The norovirus is commonly called the stomach flu. The U.S. Centers for Disease Control and Prevention (CDC) reports that the norovirus causes about 70,000 hospitalizations and 800 deaths each year, mostly in young children and the elderly. A new norovirus strain, GII.4 Sydney, was detected last year in Australia. The strain hit the U.K and sickened over a million people. It has now reached the United States and this new strain appears to be taking over. Of norovirus cases reported from September to December, 54 percent have been identified as GII.4 Sydney, according to recently released data. No vaccine is available.