The History of the Spanish Flu, the Pandemic That Killed Millions

The Spanish flu was a virulent influenza that hit the globe in 1918. It broke out in military camps and spread like wildfire, reaching every continent in weeks.

At the time, scientists estimated it had killed 21 million people worldwide. But researchers nowadays believe the real death toll was higher, probably between 50 and 100 million people (around 5% of the world’s population), making it the deadliest pandemic the world has ever seen. Here is the history of the Spanish flu.

What was the Spanish flu?

Black and white picture. A nurse and a doctor in military uniform stand next to a bed-ridden patient. They both wear face masks.
The Spanish flu killed from 50 to 100 million people worldwide. Army Hospital #4, Fort Port, New York, during the pandemic. 1918. (Photo: National Archives and Records Administration/Public domain)

The Spanish flu was a respiratory disease.

The virus is related to common influenza, and it too attaches to the airways of the host, including the lungs, and inflames them.

But this variation of the virus (called H1N1) was new among humans; it had probably recently jumped from either birds or pigs to humans.

Since humans did not have any immunity against it, it wrecked havoc in their respiratory systems.

The Spanish flu had unusual symptoms, was highly contagious, quite deadly, and, unlike seasonal influenza which circulates during the Winter, it did not respect the seasons.

The pandemic broke out in the Spring of 1918 and only lasted a year. Although it was not always present during that time. It came and went in three waves, with the second wave being the deadliest.

What were the symptoms of the Spanish flu?

Most of the people that caught the virus had mild symptoms or not symptoms at all. But others became seriously ill.

At the beginning, the epidemic startled doctors because it came with a vast array of symptoms.

Some recognized it as the flu, since some patients had chills, fever, sore throat, difficulty breathing, cough, and headache.

But other people would bleed through the nose, ears, and even eyes. A German researcher wrote that “hemorrhages occurring in different parts of the interior of the eye” were frequent.

The victims hit the hardest would cough blood and other secretions from the lungs. Within a few hours or days they turned blue (a condition called cyanosis) due to the lack of air. And then died of either bacterial or viral pneumonia (lung inflammation).

A doctor of Camp Devens, a military camp near Boston which was hit by the pandemic during the Fall of 1918, wrote on September 29:

“These men start with what appears to be an ordinary attack of (…) influenza, and when brought to the hospital they very rapidly develop the most vicious type of pneumonia that has ever been seen (…) and a few hours later you can begin to see the cyanosis extending from their ears and spreading all over the face, until it is hard to distinguish the colored men from the white. It is only a matter of a few hours then until death comes. (…) It is horrible. (…) We have been averaging about 100 deaths per day. (…) Pneumonia means in about all cases death. (…)

The Spanish flu was misdiagnosed from Europe to the Americas as cholera, typhoid fever, dengue, meningitis.

The chief pathologist of NYC’s Health Department said: “Cases with intense pain look and act like cases of dengue … hemorrhage from nose or bronchi … paresis or paralysis of either cerebral or spinal origin … impairment of motion may be severe or mild, permanent or temporary … physical and mental depression. … led to hysteria, melancholia, and insanity with suicidal intent.”

Some thought the Spanish flu was the product of biological warfare

And autopsies did little to make the picture clearer. Doctors in France found that the lungs of some of the diseased looked like they had inhaled mustard gas.

Since the flu outbreak happened during the last year of World War I, and the first cases appeared in European trenches and military training camps in the U.S., at some point the Allies thought the disease was a product of biological warfare from the Germans.

It would take doctors some time to understand exactly what they were dealing with, and that it was indeed influenza.

Fine by breakfast, dead by tea time

Outdoors, the street. Four nurses wearing masks carry a stretcher with a body. They are taking it to an ambulance with the Red Cross sign. Three other nurses and the driver look on.
The Spanish flu was swift, someone could fall ill and die within hours. Red Cross members removing a flu victim in St. Louis, Missouri, 1918. (Photo: Wikimedia/Public domain)

The disconcerting disease killed people fast, specially during the vicious second wave.

A victim could die a few hours after the onset of symptoms. Others died after 2 or 3 days.

In the U.S. it was said that a person could fall ill on their way to work and be dead in the afternoon.

The same was said in the UK: someone could be fine by breakfast and dead by tea time (around 4 pm).

Death toll of the Spanish flu

In Britain, the Spanish flu infected 1/4 of the population and killed 250,000 people. In the U.S. 675,000 people died, 455,000 in Nigeria, 400,000 in France, Italy, and Russia each; and 300,000 in South Africa and Mexico.

It killed 18 million people in India, about 6 million in China, and 1.5 million in Indonesia.

13% of the population of Tahiti died (in a month), along with 22% of Samoans, and perhaps up to 22% of all Iranians.

The Spanish flu killed more than 30% of the native inhabitants of Alaska and wiped out entire villages.

Brevig Mission, Alaska, for example, had 80 adults in 1918. The disease hit them in November 15, and five days later, 75 of them were dead. The survivors interred them in a mass grave along with the fallen children.

This flu probably infected about 500 million people worldwide (1/3 of the population).

The only regions spared were two islands in Fiji and Marajo, a remote island on the mouth of the Amazon river, in Brazil.

The rest of Brazil, though, was not that lucky. At least 180,000 of its citizens died. Even Brazil’s president, Francisco de Paula Rodrigues, caught the Spanish flu. He had just been reelected for a second term, but died from it in January 1919 before assuming office.

Unique characteristics of the Spanish flu

Age: the Spanish flu killed the young and healthy

One of the most unique features of the Spanish flu was that it killed young, healthy adults; unlike most flu viruses which hit children and seniors the hardest, since hey have weaker immune systems.

But during the pandemic 99% of all cases were under 65.

And the 20-40 age group disproportionately accounted for more than half of the deaths.

A Swiss doctor wrote that he “saw no severe case in anyone over 50.”

Scientists have speculated about that for decades, wondering if the older population was immunized because they had been exposed to a nasty flu outbreak in 1889 (which killed 1 million people), or if it was because the Spanish flu hit military camps in which most soldiers were in their twenties and thirties.

But those hypothesis were somewhat discredited when a first-cousin of the Spanish influenza, (H1N1)pdm09, spread through the world in 2009. Like the Spanish flu, it belongs to the family of H1N1 viruses. And it too targeted young adults and skipped people older than 65.

Another explanation for the young death toll could be that the 1918 virus triggered a severe response from the immune system. Since young adults have stronger immune systems, their over-zealous response caused severe inflammation in the lungs -where the virus was attached-, which more readily led to pneumonia and death.

But that is just a hypothesis. Why it killed mostly the twenty-thirty year-olds remains a mystery.

Seasons: every season was Spanish flu season

This flu circulated during all seasons, including Spring, Fall, and even Summer, while most flus limit themselves to Winter.

The Spanish flu was present in all seasons, although it did slow down during the Summer. The chart shows the three waves in the UK, with the death toll of each. The first wave was the mildest and the third wave -that lasted from September to December in the UK-, the deadliest. (Photo: CDC/Public domain)

The first wave of the Spanish flu began in Spring 1918 and lasted until early July.

The second wave, very oddly, reappeared in the world at the end of no other than Summer (end of August) and was deadliest during the Fall of 1918.

And the third wave had gotten the memo and did follow a flu-like pattern, beginning in the middle of Winter and ending during the 1919 Spring.

Some believe there were a few milder waves in 1920, but by then humans were immunized against the virus and the mortality rates remained low.

The high mortality and contagiousness of the Spanish flu

The new virus was quite contagious. Every person that had it during the second wave passed it on to an average of 3,75 other people.

In contrast, the common flu is transmitted to 1,3 other people (while Covid-19 is spread to 2,5 people).

Furthermore, in cramped spaces, the contagiousness doubled: one person could infect 7 or more.

That explains how the Spanish flu was so successful in WWI conditions which saw tens of thousands of soldiers cramped in military camps, ships, trains, and the front line.

And when those soldiers moved en masse from one continent to another, they spread the virus everywhere.

The virus was also far deadlier than the normal flu, which kills 0.1% of the infected. For the Spanish variety killed an average of 2.5 to 5% of the sick -although the death rate varied greatly from country to country.

In the U.S. military camps, which kept more accurate records, an average of 5% of the sick died. While in some communities, like villages in Alaska, the death rate was of 90%.

Did the Spanish flu really come from Spain?

Picture of a newspaper.
Spain’s press was not censored during the war so they were the first to report the outbreak. This Spanish newspaper, published on May 28, 1918, reads: “The three-day fever. There are 80,000 infected in Madrid. His majesty the king is sick.”

In spite of its nickname, the pandemic did not begin in Spain.

The thing is that in 1918 most countries were involved in the war, and their press was under heavy censorship to keep up the morale.

In contrast, Spain was neutral.

So when the flu hit them in late May 1918, and King Alfonso XIII caught the virus, the Spanish newspapers reported the situation freely and widely.

The news reached the warring countries which, unaware the epidemic had been ravaging their own military camps for two months, thought Spain was ground zero for the flu.

Nevertheless, after dozens of painstaking studies, scientist now believe there are three possible places where the epidemic could have begun -and none is Spain. The possible culprits are France, the United States and, less likely, China.

Read more: Spanish flu: The real origin of the 1918 pandemic

Key to the spread of the Spanish flu: the war

The flu spreads because of the wartime overcrowding

The military camps across the U.S. and Europe were the ideal breeding ground for the virus. Hundreds of thousands of soldiers lived in closed quarters making it easy for the flu to spread.

The U.S. went from having 375,000 soldiers before it entered the war to 4,7 million in 1918. All those soldiers lived in crowded training camps. Then they were sent to Europe in crowded ships and trains, and finally lived in the war zone in more crowded camps.

Usually, diseases that are this virulent, that kill someone in a few hours, are not all that successful. Since the person dies fast, he/she does not have much time to pass it on to anyone else.

But with the overcrowding, the virus could be swift and still infect hundreds.

Not enough doctors and nurses, they are at the front

Once the virus spread to the civilian population, another war-related condition helped it succeed. Many doctors and nurses had been drafted for the war effort.

In the U.S., for instance, 30% of the medical personnel was serving in the military. So when the towns and cities got hit, institutions like the Red Cross had to call for volunteers to act as nurses.

And countries at war, like the UK and the U.S., had to call their medical students to fill in for the doctors.

The censored media cannot report the epidemic

The countries involved in WW1 were under a news blackout. And their public officials were under pressure to keep up the morale.

In the U.S., President Woodrow Wilson created the Committee on Public Information (CPI) to spread pro-war propaganda.

After catching the CPI spinning several lies, the New York Times called it “the Committee on Public Misinformation.”

The CPI was based on the ideas of Arthur Bullard who infamously quipped: “Truth and falsehood are arbitrary terms… The force of an idea lies in its inspirational value. It matters very little if it is true or false.”

Truth was to be replaced by a narrative that supported the war effort.

Wilson had Congress pass the Sedition Act, which forbid people to say anything pessimistic, claim for peace, or talk against the government. Those things were considered treasonous and perpetrators were imprisoned for 20 years. Everyone was gagged.

All the countries at war were under similar censorship conditions.

It was not the time to report a nuisance like an epidemic decimating the population. It would bring down the morale. And the public official or newspaper that dared break the news could end up behind bars.

It is in that atmosphere that one of the oddest episodes of the Spanish influenza took place.

A parade to fund the war spreads the disease
Aerial view of a wide street flanked by tall buildings. Cars and soldiers move along the street as part of the parade. Thousands of people crowd the sidewalks to watch them
Philadelphia did not cancel its fund-raising parade. And ended up being the city with the second-highest death rate in the U.S. Pictured Philadelphia’s parade, September 28, 1918. (Photo: U.S. Naval History and Heritage Command/Public domain)

One of the cities where hiding the truth wrecked havoc was Philadelphia.

Boston was already suffering greatly from the epidemic. And a ship from Boston arrived in Philadelphia in early September 1918. Some of the sailors were sick, but Philadelphia’s Director of Public Health, Wilmer Krusen, told the citizens there was nothing to worry about.

The next day, two sailors died. Krusen said they died from the common flu.

The following day, 14 more sailors were dead. Papers and authorities claimed in unison that there was no cause for alarm.

The city had a parade planned for September 28 to raise funds for the war. Doctors begged public officials to stop it and wrote letters to the newspapers explaining why it had to be cancelled.

The letters were not published and the parade went on.

It was a massive event with 200,000 attendees, the largest in the city’s history.

Two days after the parade, the epidemic was ravaging the city. Krusen himself conceded that the situation was starting to look like the one in military camps. He finally started closing schools and banning gatherings.

But two weeks after the parade more than 800 Philadelphians were dying every day.

Corpses remained in the houses for days. Horse-drawn carriages, driven by priests, circulated through the city day and night, calling the citizens to bring out their dead. The bodies were piled up and taken to mass graves.

Cold-storage plants were used as morgues. Companies donated crates to serve as coffins.

About 20,000 Philadelphians died, most of them during the six weeks following the parade.

In New York City too, the health commissioner said the illness circulating through his city was the common flu, and not the “so-called Spanish influenza.”

Philadelphia had the second-highest death rate in the country. And New York was among the U.S. cities worst hit by the pandemic (30,000 plus deaths), along with Boston, which had held a parade of its own.

Public official’s lies lead to a higher death rate and panic

The authorities were saying one thing, but the townspeople were experiencing another. Their family members and neighbors were dying with pneumonia and hemorrhages.

Panic set in in the cities were truth was withheld.

And when authorities finally recognized the emergency and asked for help -like in Philadelphia where they asked for families to temporarily take in the orphans or for women to volunteer as nurses- the citizens did not answer the call. Instead, they shut themselves up in their houses fearing their elected officials.

In other towns were the authorities were frank about the situation from the beginning, like in St. Louis, the citizens volunteered as nurses and helped the authorities shoulder the crisis. Panic did not set in, either. And the death rate was much lower, probably because the appropriate measures were taken in time.

Lack of treatment, vaccines, and antibiotics to combat the flu

The poster reads: "Epidemic influenza (Spanish). This disease is highly communicable. It may develop into a severe pneumonia. There is no medicine which will prevent it." And then lists some social distancing measures to curve it, like avoiding gatherings.
Poster from Alberta, Canada, 1918. (Photo: Alberta Board of Health/Public domain)

Once someone was sick, there was really little doctors could do for him/her.

Back then there were no flu vaccines, anti-viral drugs to fight viruses, or antibiotics to combat the bacterial pneumonia that could set in.

They did not have ventilators either to help those with pneumonia breathe.

Doctors did try every treatment under the sun, from drugs to bloodletting. Some did nothing, one had some success (see below), and some were even harmful.

Among those that did more harm than good was aspirin.

The U.S. Surgeon General, among others, prescribed 30 gr of aspirin a day to treat the disease. Turns out that dosage was probably deadly. Nowadays the maximum recommended amount is 4 gr per day.

And the symptoms of aspirin intoxication are similar to those of this flu: hyperventilation and lungs fill with fluids.

So some flu patients may have actually died from the dosage.

Famous people that caught the Spanish flu

The Spanish king and the president of Brazil, mentioned above, were not the only head of states to catch the virus.

The prime minister of the UK, David Lloyd George; King George V of the UK; Kaiser Willhelm II of Germany; Haile Selassie I, emperor of Ethiopia; U.S. president Woodrow Wilson; future U.S. president Franklin D. Roosevelt; and the future president of Turkey Mustafa Kemal Atatürk all caught the flu and survived it.

So did Mahatma Gandhi, Walt Disney, comedian Groucho Marx, writers Franz Kafka and TS Eliot, painters Georgia O’Keeffe and Edvard Munch, aviator Amelia Earhart, actress Greta Garbo, and Pulitzer Prize winner Katherine A. Porter.

Others were not as fortunate and died from the flu, like famous Austrian painters Gustav Klimt and Egon Schiele, French poet Guillaume Apollinaire, the queen dowager of Tonga Anaseini Takipo, the prime minister of South Africa Louis Botha, and Princes Umberto and Erik, from Italy and Sweden, respectively.

Read also: 18 celebrities that tested positive for coronavirus

What worked against the Spanish flu

Plasma transfusions

Among the medical treatments, the only one that had some effect was the plasma transfusion.

When a virus infects a person, their body fights off the intruder by creating specific antibodies. After the virus is beaten, the antibodies remain in the blood.

So the idea is to inject those ready-made antibodies into the bloodstream of someone that is sick to help them fight the virus.

It is a treatment being used nowadays to fight Covid-19.

Social distancing and lockdowns

Social distancing rules and lockdowns were the best tools against the pandemic.

The chart shows the mortality in 4 U.S. cities and when each began implementing social distancing rules. The two cities that implemented them before having any cases, St. Louis and Seattle, had lower death ratios. (Photo: Peaceray/CCBYSA.4.0)

The towns that shut themselves up and prohibited or quarantined incoming visitors, banned gatherings, and closed schools and the like, were the ones that weathered the storm with few casualties.

Or in the case of Gunnison, Colorado, had zero casualties, in spite of all the surrounding towns reporting deaths from the flu.

Shishmaref, Alaska, and American Samoa also went for a total lockdown and escaped the plague.

For comparison, other villages in Alaska lost up to 90% of their population, and Western Samoa, American Samoa’s neighbor, lost 22% of its population.

In the U.S. each town and city chose how to fight -or not fight- the flu.

San Francisco acted swiftly. Before the second wave of the flu arrived, the authorities quarantined visitors and closed schools, theaters, and bars. When the plague hit them, they had social distancing rules in place and the use of masks was mandatory in public.

San Francisco had relatively few deaths during that second wave (1,800 in a population of 500,000).

But then the flu subsided and the third wave hit them.

This time local business owners refused to comply with the mayor and close their stores, thinking that the masks – and not the lockdown- had saved them the first time. Sadly, they were wrong.

In the first days of January 1919 an average of 20 San Franciscans were dying with the flu every day.

And the mild third wave that elsewhere killed few, in San Francisco killed twice as many as the second wave.

Life during the 1918 pandemic

Many towns and cities shut down to stop the spread of the virus. Witnesses said it was an eerie experience, like walking through a ghost town: the streets were empty and all the stores, closed.

The amount of corpses overwhelmed morticians and gravediggers -many of whom fell ill themselves. So the bodies piled up for days, like in Camp Devens, Boston.

A doctor from Camp Devens wrote to a friend:

“We have been averaging about 100 deaths per day (…) It takes special trains to carry away the dead. For several days there were no coffins and the bodies piled up something fierce (…) It beats any sight they ever had in France after a battle. An extra long barracks has been vacated for the use of the Morgue (…)”

In Baltimore, public employees and soldiers were asked to dig graves.

Many cities, like New York, resorted to burying their dead in mass graves. And Chicago banned public funerals because there were simply too many dead to deal with.

As in Camp Devens, many towns had a shortage of coffins.

Many families dug graves themselves for their relatives.

The hospitals got overwhelmed with the influx of patients, so authorities used schools and other buildings as temporary clinics.

There was garbage in the streets because the drivers and garbage collectors were sick. Mail delivery also suffered. As did the crops, because there was not enough people to farm them.

In some cities the authorities handed masks to everyone so they would be worn in public.

How did the Spanish flu stop?

Illustration showing three scenarios. In the first no one is immunized and everyone gets infected. In the second some people is immunized and most people get infected. In the third the majority is immunized and almost everyone remains healthy.
A chart explaining how people become immune to a disease, which is what eventually happened with the Spanish flu. Photo: Tkacher/CCBYSA4.0)

After a year the lethal flu had run its course and faded during the 1919 Spring.

One of the possibilities is that it mutated into a milder strain.

Also, estimates suggest that 1/3 -or maybe even half- of the world population had caught the bug by 1919. And scientists believe that the survivors probably became immune to the virus.

One of the main reasons that this flu virus was so successful in the first place was because no one was immune to it in 1918, so it could spread from host to host easily.

But when 1/3 or 1/2 of its possible victims became immune, it ran into a wall. It now had few people to infect -not enough to unleash an epidemic.

The legacy of the Spanish flu

A large building
The World Heath Organization’s building in Geneva, Switzerland. The WHO was created after the Spanish flu to keep track of outbreaks. (Photo: Thorkild Tylleskar/CCBYSA3.0)

After the pandemic, the World Health Organization, WHO, was established to track epidemics worldwide and to give guidance in case of an outbreak.

Countries too created internal organization to deal with epidemics, such as the CDC in the U.S. and, later on, the NHS in the UK.

The pandemic also pushed researchers to look for a vaccine for the flu, which was finally perfected in the 1940’s.

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