A big effect of the Spanish flu was the number of deaths worldwide because of the unadvanced technology. Since there weren't any vaccinations nor medicine to help out the ill, it led to the death of millions. The flu killed more people in the United States than World War I, World War II, the Korean War, and the Vietnam War combined.
Amount of deaths in different countries.
Nurses Wanted! Advertisement in The St. Mary Banner, October 12, 1918. (Library Of Congress)
"Thousands of nurses took ill during the pandemic, and hundreds of nurses died." - National Archives
"The decline in economic activity combined with elevated inflation resulted in large declines in the real returns on stocks and short-term government bonds. For example, countries experiencing the average death rate of 2 percent saw real stock returns drop by 26 percentage points. The estimated drop in the United States was much smaller, 7 percentage points." - National Bureau of Economic Research
An advertisement in the October 17 Times-Picayune admonishes readers to stay home.