What is the Flu?
Influenza (flu) is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness. Serious outcomes of flu infection can result in hospitalization or death. Some people, such as older people, young children, and people with certain health conditions, are at high risk for serious flu complications. The best way to prevent the flu is by getting vaccinated each year.
Getting an annual flu vaccine is the first and best way to protect yourself and your family from the flu. Flu vaccination can reduce flu illnesses, doctors’ visits, and missed work and school due to flu, as well as prevent flu-related hospitalizations. The more people who get vaccinated, the more people will be protected from flu, including older people, very young children, pregnant women and people with certain health conditions who are more vulnerable to serious flu complications.
While seasonal influenza (flu) viruses can be detected year-round in the United States, flu viruses are most common during the fall and winter. The exact timing and duration of flu seasons can vary, but influenza activity often begins to increase in October. Most of the time flu activity peaks between December and February, although activity can last as late as May.
Protection in the 2017/2018 Year
There are many flu viruses and they are constantly changing. The composition of U.S. flu vaccines is reviewed annually and updated to match circulating flu viruses. Flu vaccines protect against the three or four viruses that research suggests will be most common. For 2017-2018, three-component vaccines are recommended to contain:
- an A/Michigan/45/2015 (H1N1)pdm09-like virus
- an A/Hong Kong/4801/2014 (H3N2)-like virus
- a B/Brisbane/60/2008-like (B/Victoria lineage) virus
Four-component vaccines, which protect against a second lineage of B viruses, are recommended to be produced using the same viruses recommended for the trivalent vaccines, as well as a B/Phuket/3073/2013-like (B/Yamagata lineage) virus.
Signs and Symptoms
People who have the flu often feel some or all of these signs and symptoms:
- Fever* or feeling feverish/chills
- Sore throat
- Runny or stuffy nose
- Muscle or body aches
- Fatigue (very tired)
- Some people may have vomiting and diarrhea, though this is more common in children than adults.
*It’s important to note that not everyone with flu will have a fever.
Is it a Cold? Flu? or Allergies?
|Fever||Rare||Usual, high (100-102 °F), sometimes higher, especially in young children); lasts 3-4 days||Never|
|General Aches, Pains||Slight||Usual; often severe||Never|
|Fatigue, Weakness||Sometimes||Usual, can last up to 3 weeks||Sometimes|
|Extreme Exhaustion||Never||Usual, at the beginning of the illness||Never|
|Stuffy, Runny Nose||Common||Sometimes||Common|
|Cough||Common||Common, can become severe||Sometimes|
|Chest Discomfort||Mild to moderate||Common||Rare, except for those with allergic asthma|
|Treatment||Get plenty of rest.Stay hydrated. (Drink plenty of fluids.)Decongestants.Aspirin (ages 18 and up), acetaminophen, or ibuprofen for aches and pains||Get plenty of rest.Stay hydrated.Aspirin (ages 18 and up), acetaminophen, or ibuprofen for aches, pains, and feverAntiviral medicines (see your doctor)||Avoid allergens (things that you’re allergic to)AntihistaminesNasal steroidsDecongestants|
|Prevention||Wash your hands often.Avoid close contact with anyone who has a cold.||Get the flu vaccine each year.Wash your hands often.Avoid close contact with anyone who has the flu.||Avoid allergens, such as pollen, house dust mites, mold, pet dander, cockroaches.|
|Complications||Sinus infection middle ear infection, asthma||Bronchitis, pneumonia; can be life-threatening||Sinus infection, middle ear infection, asthma|
Caring for Someone Who is Sick
What do you do if someone you care for or live with is sick? Click here for tips and directions.