DECRYPTION – Since June 2021, the World Health Organization (WHO) has been using Greek letters to designate the main lines of Covid-19. However, this is not the case with the latest variants in circulation.
“BQ.1.1” in France, “BF.7” in China, “XBB.1.5” in the United States… The different names of the variants of Covid-19 currently circulating around the world are enough to get us lost. “We should use names more appropriate for the public,” suggested Mircea Sofonea, epidemiologist and lecturer at the PCCEI unit of the University of Montpellier, in Le Figaro, before asking about the subvariant “XBB. 1.5”, which is gaining momentum in the United States. Why does the scientific community choose such obscure nomenclature for laypeople?
These variants, like all those currently in circulation, “descend from the Omicron variant,” says Le Figaro Florence Débarre, researcher in evolutionary biology at the CNRS.
Use of the Greek Alphabet
To understand the non-attribution of Greek letters to current stresses, we need to go back to the beginning of the pandemic. Originally, the variants were named after their locality (“English variant”, “South African variant”, “Brazilian variant”, …). On May 31, 2021, the World Health Organization (WHO) announced that it would now use Greek letters to designate variants of Covid-19. The goal is to have names that are “easy to pronounce and remember” but also to prevent the general public and the media from using “stigmatizing and discriminatory” names that refer to the place where the first cases of variants were discovered,” the WHO explained.
Also read Covid-19: What if the “worst case” was actually in the US?
Any new variant that is determined to be of concern and is sufficiently different from the variants in circulation (alpha, beta, delta, omicron, etc.) is assigned a new Greek letter. On its website, the WHO defines a variant of concern as one “associated with one or more changes that have some public health importance at a global level”. The WHO lists three changes: “increased transmissibility”, “increased virulence” and “reduced effectiveness of public health and social measures”.
For the current sub-variants, the answer remains the same. The WHO advises Le Figaro that “a new label, i.e. a reassignment of a variant of concern, would be awarded if there was a variant that was sufficiently different in its public health implications to require a change in the public sphere health response.” Which is currently not the case.
Also readCovid-19: Could the powerful epidemic wave in China hit France and Europe?
“For now, we’re staying in the Omicron dynasty,” emphasizes Florence Débarre. BA.2 and BQ.1.1 [respectivement responsables de la sixième et de la neuvième vague en France, NDLR] have similar properties. Unlike Delta and Omicron, which do not have the same characteristics. Omicron acquired Delta at the end of December 2021. “Delta and Omicron do not come from the same branch of the family tree, they are clearly different,” Florence Débarre agrees. Even if all variants of Covid-19 have the same original strain of the virus as a “common ancestor”.
A family tree
So where do the letters and numbers used today come from? From the Pango system set up by a group of British researchers in 2020 and used by scientists even before Greek letters were used for Covid. “The basic principle is that the names of the lineages represent descent and descent,” explained in June 2021 National Geographic’s Oliver Pybus, an evolutionary biologist at the University of Oxford who was involved in Pango’s design. The latter can be read as the family tree of Covid-19. Each branch corresponds to a line. “This allows the different generations of virus lines to be traced,” explains Florence Débarre.
Pango lines work with a letter followed by numbers. A period separates the letters from the numbers and the numbers from each other. Originally there were two main lines of Covid-19 named “A” and “B”. Today only variants of the “B” line are in circulation. Thus “B.1” descends from “B”. “B.1.1.1” comes from “B.1.1” which itself comes from “B.1”. Following this same logic, “BA.1”, the first Omicron variant that replaced “Delta” in late 2021, is a cousin of “BA.2” or even “BA.5”, responsible for the seventh and eighth waves in France.
Also read A simplified nomenclature for Covid variants
Pango lines cannot have more than three points. If too many digits needed to be added, a new letter would replace them. For example, the original name of “BQ.1.1”, which is derived from “BQ.1”, is “B.1.1.529.5.3.1.1.1.1.1.1.1”. Note that “BQ.1.1” comes from the lineage of “BA.5”. “B.1.1.529” corresponds to the real name of the first Omicron variant. The new letters are given in alphabetical order according to the date of appearance of the subvariants.
The X in “XBB” is used to designate recombinants, those variants that result from the combination of two strains, such as “XBB.1.5”. So “XBB.1.5” is from the lineage of “XBB.1”, but “it has a key mutation that the parent line didn’t have,” explains Florence Débarre. Similarly, when multiple mutations occur or when a single mutation is large enough, a new lineage emerges.
If the virus changes completely, the first letter can also change. The gamma variant first detected in Brazil was therefore named P.1, although it descended from “B.1.1.28” and its name could therefore have been “B.1.1.28.1”.
mythical creatures?
This pango system serves as a common language for all scientists. To help everyone understand, some scientists use the names of mythical creatures on social networks. “BQ.1.1” was therefore nicknamed “Cerberus” – three-headed dog guarding the gate to the underworld, “BF.7” “Minotaur” – half human, half bull – and “XBB.1.5” “Octopus” – sea monster with several tentacles. “Mythological names have been around for a long time, that’s nothing new,” comments Mircea Sofonea.
However, these new names are not unanimous. “These names have no scientific basis, they were invented on Twitter,” responds Florence Débarre. “What bothers me is that these are mythological monsters that can unnecessarily worry the general public,” she laments.
Also read Thierry Wolton: “The Real Reasons for China’s Abandonment of Zero Covid”
In September 2021, the WHO said it was considering using constellation names for future variants. Without going any further.
SEE ALSO – Covid-19: should we be worried about the BQ 1.1 variant?