Flu seasons are unpredictable in a number of ways. Although epidemics of flu happen every year, the timing, severity, and length of the epidemic depends on many factors, including what influenza viruses are spreading and whether they match the viruses in the vaccine.

Flu viruses are constantly changing so it's not unusual for new flu virus strains to appear each year. For more information about how flu viruses change, visit How the Flu Virus Can Change.

The timing of flu is very unpredictable and can vary from season to season. Flu activity most commonly peaks in the U.S. in January or February. However, seasonal flu activity can begin as early as October and continue to occur as late as May.

CDC recommends a yearly flu vaccine for everyone 6 months of age and older as the first and most important step in protecting against this serious disease. While there are many different flu viruses, the flu vaccine is designed to protect against the three main flu strains that research indicates will cause the most illness during the flu season. Getting the flu vaccine as soon as it becomes available each year is always a good idea, and the protection you get from vaccination will last throughout the flu season.

Inactivated influenza vaccine effectiveness (VE) can vary from year to year and among different age and risk groups. For more information about vaccine effectiveness, visit cdc.gov.

It's not possible to predict with certainty which flu viruses will predominate during a given season. Flu viruses are constantly changing (called drift) – they can change from one season to the next or they can even change within the course of one flu season. Experts must pick which viruses to include in the vaccine many months in advance in order for vaccine to be produced and delivered on time. Because of these factors, there is always the possibility of a less than optimal match between circulating viruses and the viruses in the vaccine.

Yes, antibodies made in response to vaccination with one strain of flu viruses can provide protection against different, but related strains. A less than ideal match may result in reduced vaccine effectiveness against the variant viruses, but it can still provide some protection against influenza illness. In addition, it's important to remember that the flu vaccine contains three virus strains so that even when there is a less than ideal match or lower effectiveness against one strain, the vaccine may protect against the other two viruses. For these reasons, even during seasons when there is a less than ideal match, CDC continues to recommend flu vaccination. This is particularly important for people at high risk for serious flu complications, and their close contacts.

CDC recommends a yearly flu vaccine as the first and most important step in protecting against this serious disease. While there are many different flu viruses, the flu vaccine protects against the three main flu strains that research indicates will cause the most illness during the flu season. In addition, you can take everyday preventive steps like staying away from sick people and washing your hands to reduce the spread of germs. If you are sick with flu, stay home from work or school to prevent spreading influenza to others.

Yes. If you get sick, there are drugs that can treat flu illness. They are called antiviral drugs and they can make your illness milder and make you feel better faster. They also can prevent serious flu–related complications, like pneumonia.

• CDC recommends a yearly flu vaccine as the first and most important step in protecting against flu viruses.
• While there are many different flu viruses, the flu vaccine protects against the three viruses that research suggests will be most common.
• The 2011-2012 vaccine will protect against an influenza A H3N2 virus, an influenza B virus and the H1N1 virus that emerged in 2009 to cause a pandemic.
• Everyone 6 months of age and older should get a flu vaccine as soon as the 2011-2012 vaccines are available.
• Vaccination of high risk persons is especially important to decrease their risk of severe flu illness.
• People at high risk of serious flu complications include young children, pregnant women, people with chronic health conditions like asthma, diabetes or heart and lung disease and people 65 years and older.
• Vaccination also is important for health care workers, and other people who live with or care for high risk people to keep from spreading flu to 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.

• Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it.
• Wash your hands often with soap and water. If soap and water are not available, use an alcohol-based hand rub.
• Avoid touching your eyes, nose and mouth. Germs spread this way.
• Try to avoid close contact with sick people.
• Get plenty of sleep, be physically active, manage your stress, drink plenty of fluids, and eat nutritious food.
• If you are sick with flu–like illness, CDC recommends that you stay home for at least 24 hours after your fever is gone except to get medical care or for other necessities. (Your fever should be gone without the use of a fever-reducing medicine.)
• While sick, limit contact with others as much as possible to keep from infecting them.

• If you get the flu, antiviral drugs can treat your illness.
• Antiviral drugs are different from antibiotics. They are prescription medicines (pills, liquid or an inhaled powder) and are not available over-the-counter.
• Antiviral drugs can make illness milder and shorten the time you are sick. They may also prevent serious flu complications.
• It’s very important that antiviral drugs be used early (within the first 2 days of symptoms) to treat people who are very sick (such as those who are hospitalized) or people who are sick with flu symptoms and who are at increased risk of severe flu illness, such as pregnant women, young children, people 65 and older and people with certain chronic health conditions.
• Flu-like symptoms include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills and fatigue. Some people also may have vomiting and diarrhea. People may be infected with the flu, and have respiratory symptoms without a fever.

You may have the flu if you have some or all of these symptoms:

• fever*
• cough
• sore throat
• runny or stuffy nose
• body aches
• headache
• chills
• fatigue
• sometimes diarrhea and vomiting

*It's important to note that not everyone with flu will have a fever.

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, 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.

There are emergency warning signs. Anyone who has them should get medical care right away.

In children:

• Fast breathing or trouble breathing
• Bluish skin color
• Not drinking enough fluids
• Not waking up or not interacting
• Being so irritable that the child does not want to be held
• Flu-like symptoms improve but then return with fever and worse cough
• Fever with a rash

In addition to the signs above, get medical help right away for any infant who has any of these signs:

• Being unable to eat
• Has trouble breathing
• Has no tears when crying
• Significantly fewer wet diapers than normal

In adults:

• Difficulty breathing or shortness of breath
• Pain or pressure in the chest or abdomen
• Sudden dizziness
• Confusion
• Severe or persistent vomiting
• Flu-like symptoms that improve but then return with fever and worse cough

Yes. There are drugs your doctor may prescribe for treating the flu called "antivirals." These drugs can make you better faster and may also prevent serious complications.

CDC recommends that you stay home for at least 24 hours after your fever is gone except to get medical care or for other things you have to do and no one else can do for you. (Your fever should be gone without the use of a fever-reducing medicine, such as Tylenol®.) You should stay home from work, school, travel, shopping, social events, and public gatherings.

If you are sick:

• Stay away from others as much as possible to keep from making them sick.

• If you must leave home, for example to get medical care, wear a facemask if you have one, or cover coughs and sneezes with a tissue.
• Wash your hands often to keep from spreading flu to others. Sing the "Happy Birthday" song two times or count slowly to 20 as you wash.
• If someone in your family has the flu, there are things you can do to reduce the chance that it will spread to others in your household:
• Keep a person with flu in a separate "sick room." If there is more than one sick person, they can share the sick room if needed.

If you have more than one bathroom, have sick people use one bathroom and well people use the other one.

• Give each sick person their own drinking glass, washcloth, and towel.
• Choose one caregiver.
 If possible, ask someone else to be the caregiver if you are pregnant or have certain chronic health problems. If you get the flu, it could be much more serious for you.
• Avoid being face to face with the sick person. If possible, it is best to spend the least amount of time in close contact with a sick person.
• Avoid having other people enter the sick room.
The sick person should not have visitors other than the caregiver. If visitors must enter, they should stay at least 6 feet away from the sick person.
• Make sure to wash your hands after touching the sick person. Wash after handling their tissues or laundry.
• Cover coughs and sneezes.
Ask the sick person to cover their nose and mouth with a tissue when they cough and sneeze. Ask them to throw used tissues in the trash.
• When holding sick children, place their chin on your shoulder so they will not cough in your face.
• Keep the air clean.
Open a window in the sick room, if possible, or use a fan to keep fresh air flowing.

• Alcohol testing
• Drug screening
• Eye injury and screening exams
• Flu shots
• Flu Information
• Hearing tests
• Laboratory testing
• Non-surgical orthopedics
• Physical exams
• Prescriptions
• Primary care
• Pulmonary function testing
• Treatment for work-related illness or injury
• Urgent care
• X-rays