Seasonal Flu

Seasonal influenza, commonly called the flu, is caused by a virus that infects the nose, throat and lungs. Generally, the flu includes symptoms such as fever, cough, sore throat, runny or stuffy nose, headache, muscle aches and fatigue. Flu is highly contagious and spreads easily from person to person, primarily when an infected person coughs or sneezes.

Flu can be passed to someone else before symptoms are obvious, as well as while one is sick. Most healthy adults may be able to infect others beginning one day before symptoms develop and up to five to seven days after becoming sick. Some people, especially children and people with weakened immune systems, might be able to infect others for an even longer time.

The flu hospitalizes around 200,000 people yearly, 90% of them age 65 and older. In order to reduce the risk of getting the flu, it is important to get the flu vaccination each year.

Typically, flu shots are given in the autumn months so that protection can last during an entire season (October through March). Because the influenza virus changes from year to year, it is important to get vaccinated with a new flu vaccine every year. While there are many different flu viruses, the flu vaccine protects against the three viruses that research suggests will be most common during that year.

Flu is unpredictable and how severe it is can vary widely from one season to the next depending on many variables, including:

  • what flu viruses are spreading
  • how much flu vaccine is available
  • when the vaccine is available
  • how many people get vaccinated
  • how well the flu vaccine is matched to flu viruses that are causing illness