Coronavirus is often compared to the Spanish flu of 1918 - the most deadly pandemic in human history, which infected about 500 million people, nearly a third of the global population.

Where did Spanish flu originate? It first erupted in the spring of 1918, but its origin is still unclear - it certainly wasn't Spain. There had been earlier outbreaks in the US and on the Western FrontA 400-plus mile stretch of land weaving through France and Belgium, from the Swiss border to the North Sea., but that information was kept out of the newspapers, to avoid damaging wartime moraleCheerfulness and enthusiasm, especially in a time of suffering. , while the neutral Spanish reported an outbreak as it happened. The original source may have been Camp Funston in Kansas, where the first cases were officially recorded in March 1918; or the British Army's vast, transit camp in Etaples in northern France; or Shanxi province in China, where there was a flu-like epidemic in 1917. At any rate, by mid-April 1918 it had reached the Western Front. It came in three waves: a second and more deadly variant of the disease struck Europe, the US, and Africa in August. There was a third outbreak in 1919.

How many people died of Spanish flu? Incubated in barracksA large building or group of buildings used to house soldiers. and carried around the world by soldiers and sailors, it infected an estimated 500 million people - nearly a third of the global population. Estimates vary, but it is thought that 50 million people died - several times the number killed in the war - most of them between September and December 1918. In France, 400,000 people succumbedTo fail to resist pressure, temptation, or some other negative force. to the disease; in the US, more than half a million. It was truly global, affecting every continent except Antarctica. Iran, Brazil, Ghana, and Japan - to name but few - were badly hit. In Western SamoaSince 1997, known as the Independent State of Samoa, located in the South Pacific Ocean. Contact with Europeans began in the early 18th Century., 22% of the population died. Even harder hit were the Alaskan Inuit, with an overall death rate of 25%-50%. Asians died in the greatest numbers. India lost an estimated 17 million people - about 5% of its population.

How did it affect Britain? The first cases appeared in Glasgow in May 1918. Over the following year, the virus killed 228,000 people. Public transport ground to a halt as drivers of cabs, buses, and trains fell ill; burglaries rocketed as police officers went absent; fires raged unchecked due to the shortage of firemen. Hundreds of schools were closed. Throughout Britain, a shortage of undertakers and gravediggers led to bodies lying unburied for days.

Who did the flu kill? Unlike ordinary flu, it struck not just the very young and the elderly, but also a middle cohortA group of people who share a characteristic. of healthy young adults aged 20-40. It preferred men to women - except pregnant women, who were greatly at risk. It struck hard at the malnourishedWeak and in bad health because of a lack of food, or a lack of food that is good for you., and those living in crowded and unsanitaryDirty or unclean. conditions, but it wasn't limited to them. The flu's famous victims included General Botha, the first premier of South Africa; the French poet Guillaume Apollinaire; the Viennese artist Egon Schiele, and Sir Hubert Parry (composer of George V's coronation music). Survivors included George V himself, Britain's Prime Minister David Lloyd George, American president Franklin D Roosevelt, writer Franz Kafka, Walt Disney, artist Edvard Munch, poet Robert Graves, and Ethiopian Prince Haile Selassie.

What were the symptoms? It began, like normal flu, with a cough, headache, fever, and aching limbs. For most, it stopped there but, for some, it took a virulentExtremely severe or harmful in its effects. form, often killing them in 24 hours. The virus targeted the cells of the lungs and airways, and filled them with blood and fluid; the lips, ears, face, fingertips, and toes would turn blue - a sign of "cyanosis" (oxygen deprivation). In some cases, victims turned purple, or even black. People died struggling to clear their airways of what one doctor called "a blood-tinged froth that sometimes gushed from their nose and mouth".

What are the lessons for today? It's hard to be sure, but it seems that the Spanish flu killed around 10% of those it infected - much higher than Covid-19. But it shows what happens if a major virus outbreak is allowed to run its course. "Pandemics tend to grow exponentiallyExponential growth is when the rate of growth increases steadily over time, for instance by doubling: 1, 2, 4, 8 rather than 1, 2, 3, 4. This kind of growth has the capacity to lead to dramatic changes over relatively short time spans. to begin with, then to peak and burn out" because the virus either kills people or leaves them more or less immuneAble to avoid particular infection., says Laura Spinney, author of Pale Rider, a history of the pandemic. The main lesson, according to another historian of the subject, John M. Barry, is: "Tell the truth." In Britain and the US, the authorities were determined not to cause alarm and so, for instance, allowed ArmisticeA truce or agreement to stop fighting for a certain amount of time. Day celebrations and parades to go ahead. The public health measures we see today across the world - isolating victims, banning public gatherings, limiting people's movement - are one of the Spanish flu's most enduring effects.

Western Front - A 400-plus mile stretch of land weaving through France and Belgium, from the Swiss border to the North Sea.

Morale - Cheerfulness and enthusiasm, especially in a time of suffering.

Barracks - A large building or group of buildings used to house soldiers.

Succumbed - To fail to resist pressure, temptation, or some other negative force.

Western Samoa - Since 1997, known as the Independent State of Samoa, located in the South Pacific Ocean. Contact with Europeans began in the early 18th Century.

Cohort - A group of people who share a characteristic.

Malnourished - Weak and in bad health because of a lack of food, or a lack of food that is good for you.

Unsanitary - Dirty or unclean.

Virulent - Extremely severe or harmful in its effects.

Exponentially - Exponential growth is when the rate of growth increases steadily over time, for instance by doubling: 1, 2, 4, 8 rather than 1, 2, 3, 4. This kind of growth has the capacity to lead to dramatic changes over relatively short time spans.

Immune - Able to avoid particular infection.

Armistice - A truce or agreement to stop fighting for a certain amount of time.