A pandemic is an outbreak of a disease that occurs in many different countries at the same time. An epidemic is an infectious disease that spreads very rapidly. Pandemic influenza is a global epidemic of the disease that occurs when a new influenza A virus appears in humans and then spreads easily and rapidly from person to person worldwide. Because people have never been exposed to this new virus, everyone is susceptible. The symptoms of pandemic influenza are similar to those of seasonal flu but are usually more severe and can lead to a more serious illness. Not all outbreaks of pandemic influenza have the same degree of severity - some are far more serious than others. Three pandemic outbreaks occurred during the past century. The most recent was the Hong Kong flu in 1968-69 resulting in 1- 4 million deaths globally. The most severe outbreak was the Spanish Flu in 1918-19 resulting in 20-40 million deaths globally. The Center for Disease Control and Prevention (CDC) has estimated that a pandemic as severe as the 1918 pandemic virus would cause between 0.9 and 2.2 million deaths and between 4 million and 10 million hospitalizations in the United States. Globally between 180 million to 360 million deaths are possible. Unlike seasonal outbreaks of the flu, all segments of the population are at risk to become seriously ill and die during a pandemic influenza outbreak.

The current outbreak of avian flu among poultry in Asia and parts of Europe is a source of growing concern among public health officials. As noted in a recent World Health Organization (WHO) report (see citation below), most of these avian flu cases have been caused by the highly pathogenic H5N1 strain that has characteristics similar to the 1918 pandemic. There is mounting evidence that this strain has a unique capacity to jump the species barrier and cause severe disease, with high mortality. Scientists know that avian and human influenza viruses can exchange genes when a person is simultaneously infected with viruses from both species. This process of gene swapping inside the human body can give rise to a completely new subtype of the influenza virus to which few, if any, humans would have natural immunity. Moreover, existing vaccines, which are developed each year to match presently circulating strains and protect humans during seasonal epidemics, would not be effective against a completely new influenza virus. If the new virus contains sufficient human influenza genes transmission directly from one person to another (instead of from birds to humans only) can occur. When this happens, the conditions for the start of a new influenza pandemic will have been met. Most alarming would be a situation in which person-to-person transmission resulted in successive generations or “waves” of severe disease with high mortality. Because of these collective circumstances, epidemiologists are concerned that a new influenza pandemic in humans is a distinct possibility.

Is there a vaccine effective against H5N1 in humans?

Currently available flu vaccines will not protect against diseases caused by the H5N1 strain in humans. Flu vaccines have to be made specifically for the particular virus that is causing a flu outbreak. Steps will be taken to produce a vaccine to protect against a new pandemic strain of flu as quickly as possible, but a vaccine is unlikely to be available for the first wave of illness. A pandemic flu outbreak is likely to occur in two or more waves of infection several months apart, each lasting about two to three months. In past outbreaks each subsequent wave has tended to be more severe. Depending on the timing of the second and subsequent waves of a flu pandemic, scientists may be able to develop a vaccine so that people can get vaccinated after the first wave.

What can we do to avoid getting exposed if a pandemic flu outbreak occurs?

According to the CDC, human influenza is transmitted from person to person via virus-laden large droplets generated when infected people cough or sneeze. Accordingly, the following precautions should be taken if an influenza outbreak occurs in your community:

• If you have flu-like symptoms you should routinely cover your nose and mouth with a tissue when you cough or sneeze—throw the tissue away after you use it. Wash your hands often with soap and water, especially after you cough or sneeze.
• If you get the flu, stay at home from work or school and avoid exposing family members in the home.
• If you have been exposed to a family member or co-worker with the flu, stay at home, if possible, as the virus is contagious for at least 24 hours prior to your feeling ill.
• To avoid getting the flu, you should limit your exposure to people who are sick and try not to touch your eyes, nose, or mouth because germs are often spread this way. Wash your hands frequently, and if you are caring for an infected family member you should strictly adhere to medical advisories on how to limit your exposure to the disease. This is likely to include protective clothing, such as latex gloves and perhaps masks, plus systematically disinfecting all surfaces potentially exposed to virus-laden droplets - such as eating utensils, doorknobs, clothes and bed sheets, etc.
• During a flu outbreak public health officials might enact various intervention strategies to decrease transmission of infection such as travel advisories, school closings, limited public gatherings and isolation and quarantine of flu-impacted households.

Potential Role of Extension Professionals

• Working with agricultural producers and government agencies, Extension can assist in providing close surveillance of a possible avian flu outbreak, and, if indicated, help implement early intervention strategies to slow down the spread of the disease.
• Working with public health officials, Extension can help educate local citizens and communities about human pandemic influenza and measures that should be taken to prepare for, mitigate, and respond to a potential outbreak. This includes the dissemination of timely, factual and useful information via Extension newsletters, newspaper columns, and other media presentations. Providing risk communications during a flu outbreak is particularly important.
• Working with local emergency management officials, Extension can contribute to local contingency planning to help insure that a community is prepared to respond to the challenges of a potential pandemic flu outbreak. As previously indicated, an outbreak could place at risk the ability of the community to maintain vital services and activities central to normal community operations. Local planning is necessary to insure a continuity of all vital services during a pandemic event.

The Centers for Disease Control and Prevention (CDC)

• Information About Influenza Pandemics
• Avian Influenza Materials
• Interim Pre-pandemic Planning Guidance: Community Strategy for Pandemic Influenza Mitigation in the United States - Early, Targeted, Layered Use of Nonpharmaceutical Intereventions

Health and Human Services

• The Official U.S. Government Web Site for Information on Pandemic and Avian Influenza
• HHS Draft National Pandemic Influenza Preparedness and  Response Plan (August 2004)

University of Minnesota Center for Infectious Disease Research & Policy

• Pandemic Influenza 
• Avian Influenza

World Health Association

• WHO Pandemic Plan (August 2005)
• WHO: Pandemic Preparedness

National Institute of Allergies and Infectious Diseases (NIAID)

• NIAID: Focus on the Flu Web site for media and consumers

Association of State and Territorial Officials

• Preparedness Planning for State Health Officials, Nature's Terrorist Attack: Pandemic Influenza

Medical Reserve Corps