The World Health Organization (WHO) on Wednesday classified a coronavirus strain called Mu, which was first identified in Colombia in January, as a "variant of interest."
The WHO said in its weekly Covid-19 epidemiological report that there were indications Mu's mutations enable it to evade antibodies in vaccinated or recovered people even better than other variants.
But it said more studies were needed on the variant also known as B.1.621 to definitively prove it is more contagious or more resistant to vaccines.
There are now five "variants of interest" that the WHO is monitoring.
In addition, there are four "variants of concern," including the highly infectious Delta variant that has gained dominance around the world.
Mu has been detected in some countries in South America and Europe, the WHO wrote.
Worldwide, the portion of the variant amounts to only 0.1 per cent, according to present estimates. In Colombia, however, it is 38 per cent and in Ecuador 13 per cent - and the proportion is growing.
