The coronavirus epidemic is a candidate to be the most important health emergency of our time. Not the first, not the last and perhaps not the most creepy. It is likely that at its end it will not have produced more victims than many others, but three months after its appearance it has already gained a record: Sars-Cov-2 is the first new virus to manifest itself so quickly on a global scale. Others very similar, like its predecessor Sars-Cov, were quickly defeated. Still others, like HIV, have been plotting in the shadows for years. Sars-Cov-2 has been more daring. And his brazenness reveals something that we knew before but we struggled to measure: the multiplicity of levels that connect us to each other, everywhere, as well as the complexity of the world we live in, its social, political, economic, but also interpersonal and psychic.
As I write it is a rare 29 February, a Saturday of this leap year. The confirmed infections in the world have exceeded eighty-five thousand, almost eighty thousand only in China, the deaths are approaching three thousand. It is at least a month that this strange accounting is the background to my days. Even now I have opened the interactive map of Johns Hopkins University. The diffusion areas are identified by red circles that stand out against the gray background: alarm colors, which could have been chosen more carefully. But you know, viruses are red, emergencies are red. China and Southeast Asia have disappeared under one big spot, but the whole world is pockmarked, and the rash can only get worse.
Italy, to the surprise of many found themselves on the podium of this anxiety-provoking competition. But it is a random circumstance. In a few days, even suddenly, other countries could find themselves more naive than us. In this crisis, the expression “in Italy” fades, there are no more borders, regions, neighborhoods. What we are going through has a super-identity and super-cultural character. Contagion is the measure of how global our world has become, interconnected, inextricable.
I am aware of all this and yet, looking at the red disc above Italy, I cannot help but be suggestive, like everyone. My appointments for the next few days have been canceled due to containment measures, others have been postponed myself. I found myself in an unexpected empty space. It is a present shared by many: we are going through an interval of suspension of everyday life, an interruption of the rhythm, as sometimes in songs, when the drums disappear and the music seems to dilate. Closed schools, few planes in the sky, solitary and echoing steps in the corridors of museums, everywhere more silence than normal.
I decided to use this void by writing. To keep the omens at bay, and to find a better way of thinking about all this. Sometimes writing manages to be a ballast to stay planted on the ground. But there is also another reason: I don't want to lose what the epidemic is revealing to us about ourselves. Once the fear is overcome, all volatile awareness will vanish in an instant – it always happens with diseases.
When you read these pages, the situation will have changed. The numbers will be different, the epidemic will have spread further, will have reached every civilized corner of the world or been tamed, but it doesn't matter. Certain reflections that the contagion arouses now will still be valid. Because what is happening is not a casual accident or a scourge. And it's not new at all: it has already happened and will happen again.
I remember certain afternoons, in the two years of high school, passed to simplify expressions. Copy a very long strip of symbols from the book and then, step by step, reduce it to a concise and understandable result: 0, –½, to the second . Outside the window it became dark and the landscape gave way to the reflection of my face illuminated by the lamp. It was a peaceful afternoon. Bubbles of order in an age in which everything inside and outside of me – especially inside – seemed to be turning to chaos.
Long before writing, math was mine trick to curb anguish. It still happens to me, as soon as I wake up, to improvise calculations and numerical sequences, it is usually the symptom that something is wrong. I suppose all this makes me a nerd. I accept it. And I am embarrassed, so to speak. But it turns out, at this moment, that math is not only a pastime for nerds, but the indispensable tool to understand what is happening and shake off suggestions.
Epidemics, even before medical emergencies, are mathematical emergencies. Because mathematics is not really the science of numbers , is the science of relationships: it describes the links and exchanges between different entities, trying to forget what those entities are made of, abstracting them into letters, functions, vectors, points and surfaces. Contagion is an infection of our network of relationships.
The mathematics of contagion
It was visible on the horizon as a gathering of clouds, but China is far away, and then figured. When the infection came to us in force, it left us stunned.
To reduce the disbelief I thought of resorting to mathematics, starting from the Sir model, the transparent framework of each epidemic.
An important distinction: Sars-Cov-2 is the virus, Covid – 19 the illness. They are fatiguing, impersonal names, perhaps chosen in this way to limit their emotional impact, but they are more precise than the more popular “coronavirus”. So I will use those. For simplicity then, and to avoid misunderstandings with the contagion of 2003, from here on I will abbreviate SarsCov-2 in Cov-2.
Cov-2 is the most basic form of life we know. To understand its action, we have to go down in his stupid intelligence, see ourselves as he sees us. And to remind us that Cov-2 cares almost nothing about us, not our age, not our sex, not nationality or our preferences. The whole of humanity is divided by the virus into three groups only: the Susceptible ones, that is, all those that could still be infected; the Infected, that is, those whom it has already infected; and the Removed, that is, those who can no longer infect.
Susceptible, Infected, Removed: Sir.
According to the map of the contagion that pulsates on my monitor, the Infected in the world in this instant are around forty thousand; the Removed, between victims and healed, a little more.
But the group to keep an eye on is the other, the one that is not reported. The Susceptible in Cov -2, the humans that the virus could still infect, are seven and a half billion fewer.
Scholarships to investigate epidemics
Paolo Giordano's book, “In contagion”, will be available from 26 March, in co-edition Einaudi- «Corriere della Sera» (pp. 64). On newsstands it will come out with the “Corriere della Sera” at a cost of 8, 90 euro plus the price of the newspaper (will remain on sale for a month). In bookstores and ebooks the book comes out for Einaudi at euros 10 in the paper edition and at 6, 99 in the digital edition. It is also available in the Audible audiobook, produced by Einaudi.
The proceeds of the author will go to the creation of two bags of study at the Sissa – International School of Advanced Studies of Trieste. The first on artificial intelligence and data analysis applied to epidemiology and reserved for Italian and foreign research doctors who have recently completed their PhD course; the second reserved for Italian data journalists for an investigation into the Covid epidemic – 19 in our country.