The Swine Flu Pandemic

I wrote a paper on influenza for one of the classes I took towards the CERA designation. Here's an excerpt:

Influenza is a viral respiratory disease. According the Center for Disease Control and Prevention (CDC), influenza is “spread from person to person primarily through large-particle respiratory droplet transmission (e.g., when an infected person coughs or sneezes near a susceptible person). Transmission via large-particle droplets requires close contact between source and recipient persons, because droplets do not remain suspended in the air and generally travel only a short distance (1 meter or less) through the air.”[i]

During a typical influenza season, less than 20% of the population becomes ill and the excess mortality cause by influenza is approximately 0.013% of the population[ii]. During the 1918 influenza pandemic, the excess mortality was estimated at 0.65%, fifty-times greater than the normal influenza mortality rate. Pandemics occur when the influenza virus mutates into a strain to which the population has little resistance. During the 20th century there have been three influenza pandemics, most recently in 1968.

The influenza virus tends to be most active in cold, dry climates. CDC data for influenza seasons from 1976-2006 indicates that influenza activity tends to peak during the month of January and February[iii]. Influenza pandemics do not always follow this pattern. Historical evidence shows that influenza pandemics tend to occur in waves and that influenza can be very active during the summer months. “The pandemic of 1918-1919 occurred in three waves. The first wave had occurred when mild influenza erupted in the late spring and summer of 1918. The second wave occurred with an outbreak of severe influenza in the fall of 1918 and the final wave occurred in the spring of 1919.[iv]”

Since pandemic influenza tends to occur in waves, there is an opportunity to limit the impact of future waves. The time between waves may allow for the creation of vaccines. However, egg-based vaccines take approximately six months to create. Nasal spray vaccines can be created in as little as ten weeks, provided there are no production delays[v]. While vaccines may not be prepared in time for future wave, it may be possible to limit the impact of future waves by increasing the supply of medicines and other goods that are in high demand during an influenza pandemic.


[i] CDC Website – “Clinical Signs and Symptoms of Influenza”, Visited on 4/25/08, http://www.cdc.gov/flu/professionals/acip/clinical.htm

[ii] 0.013% is calculated by dividing the 40,000 average deaths by 302,000,000, the current population of the United States.

[iii] http://www.cdc.gov/flu/professionals/acip/clinical.htm#tab1

[iv] Department of Health and Human Services Website – “The Great Pandemic”, Visited on 4/25/08
http://1918.pandemicflu.gov/the_pandemic/01.htm

[v] CDC Website – “2007-2008 Influenza Production and Distribution”, Visited on 4/25/08
http://www2a.cdc.gov/podcasts/media/pdf/PanFluVodcast9-07.pdf