What is a Flu Pandemic?
A pandemic is a global outbreak of disease. An influenza pandemic happens when a new strain of the flu virus appears for which people have little or no immunity. As a result, it spreads easily from person to person around the world, causing widespread illness and death. Individuals, families, caregivers, healthcare workers and teachers can all take steps now to get ready for a flu pandemic before it happens.
How Does Flu Become a Pandemic?
In nature, different strains of the flu virus occur all the time among animals. Most of these flu viruses do not produce disease in people. But sometimes human flu viruses and those found in animals, like pigs and birds, mix together to produce new strains. Since the resulting virus is new to the human immune system, people have little defense against it. Some of these viruses, like the H5N1 bird flu, do not currently spread well in people. Others do. If a new flu virus spreads easily, it can produce a flu pandemic. The pandemic will likely spread quickly around the globe.
In the last 100 years, flu pandemics have occurred four times and spread around the world within months, even when most people traveled between countries by ship. In today's world, given the speed and amount of country-to-country air travel, a flu pandemic could spread much more quickly. The 2009 flu pandemic reached all continents in only 3 months.
How is Flu Pandemic Different from Seasonal Flu?
Unlike a flu pandemic, seasonal flu is a flu strain that we know will circulate from November through March. It causes symptoms like fever, cough, sore throat and muscle aches. Every year, between 5 and 20 percent of Americans come down with the flu. Most healthy people get better from seasonal flu sickness without lasting effects, but it can be deadly. However, seasonal flu kills more than 36,000 people and puts 200,000 more in the hospital every year in the U.S. Plan now for a flu pandemic.
| Seasonal Flu | Flu Pandemic |
| Outbreaks occur every year, usually in winter. | Occurs only rarely (only four times since 1918). |
| Caused by influenza viruses that are similar to those already affecting people. | Caused by a new influenza virus that people have not been exposed to before. |
| Healthy adults usually not at risk for serious complications. | Healthy adults may be at increased risk for serious complications. |
| Hospitals and healthcare providers can usually meet public needs. | Hospitals and healthcare providers may be overwhelmed and difficult to access. |
| Vaccine available at beginning of flu season. | Vaccine would probably not be available in the early stages of a pandemic. |
| Causes an average of 36,000 deaths each year in the United States. | Number of deaths could be significantly higher. In the 1918 pandemic, approximately 675,000 people died in the United States. |
| Generally does not have a severe impact on daily life. | May have a severe impact on daily life, including widespread restrictions on travel, closings of schools and businesses, and cancellation of public events. |
What about Vaccines?
Right now, more than 100 national flu centers worldwide study disease trends and monitor for the flu year-round. Each year, before the flu season arrives, scientists choose the flu viruses they will include in the upcoming season's flu vaccines. They base their selections on which strains are circulating, how they are spreading, and how well the vaccines would help protect against the expected strains of seasonal flu.
Seasonal flu vaccines are updated yearly. They protect against three types of circulating flu viruses. Since flu pandemics are caused by a new strain of the virus, seasonal flu vaccines do not protect against them. Pandemic vaccines can only be produced after a flu pandemic virus is identified. With current methods, it takes a number of months to produce vaccines for a newly recognized pandemic strain.