🦠 Spanish flu: History, causes and fascinating facts

Have you ever heard of the Spanish flu? 🤔
It wasn’t just a simple flu — it was one of the deadliest pandemics in human history, changing medicine and society forever. From 1918 to 1919, this virus spread around the world, affecting millions of lives and leaving behind lessons that are still relevant today 🧬💉.

In this post, you’ll discover everything you need to know about the Spanish flu: what caused it, how it spread, why it was called that, and how it compares to modern pandemics like COVID-19 😷.

Plus, if you’re learning Spanish, you’ll find a list of useful vocabulary and a fun quiz to test your knowledge 🎯.

Let’s travel back in time to 1918! 🕰️

🕰️ What was the Spanish flu?

The Spanish flu was one of the deadliest pandemics in human history, spreading between 1918 and 1919 🌍. It appeared during the final stages of World War I and affected countries across the world.

People wearing masks during the 1918 Spanish flu pandemic

Scientists estimate that around 500 million people were infected — about one-third of the global population at the time 😱.

Despite its name, it didn’t actually come from Spain 🇪🇸 — and that’s part of the mystery we’ll solve below 👇

🧬 What caused the Spanish flu?

The Spanish flu was caused by an H1N1 influenza A virus 🦠.
It probably came from birds before mutating and spreading among humans.

What made this flu different was that it affected young and healthy adults more severely than other groups 😷. Scientists believe this happened because of a cytokine storm — when the immune system overreacts and damages the body itself.

💡 Did you know?

Modern researchers have studied the 1918 virus using preserved lung samples to understand why it was so deadly.

🤒 Symptoms of the Spanish flu

The symptoms appeared suddenly and worsened quickly ⚡.

🤧 High fever

😵 Headache and muscle pain

😮‍💨 Difficulty breathing

😴 Extreme tiredness

🤢 Nausea and loss of appetite

💙 Blue lips or skin (due to lack of oxygen)

Most patients developed pneumonia, which often led to death 💀.

💀 Mortality rate and global impact

The mortality rate was about 2–3%, but because so many people caught it, the total number of deaths reached between 20 and 50 million worldwide 😔.

That’s more than the number of soldiers and civilians who died in World War I.

Entire communities disappeared, and many families lost several members within days 💔.

🌍 Where did the Spanish flu start?

Although it’s still debated, most experts believe the flu started in the United States, not Spain 🇺🇸.

The first cases were reported in Camp Funston, Kansas, in early 1918. From there, soldiers travelling to Europe helped spread the virus. Crowded trenches, hospitals, and trains made it easy for the disease to move quickly 🚂.

Soldiers in World War I wearing masks to protect against Spanish flu

🗞️ Why was it called the Spanish flu?

During World War I, many countries censored their news to keep morale high. Spain, however, was neutral, so its newspapers were free to report openly about the illness 📰.

As Spain was one of the first to talk about it publicly, people assumed it had started there — and that’s how it became known as the Spanish flu 🇪🇸.

💬 Curiosity:

Even the Spanish people called it  la gripe española — the Spanish flu — even though they knew it hadn’t come from Spain!

🧬 Does the Spanish flu exist today?

The original 1918 virus no longer exists. But descendants of the same H1N1 strain still circulate today and sometimes cause smaller outbreaks, such as the swine flu pandemic in 2009 🐷.

Fortunately, thanks to modern medicine and vaccines, we can control these viruses much better today 💉.

💡 What did the world learn from the Spanish flu?

The Spanish flu taught the world valuable lessons:

🧼 Hygiene matters: washing hands and using masks became essential habits.
💉 Vaccination saves lives: countries began investing in research and prevention.
🌍 Global cooperation: the experience led to the creation of public health systems and the World Health Organization (WHO) decades later.

These same lessons were applied again during the COVID-19 pandemic a century later 😷.

🧠 Vocabulary corner (for Spanish learners 🇪🇸)

Here’s a list of useful Spanish words and expressions related to illnesses, symptoms, and recovery — perfect for talking about the flu or a cold 👇

🦠 La gripe – the flu

🤧 El resfriado / el catarro – cold

🤒 Los síntomas – symptoms

🤕 El dolor de cabeza – headache

😴 El cansancio / la fatiga – tiredness / fatigue

🤢 Las náuseas – nausea

😮‍💨 La dificultad para respirar – difficulty breathing

💙 Los labios morados – blue lips (from lack of oxygen)

🌡️ La fiebre – fever

🥶 Los escalofríos – chills

🗣️ La tos – cough

🩺 El médico / La médica – doctor

💊 El medicamento / la pastilla – medicine / pill

💉 La vacuna – vaccine

🧬 El virus – virus

🧼 La higiene – hygiene

😷 La mascarilla – mask

🚿 Lavarse las manos – to wash one’s hands

🚑 El hospital – hospital

🏥 La clínica – clinic

📊 La tasa de mortalidad – mortality rate

💀 La pandemia / la epidemia – pandemic / epidemic

🧍‍♀️ El paciente / la paciente – patient

🛏️ El reposo – rest

🧣 El pañuelo – tissue

👩‍⚕️ El personal sanitario – healthcare staff

📋 El diagnóstico – diagnosis

🫁 Los pulmones – lungs

🩸 La sangre – blood

🦴 El cuerpo humano – human body

🌍 La propagación del virus – virus spread

🙅‍♂️ El contagio – contagion / infection

🪟 Ventilar la habitación – to air the room

😌 Recuperarse – to recover

💡 Tip:   Try creating your own sentences in Spanish, for example:

‘Tengo fiebre y estoy resfriado.’ (I have a fever and a cold.)

🧠 Quiz time! 💬

Here’s a 10-question quiz to check what you’ve learned about the Spanish flu and its vocabulary 👇

💬 What about you?

Did you already know that the Spanish flu didn’t start in Spain? 🇪🇸
Which fact surprised you the most? 🤔
Tell us in the comments — and check out our related articles to keep learning! 👇