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As of August 2010, pandemic H1N1 flu is no longer considered a pandemic. This fact sheet provides historical information about pandemic H1N1 flu and will no longer be updated. Please see the Centers for Disease Control and Prevention website at http://www.cdc.gov/h1n1flu/ for the latest information about H1N1 flu.

Definition

Pandemic H1N1 flu (originally called swine flu) is a respiratory infection. The pandemic H1N1 flu has spread to humans and has reached the level of a pandemic. A pandemic is a worldwide outbreak.

The pandemic H1N1 flu can cause mild-to-severe symptoms. If you think that you have this virus, call your doctor (or do as advised by local public health officials).

Causes

There are two main types of influenza virus—type A and type B. This strain passes from human to human, so it may spread rapidly.

The pandemic H1N1 flu spreads in the same way as the seasonal flu:

  • By breathing in droplets after an infected person coughs or sneezes
  • By touching a contaminated surface and then touching your eyes, nose, or mouth (The virus can survive on surfaces and infect a person for 2-8 hours after being exposed to the surface.)


Pandemic H1N1 Virus

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Risk Factors

The main risk factor for getting the pandemic H1N1 flu is contact with an infected person. Having a chronic health condition (such as, cardiovascular disease, respiratory disease, diabetes, cancer) may increase your risk of a more severe form of the infection. Also, people with physical or mental disabilities may be more at risk because they may not be able to easily communicate their symptoms or may have trouble practicing preventive measures against the pandemic H1N1 flu.

People younger than 25 years old are more likely to be affected by the virus. The pandemic H1N1 flu is more likely to affect younger people than the elderly because older people may have developed immunity against the virus.

Eating pork or pork products and drinking tap water are not risk factors for getting the pandemic H1N1 flu.

Factors that increase your risk of developing complications from the pandemic H1N1 flu:

  • Age: younger than two years and 65 years or older
  • People younger than 19 years old on long-term aspirin
  • Being pregnant
  • Having recently given birth (in the last two weeks)
  • Diabetes
  • Weakened immune systems, such as in:
    • People infected with HIV
    • People taking immunosuppressive drugs
  • Disorders that may affect breathing
  • Chronic lung, heart, kidney, liver, nerve, or blood conditions
  • Being in a chronic care facility
  • Obesity (based on early reports)

Symptoms

The following symptoms may be due to pandemic H1N1 flu. They may also be due to other conditions.

  • Fever and chills
  • Sore throat
  • Cough
  • Severe muscle aches
  • Severe fatigue
  • Headache
  • Runny nose, nasal congestion
  • Sneezing
  • Watery eyes
  • Gastrointestinal symptoms (such as, nausea, diarrhea, vomiting)

Call your doctor (or do what is advised by local public health officials) if both of the following apply to you:

  • You have a fever of 100°F (37.8°C) or higher and any of the following:
    • Stuffy nose (makes it hard for you to breathe through your nose)
    • Runny nose (you are wiping your nose often)
    • Cough
    • Sore throat
  • You have been exposed to the pandemic H1N1 flu by:
    • Being within six feet of someone known or suspected to have the pandemic H1N1 flu
    • Living or having traveled to a place where there have been confirmed cases of the pandemic H1N1 flu

See your doctor if you notice your symptoms worsening or you do not begin to feel better three days after your symptoms first appear.

If the pandemic H1N1 flu becomes severe, it can cause pneumonia. Deaths have occurred, but this has been rare. The pandemic H1N1 flu can also worsen medical conditions you may already have.

Seek urgent medical care if you have emergency warning signs.

  • Emergency warning signs in adults include:
    • Fever of 100ºF (37.8°C) or higher for more than three days
    • Trouble breathing or shortness of breath
    • Bloody or colored sputum
    • Pain or pressure in chest or belly
    • Sudden dizziness
    • Confusion
    • Severe vomiting or vomiting that does not stop
    • Flu-like symptoms get better then come back with fever and worse cough
  • Emergency warning signs in children include:
    • Fast breathing or trouble breathing
    • Blue or gray skin color
    • Not drinking enough fluids
    • Severe vomiting or vomiting that does not stop
    • Difficulty waking up
    • Being too irritable to be held
    • Little or no desire to play or interact
    • Lack of alertness
    • Flu-like symptoms get better then come back with fever and worse cough
    • Fever with a rash

Diagnosis

The doctor will ask about your symptoms and medical history. Diagnosis of the flu is usually based on symptoms.

In some cases, your doctor may take samples from your nose or throat to confirm the diagnosis.

Treatment

Talk with your doctor about the best treatment plan for you. Be sure to follow your doctor's instructions.

Do not use products sold on the Internet claiming to treat the pandemic H1N1 flu. Talk to your doctor before using such products.

Most people with the flu do not need antiviral medicine. If you have the flu, check with your doctor to see if you need antiviral medicine. You will need it if you are in a high-risk group or if you have a severe illness (like breathing problems).

Antiviral medicines do not cure the flu. They may help relieve symptoms and shorten the time you are sick. They must be taken within 48 hours of the first symptoms.

Antiviral medicines used to treat the pandemic H1N1 flu include:

  • Prescription medicines:
    • Oseltamivir (Tamiflu)—Some kinds of seasonal influenza virus are resistant to this drug in the United States, but it can be used for pandemic H1N1 flu.
    • Zanamivir (Relenza)—This may worsen asthma or chronic obstructive pulmonary disease (COPD).
    • Peramivir—This is an investigational medicine that the United States Food and Drug Administration (FDA) has allowed doctors to use for hospitalized patients if other antiviral medicines do not work. This medicine is given through an IV (a needle in the vein).

Oseltamivir (and perhaps zanamivir) may increase the risk of self-injury and confusion shortly after taking, especially in children. Children should be closely monitored for signs of unusual behavior.

Other antiviral medications sometimes used to treat some kinds of seasonal flu (amantadine or rimantadine) do not work against the pandemic H1N1 flu.

There are other measures you can take, such as:

  • Getting plenty of rest to help your body fight the flu
  • Drinking a lot of liquids, including water, juice, and non-caffeinated tea
  • Taking over-the-counter (OTC) pain relievers, such as acetaminophen, ibuprofen, or (in adults) aspirin
    • NOTE: Aspirin is not recommended for children or teens with a current or recent viral infection. This is because of the risk of Reyes syndrome. Ask your doctor which other medicines are safe for your child.
  • Taking other OTC products (such as, decongestants, saline nasal sprays, cough medicines)
    • Talk to your doctor about what is safe for you or your child to take. For example, cough and cold products can cause serious side effects in young children.
  • Using alternative therapies like elderberry extract
    • Researchers found that products (like Sambucol and ViraBLOC) containing an herb called elderberry decreased flu symptoms in some studies. But be aware that herbal remedies are not regulated by the government. So the herbal supplements that you buy may not have the same ingredients as those studied and they may contain impurities (things that should not be in the product).

Prevention

A pandemic H1N1 flu vaccine is available. The vaccine comes in two forms: a nasal spray and a shot. The nasal spray will be given in two doses (given one month apart) for children aged 2-9 years and in one dose for persons aged 10-49 years. The shot will be given in two doses (given one month apart) to children aged 6 months to 9 years old and in one dose for people aged 10 years and older. Make sure you talk to your healthcare provider about which vaccine is right for you.

There are general measures you can take to reduce your risk of getting the virus:

  • Wash your hands often, especially when you come in contact with someone who is sick. Wash your hands for 15-20 seconds with soap and water. Rubbing alcohol-based cleaners on your hands is also helpful.
  • Avoid close contact with people who have respiratory infections. The flu can spread starting one day before and ending seven days after symptoms appear.
  • Avoid crowded gatherings, especially if you are at high risk for complications from the pandemic H1N1 flu. Consider using a disposable face mask if you are at high risk and are unable to avoid crowded areas where at least one case of the pandemic H1N1 flu has been confirmed.
  • Cover your mouth and nose with a tissue when you cough or sneeze. Throw away the tissue after you use it. Coughing or sneezing into your elbow or upper sleeve is also helpful.
  • Do not spit.
  • Do not share drinks or personal items.
  • Do not bite your nails or put your hands near your eyes, mouth, or nose.
  • Keep surfaces clean by wiping them with a household disinfectant.
  • Do not use products sold on the Internet claiming to prevent the pandemic H1N1 flu. Talk to your doctor before using such products.
  • The United States Centers for Disease Control and Prevention (CDC) recommends that you or your child do not attend swine flu parties.

If you are taking care of someone who has the pandemic H1N1 flu, follow these steps:

  • To prevent areas from being contaminated, try to keep the person who is sick in one room of the house.
  • Wash your hands after having contact with the person.
  • If you cannot avoid close contact with the sick person, cover your mouth and nose with a face mask (or a N95 respirator if available).
  • Limit contact with other members of the household or community while taking care of the person.
  • The person who is sick should have little contact with others and stay home from school or work. You can go to school or work if you feel well, but remember to keep track of your health and take precautions (like washing your hands).
  • If you develop symptoms of a flu-like illness, call your doctor (or do as advised by local public health officials) immediately.

For more information, on caring for someone with the pandemic H1N1 flu visit the CDC website.

Medicines to prevent the pandemic H1N1 flu, such as zanamivir (Relenza) or oseltamivir (Tamiflu), may be considered for:

  • People who have close contact with an infected person (confirmed or suspected) and have conditions that put them at high risk for complications, including those who:
    • Have a chronic health condition or a suppressed immune system
    • Are younger than 19 years old on long-term aspirin (There is a risk of Reyes syndrome.)
    • Are aged 65 years or older
    • Are younger than five years old
    • Are pregnant
    • Live in a nursing home
  • Healthcare or public health workers who have contact with an infected person (confirmed or suspected)

Ask your doctor if you should take preventive medicine.

If you have the pandemic H1N1 flu, take these steps to avoid spreading it to others:

  • Avoid close contact with people. Before you can return to school or work, your fever should be gone for at least 24 hours without the help of fever-reducing medicine. This could take up to seven days after symptoms first appear. It is important to stay home if you have the flu, leaving your house only to see your doctor.
  • If you cannot avoid close contact, cover your mouth and nose with a face mask.
  • Wash your hands often. Rubbing alcohol-based cleaners on your hands is also helpful.
  • Cover your mouth and nose with a tissue when you cough or sneeze. Throw away the tissue after you use it. Coughing or sneezing into your elbow or upper sleeve will also keep you from spreading the flu with your hands. Do not spit.
  • Do not share drinks or personal items.
  • Wash eating utensils with hot water and soap.
  • Do not bite your nails or put your hands near your eyes, mouth, or nose.
  • Keep surfaces clean by wiping them with a household disinfectant.
  • Use the hot setting on your washing machine when washing infected laundry.