Facts about Influenza


Influenza, also called the flu, is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and lungs. It can cause mild to severe illness. The best way to prevent the flu is by getting a flu vaccine each year.

There are three types of flu viruses: A, B, and C. Types A and B cause the annual flu epidemics that have up to 20% of the population sniffling, aching, coughing, and running high fevers. Type C also causes flu, but, the symptoms are much less severe.

What is Influenza A?

Influenza A viruses are capable of infecting animals, although it is more common for people to suffer from the symptoms associated with this type of flu. Wild birds commonly act as the hosts for this virus.

The influenza A virus is constantly changing and is generally responsible for the large flu epidemics. The flu virus “A2” (and other strands of influenza) is spread by people who are already infected.  The most common flu “hot spots” are surfaces that an infected person has touched and rooms where s/he has been recently, especially areas where they have been sneezing.

Common Symptoms

  • Fever
  • Cough
  • Sore Throat
  • Runny or stuffy nose
  • Muscle or body aches
  • Headaches
  • Feeling very tired
  • Some people might experience vomiting and diarrhea, although this is more common in children than adults.

How It Spreads

The flu virus is believed to be spread mainly by droplets made when people cough, sneeze or talk. These droplets can land in the mouths or noses of people who are close by. Although less common, a person might also get the flu by touching a surface or object that has the flu virus on it and then touching their own mouth, eyes or possibly their nose.

You may be able to pass on the flu to someone else before you are even aware you are sick. Most healthy adults can spread their infection to others 1 day before symptoms develop and then for up to 5 to 7 days after becoming sick. Young children and people with weakened immune systems may remain contagious to others for even longer periods of time.


Because the flu is constantly changing, it is impossible to predict how widespread or severe flu infections will be from one year to the next. This is why it is so important to get a flu vaccine each and every year.

Dr. Jeannie Kenkare

Written by Dr. Jeannie Kenkare

Dr. Kenkare is a highly experienced clinician with a background in family medicine. As a founding member of PhysicianOne Urgent Care's parent company Happy Mountains, she is also our Chief Medical Officer. Dr. Kenkare provides guidance and leadership to our health care team, and is responsible for the review of clinical guidelines, decision tools, and outcomes to develop and implement strategies that will improve patient care and clinical quality.

Website: https://www.physicianoneurgentcare.com

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