In 1918, the world was ravaged by twin catastrophes.
World War I was
entering its climactic phase, after four years of calamity, as Allied
armies advanced across Europe to fight the Central Powers. At the same
time, a much smaller enemy was beginning to ravage cities and towns
across the globe.
Nobody is quite sure where the deadly strain of influenza virus that spread like wildfire in 1918 came from. What is known is that the pandemic killed between 17 and 50 million people, and possibly as many as 100 million, making it one of the worst catastrophes in human history.
There were two main waves of the pandemic. The one in early 1918 was similar to seasonal influenza, in that the elderly and those with underlying health conditions were most at risk. But by August, the H1N1 virus had mutated to a far deadlier form.
There are competing theories as to why the second wave of the disease
was so deadly for young people. One explanation is that it caused what
is known as a 'cytokine storm', where the immune system goes into
overdrive to fight the virus and ends up causing pneumonia and raising
the risk of mortality. In this case, a stronger immune system would have
been a liability.
The other theory is that poor hygiene standards in 1918, the lack of a vaccine and many people across the world being malnourished due to the effects of war, plus rapid spread facilitated by the movement of vast numbers of troops during World War I's closing stages were primarily to blame for the enormous death numbers.
The 'Spanish flu' was named such not because it originated in Spain, but because of wartime censorship. Newspapers were not allowed to report extensively on mortality in Allied countries, but Spain was neutral, so they could report on the effects there, thus giving the impression that Spain was particularly badly hit by the flu.
Clancy's comment: Timing was terrible. As if folks had not suffered enough.