Until recent publications the 1918 flu presented two unusual problems that were never fully understood. The age of those effected and the extreme number people who died from the flu.
The 1918 flu pandemic seemed to affect people in the prime of life. The age bracket that suffered the most was said to be between 20 and 40 years old. Recent publications suggest a an age group from age 25 to 30 years old. Prior to 1918 and after 1918 the population age most effected by the flu was the very young and the very old.
The other puzzling affect of the 1918 flu was the extreme number of people who died resulting from this pandemic. Many consider this flu epidemic to have two or even three phases of involvement. The first phase was relatively mild. The second phase was noted in the fall of 1918 when the flu was reported to have returned to the United States in a more virulent manner killing many people. It was said that people were healthy in the morning and dead by night. One common belief was the virus had mutated in Europe and returned to the United States. The virus was more virulent. The disease and the immunological system of the host created a lethal storm within the patient. The third phase returned later in the year. It was not nearly so severe as the flue in the fall of 1918.
Although viruses were known before 1900, not much was understood about them. In the late 1990’s genetic sequencing of viruses began to have a significant effect on understanding viruses. These studies, and the development of a molecular clock to help determine growth rate and development rate within various animals, has allowed scientists to determine when certain viruses developed and their pathogenicity.
In 2014, Dr. Michael Worobey, a professor of Ecology and Evolutionary Biology at Arizona University, was filmed discussing the origin of the 1918 flu virus, and why it was so severe on young adults aged 20-40 and in particular those between 18-30. His work suggest that the H1N1 virus just didn’t jump into humans in 1918, but existed for about 7-10 years previous to 1918. Furthermore, the severity of the flu was from a mismatch between the surface antigens (H & N) of the virus and prior immunity of the host in certain age groups. One thing! Most people are infected with a flu virus by age 5 and this event determines a person’s immunity to the flu for life.
For those wanting an in-depth look at this research on immunology and H1N1 viruses, watch Dr. Worobey’s YouTube presentation, “The Genesis of the 1918 Spanish Influenza Pandemic.”
It seems, according to Dr. Worobey, that within each 100 year period generally there are three pandemics in the world due to flu viruses. The 1918 flu virus was known as H1N1. The H and the N are two surface proteins that are involved in the immunology of various flu viruses. The H is a Hemagglutinin protein and the N is a Neuraminidase protein. The H is what allows the virus to enter the host cell and the N allows the new viruses within the host cell to exit.
AFIP (The Armed Forces Institute of Pathology, which is no longer functioning) had specimens dating back to the Civil War and in 1997 a virologist, Dr. Peter Hultin went to Brevig Mission, Alaska to gather lung tissue from a mass grave where in 1918, 90% of the town was buried due to dying from the 1918 flu. From this tissue Jeffery Taubenberger and his scientists were able to determine the entire genome of the 1918 flu virus. Also, using pathology specimens from AFIP, Brevig Mission, and other sources, it has been possible to identify the various pandemic flu viruses which explains clearly why this disease in 1918 was so destructive to young adults.
These young adults had no immunity to the H1N1 virus. Below is an attempt to demonstrate this.
From 1830 to 1847 the prevailing flu virus was H1N1. In 1918 these people were in their 70’s and 80’s and they had full immunity.
From 1847 to 1889 the prevailing flu virus was H1N8. In 1918 these people were 30 to 70 and because the had been exposed to the H1 protein they had partial immunity.
From 1889 to 1900 the prevailing flu virus was H3N8. In 1918 these people were 18-30 and THEY HAD NO IMMUNITY to the H1N1 flu virus.
From 1900 to 1918 the prevailing flu virus was H1N8. In 1918 again these people were under 20 and they had partial immunity.
Those in the military were under severe situations that would lower ones natural immunity and thereby allow any disease or infection to be more severe.