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About Pandemics

A pandemic is a global disease outbreak. It is determined by how the disease spreads, not how many deaths it causes.

When a new influenza A virus emerges, a flu pandemic can occur. Because the virus is new, the human population has little to no immunity against it. The virus spreads quickly from person-to-person worldwide.

The United States is not currently experiencing a flu pandemic. If a pandemic occurs, the federal government will work to identify the cause and create a vaccine. will provide updates on the steps the federal government is taking to address the pandemic.

Characteristics and Challenges of a Flu Pandemic

  1. Rapid Worldwide Spread
    • When a pandemic flu virus emerges, expect it to spread around the world.
    • You should prepare for a pandemic flu as if the entire world population is susceptible.
    • Countries may try to delay the pandemic flu’s arrival through border closings and travel restrictions, but they cannot stop it.
  2. Overloaded Health Care Systems
    • Most people have little or no immunity to a pandemic virus. Infection and illness rates soar. A substantial percentage of the world’s population will require some form of medical care.
    • Nations are unlikely to have the staff, facilities, equipment, and hospital beds needed to cope with the number of people who get the pandemic flu.
    • Death rates may be high. Four factors largely determine the death toll:
      • The number of people who become infected
      • The strength of the virus
      • The underlying characteristics and vulnerability of affected populations
      • The effectiveness of preventive measures 
  1. Inadequate Medical Supplies
    • The need for vaccines is likely to be larger than the supply. Those at highest risk will likely get the vaccine first.
    • Early in a pandemic, the need for antiviral medications is likely to be larger than the supply. Those at highest risk will likely get antiviral medications first.
  2. A pandemic can create a shortage of hospital beds, ventilators, and other supplies. Alternative sites, such as schools, may serve as medical facilities.

  3. Disrupted Economy and Society
    • Travel bans, event cancellations, and school and business closings could have a major impact on communities and citizens.
    • Caring for sick family members and fear of exposure could result in significant employee absenteeism.

Seasonal Flu versus Pandemic Flu  

Pandemic Flu

Seasonal Flu

Rarely happens (three times in 20th century) Happens annually and usually peaks in January or February
People have little or no immunity because they have no previous exposure to the virus Usually some immunity built up from previous exposure
Healthy people may be at increased risk for serious complications Usually only people at high risk, not healthy adults, are at risk of serious complications
Health care providers and hospitals may be overwhelmed Health care providers and hospitals can usually meet public and patient needs
Vaccine probably would not be available in the early stages of a pandemic Vaccine available for annual flu season
Effective antivirals may be in limited supply Adequate supplies of antivirals are usually available
Number of deaths could be high (The U.S. death toll during the 1918 pandemic was approximately 675,000) Seasonal flu-associated deaths in the United States over 30 years ending in 2007 have ranged from about 3,000 per season to about 49,000 per season.
Symptoms may be more severe Symptoms include fever, cough, runny nose, and muscle pain
May cause major impact on the general public, such as widespread travel restrictions and school or business closings Usually causes minor impact on the general public, some schools may close and sick people are encouraged to stay home
Potential for severe impact on domestic and world economy Manageable impact on domestic and world economy