The Flu and You: What Is the Flu?

By Christina Elston

Influenza virus is a piece of genetic material, surrounded by a coat of protein, which invades our bodies’ cells. You are most likely to be infected by touching someone who is ill or touching something they recently touched, and then touching your eyes, nose or mouth. You can also inhale virus that someone else coughed or sneezed out.

The flu viruses’ protein coats, which function as their “armor,” are described with letters and numbers:
• H1N1 is "swine" flu,

• H5N1 is "avian" flu, and

• H3N2 is the most common type of seasonal flu.

When our bodies encounter a virus, they try to fight it off. This is called our "immune response."

The problem with influenza viruses is that they tend to change their armor.

Minor changes produce each year’s crop of seasonal influenza, which is similar to viruses our bodies have battled before. “It’s because of those small, incremental movements over time that we need a new vaccine every year,” explains Maureen Lichtveld, M.D., a former researcher with the national Centers for Disease Control (CDC) who now heads up the Flu Emergency Task Force at Tulane University.

Big, abrupt changes in those protein coats produce brand-new viruses like H1N1, which our bodies don’t yet know how to fight. “We don’t recognize the armor that it is wearing, so we don’t know how to make antibodies against it,” Lichtveld says.

Our “flu” symptoms – the fever, aches, chills, cough, sore throat and runny nose – are the result of our bodies trying to fight off the virus.

"It’s kind of overkill,” says Jim Sears, M.D., a pediatrician from the renowned Sears medical family and a co-host of The Doctors television program shown in cities nationwide. “The body’s immune system tends to overreact to the virus.” Usually the result is several days of discomfort, but in some cases infection with flu virus paves the way for serious – even deadly – complications such as pneumonia.

More about The Flu and You:

  • 4 things you need to know about H1N1 and the seasonal flu

  • What is the flu?

  • How do you keep from getting sick?

  • What about flu shots?

  • What if YOU get sick?


    More Resources

    National Centers for Disease Control Follow the Web site for this health monitoring and research organization for information on the spread of flu, prevention, and vaccine guidelines. This U.S. Department of Health and Human Services Web site bills itself as a one-stop source of information on H1N1, avian and pandemic flu. Here you’ll find prevention tips, including for pregnant women, flu monitoring information state by state and more.

    Flu Busters Find flu vaccination clinics in your area.