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General information about pandemic flu

Influenza viruses cause infections of the respiratory tract (breathing tubes and lungs). In some persons, complications of influenza can be severe, including pneumonia.

Pandemic influenza is a global outbreak of disease from a new influenza A virus that is unlike past influenza viruses. Because people have not been infected with a similar virus in the past, most or all people will not have any natural immunity (protection) to a new pandemic virus.

A pandemic flu is a new influenza virus that could be a much more serious flu virus than seen in a typical flu season. Different from the typical strains of flu, humans would have no or little natural resistance to a new strain of influenza. As a result, pandemic flu is likely to be more severe, affect more people, and cause more deaths than seasonal influenza. Also, there is a vaccine for seasonal flu, which is prepared each season against new variations of the seasonal influenza. There is no vaccine available at this time for a pandemic flu, and it is expected to take at least six months after a pandemic flu appears to develop a vaccine.

Learn more about seasonal influenza.

Because most or all people would not have immunity to a new pandemic virus, large numbers of persons around the world can be infected. If the pandemic virus causes severe disease, many people may develop serious illnesses. Some of those who develop severe influenza will die.

Once a pandemic virus develops, it can spread rapidly causing outbreaks around the world. The U.S. Centers for Disease Control and Prevention (CDC) predicts that as much as 25% to 30% of the US population could be affected. In King County alone, a severe pandemic flu could make 540,000 people ill, 270,000 would need outpatient care, over 59,000 would need hospitalization, and 11,500 could die.

High levels of illness and death during a pandemic could lead to other forms of social and economic disruption. With so many people in so many places becoming ill, caring for the ill, and looking after their children at home, the available workforce will be reduced. Impacts of a pandemic on everyday life may include school and business closings, the interruption of basic services such as public transportation and food delivery, and cancellation of large public gatherings.

Public Health – Seattle & King County is working with federal, state, and other local government agencies to respond to pandemic influenza and to maintain essential health care and community services if an outbreak should occur. In fact, governments all around the world are preparing for the possibility of a pandemic outbreak under the leadership of the World Health Organization.

It is not possible to prevent or stop a pandemic once it begins. A person infected with influenza virus can be contagious for 24 hours before the onset of symptoms, and for five to seven days thereafter, making it extremely easy for the virus to spread rapidly to large numbers of people.

Although the federal government is stockpiling medical supplies and antiviral drugs, no country in the world has enough antiviral drugs to protect all their citizens. Anti-viral drugs can be used to treat severe cases as long as there was a reasonable chance that the drugs might help save lives. Antiviral drugs might also be prioritized for people who work in essential occupations, such as health care workers.

Other strategies for slowing the spread of a severe influenza outbreak could include temporarily closing schools, sports arenas, theaters, restaurants, taverns, and other public gathering places and facilities.

There currently is no vaccine to protect humans against a pandemic influenza virus because the pandemic virus has not yet fully developed. However, vaccine development efforts are under way to protect humans against a pandemic influenza virus that might develop from the current bird flu virus in Asia. (See information on bird flu below).

Influenza pandemics occur naturally. There were 3 pandemics in the 20th century. The pandemic of 1918-19 was the most severe pandemic on record, in which 50 million or more persons around the world died, including approximately 650,000 Americans.

It is not possible to predict accurately when influenza pandemics will occur or how severe they will be. However, the current outbreak of avian influenza in Asia, Europe, and Africa has influenza experts concerned that a pandemic is developing that may be severe.

New human influenza viruses arise from bird influenza viruses that then change to a form that can infect humans and spread readily from person to person. The current bird flu outbreak in Asia, Europe, and Africa is caused by a type of influenza A virus called H5N1. The H5N1 outbreak among domestic chickens and ducks in Asia is widespread and uncontrolled. Human infections and deaths due to the avian H5N1 virus have occurred. Most of these cases involved direct or close contact with infected birds or surfaces possibly contaminated from feces of infected birds. However, at this time, the virus has not developed the ability to pass easily from person to person and cause outbreaks in humans.

Learn more about avian influenza (bird flu).

The reported symptoms of bird flu in humans have ranged from typical influenza-like symptoms (e.g., fever, cough, sore throat, and muscle aches) to eye infections (conjunctivitis), pneumonia, acute respiratory distress, viral pneumonia, and other severe and life-threatening complications.

Stay informed. These web sites provide regularly updated information about bird flu and pandemic flu:

Stop germs from spreading.

  • Wash your hands frequently.
    • Wash thoroughly with warm water and soap for 20 seconds.
    • Make sure to wash your hands before eating, or touching your eyes, nose and mouth.
    • If caring for ill persons, wash hands after providing assistance.
    • Always wash your hands after sneezing, blowing your nose, or coughing, or after touching used tissues or handkerchiefs.
    • If hand washing is not possible, use an alcohol-based hand cleaner.
  • Avoid touching your mouth, nose and eyes.
  • When coughing and sneezing, cover your mouth and nose with tissue, or cough and sneeze into your upper sleeve. Put used tissues in the trash.
  • Don't share items such as cigarettes, towels, lipstick, toys or anything else that might be contaminated with germs.
  • Don't share food, utensils or beverage containers with others.

Stay home when you are sick.

  • See your health care provider as soon as you can if you have a cough and a fever, and follow their instructions, including taking medicine as prescribed and getting rest.
  • If asked, use a mask when visiting your health care provider.
  • Visit Public Health's Stop Germs website for more information and educational materials on stopping germs and staying healthy.

Sign up for Public Health News Alerts.

If you plan to travel overseas, check the CDC web site for travel advisories

Pandemic influenza would be spread from person to person primarily through "respiratory secretions," the same way seasonal influenza viruses and other common respiratory infections spread. Respiratory secretions are virus-containing droplets (such as spit or mucous) that are spread when infected persons cough or sneeze. These droplets can then land on the surfaces of the mouth, nose, and throat of persons who are near (i.e., within 3 feet) the ill person. The virus may also be spread through contact with the infectious respiratory secretions on the hands of an infected person and other objects and surfaces. Adults can spread influenza virus one day before symptoms appear and up to five days after the onset of illness.

Even if there is mild pandemic, doctors; offices will be busier than usual. But if there is a severe pandemic, there may be as many as 540,000 ill people in King County alone during an 8-week period, with 270,000 needing outpatient care and nearly 60,000 requiring hospitalization. These large numbers of sick people may overwhelm hospitals and clinics that may simultaneously be experiencing substantial staff shortages due to illness.

Be prepared for changes in the healthcare system. For example, it may be difficult to get medical care or to talk directly to your healthcare provider. There may not be enough medical supplies, healthcare providers, and hospital beds for all persons who are ill. As a result, healthcare providers will need to make tough decisions about who receives medical care and how much treatment can be administered.

What to do if you can't see a doctor during a pandemic

Vacant hospital beds may be scarce, but most people who get a pandemic flu virus can be cared for at home. (See Caring for someone with influenza.) During a pandemic, updated information and advice will be available on this Public Health website and through a telephone hotline. Alternate medical care facilities will also be set up throughout to ease the burden on hospitals and clinics. Be prepared to follow instructions from your healthcare provider and public health officials about how to obtain medical care. Health care information and hotline numbers will be broadcast over local news media and on this website.


Guidance for when a pandemic flu is present

Begin now to practice simple but important habits that reduce the spread of germs:

  • Wash your hands frequently.
    • Wash thoroughly with warm water and soap for 20 seconds.
    • Make sure to wash your hands before eating, or touching your eyes, nose and mouth.
    • If caring for ill persons, wash hands after providing assistance.
    • Always wash your hands after sneezing, blowing your nose, or coughing, or after touching used tissues or handkerchiefs.
    • If hand washing is not possible, use an alcohol-based hand cleaner.
    • Avoid touching your mouth, nose and eyes.
    • When coughing and sneezing, cover your mouth and nose with tissue, or cough and sneeze into your upper sleeve. Put used tissues in the trash.
    • Don't share items such as cigarettes, towels, lipstick, toys or anything else that might be contaminated with germs.
    • Don't share food, utensils or beverage containers with others.

  • Stay home when you are sick.
    • See your health care provider as soon as you can if you have a cough and a fever, and follow their instructions, including taking medicine as prescribed and getting rest.
    • If asked, use a mask when visiting your health care provider.
    • Visit Public Health's Stop Germs, Stay Healthy! website for more information and educational materials on stopping germs and staying healthy.

  • Minimize your exposure to ill people as much as possible. During a flu pandemic, this may mean avoiding large social gatherings and events, such as concerts, movie theaters, and sports venues.
Tamiflu is a prescription antiviral drug that works against influenza viruses. It is not known if it will be useful against a pandemic influenza virus. Tamiflu is not recommended for persons to keep at home in case of a pandemic.

The federal government is stockpiling medical supplies and antiviral drugs (such as Tamiflu) and King County is also purchasing a supply for this region. However, there is simply not enough Tamiflu available for any country in the world to protect all their citizens.

Public health officials have recommended using available supplies of Tamiflu to first treat persons with severe infections that require hospitalization, and persons that will perform vital functions that the public will need in a pandemic. These groups include healthcare workers and emergency responders.

During a pandemic, Tamiflu is not recommended to prevent influenza infections because using the drug for this purpose requires daily doses for weeks. The limited supply of Tamiflu means that it must be saved to treat those who are severely ill.

Tamiflu is currently manufactured by one company in Switzerland. Government agencies and the manufacturer of Tamiflu are attempting to find ways to is negotiating with generic drug companies to increase production of the medicine.

Masks are recommended for use in health care settings by ill persons and healthcare workers to prevent spread of infection. At this time, masks are not recommended for use by well persons in the community. There is no guarantee that masks would prevent the spread of the infection in the population. If persons decide to wear masks during a pandemic influenza outbreak, it is likely they will need to wear them any time they are in a public place and when they are around other household members. More information on the use of masks, CDC

Wipe down any surfaces that may have been contaminated by saliva or other respiratory secretions.

Influenza viruses are known to survive on non-porous surfaces such as steel and plastic, for up to 24 to 48 hours after inoculation and from cloth, paper, and tissues for up to 8 to 12 hours. Viable virus can be transferred from non-porous surfaces to hands for 24 hours and from tissues to hands for 15 minutes.

Use a household disinfectant labeled for activity against bacteria and viruses, an EPA-registered hospital disinfectant, or mix and use 1/4 cup chlorine bleach with 1 gallon of cool water.

Vaccine production is a complicated and lengthy process. Because viruses change over time, a specific pandemic influenza vaccine cannot be produced until a pandemic influenza virus emerges in humans. Once a pandemic influenza virus has been identified, it will likely take 4-6 months to develop, test, and begin producing a vaccine.

In preparation, the U.S. government is making efforts to increase manufacturers' ability to produce vaccine. Research is also underway to develop new ways to produce vaccines more quickly.