The recently discovered B.1.1.529 strain of COVID-19, named as 'Omicron' has been declared as a variant of concern by World Health Organization (WHO).
The classification puts Omicron into the most-troubling category of Covid-19 variants, along with the globally-dominant Delta, plus its weaker rivals Alpha, Beta and Gamma.
Nations rushed to ban flights to slow the spread of Omicron on Friday, while stock markets and oil prices plunged on fears surrounding the variant, potentially dealing a heavy blow to the global economic recovery.
The UN health agency in a statement said, "Based on the evidence presented indicative of a detrimental change in Covid-19 epidemiology… the WHO has designated B.1.1.529 as a variant of concern (VOC), named Omicron."
The WHO said it could take several weeks to complete studies of Omicron to see if there are any changes in transmissibility, severity or implications for Covid vaccines, tests and treatments.
According to reports, the change in classification came after a quickly-assembled virtual meeting of the WHO's Technical Advisory Group on SARS-CoV-2 Virus Evolution.
The variant was first reported to the WHO from South Africa on Wednesday.
The first known confirmed Omicron infection was from a specimen collected on November 9. In recent weeks, infections in South Africa have increased steeply, coinciding with the detection, reported NDTV.
WHO said that this variant has a large number of mutations, some of which are concerning pointing to worrying characteristics.
"Preliminary evidence suggests an increased risk of reinfection with this variant, as compared to other VOCs," the health agency said.
It further said that the number of Omicron cases appeared to be increasing in almost all provinces of South Africa.
As for testing for the strain, the WHO added: "Current SARS-CoV-2 PCR diagnostics continue to detect this variant."