Influenza (the flu) is an infection of the nose, throat and lungs caused by influenza viruses that are constantly changing. It affects all age groups, though kids tend to get it more often than adults. In the United States, flu season runs from October to May, with most cases happening between late December and early March. The flu is often confused with the common cold, but flu symptoms usually are more severe than the typical sneezing and stuffiness of a cold.

Flu vs Cold

Flu illness can vary from mild to severe. Flu can be especially dangerous for young children and children of any age who have certain long term health conditions, including asthma (even mild or controlled), neurological conditions, chronic lung disease, heart disease, blood disorders, endocrine disorders (such as diabetes), and weakened immune systems due to disease or medication. Children with these conditions, can have more severe illness from the flu.

The flu is contagious, spread by viruses-infected droplets made when people with the flu cough, sneeze, or talk. These droplets can land in the mouths or noses of people who are nearby.  Less often, a person might get the flu by touching something that has flu virus on it and then touching their own mouth, eyes or nose. People who are infected are contagious from a day before they feel sick until their symptoms have ended (about 1 week for adults, but this can be longer for young kids).

Symptoms, which usually begin about 2 days after exposure to the virus, can include:

• fever
• chills
• headache
• muscle/body aches
• dizziness
• loss of appetite
• tiredness/fatigue
• cough
• sore throat
• runny/stuffy nose
• nausea or vomiting
• weakness
• ear pain
• diarrhea
• Some people with flu will not have a fever.

A number of flu tests are available to detect influenza viruses. The most common are called “rapid influenza diagnostic tests.” These tests can provide results in 30 minutes or less. Unfortunately, the ability of these tests to detect the flu can vary greatly. Therefore, you could still have the flu, even though your rapid test result is negative. In addition to rapid tests, there are several more accurate and sensitive flu tests available that must be performed in specialized laboratories, such as those found in hospitals or state public health laboratories. All of these tests require that a health care provider swipe the inside of your nose or the back of your throat with a swab and then send the swab for testing. These tests do not require a blood sample.

During an influenza outbreak, a positive rapid flu test is likely to indicate influenza infection. However, rapid tests vary in their ability to detect flu viruses, depending on the type of rapid test used, and on the type of flu viruses circulating. Also, rapid tests appear to be better at detecting flu in children than adults. This variation in ability to detect viruses can result in some people who are infected with the flu having a negative rapid test result. (This situation is called a false negative test result.) Despite a negative rapid test result, your health care provider may diagnose you with flu based on your symptoms and their clinical judgment.

People with the flu may infect others from 1 day before getting sick to 5-7 days after. Children and people with weakened immune systems can shed virus for longer and might still be contagious past 7 days, especially if they still have symptoms.

No. Your child should stay home to rest and to avoid giving the flu to other children or to caregivers.

Keep your child home until at least 24 hours after their fever is gone, without using fever-reducing medications, like acetaminophen (Tylenol) or ibuprofen (Motrin or Advil). A fever is defined as 100.0 F or higher.

Cases of the flu rarely require specific medical treatment. But some kids with chronic medical conditions (such as asthma, diabetes, or HIV infection) or children under 2 years old might become sicker with the flu and may have a greater risk of complications. Some kids with the flu need to be hospitalized.

For a severely ill child or one with other special circumstances, a doctor may prescribe an antiviral medicine that can shorten the illness by 1-2 days and prevent potential problems of the flu. This medicine is only helpful if given within 48 hours of the start of the flu. Most healthy people who get the flu do not need to take an antiviral medicine. If an antiviral medication is prescribed, be sure to discuss any possible side effects with your doctor. These at-home tips can help most otherwise healthy kids cope with the flu:

• drink lots of fluids to prevent dehydration
• get plenty of sleep and take it easy
• take acetaminophen or ibuprofen to relieve fever and aches (do not give aspirin to children or teens because of its association with Reye syndrome)
• wear layers, since the flu often makes them cold one minute and hot the next (wearing layers — like a T-shirt, sweatshirt, and robe — makes it easy to add or remove clothes as needed)

Children who are sick should stay home from school until they are without fever for at least 24 hours without the use of a fever-reducing medicine. Some might need to stay home longer, depending on how they feel. If you have questions or concerns, talk to your doctor.

1. Nasal Spray flu vaccine (LAIV, FluMist®, AstraZeneca) is not recommended to be used in any setting during the 2016-17 influenza season. This recommendation was made because of evidence of low vaccine effectiveness among children 2 through 17 years of age against the H1N1 strain of influenza virus during the 2013–14 and 2015–16 seasons. The CDC recommends use of the conventional flu shot this season: either the inactivated influenza vaccine (IIV) or the recombinant influenza vaccine (RIV).
2. A history of egg allergy is no longer considered to be a contraindication or precaution to influenza vaccination. Multiple studies have found that severe allergic reactions to egg-based influenza vaccines in persons with egg allergy are unlikely. For the 2016–17 influenza season, ACIP recommends that people with a history of egg allergy who have experienced only hives after exposure to egg should receive any inactivated influenza vaccine without specific precautions (except for the recommended 15-minute observation period for syncope for any vaccine). People who report having had an anaphylactic reaction to egg may also receive any age-appropriate influenza vaccine. The vaccine should be administered in a medical setting such as a hospital, clinic, health department, or physician office. Vaccine administration should be supervised by a healthcare provider who is able to recognize and manage severe allergic conditions. Although not specifically recommended by ACIP, providers may prefer an egg-free recombinant vaccine (FluBlok®, Protein Sciences) for people age 18 years and older with severe egg allergy. More information on influenza vaccination and egg allergy is available on Immunize.

People who received the vaccine one year aren't protected from getting the flu the next because the protection wears off and flu viruses constantly change. That's why the vaccine is updated each year to include the most current strains of the virus.

So to have the best protection against the flu, it's important to get the vaccine every year.

• Vaccine reactions, if they occur, are usually mild and can include soreness, redness and swelling where the shot is given or runny nose after getting the nasal spray. Some people have experienced fever, body aches, headache and fatigue. These reactions usually begin soon after the vaccine is given and last 1-2 days.
• A vaccine, like any medicine, could possibly cause more serious problems, such as severe allergic reactions. The risk of a vaccine causing serious harm is extremely small. Life threatening allergic reactions from vaccines are very rare. If they do occur, it is usually within a few minutes to a few hours after the vaccination.
• More detailed information about flu vaccine is available at Immunize. At this site you will find Vaccine Information Statements about inactivated and live influenza vaccines (the shot and the nasal spray) designed to educate and inform in many languages.

• Yes. While no vaccine is 100% effective, influenza vaccine is the best protection against getting the flu.
• Influenza vaccine tends to be most effective in people who are younger and healthy. It takes about two weeks after vaccination to protect against flu, so vaccination does not protect immediately. Also, flu viruses are always changing, so the vaccine needs to be updated every year, before flu season starts. When the vaccine isn't a good match with the flu viruses that are circulating, it offers less protection.
• People who get flu vaccine are much less likely to get the flu than those who don't get vaccine and, if vaccinated people get sick with the flu, their illness is not as severe.
• It can take about 2 weeks after the vaccine for the body to build up protection to the flu. Getting the vaccine before the flu season is in full force gives the body a chance to build up immunity to (protection from) the virus.
• You can get a flu vaccine well into flu season, but it's best to try to get it as early as possible so the body has time to build up immunity.

Check with your health care provider about this season's flu shot. County Health Departments provide flu shots to all children, and to adults who lack insurance coverage. Flu shots are also widely available at pharmacies and retail centers. Find one near you by entering your zip code in the Flu Shot Locator.

• Cover coughs and sneezes with a tissue. Throw the tissue in the trash after use. If a tissue isn't available, cough or sneeze into your upper arm, not into your hands. 
• Stay away from people who are sick.
• Wash hands often with soap and water.
• Use an alcohol-based hand rub if soap and water are not available
• Never pick up used tissues
• Don't share cups and eating utensils.
• Contact your healthcare provider if your child gets sick, especially if the child is very young (under 5) or has long-term health conditions.
• Seek emergency care if your child has trouble breathing, fast breathing, turns bluish or gray, has severe or persistent vomiting, has trouble waking up, or doesn't interact normally.