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Seasonal flu

The flu is a contagious respiratory disease caused by a common group of viruses (influenza viruses). In the United States, “flu season” begins every fall and ends every spring, when an average of 5 to 20 percent of the population will show signs of infection. The flu that people so often get during that season is called “seasonal flu.” Some influenza viruses can also infect birds, pigs, horses, seals, whales and other animals. Most people who get seasonal flu recover within a week or two and do not require medical treatment. The very young, the very old and the very sick are most likely to become seriously ill.

Pandemic flu

Sometimes, a new type of flu virus may emerge to which people have no resistance. When this happens, it can spread more easily from person to person around the world in a very short time, causing serious illness and death. This is “pandemic flu.” It is more serious than seasonal flu. Pandemic flu is different because more people who get it might not recover, even with medical treatment, and people of every age may be at risk of serious illness or death. Unlike seasonal flu, there may not be a vaccine for pandemic flu until researchers and pharmaceutical companies are able to create one. Vaccine development depends on the scientific understanding of the specific virus causing the disease. If a vaccine is developed for pandemic flu, it will be a challenge to produce enough for everyone and dispense it to all the people that need it in a timely manner.


The symptoms of pandemic flu are likely to be similar to those of seasonal flu, which are:

  • Fever
  • Sore throat
  • Cough
  • Runny or stuffy nose
  • Extreme fatigue
  • Headache
  • Muscle aches and pains
  • Stomach problems, such as nausea, vomiting and diarrhea (more common in children)

How the flu spreads

Flu viruses spread mainly from person to person when people with influenza cough, sneeze, or touch things that others touch. People infected with common flu virus can spread it to others one day before symptoms develop and up to seven or more days after becoming ill. That means that you may be able to pass the flu to someone before you know you are sick and after you start to feel better.

What is the difference between a vaccine and an antiviral?

Vaccines are usually given as a preventive measure. Viral vaccines are usually made from killed or weakened versions of the live virus or pieces of the virus that stimulate an immune response to the virus. Once immunized with the weakened strain, the body produces antibodies that more effectively protect it from overall infection.

Antivirals are prescription drugs that decrease the ability of flu viruses to reproduce. While getting a flu vaccine each year is the first and most important step in protecting against flu, antiviral drugs are a second line of defense in the prevention and treatment of flu. Your health care provider will determine if antivirals are appropriate for your situation.

Stay healthy

There are some actions that everyone can practice to slow the spread of the flu and reduce its impact, whether the viruses involved are seasonal or pandemic flu.

Wash your hands. Frequent and proper hand washing can reduce or prevent the spread of the flu from one person to another. Wash your hands with soap and water for at least 20 seconds, or clean them with an alcohol-based hand sanitizer, or do both. For visibly soiled hands, first wash with soap and warm water. When using soap and water:

  • Wet hands with water and apply an amount of soap recommended by the manufacturer.
  • Rub hands together vigorously for at least 20 seconds, covering all surfaces of the hands and giving added attention to fingernails and surfaces where jewelry is worn.
  • Rinse hands with water.
  • Dry thoroughly with a disposable towel.
  • Use a disposable towel to turn off faucet.

When using hand sanitizer (60 to 95% per alcohol):

  • Use the amount of sanitizer directed in the instructions on the product.
  • Rub thoroughly over all surfaces of the hands, including nail areas and between the fingers.
  • Continue to rub until product dries.

Cover your mouth and nose with a tissue when you cough or sneeze, and clean your hands afterwards.

  • Use soap and water or an alcohol-based hand sanitizer (as above).
  • If you don’t have a tissue or handkerchief, cough or sneeze into the inside of your elbow or upper arm.
  • Whenever possible, avoid coughing or sneezing into your hands.
  • Keep your hands away from your eyes, nose and mouth to keep flu germs from entering your body.

Stay home if you are feeling sick. Get plenty of rest and drink lots of fluids. Avoid close contact with people who are sick. The flu virus is spread by respiratory droplets passed from one person to another. These droplets can pass among people in close contact. Avoid sharing objects - such as utensils, cups, bottles and telephones. If you must share, disinfect the objects before and after using them. Keep your living and work areas clean.

For more information on the flu, see: