Thread by @arijitchakrav

(🧵 0/5, Foreword):

It's been ~5yrs since 𝑆𝐀𝑅𝑆-𝐂𝑂𝑉-𝟐, the virus that causes 𝐂𝑂𝑉𝐈𝐃, made its fateful jump into humans. Now seems as good a time as any to ask "is it over yet?" (For the 10th time, but who's counting?)

Let's talk about how this ends, shall we? (1/)

Every few months over the past 5 yrs, we've been reminded that the pandemic is over now, or perhaps it ended a long time ago, no one really knows.

The important thing is that it'll never go away, so we have to learn to live with it.

But not to worry, it's all very mild. (2/)

The dead moth buried in that word salad is the belief that newly emergent pathogens must eventually become endemic, that this process is about managing our own feelings about the situation.

A seven-stages-of-grief thing that we must all eventually accept. For our own good. (3/)

As it so happens, a pandemic is not a state of mind, a point made by @heavyredaction & me 1yr ago. The term belongs to the discipline of epidemiology, not psychology. It has a specific meaning. Pandemics are global, severe, dynamic & unpredictable (4/):

thenation.com/article/societ…

That said, these ideas are repeated widely by PH "experts" & officials: we have always lived with infectious diseases, our immune systems have evolved/adapted, immunity is a 'muscle' that strengthens with exercise, most people will no longer get severely ill from 𝐂𝑂𝑉𝐈𝐃 (5/)

We have been repeatedly assured that the virus has become mild now, and that the worst is behind us. We have been told that moving on - accepting repeated infections- is the best possible course of action for the economy.

It's a very pervasive narrative. But is it true? (6/)

Over the last few weeks, this question has piqued my own curiosity, leading me to dig into my own bookshelf & the literature on the subject. (My interest in the subject dates way back, long before I ever expected to have a personal stake in these answers.) (7/)

My collaborators & I have published academic papers about the current pandemic since '20, blending evo theory & epi models, on a wide range of topics.

But one question has been gnawing at some of us for years - how will the pandemic end, on the current course of (in)action? (8/)

Will the virus eventually "settle into endemicity", "running out of evolutionary space" and becoming tame, nothing more than a common cold? (9/)

Are Public Health officials truly modern-day bronco busters, tasked with riding the bucking wild horse that is an emergent pathogen until it learns to accept the saddle of endemicity? (10/)

It's an encouraging thought. After all, there are many diseases that are endemic, & a school of thought from the 19th century says that emergent pathogens always become milder. Unfortunately, as we shall see, this idea (like many other ideas from the 19th century) is dated. (11/)

Pandemics lie at the intersection of history and biology, as they are usually marked by the emergence (or re-emergence) of a pathogen into a human population. So, to answer the question "how does this pandemic end", we can look to two bodies of knowledge for our answer. (12/)

First, we can ask the question, "What does biology teach us about the emergence of novel pathogens?", dipping into evo theory in humans, mammals and other living creatures. (13/)

Next, we can ask,"What does history teach us about pandemics?", focusing our attention on a few pandemics that have been well studied (The Black Death, Influenza 1918, Smallpox in the New World -actually an epidemic), & looking at the implications for human societies (14/)

In the 3rd 🧵 in the series, we'll ask the questions: "How predictable has the evolutionary trajectory of 𝑆𝐀𝑅𝑆-𝐂𝑂𝑉-𝟐 been so far?", showing that much of where we are today was precisely predictable from first principles, as we and others pointed out years ago. (15/)

In the 4th 🧵, we look at what the future holds, discussing specific predictions for the outcome of the pandemic with the current course of (in)action.

(Spoiler alert: It's looking pretty bad. TL;DR is that the current "plan" has significant unmitigated tail risks).
(16/)

In the 5th and final 🧵, we will ask the question "How do we win against 𝑆𝐀𝑅𝑆-𝐂𝑂𝑉-𝟐?", leveraging our understanding of the biology and history of pandemics to propose practical changes that can be made to the current course of action (17/)

As an epistemological aside, most of what we will discuss relies on deductive reasoning to infer what can or might happen.
Emergence events are very rare in the historical record, making the question of what always or never happens unanswerable given the small sample size. (18/)

The ability to reason deductively from first principles is a survival skill. If you're driving down a deserted highway late at night, and you see the road ahead of you blocked by planks with nails in them, you don't get out of the car. (19/)

It's easy to infer that (a) the planks didn't just fall from the sky, (b) whoever placed them there wants you to get out of the car & (c) it's not so that they can share a beer with you. Deductive reasoning suggests that reversing & driving away is the best course of action.(20/)

If there's a voice inside your head saying "you're probably over-reacting, there's no reason to worry", you (should) ignore it. Feeling concerned in response to a real threat is a rational survival response, & a lack of fear can be maladaptive. Evolutionarily speaking. (21/)

In the same vein, it's important to be able to talk and think rationally about unprecedented risks.

As Nassem Taleb, in his book, the Black Swan, puts it "The life of the turkey tells us that it's very dangerous to extrapolate the past to predict the future." (22/)

Just because something has never happened before, doesn't mean that it can't or won't happen.

This is especially important when talking about scenarios like pandemics, which have occurred only a handful of times in human history. (23/)

Pursuing the wrong course of an action for an extended period of time increases, rather than decreases, risk.

And, on that happy note, let's dive into our first question- "What does biology teach us about the emergence of novel pathogens?" (24/)

theguardian.com/us-news/2024/o…

[H/T @TRyanGregory and @madistod for stimulating discussions during the creation of this material, and @0bj and @gckirchoff for helpful feedback] (25/)

@TRyanGregory @madistod @gckirchoff Sorry, wrong person acknowledged in the H/T! I meant @0bj3ctivity!