How common is flu?
The World Health Organization estimates that annual influenza epidemics infect 5-15% of the world population each year, cause 3-5 million cases of severe illness and 250,000-500,000 deaths. About 300 million people get the flu vaccine each year. Without it, says Smith, a person can expect to catch the flu about once every 10 years. Smith says the findings are important for the experts who formulate the new flu vaccine each year. It typically includes a cocktail of three strains, and the scientists try to predict which strains will cause the most trouble each year. “If we are trying to predict what will happen a year from now we should be paying attention to what is happening in east and southeast Asia,” he says. The researchers say their study does not have any bearing on what might happen in a pandemic of a new source of flu, such as the H5N1 virus now circulating mostly among birds in Asia, Europe and Africa.
