In the last article we covered some of the historical pandemics that rocked the world - smallpox, typhoid, and the bubonic plague. We ended on a hopeful note - many of the pandemics that plagued the world in the past have faded, and that modern pandemics have been far less fatal than historical ones.

In this article we’ll dive into one big pandemic of the 20th century - influenza. The next article in the series is going to start in on the coronavirus pandemics of the last few decades, and then we’ll end with an in-depth analysis of what’s going on with COVID-19.

A century of little victories

Since the discovery of antiviral and antibiotic medicines, human existence on earth has gotten a lot easier. While access to medicine has not always been ideal, we’ve made amazing steps towards improving human quality of life by decreasing disease. Through concerted vaccination programs, we’ve eradicated smallpox and closed in on the poliovirus. We’ve nurtured a global organization, the World Health Organization, whose mission is the attainment of health for all humans. They’re the ones that monitor endemic and epidemic diseases and come up with a coordinated effort that’s capable of halting the spread of disease. The WHO has been around since the 1940s, and new technologies have seriously improved their ability to evaluate how diseases spread. Monitoring is so good at this point that it’s possible to sit on the internet in Dubuque, Iowa or the Kalahari desert and track the development of COVID-19 in real time.

In addition to information technology, there’s also been an explosion of molecular techniques that allow us to better identify what we’re dealing with. Sequencing, protein crystallization, high throughput mechanism studies all happen quickly enough to make your head spin. The global response to the pandemic, barring some political hiccups, has been amazing. It becomes even more astounding when you compare the fallout from COVID-19 with something like the 1918 influenza pandemic.

A simpler time

Let’s set the scene a little. It’s January 1918. The war has been going since the assassination of Archduke Ferdinand in 1914, and something like 3.5% of the world’s population has been mobilized to the front. The front is crowded, cold, and dangerous. Soldiers are dying of prosaic illnesses - tuberculosis, typhoid, trench foot. They spend months at a time in open trenches filled with human and animal waste. The war is largely at a detente, with few real gains or losses. Except, that is, for loss of life. New weapons like tanks and flamethrowers increase the lethality of combat. Chlorine gas, it’s ubiquity a side-effect of burgeoning industrialization, is used for the first time as a weapon. War is hell, and these soldiers, besieged by a new generation of tools of destruction, regularly confront the possibility that the world might actually be ending.

Science can explain how things happen, but poetry is a much more effective at explaining how things feel. I leave it to Wilfred Owen, the ill-fated poet who died just months before the armistice was signed in November of 1918, to describe the utter horror in his poem, Dulce et Decorum Est.

Bent double, like old beggars under sacks, Knock-kneed, coughing like hags, we cursed through sludge, Till on the haunting flares we turned our backs, And towards our distant rest began to trudge. Men marched asleep. Many had lost their boots, But limped on, blood-shod. All went lame; all blind; Drunk with fatigue; deaf even to the hoots Of gas-shells dropping softly behind.

Gas! GAS! Quick, boys!—An ecstasy of fumbling Fitting the clumsy helmets just in time, But someone still was yelling out and stumbling And flound’ring like a man in fire or lime.— Dim through the misty panes and thick green light, As under a green sea, I saw him drowning.

In all my dreams before my helpless sight, He plunges at me, guttering, choking, drowning.

If in some smothering dreams, you too could pace Behind the wagon that we flung him in, And watch the white eyes writhing in his face, His hanging face, like a devil’s sick of sin; If you could hear, at every jolt, the blood Come gargling from the froth-corrupted lungs, Obscene as cancer, bitter as the cud Of vile, incurable sores on innocent tongues,— My friend, you would not tell with such high zest To children ardent for some desperate glory, The old Lie: Dulce et decorum est Pro patria mori.





It’s in this world that a new sort of flu appears. It’s more virulent and deadly than any that has come around in human memory. The first cases are reported simultaneously in multiple locations. There’s some in France, England, the US. They’re reported as medical curiosities by doctors in the field - blood in the sputum, purulent bronchitis, dusky heliotrope cyanosis - the side effect of a patient drowning in their own lungs.

Because the war is still going, and casualties are higher than they’ve ever been in another armed conflict, there’s no time for these doctors to institute reasonable quarantine measures. Those that are so sick they can’t keep on their feet are in the field hospital - everyone else? They’re out in the trenches, quietly spreading the infection. Troop movements, an overall lack of sanitation, a lack of consideration for a more lethal version of a common ailment all contributed to the wildfire spread of the virus. Over the course of the next year, more people would be dead of the flu than died in the Great War.

How does a virus appear out of nowhere?

The frustrating answer is that we can’t really say. The war consumed attention resources to such a degree that tracing the origins of the pandemic. Combine that with a lack of data on viruses that preceded the 1918 flu, and you’ve got a perfect mystery on your hands.

Our best bet at understanding what happened leading up to the 1918 pandemic comes by way of reconstructions from original data sources. Historians, including J.R. Oxford, cited above, have looked at medical records from the WWI front, and have identified ‘herald waves’ of the virus.

Herald waves are like small eruptions before the big show - usually more deadly than the subsequent pandemic.

They’re more deadly because the virus is new, and people exposed to it have no immunity yet. The virus has managed to find a new host, but still needs to fine tune it’s lethality in order to spread like wildfire. Too harsh of an infection is costly to reproductive fitness, as your host will die before you can be distributed through the community.

As we’ve seen with recent coronavirus pandemics, animals can be viral reservoirs. Under the right conditions, these species-specific infections can mutate in such a way that promotes survival, replication, and transmission inside of a human host. Soldiers at the front were living in exactly the kind of conditions that promote intra-species transmission.

Trenches at the front were often filled with a wet sludge - high water tables would flood them as they were dug, and the muck inevitably filled up with a foul combination of human and animal waste. Since frequent handwashing was inaccessible, transmission of the virus across species lines was almost inevitable, given the oro-fecal transmission of swine and avian influenzas. Another version of events has the virus spreading outward from China, starting the fall of 1917.

The reality is, we can’t pinpoint the origin as well as we can today. What we do know is that influenza infections were widespread by summer of 1918.

The Flu Stalks its Prey

Once the virus had spread through the trenches, it was only a matter of time before it reached the general population. Soldiers, on average, had eight month deployments before being sent on furlough. Those that were healthy enough to be in the trenches were given leave, and they scattered the viral seeds as they went.

The pandemic spread through the global population in three waves (an explanation for the cyclic nature of the flu warrants revisiting in a later article…). The first wave washed across the world in June/July of 1918, and killed about 5/1,000, which gives a total fatality rate of 0.5%. The second wave was the voraciously deadly one - 2.5% of the population died. In certain places, the impact was much worse. Over the course of five days, 72 of 80 Inuit adults died in Brevig Mission, AK. In Philadelphia, 1,000 people a day were dying at the peak of the pandemic.

It’s during this second phase of the pandemic that a strange feature of lethality emerges, one for which there still isn’t a clear explanation. Normally, the majority of flu deaths come from people over the age of 65 and below the age of 1. This gives a U-shaped mortality curve where the people in middle age show the lowest mortality rate. But the 1918 flu was different - it showed a characteristic W-shaped mortality curve. In the fall of 1918, patients between the ages of 25 and 35 were the likeliest to succumb.