The 1918 influenza pandemic, also known as the “Spanish Flu” was a highly contagious and deadly disease.  The virus was H1N1, and caused an estimated 40 million deaths worldwide in less than one year.  From 1918-1920, it killed somewhere between 50 million and 100 million people across the globe; no other event in the past 100 years has had such a negative impact worldwide. 

The graph above shows the Mortality pattern for the 1918 influenza pandemic (red line).  The characteristic “W” curve shows a peak in mortality (death rate) in the 25-35 year age group.  From ages 1-4 the high mortality rate is attributed to the lack of protective antibodies in young children.  The decrease in mortality from ages 5-14 is due to a phenomenon where children can tolerate certain viruses better than adults because of a natural immune response.  From age 15-25, as age increases the virus becomes more severe.  The drop of mortality in the older age group is because of partial protection in people who were exposed to an H1 like virus that circulated before 1889.  The blue dotted line represents what probably would have happened if that same older population did not have this immunology; remote villages in Alaska proved this point because they did not have this immunology and the only people to survive the outbreak were the young.   

On a positive note, today’s health care advances and medical research will make a difference.  Researchers studied the H5N1 virus from Vietnam and Hong Kong and found that the virus will need several additional genetic changes before it is capable of spreading person to person.  By monitoring the mutations of the virus, we can track the virus and have some warning time of when it is able to spread from person to person.  Scientists also studied the 1918 virus and created therapeutics for it.  This advancement may help in the treatment of the next pandemic influenza.  Research also offers clues to the potential source of the outbreak. 

Much has changed in our world since the 1918 pandemic influenza.  Today, more people live with impaired immune systems due to medical advances that allow people to live longer.  Examples of people with suppressed immune systems that could be easily affected by influenza are the elderly, transplant recipients, cancer survivors who have undergone chemotherapy or radiation, and those with HIV.  International trade and travel have expanded immensely since 1918.  This would increase the chances for its spread, as well as the degree of disruption and related stress in our normal lives.   

The World Health Organization (WHO) has shown great competence in controlling recent pandemics.  It identified and contained the 1997 H5N1 outbreak; in 2003 it also contained SARS, which was feared to be a new pandemic influenza threat at the time.  It controlled the H7N7 avian influenza outbreak in the Netherlands, and so far has performed very well with H5N1. 

The main lessons from the 1918 pandemic influenza are to be prepared, educated, and vigilant, and not to forget the basics of good personal hygiene and stopping the spread through hand-washing and social distancing.  In 1918, the influenza outbreak brought terror to people’s homes.  Part of the terror came from people not knowing anything about what was happening—they could not trust public officials or the press.  This fear prevented people from caring for their own family members, and nurses from responding to urgent calls.  Today, we can prevent this type of panic by staying educated, and preparing our families for a pandemic influenza outbreak.