The UN health agency says one aim of the move is to avoid stigmatising the countries where coronavirus variants are first detected.
The new system applies to variants of concern – the most troubling of which four are in circulation – and the second-level variants of interest being tracked.
“As a result, people often resort to calling variants by the places where they are detected, which is stigmatising and discriminatory.”
The four coronavirus variants considered of concern by the United Nations agency and known generally by the public as the UK, South Africa, Brazil and India variants have now been given the letters Alpha, Beta, Gamma, Delta according to the order of their detection.
Other variants of interest continue down the alphabet.
“The labels don’t replace existing scientific names, which convey important scientific information and will continue to be used in research,” WHO’s technical lead Maria Van Kerkhove tweeted.
“These labels will help with public discussion about VOC/VOI as the numbering system can be difficult to follow.”
WHO in the statement said it encouraged media outlets and national authorities to adopt the new labels.
Earlier this month, US President Joe Biden signed a hate crimes law aimed at protecting Asian Americans who have suffered a surge in attacks during the COVID-19 pandemic.
US anti-extremism groups say the number of attacks and hate crimes against Asian Americans has exploded since the beginning of the crisis.
Months of deliberations
The choice of the Greek alphabet came after months of deliberations in which other possibilities such as Greek Gods and invented, pseudo-classical names were considered by experts, according to bacteriologist Mark Pallen who was involved in the talks.
But many were already brands, companies or alien names.
Another idea to refer to variants of concern as VOC1, VOC2 etc was scrapped after he pointed out it resembled an English swear word.
Historically, viruses have often been associated with the locations from which they are thought to have emerged such as Ebola which is named after the eponymous Congolese river.
But this can be damaging for the places and often inaccurate such as with the so-called “Spanish flu” pandemic of 1918 whose origins are unknown.
Before the new WHO scheme, some scientists had adopted their own simplified nomenclature for variants such as a February paper using bird names. However, it was criticised on the grounds that this could imperil birds and by the mother of a girl named Robin.