Influenza, commonly called “the flu,” is a common disease that infects the respiratory tract (nose, throat, lungs). Unlike some other viral respiratory infections, such as the common cold, the flu can cause severe illness and life-threatening complications in many people – especially those with underlying medical conditions such as asthma.
Seasonal flu is a term used to describe one of the many combinations of influenza viruses that mutate and circle the globe each year. It’s called “seasonal” because it strikes most often during the fall and winter. In the U.S., flu season can begin as early as October and run through March.Most people gradually build up an immunity to the viruses in seasonal flu, assisted by annual flu vaccinations.
Pandemic flu refers to a global outbreak of influenza (flu), such as the 2009 one involving H1N1 influenza. During a pandemic, the virus spreads quickly around the world because people have less immunity to it, either because they have not been exposed to it before or have not been exposed in a long time.
What are the symptoms of influenza?
Does the flu have complications?
Is the flu contagious and how does it spread?
How do I protect myself?
What are the risks from getting a flu shot?
What Is FluMist™ and how does it differ from the flu shot?
What should I do if my child can’t get the flu vaccine?
- extreme tiredness
- dry cough
- sore throat
- runny or stuffy nose
- muscle aches
Children sometimes have additional gastrointestinal symptoms, such as nausea, vomiting, and diarrhea, but these symptoms are uncommon in adults. Although the term “stomach flu” is sometimes used to describe vomiting, nausea, or diarrhea, these illnesses are caused by certain other viruses, bacteria, or possibly parasites, and are rarely related to influenza.
Does the flu have complications?
Some of the complications caused by flu include bacterial pneumonia, dehydration and worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes. Children may get sinus problems and ear infections as complications from the flu. Generally, those aged 65 years and older and persons of any age with chronic medical conditions are at highest risk for serious complications of flu.
Is the Flu Contagious and How Does it Spread?
The flu IS contagious. The period when an infected person is contagious depends on the age of the person. Adults may be contagious from one day prior to becoming sick and for five days after they first develop symptoms. Some children may be contagious for longer than a week. The time from when a person is exposed to flu virus to when symptoms begin is about one to four days, with an average of about two days.
The main way that influenza viruses are spread is from person to person in respiratory droplets of coughs and sneezes. (This is called “droplet spread.”) This can happen when droplets from a cough or sneeze of an infected person are propelled (generally up to 3 feet) through the air and deposited on the mouth or nose of people nearby.
Though much less frequent, the viruses also can be spread when a person touches respiratory droplets on another person or an object and then touches their own mouth or nose (or someone else’s mouth or nose) before washing their hands.
How Do I Protect Myself?
By far, the single best way to prevent the flu is for individuals — especially people at high risk for serious complications from the flu and those in close contact with them (including household members) — to get a vaccination each fall. According to the Centers for Disease Control (CDC), people who should get vaccinated for seasonal flu are:
- Children aged 6 months up to their 19th birthday
- Pregnant women
- People 50 years of age and older
- People of any age with certain chronic medical conditions
- People who live in nursing homes and other long-term care facilities
- People who live with or care for those at high risk for complications from flu, including:
- Healthcare workers
- 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)
Influenza vaccine provides the best protection available from flu—even when the vaccine does not closely match circulating flu strains, and even when the person getting the vaccine has a weakened immune system. Vaccination can lessen illness severity and is particularly important for people at high risk for serious flu-related complications and close-contacts of high-risk people.
In addition to an annual flu vaccination, frequent hand washing is the most effective prevention technique. For more practical prevention tips, click here.
The viruses in the flu shot are killed (inactivated), so you cannot get the flu from a flu shot. The risk of a flu shot causing serious harm is extremely small. However, a vaccine, like any medicine, may rarely cause serious problems, such as severe allergic reactions. Almost all people who get influenza vaccine have no serious problems from it.
Some people who should talk with their doctor before getting the flu vaccination include:
- People who are have a severe allergy to hens’ eggs
- People who have had a severe reaction to a flu vaccine in the past
- People who previously developed Guillain-Barré Syndrome (GBS) in the 6 weeks after getting a flu shot
Sometimes, a person will experience flu-like symptoms after receiving the vaccination. There are several reasons why this might happen:
- People may be exposed to an influenza virus shortly before getting vaccinated or during the two-week period that it takes the body to gain protection after getting vaccinated. This exposure may result in a person becoming ill with flu before the vaccine begins to protect them.
- People may become ill from other (non-flu) viruses that circulate during the flu season, which can also cause flu-like symptoms (such as rhinovirus).
- A person may be exposed to an influenza virus that is not included in the vaccine. There are many different influenza viruses. For more information, see Influenza (Flu) Viruses.
- Unfortunately, some people can remain unprotected from flu despite getting the vaccine. This is more likely to occur among people that have weakened immune systems. However, even among people with weakened immune systems, the flu vaccine can still help prevent influenza complications.
What is FluMist® and how does it differ from the flu shot?
The nasal-spray flu vaccine FluMist (sometimes called LAIV for Live Attenuated Influenza Vaccine) is different from the other licensed influenza vaccine (also called the “flu shot”) because it contains weakened live influenza viruses instead of killed viruses and is administered by nasal spray instead of injection.
When the viruses are sprayed into the nose, they stimulate the body’s immune system to develop protective antibodies. The weakened viruses are cold-adapted, which means they are designed to only cause infection at the cooler temperatures found within the nose. The viruses cannot infect the lungs or other areas where warmer temperatures exist.
According to CDC, FluMist is approved ONLY for use in healthy people between the ages of 5 and 49 years.
Some people who may not be eligible for the nasal-spray flu vaccine include:
- Children less than 24 months old
- People 50 years of age and over
- Children younger than 5 with asthma or one or more episodes of wheezing within the past year
- People with a weakened immune system or long-term medical conditions such as asthma, heart or lung disease, kidney or liver disease, metabolic diseases such as diabetes and blood disorders such as anemia
- Children or adolescents receiving aspirin
- People with a history of Guillain-Barré syndrome, a rare disorder of the nervous system
- Pregnant women
- People with a history of allergy to any of the components of LAIV or to eggs
What should I do if my child can’t get the flu vaccine because of an egg allergy or other reason?
If your child has an egg allergy, check with your pediatrician about vaccine options. If you and your physician decide your child should not get a flu vaccine, all other family members and caregivers should receive the vaccine as early as possible. Make sure to check with your physician about the use of antiviral medications if your child develops flu symptoms. You should also follow prevention methods such as regular and through hand washing, keeping your hands away from your mouth, lips and eyes.
The above information is adapted from the Centers for Disease Control and Prevention (CDC).