The pandemic of 1918 was known as the Spanish flu pandemic, an influenza pandemic caused by the H1N1 influenza A virus. Lasting from February 1918 and April 1920, killing more people than the World War I, at somewhere between 20 to 40 million people due to the lack of effective drug or vaccines. The flu was first observed in parts of Europe, the United States and parts of Asia and later spread to other parts of the world. In United States it was first seen in military personnel in 1918.
By 1918 the first world war was coming to an end and the allies were emerging victorious after US entered the war, due to this the early reports of the flu were kept minimal to maintain morale of the people. But newspapers felt free to report the effects of pandemic in Spain which made it seem like Spain especially was impacted badly by the virus, which gave it the name ‘Spanish flu’. Other influenza viruses were life threatening for the extremely young or the older population, but the Spanish flu resulted in higher mortality rate of young adults.
The first wave of the virus in 1918 was mild and the people infected by it showed common flu symptoms such as chills, fever and fatigue and recovered quite quickly, it was the second wave of the pandemic which proved to be deadly. During the second wave, which occurred in the later half of the same year and spread to Russia, Africa, all of North America, Brazil, China and Japan, people started to show symptoms such as skin turning blue and lungs filling with fluid which lead to a persons death within hours or a few days, the virus around this time was highly contagious and took many more lives. The third wave spread far and wide affecting even Australia, it was less severe than the second wave. The fourth wave occurred in 1920 in isolated regions further increasing the mortality rate.
The cause and origin of the Spanish flu is unknown. Some theories point to France, China, Britain, and United States from where the early cases were reported. Some believe that infected soldiers who came back home after the war spread the virus to different countries. By the summer of 1919, the pandemic came to an end in many places and the infected either died of developed immunity. Since 1918 there have been several other influenza breakouts but none as deadly.