Thread by @yaneerbaryam

Let’s talk virus mutations as in UK & South Africa that can transmit more rapidly

Attached is a simple model of hosts (green) and virus (red). The virus mutates, brighter shades are more rapidly spreading. It makes sense rapidly spreading variants become dominant over time

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But watch again. The brightest ones actually go extinct over time. Why? Because they kill off their hosts and run out of hosts to infect. This is because of local extinction of the hosts.

But what happens if we add long range transportation?

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Each image shows what it looks like with a bit more long range transportation. The virus, escaping local extinction, becomes progressively faster transmitting (shifting colors).

But, the last image is just before everything goes extinct, host and pathogen together.

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We call this “transition to extinction.” The system makes a sharp transition from local extinction to global. It happens for a quite small amount of transportation. Red shows shift from survival probability of 1 to 0

This is why I have been working on pandemics for 15 years

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Link to the paper and a press release (2006):

“The increased ease and frequency of global travel may make the risk of pandemics more severe than previously thought, a new report warns.

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necsi.edu/longrange-inte…

“A computer model developed by researchers at the New England Complex Systems Institute (NECSI) demonstrates that when the amount of long-distance travel reaches a certain critical level, diseases that were once locally contained can quickly grow to pandemic proportions.

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“The two authors have extensively studied computer models of predator-prey and host-pathogen systems. In their previous work, they have shown that exceptionally deadly diseases usually disappear because they rapidly exhaust the local supply of hosts to infect.

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“Their newest model shows what can happen if a disease can spread not just locally, but globally as well. This is exactly what happens when an infected traveler takes an international flight or if infected livestock is shipped overseas.

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“Rauch and Bar-Yam found that up to a certain point, increased global travel had little effect on the overall severity of a disease outbreak. However, when the rate of long-distance trips increases to a critical value, then the disease behaves very differently.

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“Instead of forming isolated, contained pockets of infection, the disease spreads unchecked and can become a devastating pandemic. The report addresses such diseases as Ebola, SARS

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“Due to increasing global transportation,” the authors warn, “human beings may cross the transition into the realm of pandemics unless preventive actions are taken that either limit global transportation or its impact.”

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Read:

Transition to extinction: Pandemics in a connected world

link:
necsi.edu/transition-to-…
or on medium
medium.com/complex-system…

Last paragraph of the 2006 paper

The traditional approach to public health uses historical evidence analyzed statistically to assess the potential impacts of a disease.

As the connectivity of the world increases, past experience is not a good guide to future events.

From:
necsi.edu/transition-to-…