Influenza: A Contagious Respiratory Illness

What It Is:

As the title declares, influenza is a contagious respiratory illness caused by flu viruses. Influenza is also known by the name ‘flu’. It can cause mild to severe illness, and at times can lead to death. The flu is different from a cold. The flu usually comes on suddenly and may include these symptoms:

  • Fever  (usually high)
  • Headache
  • Extreme tiredness
  • Dry cough
  • Sore throat
  • Runny or stuffy nose
  • Muscle aches
  • Stomach symptoms, such as nausea, vomiting, and diarrhea, also can occur but are more common in children than adults

Above symptoms are usually referred to as ‘flu-like’ symptoms.

Span of the disease: Every year in the United States, on average:

  • 5% to 20% of the population gets the flu;
  • more than 200,000 people are hospitalized from flu complications, and;
  • about 36,000 people die from flu.

Some people, such as older people, young children, and people with certain health conditions (such as asthma, diabetes, or heart disease), are at high risk for serious flu complications.

Spread of Influenza:

Flu viruses spread mainly from person to person through coughing or sneezing of people with influenza. Sometimes people may become infected by touching something with flu viruses on it and then touching their mouth or nose. Most healthy adults may be able to infect others beginning 1 day before symptoms develop and up to 5 days after becoming sick. 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.

Prevention of Influenza:

Medical science has been able to come out with vaccines for Influenza. These are of two types:

  • The “flu shot” – an inactivated vaccine (containing killed virus) that is given with a needle. The flu shot is approved for use in people 6 months of age and older, including healthy people and people with chronic medical conditions.
  • The nasal-spray flu vaccine – a vaccine made with live, weakened flu viruses that do not cause the flu (sometimes called LAIV for “Live Attenuated Influenza Vaccine”). LAIV is approved for use in healthy* people 2-49 years of age† who are not pregnant.

About two weeks after vaccination, antibodies develop that protect against influenza virus infection. Flu vaccines will not protect against flu-like illnesses caused by non-influenza viruses.


Two flu antiviral drugs are recommended for use in the United States during the 2007-08 flu season: oseltamivir and zanamivir. Oseltamivir and zanamivir are effective against both influenza A and B viruses.

  • oseltamivir is approved to both treat and prevent flu in people one year of age and older.
  • anamivir is approved to treat flu in people 7 years and older and to prevent flu in people 5 years and older.