WASHINGTON (AP) — Government medical advisers on Wednesday issued their recommendations for next season's flu vaccine, the front line defense against a disease that kills an estimated 36,000 people a year. A Food and Drug Administration advisory panel recommended only a slight change for the 2009-2010 season from the current vaccine, which protects against infection by three kinds of flu viruses. For Type A flu_the most serious kind_the FDA advisers recommended no change. Next season's vaccine will protect against the same two Type A strains that are in circulation now. However, for the milder Type B strain, next year's vaccine will be slightly different, replacing a Type B/Florida strain of the virus with a version called Type B/Brisbane. Because different strains of flu circulate every winter, people need to be vaccinated annually. Manufacturers start preparing the following season's vaccine well in advance, based on close study of current infection patterns. The government recommends that people over 50, pregnant women, those with chronic medical conditions and children older than six months be vaccinated each year.