The World Health Organisation (WHO) has said that there have been at least four types of coronavirus that have been circulating in the world since the infection was first detected in Wuhan in November 2019.
The Organisation said since the start of the pandemic, it has received several reports of unusual public health events that are possibly due to the coronavirus variants.
A SARS-CoV-2 variant with a D614G substitution in the gene encoding spike protein emerged in late January-early February last year.
However, over a period of several months the D614G mutation replaced the initial coronavirus strain that was identified in China.
According to a WHO statement, by June last year, the mutation became a more dominant form of COVID-19 circulating globally.
Studies have suggested that the D614G substitution increased infectivity and transmission as compared to the initial virus strain.
Yet another variant was reported in August and September linked to infection among farmed mink that subsequently transmitted to humans.
This was known as the ‘Cluster 5’ variant and was identified in Denmark.
“Preliminary studies conducted in Denmark show that this variant may result in reduced virus neutralisation in humans, which could potentially decrease the extent and duration of immune protection following natural infection or vaccination,” the WHO said.
In December, the UK government reported a variant, which was referred to as SARS-CoV-2 VOC 202012/01.
This variant is not phylogenetically related to the SARS-CoV-2 virus that was already circulating in the UK at that time.
It remains unclear how and where SARS-CoV-2 VOC 202012/01 originated.
The SARS-CoV-2 VOC 202012/01 variant has now been reported in 31 countries, territories and areas in five of six of WHO regions.
In December, South Africa announced the detection of yet another variant that was rapidly spreading in three provinces of the country.
This variant has been named 501Y.V2.
“While SARS-CoV-2 VOC 202012/01 from the UK also has the N501Y mutation, phylogenetic analysis has shown that 501Y.V2 from South Africa are different virus variants.
“In the week beginning 16 November, routine sequencing by South African health authorities found that this new SARS-CoV-2 variant has largely replaced other SARS-CoV-2 viruses circulating in the Eastern Cape, Western Cape, and KwaZulu-Natal provinces,” the WHO observed.
According to the Organisation, four other countries have reported that variant.