Influenza
Influenza, commonly called "the flu," is caused by the influenza virus, which infects the respiratory tract (nose, throat, lungs). Unlike many other viral respiratory infections, such as the common cold, the flu causes severe illness and life-threatening complications in many people. Each year in the U.S., more than 200,000 persons are hospitalized for flu-related complications and about 22,000 die from complications of the flu. The best protection is to get a flu vaccine.
Symptoms of flu include fever, headache, extreme tiredness, dry cough, sore throat, runny or stuffy nose, and muscle aches. Children can also have gastrointestinal symptoms (nausea, vomiting, and diarrhea), but these symptoms are uncommon in adults.
The main way that influenza viruses are spread is from person to person in respiratory droplets of coughs and sneezes. Droplets from a cough or sneeze of an infected person are propelled, generally up to 3 feet, through the air and deposited on the mouth or nose of people nearby. The viruses also can be spread when a person touches respiratory droplets on another person or object and then touches his or her own mouth or nose before washing their hands.
You can pass the flu to someone even before you know you are sick. Healthy people can infect others one day before symptoms develop and up to 5-7 days after becoming ill.
The single best way to prevent the flu is to get the flu vaccine each year.
There are two versions of the vaccine:
- The "flu shot" is an inactivated vaccine (containing a killed virus) that is given with a needle, usually in the arm. The flu shot is approved for use in people older than 6 months, including healthy people with chronic medical conditions.
- The nasal-spray flu vaccine is a vaccine made with live, weakened flu viruses that do not cause the flu (sometimes called LAIV for the “live attenuated influenza vaccine” or FluMist®). LAIV (FluMist®) is approved for use in healthy people 2-49 years of age who are not pregnant.
The 2011-12 U.S. seasonal influenza vaccine virus strains are identical to those contained in the 2010-11 vaccine. These include A/California/7/2009 (H1N1)-like, A/Perth/16/2009 (H3N2)-like, and B/Brisbane/60/2008-like antigens. The influenza A (H1N1) vaccine virus strain is derived from a 2009 pandemic influenza A (H1N1) virus (3). After receiving the flu vaccine, it will take about 2 weeks for your body to develop protection against the flu.
The flu vaccine is recommended for anyone 6 months of age and older. Persons who are at increased risk for complications from the flu virus are highly encouraged to receive the flu vaccine. These people include:
- All children 6 months through 5 years of age, but especially children younger than 2 years;
- Persons 50 years of age or older;
- Children and adults with underlying chronic medical conditions;
- Anyone who has a compromised immune system;
- Residents of long-term care facilities;
- All women who will be or are pregnant during the influenza season.
To prevent transmission of the flu to people in the above groups, flu vaccines are also recommended for:
- Health care workers - See Recommendations of the Advisory Committee on Immunization Practices (ACIP)
- Household contacts and caregivers of children <5 years of age or adults aged >50 years of age with particular emphasis on vaccinating contacts of children <6 months of age
- Household contacts and caregivers of persons with medical conditions that put them at higher risk for severe complications from influenza
Businesses and workplaces can also help keep people healthy.
In addition to getting a yearly flu vaccine, there are other things people can do to help prevent getting and spreading the flu. These include:
- Wash your hands often with soap and water for at least 20 seconds. When soap and water are not available, use antibacterial hand gel
- Cover your nose and mouth with a tissue when coughing or sneezing, then dispose of the tissue and wash your hands or cough or sneeze into your sleeve
- Avoid close contact with people who are sick
- Stay home when you are sick
- Eat right, exercise, and get plenty of sleep
- Do not share utensils, such as silverware