Hospitals in Northwest Florida are seeing an uptick in flu cases.

Sacred Heart Health system reported an increase in influenza at its hospitals in the area. during the second week of January, 158 patients were tested for flu-like symptoms, with 14 percent receiving positive results for influenza, according to a press release.

?Many patients are not officially tested for flu when they have flu-like symptoms,? Donna Mayne, Microbiology Lab manager at Sacred Heart Hospital in Pensacola, said in the release. ?That means the actual number of people suffering from the influenza virus could be much greater than our percentages indicate.?

The timing of flu is very unpredictable and can vary from season to season, according to the U.S. Centers for Disease Control and Prevention. Flu activity most commonly peaks in the U.S. in January or February. however, seasonal flu activity can occur as late as May.

This year, most of the flu cases seen in the U.S. have been due to a Type A virus called H3N2, according to the Sacred Heart release. this virulent virus tends to trigger more pneumonia and other complications.

The 2010-2011 flu vaccine will protect against three different flu viruses: an H3N2 virus, an influenza B virus and the H1N1 virus that caused so much illness last season, according to cdc.gov.

There is still plenty of this year?s flu vaccine available, but those interested in getting it should do so right away since it takes about two weeks to take effect. The CDC recommends vaccine for most everyone, except infants younger than 6 months and people with severe allergies to eggs.

A person can spread the flu as early as one day before he or she even feels sick, and can continue to pass the flu virus to others for five to seven days after symptoms start. People who have the flu often feel some or all of these symptoms: cough, sore throat, runny or stuffy nose, muscle or body aches, headaches and fatigue. many, though not all, patients, have fever or chills and vomiting and diarrhea, cdc.gov says.