XBB dot what? Where do these variant names come from?

October 19, 2023 Guest User

By Alison Adduono, Director of Marketing Communications

Have you wondered how the COVID-19 variants got their names? I did not until Omicron came around, when I thought, ‘why is each variant a never-ending alphabet soup only a scientist could love’? Or, ‘why don’t we have more menacing names like Vader or Khan’? Then I heard about Kraken, Eris and Pirola and my curiosity got the better of me, and I had to do some digging.

Because scientific names can be hard to pronounce or remember, the World Health Organization (WHO), in May 2021, started to assign “labels” designated as Variants of Interest, Variants of Concern, and Variants Being Monitored. However, these labels did not replace the existing names (e.g., those assigned by GISAID, Nextstrain, and Pango) which provide important scientific information and will be used in research for the near future.

According to the World Health Organization Best Practices for the Naming of New Human Infectious Diseases from 2015, the WHO uses a naming practice in order to ensure that any labels/names assigned to diseases don't have unnecessary negative effects on trade, travel, tourism, or animal welfare, and they do not cause offence to groups of any cultural, social, racial, or ethnic background. These best practices were formed in collaboration with the World Organization for Animal Health (OIE) and the Food and Agriculture Organization of the United Nations (FAO). With that said, in the case of COVID-19, the WHO elected to use the Greek alphabet for its naming convention.

Why did the WHO skip two letters in the Greek alphabet?

Since the WHO started tracking variants with Greek letters, we have seen everything in succession from Alpha, Beta, Gamma, Delta, Epsilon, Zeta, Eta, Theta, Iota, Kappa, Lambda, Mu and then Omicron. But what happened to Nu and Xi? In a statement to CNN, the WHO indicated that “Nu is too easily confounded with ‘new’ and Xi was not used because it is a common surname.” The next time the WHO determines there is a new key variant to track, one could assume that its name will be Pi.

What is with all the confusing letters and numbers?

Well, we all know that SARS-CoV-2 continues to mutate, and as it does, the number of mutations each has affects its level of transmission and severity determining its lineage. Each subvariant is labeled according to the Pango Lineage System. Pango creates a phylogenetic tree (family tree) that tracks the ancestry of each variant offshoot. Developed by infectious disease experts at Oxford and Edinburgh Universities, Pango was adopted by international organizations in 2021. For additional detailed information, refer to the CDC’s SARS-CoV-2 Variant Classifications and Definitions.

So where do the nicknames come from?

As it turns out, the unofficial nicknames have been coming from a small group of scientists initially gathered in August 2022 via Twitter to have clearer (and catchier) naming conventions for the COVID-19 subvariants deemed significant. Initially, they started with mythological creature names such as Gryphon, Basilisk, and Minotaur, etc. When they used the name of the mythical sea monster Kraken for variant XBB.1.5, it appears some experts felt it would unnecessarily spread fear. Garnering too much attention, unofficial group spokesperson Ryan Gregory, evolutionary biologist at Canada’s University of Guelph, and team elected to switch to a more neutral system with an extensive user guide. This guide utilizes the names of constellations and other celestial objects instead. And unlike the Greek alphabet, Ryan’s team is unlikely to run out of naming conventions anytime soon with all the moons, stars, planets, and galaxies at their disposal. A couple of examples are EG.5 (aka Eris) and FL.1.5.1 (aka Fornax) – both nicknamed by Gregory.

Additionally, the team is using a naming method where it will indicate a variant’s lineage and whether it is a recombinant strain. For example, in XBB.1.16, or “Arcturus”, the A indicates it's from the BA.2 lineage, and the R indicates it's recombinant.

BA.2.86 was nicknamed “Pirola” by scientist and infectious disease modeler JP Weiland, as he felt it was distinctly different from Omicron and would follow along with the WHO’s use of the Greek alphabet that can easily be switched to "Pi" or "Rho" if the WHO designates it as a key VOI or VOC.

In an interview with VaccinesWork, Professor Gregory stated: “When we give something a nickname, it is because we think people are going to be trying to talk about it, and it is a simpler way of communicating. If that is useful to people, they can use the nickname. But if you do not like Pirola, you can call it BA.2.86, or Omicron, or even SARS-CoV-2.”

It is important to note; however, that the WHO and the CDC – the authorities for any decision making - have not adopted this nicknaming convention as of yet. In fact, Maria Van Kerkhove, a WHO epidemiologist, tweeted at the end of a Twitter thread about XBB.1.16, “We are not using nicknames for these subvariants, and I would kindly encourage you not to. Please.” So, while the CDC and the WHO may not be onboard, I am sure many of us laypeople can appreciate the nicknames over the confusing “Dewey-Decimal System” like names.

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