The History of Flu Pandemics In the 20th Century

Pandemic flu: virulent human flu that causes a global outbreak, or pandemic, of serious illness. (Center for Disease Control).

In the 20^th century, the United States and the world have been faced with influenza pandemics or the threat of pandemics. These pandemics differ from the seasonal or common flu in that there is little natural immunity to pandemic flu while there is some immunity to the common flu and vaccines are available. Each year in the United States, an average of 36,000 people die from the common flu virus.

In 1918, an influenza pandemic, named the Spanish flu, started in Kansas and spread throughout the world. During the course of the pandemic, from 1918 through 1919, it is estimated that up to 50 million people may have died from the virus and secondary infections. In the United States alone, an estimated 675,000 people died. Many of those who succumbed to the disease were younger or middle aged. This was different from statistics regarding the common flu where most of those who die are the elderly or very young. The disease spread quickly among the military and was transferred around the world by the soldiers fighting in World War I. The Spanish flu killed more people than were killed in all of the first World War.

A pandemic of the Asian flu in 1957 through 1958 resulted in the deaths of about 69,800 people in the United States. Health officials reacted to this pandemic with new programs of vaccines and publications about the flu. Initially, there were small outbreaks in the United States during the summer, but when children returned to school in the fall, the disease quickly spread. The vector for this strain of the flu started in the classrooms where children infected each other who in turn infected their families.

The Hong Kong flu pandemic in 1968 was the mildest pandemic during the 20^th century. Approximately 33,800 people in the United States died during this pandemic and most of the victims were over the age of 65. There are a couple of reasons why this pandemic may have not been as virulent as other pandemics. To begin with, it is possible that following the Asian flu pandemic of 1957-1958, people developed some immunity to the Hong Kong flu. Also, the pandemic was gaining speed near the holiday season in December. When schools closed for the holidays, the opportunity for the disease to spread was diminished. In addition, medical care had greatly improved at this time.

There have been threats of pandemic throughout the years where it was feared that the flu virus would spread to pandemic proportions but the pandemic never materialized. In 1976, there was a Swine flu threat that originated at Fort Dix. In part due to a mass vaccination campaign, this strain of flu never spread beyond Fort Dix. The Russian flu was reported in 1977 and affected primarily children. It is thought that the reason children, or those under the age of 23 were primarily affected was that those over the age of 23 may have developed some immunity due to the 1957 Asian flu pandemic.

Most recently, threats of Avian (Bird) flu originated in Hong Kong in 1997 and 1999. This virus spread directly from chickens to people and did not spread easily from person to person. In response to the threat, all of the chickens in Hong Kong were killed. This was approximately 1.5 million chickens. Only 6 people ultimately died from the 1997 threat. In 1999, two children were infected but the virus did not spread further.

The current threat of a flu pandemic is still emerging. Improvements in communications, tracking, and reporting have a number of benefits when facing this new threat. It means that the public are more informed about the spread of the virus and officials are able to respond quickly to new reports. Conversely, containment of the spread of the virus is very difficult because of the prevalence and ease of international travel. How this current threat will play out is yet to be seen.

References

Center for Disease Control and Prevention. 2009. http://www.cdc.gov