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What is the flu?

Influenza, also known as the “flu,” is an infection of the respiratory system that is caused by the influenza virus.


What is flu season?

Influenza season may begin in October and peaks between late December and March, although this can vary each year. The flu is responsible for many hospitalizations and deaths every year in the United States.


How do you get the flu?

Influenza is spread when a person who has the flu coughs, sneezes and talks. The influenza virus is then in the air and can land in the mouth and nose of others around them who may develop the flu. The influenza virus may also survive on surfaces and be transferred when a person touches the surface, then touches their mouth, eyes and nose. Influenza is often contagious before a person has symptoms.

Flu Prevention Tips


How can you prevent the spread of the flu?

The best way to prevent the spread of the flu is getting the flu vaccine each year. Here are other ways you can help prevent the spread of the flu:

  • Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissues in the trash after you use them.

  • Cough or sneeze into your elbow if tissues aren’t available.

  • Wash your hands often with soap and water, especially after you cough or sneeze.

  • Use alcohol-based hand cleaners when soap and water are not available.

  • Avoid touching your eyes, nose or mouth. Germs spread this way.

  • Try to avoid close contact with sick people.

  • Wear a well-fitting mask when around others. 

  • Stay home if you are sick to prevent infecting others and spreading the virus further. Stay at home until you have been fever-free for 24 hours without using fever-reducing medications.

  • Don’t use a scarf to wipe your nose or cover a sneeze/cough. This contaminates those items.

  • Don’t remove gloves and mittens with your teeth. This allows the germs from the gloves to move into your mouth.

  • Wash your hands before putting on gloves/mittens.

  • Wash scarves, facemasks, gloves and mittens weekly or when dirty.

  • Remove your gloves/mittens before touching ATM machines, shopping carts, elevator and crosswalk buttons, trash cans and other commonly used items. It’s easier to clean your hands than your gloves or mittens.

Flu Symptoms

Symptoms of the flu typically begin very quickly. Symptoms often include muscle aches, feeling very tired, fever with chills, headache, cough and a sore throat. In addition, children may also have a high fever, diarrhea, vomiting and seizures. Most people recover from the flu in 1 – 2 weeks. However, some people, especially the very young and the elderly, can have flu-related complications that can be serious.


In some people, the flu can lead to serious complications. Some people develop influenza pneumonia or a secondary bacterial pneumonia. People with asthma and other chronic lung diseases may have worsening of respiratory symptoms that require stronger treatment. They also have a higher risk of developing pneumonia from influenza. Rare complications include Reye’s syndrome, Guillain-Barre Syndrome and myocarditis and pericarditis, which affect the heart.

Protecting Others after Someone Becomes Infected

Flu is spread through infectious droplets that are transmitted from person-to-person or to environmental surfaces when a person with flu coughs or sneezes. If someone in the family has flu, that person should make sure to cover their coughs and sneezes and use tissues that are thrown into a waste bin right away. In addition, wash hands often and, if possible, rest in a separate room.

Family members should:

  • Practice good hand hygiene by washing hands with soap and water or using hand sanitizer often

  • Avoid touching the face, which is the easiest way for germs to enter the body,

  • Avoid sharing utensils, dishes and glassware, or other common items that might become contaminated with flu and lead to transmission from hands to the face, eyes, nose and mouth,

  • Thoroughly clean services and common areas in the home including keyboards, remote controls and other items used by the sick person,

  • Although difficult, try to stay three to six feet away from the person who is sick whenever possible.

  • A doctor might prescribe an antiviral (oseltamivir/Tamiflu) to help shorten the time of illness.

  • Talk with the doctor if at high risk for complications of the flu and about prescribing an antiviral (oseltamivir/Tamiflu) to help shorten the time of illness

  • Get a flu vaccine each year if six months of age and older

Flu Vaccine

Fortunately, the flu vaccine can prevent many illnesses and deaths associated with the flu. The flu vaccine contains either killed (inactivated) or weakened (attenuated) influenza viruses that cause your immune system to develop antibodies. It takes two weeks to build an adequate level of antibodies to protect against the flu. When you are exposed to the flu, these antibodies then fight off the flu viruses. While the vaccine does not always prevent the flu, the vaccine reduces the risk of complications and the severity of the illness.

Who Should Get the Flu Vaccine?

Everyone 6 months and older should get the flu vaccine every year. People in the following groups should receive the highest priority for vaccination if vaccine supply is limited:

  • Children aged 6 months through 4 years,

  • Adults 50 and older,

  • Nursing home and long-term care residents,

  • People with chronic respiratory diseases such as asthma, COPD (emphysema, chronic bronchitis), cystic fibrosis or bronchiectasis, or chronic cardiovascular (except hypertension), renal, hepatic, neurologic, hematologic, or metabolic (including diabetes) disorders,

  • People who have a weakened immune system,

  • Children and teens aged 6 months through 18 years of age on long-term aspirin therapy,

  • People who are morbidly obese,

  • Women who are pregnant or will be pregnant during the flu season,

  • American Indians/Alaska Natives,

  • Household members of people in high risk groups and

  • Health care providers.

The vaccine is safe for children six months of age and older. 

When to Get the Vaccine

Each year the flu vaccine is developed with the three (trivalent) or four (quadrivalent) main strains of influenza virus. These strains have been identified as the potential cause for the illness in the upcoming year. The flu vaccine must be given every year for protection against the flu. The flu vaccine can be given as soon as it becomes available each fall. It could also be given throughout the flu season. 

Types of Flu Vaccines Available This Year


Common Side Effects of the Flu Vaccine

The flu vaccine is safe for almost everyone. Because the vaccine is made from killed or weakened viruses, a person cannot “get” the flu from the vaccine. Some people experience a few minor side effects from the flu shot. These can include: swelling, redness or soreness at the area of the shot, muscle aches and a low-grade fever for a few days.
Severe side effects are rare, but include an allergic reaction which may occur several minutes to a few hours after the flu shot.
When the swine flu vaccine was given in 1976, more serious side effects, such as Guillain-Barre Syndrome, were reported. There has been no increased incidence of Guillain-Barre Syndrome since that time.
There has been some concern about reactions to Thimerosol, the preservative in the multi-dose vial flu shot. It is used at a very small amount and has not been shown to be a problem. However, if you are concerned about Thimerosol, you can check with your doctor about a “preservative free” flu vaccine. This is usually a single-dose vaccine.

Before You Get the Flu Vaccine

There are certain groups of people who should check with their doctor before getting a flu vaccine. These include:

  • People who have had an allergic reaction to a flu shot in the past,

  • People who have an allergy to eggs and have never had a flu vaccine and

  • People who developed Guillain-Barre Syndrome 6 weeks after getting a flu shot.

Egg Allergy

Most flu vaccines are produced using eggs. However, there are newer vaccines being manufactured that do not use eggs. The United States Advisory Committee for Immunization Practices regularly updates their recommendations for vaccination of persons who report egg allergies. The vast majority of people with egg allergies can safely receive influenza vaccination.


If someone is exposed to influenza before they are vaccinated or soon after vaccination, the vaccine may not protect them from getting the flu. Additionally, there are many strains of influenza virus and the vaccine does not always cover the strain that ends up circulating in a given year. Treatment with antiviral medicine is available when someone gets the flu. These medicines help lessen the symptoms and the length of time a person is ill. Antiviral medicine with a prescription only and must be started within the first two days after symptoms begin. These medicines include:

  • Tamiflu® (oseltamivir), - available as a pill or liquid that is swallowed
  • Relenza® (zanamivir), - available as a powder that is inhaled for people without lung problems

Please discuss any questions you have about the flu vaccine with your health care provider. The Center for Diseases Control and Prevention (CDC) has helpful Vaccine Information Statements (VIS) at


This information has been approved by Infection Preventionist Rosine Angbanzan, MPH, (September 2020)