Going forward, the organisation’s tracking system – a Greek alphabet-based approach to naming major variants of concern – will consider the classification of Omicron sublineages as variants under watch, variants of interest or, in the case of the greatest potential threats, as variants of concern.
As of February 2022, “Omicron and its many sublines have almost completely replaced the other variants,” noted Dr. Maria Van Kerkhove, infectious disease epidemiologist who is technical lead for the WHO’s COVID-19 response. in a series of social media posts.
The family of Omicron-like viruses now represents more than 98% of publicly available sequences, The WHO said in a statement on Thursdayadding that the previous naming system lacked the “granularity” needed to compare them.
Moving to a new system involves several key changes:
WHO will continue to assign Greek alphabet labels to variants of concern, but will no longer do so for variants of interest.
Variants such as Alpha, Beta, Gamma, and Delta, as well as the parent line Omicron (B.1.1.529), are now considered previously circulating variants of concern.
Infectious disease specialist Dr Isaac Bogoch, who works at the University Health Network in Toronto, called the WHO decision a “smart decision”.
“We’ve been in the Omicron era for over a year, and the various sub-lines have increasingly complex names that may be difficult for some members of the general public to follow,” he said in an email to CBC News, noting the convoluted classifications of many of these offshoots, including BQ.1.1, CH.1.1 and XBB.1.5.
“Revisiting the definition of what a variant of concern is and naming them more appropriately can facilitate more effective communications between public health teams and the general public.”
Bill Hanage, an epidemiologist at Harvard TH Chan School of Public Health in Boston, said the change also reflects the fact that none of the lineages since the first wave of Omicron have remotely had the impact of Alpha, Delta or the first strain of Omicron, “with the important exception of China, which has just emerged from its first tussle with [Omicron].”
But overall, since then, the world has seen ramifications of SARS-CoV-2 that include relatively small changes that have “real but not huge” impacts on immunity evasion, Hanage said, adding that it does not make sense to call these variants of concern.
‘Appropriate’ for naming XBB.1.5 a variant of interest
What WHO To fact is believed to be Omicron’s XBB.1.5 subvariant – which appears to account for nearly half of all recent COVID-19 cases in Canada, which are still piling up federal data shows – as a new unique variant of interest, alongside several variants under surveillance.
This means that it does not yet have a name in the Greek alphabet, and it will not unless it is later declared a variant of concern.
Sub-variant increased in more than 70 countries since it was first identified last fall and thought to contain mutations that give it a major growth advantage.
“Fortunately, the variants we have seen within Omicron, including the latest XBB.1.5, do not appear to be more severe, but their increased transmission means more cases, not just now, but in the future,” said Said Sarah Otto. , an expert in modeling and evolutionary biology at the University of British Columbia in Vancouver.
“Thus, raising XBB.1.5 to [a variant of interest] is entirely appropriate.”
Scientists wonder if Omicron would be the latest variant of concern despite its ongoing evolution, she said in an email exchange with CBC News, noting that the WHO has been playing “catch up” with this virus.
“This latest announcement indicates that the WHO recognizes that variants of concern can breed even more worrying variants, as we have seen with the evolution of different Omicron waves,” she said.
The WHO said it would continue to publish regular risk assessments for variants of interest and those found to be of concern.
The organization also stressed that changes to its naming system do not imply that Omicron no longer poses a threat to public health.
“Rather, the changes have been made to better identify additional or new threats in addition to those posed by currently circulating Omicron viruses,” the organization’s statement said.
Dr Zain Chagla, an infectious disease specialist at McMaster University in Hamilton, agreed that the changes made by the WHO to take Omicron into account “make sense”, since these tracking systems are really intended to alert systems. of health of anything that could “change the current dynamics of the pandemic”. .”
But there is also always the possibility of an evolutionary curve, according to Van Kerkhove, who wrote that “the emergence of a completely new variant outside of the Omicron family always remains possible”.