Cold? Flu? H1N1? How can you tell the difference?

Symptoms of the cold are more common, and can make the patient miserable for three to five days. A patient usually has a stuffy nose, congestion, some body aches and a growing cough.

According to the CDC seasonal flu and H1N1 symptoms consist of fever, more painful body aches, dry cough, diarrhea and severe fatigue. It's hard, without testing, to tell apart the seasonal strain of flu from the H1N1 variety.

"People need to take notice when they begin to feel bad. If they start to have respiratory problems, or are dehydrated because of a bug, they should go to the doctor. It could be H1N1 or seasonal influenza," says Shoham. "Some people with influenza can get very sick and could end up in the hospital if it's not taken care of."

People at greatest risk for catching H1N1 include young people ages 6 months to 25 years, pregnant women, and people with chronic health conditions like asthma, diabetes or heart and lung disease. The CDC recommends that these groups -- as well as health care workers -- get vaccinated first.