Many people who think they have the flu actually have a cold. The main difference is that with fever the fever can rise to 39 degrees or more within 12 hours and usually lasts for three to five days. With a cold adults almost never get a fever, children sometimes. The flu symptoms are also different and more severe. This often starts suddenly with chills, fever, headache and muscle aches. The viruses spread mainly through small droplets through the air (think of sneezing, coughing). Its distribution is easy in busy places. In winter these rooms are often less well ventilated and that is the reason that cold and flu occur more frequently in this season. It also spreads more easily through dry air and at low temperatures. Off to a good winter in well-ventilated spaces!