As the coronavirus has spread throughout the world, the connectivity of modern life has come into fresh focus.  Research from Georgia State University visualizes these transmission networks to highlight how they cross borders and even oceans.

The researchers used viral genome data from across the world to understand how the virus has spread out of Wuhan across the world.  They’ve used this to create a global COVID-19 transmission network.

“The data on the virus is growing as fast as the virus,” they explain. “This is actually the first outbreak in history where we have so much data. It’s the first global public health emergency for which next-generation sequencing technologies have been employed at such a vast scale. For Ebola, we had nothing of this magnitude.”

Open data

The researchers have tapped into the GISAID database, which is a global repository of virus sequences and related clinical and epidemiological data.  The analysis allows the team to understand where the virus had already peaked, is currently peaking, and will peak in future.

“Right now we see that the hotspots like New York City, Italy, and Spain, have reached their maximum incidence rate,” the researchers say. “They are leveling off or just started to follow a downward trend, though at very high levels.”

The first genome sequence of the coronavirus was completed in January, with over 5,000 undertaken since then.  The data reveals that most countries had multiple introductions to the virus, across both land and sea.  For instance, the virus was probably introduced into France via Iceland, Switzerland, Portugal, Spain, Australia and Finland.

No patient zero

These multiple points of entry underlines the fact that looking for a ‘patient zero’ is not enough to determine the growth curve of the virus in a region.  When the pandemic is global, however, it isn’t really enough, and closing down travel from single locations doesn’t help, as by the time people realize the danger, the virus has already dispersed.

“An epidemic is formed by clusters, or local outbreaks, that are not entirely synchronous,” the researchers explain.

These clusters help us to gain an understanding of the overall picture of the pandemic across the world, whilst also allowing us to drill down into local outbreaks to understand how and where the virus is moving.  This enables officials to know where the severest outbreaks are occurring, and even to predict what lies ahead in the coming weeks, both locally and globally.

It’s a level of connectivity akin to an individual on Twitter having a few million followers.  Whilst their network can be enormous, the network of some of their followers may only be a handful of nodes.  The researchers believe this is crucial knowledge, as viruses spread through what is known as the “naive population”, or humans who have never encountered the virus, and so have no immunity to it.

The hope is that by studying these transmission networks, researchers will be able to better understand where the most intense outbreaks are occurring, and indeed which strains of the virus are most prevalent.