>"In 1918 the flu had a mortality rate of about 3-5%. It killed 5% of the total world population."<
Most flu infections can be attributed to poor sanitation, lack of hand washing, hygiene techniques, etc.
In 1918, many people did not get sick at all.
Flue vaccine immunity is a myth. A vaccine only provides temporary immunity, at best is about 70 - 80 % effective...temporarily. That drops to about 30 - 40 % for people over 65.
There is no reason for someone with a healthy immune system to get a flu shot.
http://www.vaccineinfo.net/immunization/vaccine/influenza/flu_vaccine_facts.shtml
"...70 to 80 percent effective in temporarily preventing the flu of the season in healthy persons less than 65 years old (the efficacy rate drops to 30 to 40% in those over 65 years old but the vaccine is thought to be 50 to 60% effective in preventing hospitalization and pneumonia and 80% effective in preventing death from the flu in the over 65 age group)..."
"One consideration with the mass use of flu vaccine in healthy children is the removal of natural antibodies to flu which are obtained from natural infection. The question of whether it is better for healthy children, who rarely suffer complications from flu, to get the flu and develop permanent immunity to that flu strain or it is better for children to get vaccinated every year to try to suppress all flu infection in early childhood is a question that has yet to be adequately answered by medical science."
Good hygiene can't hurt but it does nothing to prevent catching the disease via airborne droplets expelled though sneezing or coughing. The extremely rapid spread (i.e. hours) of the Spanish flu among troops at military bases can only be explained by airborne transmission.