Seasonal influenza, commonly called the flu, is caused by a virus that infects the nose, throat and lungs. Generally, the flu includes symptoms such as fever, cough, sore throat, runny or stuffy nose, headache, muscle aches and fatigue. Flu is highly contagious and spreads easily from person to person, primarily when an infected person coughs or sneezes.
Flu can be passed to someone else before symptoms are obvious, as well as while one is sick. Most healthy adults may be able to infect others beginning one day before symptoms develop and up to five to seven days after becoming sick. Some people, especially children and people with weakened immune systems, might be able to infect others for an even longer time.
The flu hospitalizes around 200,000 people yearly, 90% of them age 65 and older. In order to reduce the risk of getting the flu, it is important to get the flu vaccination each year.
Typically, flu shots are given in the autumn months so that protection can last during an entire season (October through March). Because the influenza virus changes from year to year, it is important to get vaccinated with a new flu vaccine every year. While there are many different flu viruses, the flu vaccine protects against the three viruses that research suggests will be most common during that year.
Flu is unpredictable and how severe it is can vary widely from one season to the next depending on many variables, including:
- what flu viruses are spreading
- how much flu vaccine is available
- when the vaccine is available
- how many people get vaccinated
- how well the flu vaccine is matched to flu viruses that are causing illness
Preventing the Flu
Get your flu shot.
Protect yourself and your family. Be sure to get your flu shot every year. Everyone over the age of 6 months should be vaccinated.
Avoid close contact.
Avoid close contact with people who are sick. When you are sick, keep your distance from others to protect them from getting sick too.
Stay home when you are sick.
If possible, stay home from work, school, and errands when you are sick. You will help prevent others from catching your illness.
Cover your mouth and nose.
Cover your mouth and nose with a tissue when coughing or sneezing. It may prevent those around you from getting sick.
Clean your hands.CDC.gov - Handwashing
Washing your hands often will help protect you from germs. If soap and water are not available, use an alcohol-based hand rub.
Avoid touching your eyes, nose or mouth.
Germs are often spread when a person touches something that is contaminated with germs and then touches his or her eyes, nose, or mouth.
Practice other good health habits.
Get plenty of sleep, be physically active, manage your stress, drink plenty of fluids, and eat nutritious food.
The CDC recommends that the following individuals receive a yearly flu shot:
- Children 6 months of age and older
- Women who are pregnant
- People with chronic health conditions like asthma, diabetes or heart and lung disease
- People 50 years and older
- Vaccination is also important for health care workers, and other people who live with or care for high-risk people
Children younger than 6 months are at high risk of serious flu illness, but are too young to be vaccinated. People who care for them should be vaccinated instead.
Questions About the Flu
When does flu occur?
Flu occurs in the United States most often in the fall and winter and commonly peaks in February. Flu-like symptoms in summer months are usually due to other viruses. (See H1N1)
What's the difference between influenza and the "flu?"
Influenza is commonly called the "flu." However, not all things called the "flu" are caused by influenza, so how do you know? Influenza infects the nose, throat, windpipe, and lungs (respiratory tract), but not the intestines (gastrointestinal or GI tract). So flu is not the same as what many people call the "stomach flu." The best way to tell if you have influenza is for a health care provider to swab your throat and have a lab confirm the diagnosis.
How does one “catch the flu?”
The flu spreads easily from person-to-person by coughing and sneezing. Influenza viruses change each year and this is why it's called "seasonal" or "yearly" flu. A new batch of vaccine is made each year based on these viruses. Get vaccinated every year for the best protection against the flu.
What are the symptoms of flu?
People with flu often have high fever, cough, sore throat, body aches, fatigue (tiredness), headache, and sometimes nasal congestion. If you or someone you know has these symptoms and they are severe, contact your doctor, nurse, or clinic as soon as possible. The best way to tell if you have the flu is for a health care provider to swab your throat and have a lab confirm the diagnosis.
Are you immune from the flu if you had it before?
No, because viruses that cause flu change frequently, people who have had the flu or a flu shot in previous years may become infected with a new strain.
About the Flu Vaccine
Can people get the flu from the flu vaccine?
No, you cannot get the flu from the vaccine. This has been a myth that is difficult to dispel. The flu shot only contains proteins from the influenza virus, so the virus cannot reproduce itself and cause illness. The only side affect may be some soreness where the shot is given.
Does the vaccine protect throughout the flu season?
Yes, getting vaccinated early will protect you throughout the flu season. But you will need a flu shot every year for each flu season.
How effective is the flu vaccine?
The effectiveness of flu vaccines can vary. It depends on the match between the strains in the vaccine and the flu viruses that are circulating in the community as well as the age and health of the person being vaccinated. Flu vaccines protect 70 to 90 percent of healthy people under age 65 when the vaccine strains are similar to the circulating strains. It takes about two weeks for your body to build immunity for protection against the flu and lasts for about one year.
For more information, visit the Centers for Disease Control and Prevention's Flu Vaccine Effectiveness: Questions and Answers.
Who provides flu vaccinations?
- Check with your doctor or medical provider
- Contact your local health department
- The CDC offers a flu vaccine locator
- Many pharmacies offer the vaccine
Is there something available other than shots?
Yes, nasal spray is available for healthy kids, teens, and non-pregnant adults aged 2 to 49 years. The nasal spray vaccine contains live, weakened flu viruses. The spray can cause mild congestion and runny nose. Some may get a low-grade fever or feel achy for one to two days while their immune system responds to the vaccine. More information on flu vaccine is available on the Centers for Disease Control and Prevention's website.
Who should NOT get a flu vaccine?
- Babies younger than 6 months are at high risk of serious flu illness, but are too young to get vaccine - people who live with and care for them should get vaccinated instead
- Those with a severe allergy to chicken eggs or have had an allergic reaction to flu vaccines in past
- Those who have ever had Guillain-Barré Syndrome (a severe illness, also called GBS)
- Check with your doctor before getting a flu vaccine if you are ill with fever
What Should I Do if I Get Sick?
If you get sick with flu-like symptoms, you should stay home and avoid contact with other people except to get medical care. Most people with the flu have mild illness and do not need medical care or antiviral drugs.
However, some people are more likely to get flu complications (for example young children, people 65 and older, people with asthma or diabetes or women who are pregnant) and they should talk to a health care provider about whether they need to be examined if they get flu symptoms. Also, it's possible for healthy people to develop severe illness from the flu so anyone concerned about their illness should consult a health care provider.
What are antiviral medications?
Antiviral drugs are prescription medicines that fight against the flu in your body. A flu vaccine is the first and most important step in preventing flu. Antiviral drugs are a second line of defense to treat the flu if you get sick. You must have a prescription to get antiviral drugs; they are not sold over-the-counter. Antiviral drugs are not antibiotics.
It’s very important that antiviral drugs be used early to treat flu in:
- People who are very sick (for example people who are in the hospital)
- People who are sick with flu and have a long-term health condition that puts them at a greater risk of serious flu complications, like asthma, diabetes or chronic heart disease
- Young children, older people and women who are pregnant or have recently delivered a baby and who are sick with flu
What are the benefits of antiviral drugs?
When used for treatment, these drugs can make you feel better and shorten the time you are sick by 1 or 2 days. They also can prevent serious flu complications.
Studies have shown that flu antiviral drugs work best for treatment when they are started within 2 days of getting sick. However, getting them later can still be helpful especially if the sick person is at greater risk of serious flu complications or if the person has certain symptoms (such as shortness of breath, chest pain/pressure, dizziness, or confusion) or is in the hospital because of the flu.CDC.org - The Flu: What To Do If You Get Sick