The Spanish flu was honestly an utterly fascinating pandemic, in part because it was one of the best-documented pandemics of the early 20th century. The 1918 Influenza, better known in America as the Spanish Flu, changed the landscape of the western world. However, this shall focus mainly on the effects it had on America to limit the scope of the answer. Why did the 1918 Flu stopped spreading? It must be broken down into three parts: what it was, why it spread, and how it died out.
So, what was the 1918 Spanish Flu? In short, it is a highly contagious viral mutation of the illness best known as the flu. Infecting between 3-11% of Americans every year, it usually is not very deadly, primarily killing the elderly, the very young, or anyone else with a comprised immune system. The virus, which mutates and changes often, has various strains with varying levels of severity, in part because it often hops between species.
The 1918 influenza was remarkable because of how deadly it was and how quickly it spread. The most popular theory right now is it was an avian virus that mutated to infect swine, and then onto humans. (Nelson, Worobey 2018, p. 2498). Of course, this is not definitive due to the difficulty in studying such an infectious disease. Especially considering the limited number of viable samples. However, assuming this is true, it can begin to explain why it had a higher mortality rate than most recorded influenza strains. There were other factors at play as well, which also merits consideration.
40 Million Dead From Spanish Flu
From 1914 to 1918, the first world war ravaged the western world, causing around 40 million casualties (Encyclopedia Britannica, 2020). While movies portray the World Wars as glorious and bloody, with young men dying bravely for king and country, the fact is disease killed more people than the fighting ever did. (Diseases in World War I – World War I Centennial, n.d.). Soldiers lived in squalid conditions, that are frankly unimaginable to the modern American. Dead bodies left to rot and fester where they lay, near the trenches that so many soldiers spent months in, knee-deep in mud, little food, and very tight quarters. It was a petri dish of disease and death.
Of course, military hospitals and training camps were barely better. After all, not even a century beforehand, doctors had barely considered handwashing, and it took decades before it caught on in the greater medical community. (Geneva: World Health Organization, 2009). It should be no surprise then that the first recorded case of the 1918 influenza case was in an American military base in Kansas. (Centers for Disease Control and Prevention, 2018). The first wave of the disease was in the spring of 1918, where over the next six months, it spread in small bursts.
Fall of 1918, More Infectious
However, the virus changed around the fall of 1918 when the Spanish flu suddenly became markedly more infectious and deadly. As noted above, influenza viruses are volatile, mutating frequently, which is why there is a new vaccine every year. The virus likely would not have been half as deadly, had it not been for the war. People who would ordinarily never travel farther than a few towns away from where they were born were suddenly going to countries they would otherwise never have seen. The virus was their invisible passenger.
October alone saw almost 200,000 Americans dead, terrifyingly high number. Nurse and doctors were falling like flies; fighting was slowing down in Europe, partly because the soldiers there were too sick or dead to fight (Holmes). And it was getting harder and harder to get new soldiers out on the battlefield- they kept dying in transit. November saw the end of the bloodiest war the world had seen at that point because there were not enough men healthy enough left to fight.
So the Spanish Flu reigned for the next year or so, leaving piles of bodies in its wake. With our background in hand, now the question at hand can be answered. Why exactly did the 1918 pandemic fizzle out? Well, there are three main reasons. First, the end of the first world war had a significant impact on restricting the spread of the disease. It freed up the doctors and nurses who had been serving on the front lines. While it would be easy to assume that the Americans returning home after the armistice would infect those around them, soldiers often remained in military care until recovered from the Spanish flu. This was partly because those afflicted were usually too sick to transport.
Public Health Education
Secondly, public health education programs were profoundly effective, in combination with new laws. Many of the hygienic habits we have today stem from work during the pandemic to promote personal sanitation. (Marisam, 2007, p. 279.2). The National Institute of Health, or NIH (which was founded to fight the 1918 Spanish Flu), promoted, along with local efforts, things like handwashing, wearing masks, social distancing, and not spitting in public. There are a heap of pictures from the period that show the posters, telling citizens to practice what is now basic hygiene.
Finally, the biggest reason the Spanish flu pandemic died out was that the virus mutated. While it is easy to assume the deadlier the virus, the better it is doing for itself, which simply isn’t true. However, if a virus kills all of its hosts, then it no longer has any viable hosts. Instead, the most successive virus is the one that can chill in a host long enough to spread. There is also the fact that virus mutation is luck of the draw. Sometimes the mutation is efficient for survival. Other times not so much, just like humans are sometimes born with harmful genetic mutations.
It also be noted while the exact Spanish flu strain which killed so many during the fall 1918, the flu, and even H1N1 are rarely fully eradicated. It burned itself out too fast. When it mutated, it could not survive against the public health measures people had taken
[Collection of photos from 1918]. (1918). Getty Imagines. https://www.gettyimages.com/photos/1918-flu-pandemic