The Spanish Flu
The 1918 Influenza Pandemic

The Spanish Flu, also known as the 1918 influenza pandemic, was the most devastating pandemic in history, killing an estimated 40-100 million people - and paling even the Black Plague.

The Spanish Influenza Pandemic of 1918 actually killed more people than died in World War I.

Otis Historical Archives
National Museum of Health and Medicine
1918 Pandemic - Hospital

Emerging quietly in the spring of 1918, the first wave of three waves of the Spanish Flu, hit unexpectedly and started a flu pandemic , a worldwide epidemic, that the world will never forget.

What made this killer flu virus different from other, seasonal flus?

• It was first seen in the spring of 1918—a time conditions are not favorable for flu viruses spreading.

• The 1918 Flu Pandemic came in 3 waves of illness.
  • Spring-summer, 1918 - 1st wave of the 1918 flu epidemic
  • Summer-fall - 2nd wave of influenza, 1918
  • Winter (northern hemisphere) 1918-1919 - 3rd wave of 1918 influenza pandemic

• The second wave of illness occurred from September to November – in both the southern and northern hemispheres. This just does not occur. Each hemisphere has its seasonal flu, which occurs in the colder months.

• The second wave of illness was the most deadly. Scientists speculate that the pandemic flu virus mutated in just months, rather than taking years to make changes. The current H1N1 swine flu virus has shown that it has the ability to change rapidly.

• The flu was most deadly for people in their prime – young adults who were 20-40 years old. Typically, if there are complications from the flu, such as pneumonia, they are seen in older adults over 65 and young children.

• The pandemic flu virus spread readily from person to person. An estimated 25% of Americans got the flu and 20-33% of people worldwide. It spread faster than seasonal flu and infected more people. It was highly transmissible.

• The Spanish flu was more severe and deadly than seasonal flu. It killed 2-20% of the people who got the flu virus. Normal seasonal flu kills about .1% and the current H1N1 has a death rate of .4% (4 times the normal seasonal flu). Bird flu, H5N1, in contrast, has killed over 60% of those who were infected by it.

• Spanish influenza was characterized by severe illness. Many died of what is known as a cytokine storm —it occurs when the body's immune system over-reacts and turns against itself. Death is swift and can be horrible! There are many stories of people who got sick and then died within hours, suffering greatly until they succumbed. Spanish influenza had a high mortality.

• The Spanish influenza virus had not been seen before. It was a novel, unknown virus that seemed to appear from no where. Even though it is believed to have been an avian virus,mixed with human virus, there are no records of birds being found sick or dead before the outbreak.

As you can see, the Spanish Flu of 1918 appeared on the international scene quite unexpectedly. Everyone thought that the flu pandemic was over when the summer came and people stopped getting sick.

But they had only experienced the first wave. What a surprise when the flu virus returned in September—with a vengeance. Thus the second wave of the Spanish flu pandemic began--and the world then experienced the worst pandemic in history. A flu pandemic we will never forget!

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