Natural evolution of the hCoV-19 virus, April 13, 2020

GISAID Comments on the Discussion of Different Types or Clades of the hCoV-19 Virus and their Origin

As the outbreak evolves over time and more data becomes available, several colleagues have analyzed and proposed different "types" of the virus and their origin. Depending on choice of definitions one can classify the circulating virus strains into a different number of clades based on genetic variants. These are part of the natural evolution of the virus currently not known to be associated with any differences in virulence.

Changes in prevalence of these variants in the short term are expected and often driven by chance or so-called founder effects rather than immediate evolutionary pressure. GISAID's daily summaries of strains distinguishes clades based on genetic marker variants but this is subject to change following the viral evolution.

It is important to note that there is currently not enough data from the early outbreak period to interpret the early history of global transmissions from few genomes in detail. Links that seem directly connected now are likely to be connected via other cases also from other countries not sampled and sometimes can be connected differently later with more data.

A prime example for this was the first German sample from Bavaria which initially looked like the ancestor of most subsequent European cases only until more sequences came in from China and the Netherlands confirming that the very same variant has been present in multiple locations at the same time which means the transmission routes are much more complex than the early incomplete picture suggested. More data and analysis on ongoing evolution of the virus is becoming available daily via the GISAID platform.