country since the start of the pandemic. As of August 27, 34,247,170 doses of vaccine had been administered.
News reports from South Africa said scientists were closely monitoring the development of another new variant there.
However, C.1.2 is not yet a variant to follow, nor a variant of concern, according to the classification of WHO.
“It does not appear that its circulation is increasing,” said Margaret Harris, a spokesperson for the WHO, at a UN press briefing in Geneva on Tuesday.