What's in a (nick)name

On the value of accessible names for SARS-CoV-2 variants

When giving names to things, it’s important to be able to make sense of the names and how they relate to each other.

Why do people give names to things? We name things so that we can know them. Languages spoken by people living in cold regions have many more words for snow than those in warm regions- the Sami people of Scandinavia have hundreds and the Finns have forty, but Hindi has only three. Surprisingly, English has dozens of words for snow, but words like firn and sastrugi only have meaning for mountaineers and skiers. If you’re a back-country skier, you’ll learn the word “sastrugi” pretty quickly! It’s hard, unforgiving windswept snow that can damage your skis and wear out your knees. Knowing the name of the hazard makes you more aware of it, and lets you avoid it. It’s a practical thing.

This is why people name storms, too. Tropical storms are named, before they escalate to the hurricane stage, out of a list that’s rotated every six years. It’s simple and gets the naming part of the equation out of the way quickly. The specific name, or the need to assign one to a storm in progress, is not debated in real-time. Crucially, this lets the National Hurricane Center focus on tracking hurricane trajectory and severity, rather than wallow in etymological debates in the face of a potential threat. If you hold off on naming hurricanes until it’s clear that they’re a serious threat, the name is only useful for the history books!

We are scientists with a strong research interest in viral evolution. One co-author (A.C.) has led a team of volunteers over the past three years, publishing extensively on SARS-CoV-2 viral evolution and epidemiology. The other co-author (T.R.G.), an evolutionary and genome biologist, collaborates with a team of volunteer scientists who have been closely following the evolution of SARS-CoV-2 to assign ‘nicknames’ to subvariants as they emerge in the population. We believe that these nicknames are an important practical tool for managing SARS-CoV-2 risk at this point.

As SARS-CoV-2 viral evolution has proceeded at a breakneck pace, its evolutionary tree has exploded with complexity. The most widely adopted technical naming system, Phylogenetic Assignment of Named Global Outbreak (PANGO) nomenclature, was designed to manage this complexity. Although PANGO lineages are useful for researchers by conveying ancestor-descendant relationships within lineages, this becomes less clear as lineages continue to evolve. The challenges with using the PANGO system in non-technical communications became apparent very early on in the pandemic, and even public health officials and virologists have long expressed difficulty in keeping PANGO names straight at a time when the situation was far less complex than it is today (and indeed, errors continue to creep into communications about variants). 

This was addressed by the WHO in May 2021 with the introduction of a formal nicknaming system in which Variants of Concern (VOCs) and Variants of Interest (VOIs) were assigned Greek letters. However, this system was only used for a few months- no Greek letters have been assigned by the WHO since late 2021, despite the evolution of more than 1,700 new PANGO lineages within “Omicron”. In March 2023, WHO updated the working definitions of VOCs and VOI, indicating that only VOCs would receive Greek letters in the future, and adding a third, lowest-risk category (Variants Under Monitoring, or VUMs).

There are several problems with the current situation. First, the significance of the Greek-letter variants is hard to interpret- for example, (see figure), the genetic divergence between the Greek-letter variants Alpha, Beta and Gamma is a lot smaller than the divergence between the major Omicron lineages. Second, similarities in PANGO labels are no guarantee of functional similarity among lineages. For example, it may come as a surprise, but the highly-mutated “Omicron” variant BA.2.86 is far less similar to BA.2.85 than it is to JN.1 (an alias for BA.2.86.1.1). Labeling all subvariants “Omicron” also creates the false perception that viral evolution has slowed, when exactly the opposite is true. Third, the label Omicron itself has now become a clade- a large evolutionary group that contains the ancestry and only/all of its descendants. Clades can be confusing- for instance, humans are part of the “fish” clade. Labeling BA.2.86 Omicron is as meaningful as labeling humans as fish, it’s technically correct, but extremely confusing. Fourth, only naming VOCs is akin to only naming tropical storms after they have escalated to the level of hurricanes. Variant classification already has a severity scale (VUMs, VOIs, VOCs) that allows for the communication of threat potential.

Evolutionary tree (unrooted, scaled to divergence) of SARS-CoV-2 variants. Those with formal nicknames (Greek letters) are indicated, along with the numerous, very divergent lineages within “Omicron”, some of which have been given informal nicknames by variant trackers. From Nextstrain.org.

Before the use of formal nicknames based on Greek letters, researchers were using their own nicknames based on birds or human names. Similarly, the gap left by the lack of new formal nicknames for the past 2 years has been filled by an informal system used by variant trackers. Drawing names from Greek mythology and astronomy, these nicknames have been proposed by the community of scientists involved in discovering, characterizing, and tracking new variants. Receiving one of these informal nicknames is not related to the “severity” of a variant,  but rather on whether there is a need for accessible communication in the context of viral evolution. Not surprisingly, these nicknames have been widely adopted by the media- they are easier to use in day-to-day conversation than PANGO lineages.

So, why name variants at all at this point? Coming back to the original point- people living in cold regions have many names for snow. “Learning to live with covid” (permitting widespread transmission of SARS-CoV-2) means that we will be living with the repeated emergence of new viral variants. The risk of the virus “surprising” us with a highly immune evasive variant, capable of both spreading widely and having a higher acute severity, remains on the table, At the same time, the evolution of new variants, driven by immune evasion, has resulted in a “variant soup” that steadily increases the baseline of total cases. Thus, the state of play of the ongoing pandemic remains unstable. Much as with tropical storms, being able to monitor viral evolution and communicate findings clearly and quickly with the public is critical. Assigning nicknames to subvariants quickly and freely remains as crucial now as it was in early 2021, as it allows us to provide an effective early warning system.