Influenza H1N1 virus

The 1918–1920 influenza pandemic, also known as the Great Influenza Epidemic or the Spanish Flu, was a particularly deadly worldwide influenza pandemic brought on by the H1N1 influenza A virus. The first case was reported when "epidemic influenza," often known as "the grip," first surfaced in Kansas in the United States in the late spring of 1918, followed by early reports from Spain appearing on May 21. Both locations reported that it was a "three-day fever." In April, cases were also reported in France, Germany, and the United Kingdom.

Two years later, four subsequent waves of infection had affected over 500 million people worldwide, or close to one-third of the world's population. After the Black Death bubonic plague of 1346–1353, estimates of mortality range from 17 million to 50 million, and possibly as high as 100 million, making it one of the deadliest pandemics in human history.

Give it a name

Newspapers openly covered the pandemic's outbreak in neutral Spain during a time when wartime censors suppressed unpleasant news in the belligerent countries to maintain morale, giving the misleading impression that Spain was the pandemic's epicentre and giving rise to the term "Spanish flu."

The Oakland Municipal Auditorium in use as a temporary hospital. The photograph depicts volunteer nurses from the American Red Cross tending influenza sufferers in the Oakland Auditorium, Oakland, California, during the influenza pandemic of 1918.

From the Joseph R. Knowland collection at the Oakland History Room, Oakland Public Library.

The illness quickly acquired the incorrect term "Spanish influenza" outside of Spain. Without specifically mentioning "Spanish influenza," a correspondent in Madrid reported 100,000 cases of "…the unexplained disease...clearly of a gripal character" in a dispatch from The Times of London dated June 2, 1918, titled "The Spanish Epidemic."

The Times stated in an article published three weeks later that three days later, a Formamint tablet advertisement for "Spanish influenza prevention" appeared in The Times. In Russia, it was referred to as "Ispánka (the Spanish lady) is in town."

Advertisement in The Times, 28 June 1918 for Formamint tablets to prevent "Spanish influenza"

The Times Archive | The Times & The Sunday Times

The outbreak did not start in Spain (see below), but reporting did as a result of restrictions during hostilities in combatant countries. Because Spain was a neutral nation that was not concerned with maintaining an appearance of readiness for battle and lacked a wartime propaganda apparatus to boost morale, its newspapers freely reported the effects of the epidemic, including King Alfonso XIII's illness, making Spain the epidemic's apparent epicentre. Spain's health officials were unaware that its neighbours were also subject to the censorship because it was so successful.

Victims of the Spanish flu as they lie in beds at a barracks hospital on the campus of Colorado Agricultural College, Fort Collins, Colorado, in 1918,

American Unofficial Collection of World War I Photographs/PhotoQuest/Getty Images

First Wave Timeline

There are conflicting theories on the pandemic's initial spread, making the pandemic's origin uncertain due to a lack of historical epidemiological evidence.

Despite there having been cases before him, the pandemic is traditionally regarded as having started on 4th March 1918, when the case of Albert Gitchell, an army cook at Camp Funston in Kansas, United States, was recorded. 


In January 1918, the illness had already been identified 200 miles (320 km) away in Haskell County, prompting local physician Loring Miner to alert the editors of the scholarly journal Public Health Reports of the U.S. Public Health Service. 522 of the camp's soldiers had reported becoming ill in the days following the initial occurrence. The virus had reached Queens, New York, by 11th March, 1918. It was rapidly spreading.

St. Louis Red Cross Motor Corps personnel wear masks as they hold stretchers next to ambulances in preparation for victims of the 1918 influenza epidemic.

Library of Congress via AP

The disease quickly spread from Camp Funston, a crucial training ground for American Expeditionary Forces soldiers, to other U.S. Army camps and Europe after the United States had entered the First World War. 

The disease quickly spread from Camp Funston, a crucial training ground for American Expeditionary Forces soldiers, to other U.S. Army camps and Europe after the United States had entered the First World War.  The remainder of France, Great Britain, Italy, and Spain were soon affected, and Wroclaw and Odessa in May. 

After the Treaty of Brest-Litovsk was signed in March 1918, Germany began releasing Russian prisoners of war, who later spread the disease throughout their nation.

A scientific graph from the 1918 ‘Spanish’ flu pandemic showing mortality rates in the US and Europe.

Public Domain

The first flu wave was only mildly contagious. In the United States, 75,000 flu-related deaths were reported in the first half of 1918, compared to 63,000 during the same period in 1915, indicating that mortality rates were not noticeably above average.

Less than 1,000 influenza-related deaths occurred in Madrid, Spain, during May and June 1918.

The first three months of 1918 saw no reported quarantines. With almost 900,000 sick German soldiers, 75% of the British forces, and 75% of the French troops, the first wave significantly hampered military operations in the First World War.

Black and white poster of a Red Cross nurse with a gauze mask over her nose and mouth. Text next to the image provides public health information "To prevent influenza!" Photograph by Paul Thompson (1878 - 1940).

Published in New Haven, Conn. : Illustrated Current News, 1918.

To prevent influenza! - Digital Collections - National Library of Medicine (

The second wave strikes

The second wave started in the second half of August 1918 and presumably spread by ships from Brest, where it had probably arrived with American troops or French recruits for naval training, to Boston and Freetown, Sierra Leone.

Approximately 30 miles west of Boston, at Camp Devens (later renamed Fort Devens) and the Boston Navy Yard, other U.S. military installations and troops being sent to Europe were soon affected.

Over the course of the following two months, it spread throughout all of North America with the aid of military movements before moving on to Central and South America. Ships also carried it to Brazil and the Caribbean.

The Ottoman Empire first noticed instances in a few soldiers in July 1918.

A graph showing the percentage of people dying in US cities from the 1918 flu pandemic.

Public Domain

Emergency hospital during influenza epidemic, Camp Funston, Kansas. Emergency hospital during influenza epidemic, Description: Beds with patients in an emergency hospital in Camp Funston, Kansas, in the midst of the influenza epidemic. The flu struck while America was at war and was transported across the Atlantic on troop ships. Date: circa 1918.

National Museum of Health and Medicine

The pandemic began in Freetown and continued to spread throughout West Africa along the coast, rivers, and colonial railways as well as from railheads to farther-flung communities. In September, it arrived in South Africa on ships carrying South African Native Labour Corps members who had just returned from France.

In November, it reached Ethiopia after spreading from there throughout southern Africa and beyond the Zambezi. New York City experienced its first influenza-related fatality on September 15. A severe outbreak of the illness spread among those who had attended the Philadelphia Liberty Loans Parade, which was conducted in Philadelphia, Pennsylvania, on September 28, 1918, to support government bonds for World War I, and led to 12,000 deaths.

Seattle policemen wearing cloth face masks handed out by the American Red Cross during the Spanish flu pandemic, December 1918.

The Influenza Epidemic of 1918 (

The second wave originated in Europe and swept through Russia in a southwest-northeast diagonal front, reaching Iran (where it spread through the holy city of Mashhad), and then spreading throughout Asia after the Russian Civil War and the Trans-Siberian railway, reaching India in September, China, and Japan in October.

Lima and Nairobi experienced outbreaks in conjunction with the 11 November 1918 Armistice celebrations, but by December the wave had mostly passed.

The second wave caused a lot more deaths than the first. The initial wave had resembled a conventional flu epidemic; the sick and old were most at risk, while younger, healthier individuals quickly recovered. The pandemic's peak fatality rate occurred in the month of October 1918.

A bar chart showing the relative number of deaths in US cities from the flu pandemic. 

Public Domain

Extract of letter from nurse to her friend at the Haskell Indian Nations University, Kansas, 17th October 1918. Bureau of Indian Affairs.

In this letter, a volunteer nurse assigned to various military bases, writes to friend about her experiences. Her initial reaction to death is a window into a personal experience, rather than an official report: "the first one [officer] that died sure unnerved me-I had to go to the nurses' quarters and cry it out."

volunteer-nurse-letter.pdf (

Between September and December 1918, 292,000 deaths were reported in the United States, compared to 26,000 deaths during the same time period in 1915.

More than 40,000 deaths from influenza and acute respiratory illnesses were documented in the Netherlands. In Bombay, which has a population of 1.1 million, 15,000 people have died. An estimated 12.5–20 million people died from the 1918 flu epidemic in India alone in the final quarter of that year.

Children wearing masks during the Spanish Flu pandemic in 1918, many of which continued to attend school during the outbreak.

Canmore Museum

Third Wave of 1919

After a marine quarantine was lifted in Australia in January 1919, the third wave of the flu soon moved to Europe and the United States, where it persisted through the spring and into June 1919, killing between 12,000 and 20,000 people.

In comparison to other nations at the time, Australia's death rate of 2.7 per 1000 people was among the lowest. Nevertheless, up to 40% of the population was infected, and certain Aboriginal communities saw a mortality rate of 50%.

An pneumonia porch at the U. S. Army Camp Hospital in Aix-les-Bains, France, during the Spanish Flu epidemic of 1918-19. Most flu deaths were of healthy young adults, who died from bacterial pneumonia, a secondary infection caused by the influenza.

Everett Collection Art - Pixels

The third wave killed hundreds of thousands of people worldwide, mainly in Spain, Serbia, Mexico, and Great Britain. Although it wasn't as bad as the second wave, it was still a lot deadlier than the first wave. A few American cities, including Los Angeles, New York City, Memphis, Nashville, San Francisco, and St. Louis, experienced localised epidemics. During the first half of 1919, there were tens of thousands of deaths in America.

Walter Reed Hospital, Washington, D.C., during the great Influenza Pandemic of 1918 - 1919, also known as the "Spanish Flu". Patients are set up in rows of beds on an open gallery, seperated by hung sheets. A nurse wears a cloth mask over her nose and mouth.

Harris & Ewing photographers - Photo by Harris & Ewing via Library of Congress website

1920: Fourth outbreak

Throughout the spring and summer, there were a spate of isolated or solitary instances of flu being reported across the United States.

Even though there had been an increase in isolated cases since September, Chicago began to see one of the first significant flu outbreaks in the middle of January.

Days after Chicago's rapid increase in cases, it was clear that the flu was spreading there even more quickly than it had in winter 1919, though there were fewer fatalities.

The number of new cases in the city surpassed the peak of the 1919 wave within a week. New York City started to experience a dramatic rise of cases around the same time, and other cities throughout the nation quickly followed.

Poster advising what precaution to take to prevent spreading catching and spreading Spanish Flu, 1920.

Broadside : 12421 (

At a free community clinic, patients wait for a doctor’s attention. Palestine, 1920.

JDC during the Time of the Spanish Flu (1918–1920) | JDC Archives

In cities like Chicago, Memphis, and New York City, certain pandemic restrictions—including the closure of schools and theatres and staggered business hours to reduce congestion—were reinstated in the hope they would help restrict the spread of the flu.

The fourth wave in the United States peaked in early February before dissipating as quickly as it had risen. Data at the time showed that the outbreak caused one-third as many deaths as the events of 1918–1919. Between December 1919 and April 1920, New York City alone reported 6,374 deaths, about twice as many as the initial wave in spring 1918.

Other US cities were particularly heavily struck, with death rates exceeding those of the entire year 1918. These cities included Detroit, Milwaukee, Kansas City, Minneapolis, and St. Louis.

Early in 1920, when the pandemic reached its height in the Territory of Hawaii, 1,489 people there died from flu-related causes, compared to 615 in 1918 and 796 in 1919.

Similarly, Nenana, Alaska, missed the worst of the epidemic for the first two years, but by May 1920, the town had been overrun by an outbreak.

According to reports, the majority of the town's residents contracted the disease within the first two weeks of the month; 10% of the population is thought to have perished.


A Philadelphia streetcar is shown during the pandemic adorned with the 'Spit spreads death' sign, reminding people of the dangers of infection.


A fourth wave also occurred in a number of locations in the winter and spring of 1920, including Switzerland, Scandinavia, Mexico, and some South American islands. In contrast to the peak of 92 deaths in December 1918, Poland saw a devastating outbreak over the winter months. However, the 1920 pandemic vanished in a matter of weeks, whereas the 1918-1919 wave had evolved during the entire second half of 1918.

"Coughs and Sneezes Spread Diseases - As Dangerous as Poison Gas Shells". U.S. Public Health ad on dangers of Spanish Flu epidemic during World War I.

Western Europe, in contrast, experienced a "benign" outbreak, with the age distribution of fatalities beginning to resemble that of a seasonal flu. Between January and April 1920, five European nations—Spain, Denmark, Finland, Germany, and Switzerland—recorded a late high. Early 1920 saw a late wave in Peru, and late 1919 to early 1920 saw one in Japan, with the last cases occurring in March.

By 1920, the pandemic virus had developed into a far less dangerous strain that only caused seasonal flu going forward. Deaths had reached pre-pandemic levels by 1921.

A group of people standing outside are shown wearing masks during the pandemic. One woman wears a sign saying, 'wear a mask or go to jail.'

Niday Picture Library/Alamy


This pandemic featured extremely high mortality rates for young adults, unlike other influenza epidemics, which disproportionately kill the young and the old with a higher survival rate in between. The high fatality rate has numerous explanations from scientists, including a six-year climate anomaly that affected disease vector migration and increased the possibility of disease dissemination through bodies of water.

Comparison of the different waves of Spanish Flu across the globe.

Lessons from the 1918-1919 Spanish Flu Pandemic in Africa – Africa Center for Strategic Studies

Although the viral infection appeared to be no more aggressive than earlier influenza strains, the virus was particularly deadly because it sparked a cytokine storm, decimating young people' stronger immune systems. Malnutrition, overcrowding in hospitals and medical camps, and inadequate hygiene, all made worse by the war, encouraged bacterial superinfection, which led to the majority of victims passing away after a generally protracted time on their deathbeds.


Doctors would rely on a haphazard collection of drugs with varying degrees of effectiveness, such as aspirin, quinine, arsenics, digitalis, strychnine, epsom salts, castor oil, and iodine, since there were no antiviral drugs to treat the virus and no antibiotics to treat the secondary bacterial infections. Traditional medical practices like bloodletting, ayurveda, and kampo were also used as treatments.

Impact on the First World War

Having such a devastating disease running amok across Europe while the First World War was occurring would have inevitably impacted on the various warring sides to some degree.

  • An increase in soldiers unable to fight due to them catching the flu.
  • Tired and weakened troops being more susceptible to the disease in the first place.
  • The increased strain on medical units to cope with an influx of non-battlefield patients.
  • Poor sanitation and living conditions.
  • Wandering refugees acting as carriers for the disease and they moved from area to area seeking shelter.
  • An absence of effective precautions or preventative measures.

All would have had an impact.

Report on staffing crisis at military depot in Philadelphia, October 8, 1918. Office of the Quartermaster General. The flu was highly contagious and spread rapidly, as documented in a military report notifying the Office Quartermaster General in Washington D.C., of a staffing crisis. The report notes 11 officers and 1,489 employees "absent today," with the situation not improving.

The economy

While many companies in the leisure and service sectors reported revenue declines, the healthcare sector experienced profit increases. The pandemic and the rise in female college enrollment, according to historian Nancy Bristow, were both factors in the success of women in the nursing profession.

This resulted in part from the majority-male medical professionals' failure to control and stop the disease. The majority-female nursing staff took pride in providing successful patient care and did not link the disease's spread to their jobs.

Life goes on: A baseball player wearing a mask during the Flu epidemic of 1918.

George Rinhart/Corbis via Getty Images


Eventually, the Spanish Flu began to fade from the public consciousness, overshadowed by the First World War and its aftermath. As terrible as the flu was, its horror was overshadowed by the four years of death and destruction which dominated the media and remained firmly in the public eye. When people read the obituaries, they saw the influenza deaths next to the war or postwar dead. The virus may not have had a significant psychological effect or may have appeared to be a continuation of the war's horrors, especially in Europe where the war's toll was great.

The length of the pandemic and the conflict may have also had an impact. Normally, the sickness would only stay in one place for a month before moving on. But even though it was initially anticipated that the conflict would end quickly, it had already been going on for four years when the epidemic began.

This has led some historians to refer to the Spanish flu as the “forgotten pandemic".

Further reading



Photo ID: NCP 1603 Source Collection: OHA 250: New Contributed Photographs Collection, Otis Historical Archives, National Museum of Health and Medicine.



Red Cross

New York Times

National Geographic

Los Angeles Times

Nancy K Bristow

American Unofficial Collection of World War I Photographs/PhotoQuest/Getty Images

George Rinhart/Corbis via Getty Images

Harris & Ewing photographers - Photo by Harris & Ewing via Library of Congress website