Questions & Answers
Influenza - Seasonal - The Disease
Back to Parent Q&A Category Back to All Influenza - Seasonal Q&A Back to All Q&A Back to Influenza - Seasonal

General Information

  1. What is seasonal influenza disease?

    Influenza is a contagious respiratory illness caused by influenza types A or B viruses. Influenza viruses are easily spread by airborne respiratory droplets from person to person (often by sneezing or coughing).

    Symptoms of infection include fever, muscle aches, headache, malaise (a general feeling of sickness), nonproductive cough, sore throat, and runny nose. The flu causes mild illness in most people, the majority of whom will not need medical care or antiviral drugs, and usually recover in less than two weeks. Some people, however, can suffer flu complications that result in being hospitalized. Sometimes influenza infection results in death.

    Pneumonia, bronchitis, sinus infections and ear infections are examples of more severe flu-related complications. The flu also can make chronic health problems worse. For example, people with asthma may experience more frequent asthma attacks while they have the flu. The flu may also worsen congestive heart failure in people with this condition.

  2. How soon will I get sick after exposure to the influenza virus?
    Most healthy adults may be able to infect others beginning 1 day before symptoms develop and up to 5 to 7 days after becoming sick. Children may pass the virus for longer than 7 days. Symptoms start 1 to 4 days after the virus enters the body. That means that you may be able to pass on the flu to someone else before you know you are sick, as well as while you are sick. Some persons can be infected with the flu virus but have no symptoms. During this time, those persons may still spread the virus to others.

  3. Will new strains of influenza virus circulate this season?

    Influenza viruses are constantly changing, so it is not unusual for new strains of influenza virus to emerge at any time of the year. This year's influenza vaccines were made using the following strains:

    • A/California/07/2009 (H1N1)-like virus
    • A/Victoria/361/2011 (H3N2)-like virus
    • B/Massachusetts/2/2012-like virus 
    • B/Brisbane/60/2008 like virus (for the quadravalent influenza vaccine)

    The B/Massachusetts and B/Brisbane strains are a change from last year's formulation.

  4. How does influenza spread?
    Influenza spreads from person-to-person through aerosolized respiratory droplets released when a person coughs, sneezes, or breathes. People may also become infected with influenza by touching something contaminated with the virus and then touching their mouth, nose, or eyes.

  5. What should I do if I am infected with the influenza virus?
    Getting plenty of rest, drinking fluids, and avoiding alcohol and tobacco will allow your body to fight off the illness more quickly. If you use over-the-counter medications to relieve symptoms, it is important to follow the manufacturer's instructions. Protect others by covering your mouth when coughing and sneezing, wash your hands frequently, and stay at home if you are feeling ill.

  6. Who is at high risk for developing flu related complications?

    Children younger than 5 but especially children younger than 2 years of age, adult 65 years and older, pregnant women and individuals with various chronic medical conditions are at greatest risk for hospitalization and possibly death related to infection.

    A full list of high-risk conditions can be found at: