When you have a cough and a bit of a headache, that's not the flu. When you're knocked on your ass with a fever, chills, sore muscles, headache and cough, that's the flu. It kills hundreds of thousands of people each year around the world. And each year, the World Health Organization predicts which strains of influenza will be most active, so pharmaceuticals can work on a vaccine.
But a vaccine doesn't always work. The virus can mutate. And if there's a pandemic, like with H1N1, the vaccine can be in short supply (unless you play for the Calgary Flames). Well, British researchers have been working on a universal vaccine, and so far, so good. The first human trials were a success.