Typically, cases of the flu peak in January and February, affecting millions of people. The incubation period for influenza is short and the illness spreads quickly. Patients generally become ill within 2-3 days of contact. It often starts with a headache, fever, chills, and generalized aching. The symptoms usually precede respiratory problems by 12 to 24 hours.
Afflicted individuals can develop a sore throat, nasal discharge and a cough.
Remember that the flu shot only begins offering protection about two weeks after it is administered. The flu virus changes from year to year due to subtle genetic mutations that allow new strains to develop. Due to this continually changing phenomenon, a new vaccine must be created each year to fight the mutating virus. This year there were difficulties in growing one of the viruses, causing shortages of the vaccine. The flu vaccine cannot cause the flu, but you could get infected if you happen to be exposed to the virus soon after you are vaccinated.