Optimizing Barrier Protection During a
Pandemic Event Caused by Influenza A

History of Pandemic Events A pandemic is based on historical patterns. Influenza pandemics can be expected to occur, on average, three to four times each century when new virus subtypes emerge and are readily transmitted from person to person. The occurrence of influenza pandemics is unpredictable. In the 20th century, the great influenza pandemic of 1918-1919 (the Spanish Flu) caused an estimated 40 to 50 million deaths worldwide. 1 It is known as one of the most deadly pandemics in human history.1 The Asian Flu pandemic occurred in 1957-58 and killed 70,000 people. The pandemic of 1968-69 (the Hong Kong Flu) killed approximately 34,000 people; this pandemic is known as the mildest flu pandemic of the 20th century. Today, annual influenza epidemics cause 36,000 deaths and approximately 226,000 hospitalizations in the United States.1 Experts agree that another influenza pandemic is inevitable and possibly imminent.2 Influenza outbreaks occur annually due to minor changes in surface proteins of the viruses that allow them to evade the immunity humans have developed after previous infections, or in response to vaccinations. When a major change occurs spontaneously in either one or both of the viruses’ surface proteins, a completely new virus is developed, rendering everyone susceptible. If this new virus has a capacity for transmission from one person to another, a pandemic will occur.3 Outbreaks of influenza in animals, especially when occurring simultaneously with annual outbreaks in humans, increase the chances of a pandemic through the merging of animal and human influenza viruses. During the last few years, the world has faced several threats with pandemic potential, making the occurrence of the next pandemic a matter of time.4

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