Nada, said the Bard 400 odd years ago and we believed . We believed that the pathogen that causes Covid pandemic , would by any other name be dangerous to humanity. So when the pandemic took us by surprise and shook us top to toe, we referred to the variants of concern (VOC) by the country where they were first detected and identified. Thus we discussed at length about the UK , Indian , South African and Brazilian variants as an easier alternative to the string of alphanumerics such as B.1.1.7 or B.1.167.2 etc. Because a dot or a number this way or that and one would have gotten it all wrong. Though the general public was comfortable to use the simple GI tags, several country heads rebelled and protested against this geographical labelling. For the first time perhaps being bestowed with a GI tag was no honour. To settle matters amicably, the World Health Organisation announced its decision to use Greek alphabets to indicate the SARS-CoV-2 variants. This decision was not taken in a hurry or in isolation but after much deliberations with agencies such as the Virus Evolution Working Group, the WHO COVID-19 reference laboratory network, representatives from the current scientific nomenclature groups and experts and organisations from several countries. As stated by WHO, the idea was to come up with easy-to-pronounce and non-stigmatising labels for the variants. The Greeks have so far not protested against the (mis)use of their alphabets !
Thus B.1.1.7 which was popularly known as the UK variant has been renamed as the Alpha variant, B.1.351, the South African variant becomes the beta variant, P.1 the Brazil variant becomes the Gamma variant and B.1.617.2, the Indian variant becomes delta variant. Scientific communities will continue to use the alphanumeric notations known as the Pango Nomenclature because those are loaded with information.
To study variants of a given strain, scientists generally draw up a family trees that clearly depict the immediate ancestors and their descendants in other words, the lineage. These are called phylogenetic clusters or clades. The blue, green and orange blocks below depict typical family clusters.
SARS-CoV-2 virus has been unusual in many of its characteristics, especially the speed with which it mutates. A simple family tree as shown above was found grossly inadequate. It became an absolute necessity that a dynamic grouping system be in place to accommodate the rapidly increasing variants. A group of scientists in U.K . developed the Pangolin or Pango system (Phylogenetic Assignment of Named Global Outbreak LINeages) of nomenclature. During the initial days of the outbreak of the pandemic in Wuhan two types of dominant variants were identified: A and B. (Scientists till now haven't been able to zero in on their common ancestor. That is another story, let us not go there now). Several direct lineages of B have so far been identified, of which B.1 is the most predominant line. It has 1000+ sub-lineages and sub.sub-lineages. In the Pango system, the alphabetic prefix denotes clear ancestry, each dot means next generation and the number denotes the order in which it was identified. Thus B.1, is the first identified of the 4009 direct descendants of B and B.1.617 is the 617th identified descendant of B.1. In order to avoid unwieldy long numbering, each cluster has just three levels, primary, secondary and tertiary. Example B1, B.1.1. and B.1.1.1 form one cluster. B.1.1.1. takes on n alias C and its first identified descendant is designated as C.1 and not B.1.1.1.1 .
The Pango is dynamic and flexible enough to accommodate all variants identified so far and yet to be . Though a bit labyrinthine at first glance it is simple and easy to navigate.
