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Influenza: What You Need to Know

Influenza, also called "flu," is a viral illness that causes fever, sore throat, muscle aches and cough. Influenza can weaken the body’s defenses and lead to complications like bacterial pneumonia. It can also worsen existing chronic health problems like heart disease and diabetes.

The flu season can be as early as October and as late as May. During an average flu season, 36,000 Americans die and more than 200,000 are hospitalized because of complications from influenza. Some people, such as young children, the elderly, pregnant women and people with certain chronic health conditions are more likely to have complications related to influenza. While most deaths occur among the elderly and people with chronic health conditions, deaths can also occur among younger adults and children.

Who can get the flu?

Anyone can become infected with the influenza virus. During an average flu season, 10 to 20% of people are infected. Influenza spreads easily from person to person when an infected person coughs or sneezes. The influenza virus can also survive on surfaces outside the human body for hours. People can become infected by getting the virus on their hands, then rubbing their eyes or nose. Healthy adults can spread the virus from one day before they have symptoms until five days after their beginning of symptoms. They can pass influenza virus to others even before they feel ill. Children may shed the virus for a longer period of time than adults. Flu viruses change every year, so immunity is not long-term.

What are symptoms of the flu?

Typical flu symptoms include high fever, cough, sore throat, runny or stuffy nose, headache, muscle aches, and extreme fatigue. Symptoms such as nausea, vomiting or diarrhea are more common among young children. However, influenza is not the “stomach flu”; it is a respiratory illness.Influenza is different from a cold although the symptoms can overlap. In general, the flu is worse than the common cold, and symptoms such as fever, body aches, extreme tiredness, and dry cough are more common and intense with flu. Colds are usually milder than the flu, and more likely to cause a runny or stuffy nose. People with influenza usually recover completely in one to two weeks, but some people suffer severe complications. Colds generally do not result in serious health problems.

What are complications of the flu?

Complications of flu can include bacterial pneumonia, ear infections, sinus infections, dehydration, and worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes. Hospitalization and death can result from influenza infection complications.

Is there a vaccine for the flu?

Yes. There are two different types of vaccine: a shot and a nasal-spray. The “flu shot” vaccine contains killed influenza viruses and the nasal-spray vaccine contains live-attenuated (weakened) influenza viruses. The killed or weakened vaccine viruses stimulate the immune system to recognize and fight dangerous circulating influenza viruses. Each year, the vaccines are updated to prevent the new strains of influenza that are expected to circulate during the influenza season. Because the circulating influenza viruses change constantly, people should get vaccinated every year. The flu vaccine prevents influenza illness, which can be serious, but will not protect against other viruses that cause colds or other respiratory illnesses.

Who should get a flu vaccine?

The “flu shot” is approved for people age 6 months and older, including healthy people and people with chronic health conditions. The nasal-spray vaccine is approved for healthy people 2 to 49 years of age who are not pregnant.

Anyone wanting to protect themselves against flu should consider getting vaccinated. Vaccination is recommended for most people, especially those most likely to experience complications of the flu and people who live with or care for people at highest risk.

Those at highest risk include:

  • people 50 years and older;
  • people who live in nursing homes and other long-term care facilities that house those with long-term illnesses;
  • people with chronic health conditions;
  • women who will be pregnant during the influenza season;
  • children 6 months of age to 18 years of age.

People who live with or care for those at high risk for complications from influenza, including:

  • household contacts of persons at high risk for complications from the flu;
  • household contacts and out of home caregivers of children less than 6 months of age (these children are too young to be vaccinated);
  • healthcare providers.

Who should not be vaccinated?

The following people should first consult their healthcare provider before receiving influenza vaccine:

  • people who have a severe allergy to chicken eggs;
  • people who have had a severe reaction to an influenza vaccination in the past;
  • people who developed Guillain-Barré syndrome within 6 weeks of getting an influenza vaccine previously;
  • children less than 6 months of age (influenza vaccine is not approved for use in this age group).

People who have a moderate or severe illness with a fever should wait to get vaccinated until their symptoms lessen.

Where can I get a flu vaccine?

Flu vaccines are given at most public health departments and doctors' offices as well as some workplaces, and other community settings. The best time to get vaccinated is in October or November, but people can still get vaccinated throughout the flu season.

What are the vaccine side effects?

The flu shot contains only killed viruses and cannot give you the flu. The vaccine boosts the immune response against influenza. Some minor side effects that could occur are soreness, redness, or swelling where the shot is given, low grade fever or aches that last 1-2 days. The nasal-spray vaccine contains weakened viruses and does not cause the severe symptoms of an influenza illness. Side effects could include runny nose, headache, vomiting, aches, fever, sore throat or cough. Serious side effects are very uncommon with either vaccine and the risks associated with the disease are much greater than the risks associated with vaccination.

What can I do to keep from getting the flu?

The best way to prevent the flu is to get a flu vaccine each year.Wash your hands frequently with soap and water or use alcohol-based hand rub. Avoid rubbing your eyes or nose until you have washed your hands. Cover your cough and/or sneeze with a tissue or cough into your sleeve, not your hands.

What do I do if I get the flu?

Get plenty of rest and drink plenty of caffeine-free liquids to avoid becoming dehydrated. Avoid using alcohol and tobacco. To reduce fever, take a non-aspirin pain reliever. There are two antiviral medications approved for treatment of the flu: oseltamivir (Tamiflu®) and zanamivir (Relenza®). They require a prescription and are most effective if started within 48 hours of getting symptoms. Stay home from school or work if you are ill to avoid spreading the flu to others.