Seasonal Flu
- The seasonal flu is contagious and can cause mild to severe illness; and in some cases can lead to death. More…
- Type A and B flu viruses cause epidemics in the United States every year. More…
- The symptoms for the common cold and the seasonal flu are similar. More…
- Get vaccinated to protect yourself from the flu. If you do get sick, follow our treatment advice. More…
Seasonal Flu Basics
Influenza (the flu) is a contagious respiratory illness caused by influenza viruses. It spreads from person-to-person and can cause mild to severe illness; and in some cases, can lead to death.
- In the United States, yearly outbreaks of seasonal flu usually happen during the fall through early spring.
- The best way to prevent the flu is by getting a flu vaccination each year.
- Flu viruses can cause illness in people of any age group. Children are most likely to get sick because their immune systems aren’t strong enough to fight off the infection.
- Some groups are more likely to have complications from the seasonal flu. These include:
- those age 65 and older
- children younger than 2 years old
- people of any age who have chronic medical conditions (e.g. diabetes, asthma, congestive heart failure, lung disease)
- Complications from the flu can include:
- bacterial pneumonia
- ear or sinus infections
- dehydration
- worsening of chronic medical conditions
Every year in the United States, on average:
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Flu Viruses
There are three types of flu viruses: A, B and C. The A and B viruses cause epidemics (widespread outbreaks in a country) of infection in people every year in the United States.
- Type C infections cause mild respiratory illness and are not thought to cause epidemics.
- Type A viruses are divided into subtypes. Subtypes of type A that have been found in people worldwide include H1N1, H1N2, and H3N2 viruses.
- Flu viruses are constantly changing. A global flu pandemic (worldwide outbreak) can happen if three conditions are met:
- A new subtype of type A virus is introduced into the human population.
- The virus causes serious illness in humans.
- The virus can spread easily from person-to-person in a sustained manner.
- The H1N1 Flu met all three conditions and caused a worldwide outbreak. In late spring 2009, the WHO declared that a H1N1 flu pandemic was underway.
Flu Symptoms and Cold vs. Flu
Common Symptoms | Possible Symptoms |
| These symptoms may occur, but are more likely in children than adults:
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Is it a Cold or the Flu?
Flu and the common cold are both respiratory illnesses, but they are caused by different viruses.
- Flu and the common cold have similar symptoms (e.g. fever, sore throat). It can be difficult to tell the difference between them.
- Your doctor can give you a flu test within the first few days of your illness to determine whether you have the flu.
- In general, the flu is worse than the common cold.
- Symptoms such as fever, body aches, extreme tiredness, and dry cough are more common and intense with the flu.
- Colds are usually milder than the flu. People with colds are more likely to have a runny or stuffy nose.
- Colds generally do not result in serious health problems, such as pneumonia, bacterial infections, or hospitalizations.
Seasonal Flu – Vaccination, Prevention and Treatment
- Vaccination is the best protection against contracting the flu. More information on Vaccination
- For more prevention information, and to find out what to do if you get the flu, follow our advice for Prevention and Treatment
- Vaccine Selection for 2010-2011 Influenza Season
A key U.S. Food and Drug Administration Advisory Committee has recommended that protection against the 2009 H1N1 virus, which was first identified in April 2009, be included in the 2010-2011 seasonal influenza vaccine starting this fall. That means that, barring some unforeseen circumstance, this fall, most Americans will be able to return to having one flu vaccine to protect them against the major circulating flu viruses. As is always the case with seasonal vaccine, younger children who have never had a seasonal vaccine will still need two doses.
