Rotarix is an oral, two-dose, live attenuated vaccine against rotavirus disease in infants that was licensed in 1997 by Avant Immunotherapeutics to GSK for worldwide commercialization. Rotavirus infection is the leading cause of severe diarrhea and vomiting in infants and young children between three to 24 months worldwide. Rotarix is designed to provide broad protection against multiple rotavirus strains and to provide early protection before the onset of rotavirus illness. The vaccine works by stimulating the body to mimic the immune response to natural rotavirus infection, which protects against the subsequent development of moderate to severe rotavirus disease. "We are very pleased to see the start of this global launch of Rotarix, which will mean increasing royalty revenues to Avant over the next several years," said Dr Una Ryan, Avant president and CEO. Rotarix obtained licensure in July 2004 from the Mexican regulatory authorities, and GSK has already filed for market approval in more than 20 countries worldwide. GSK plans to launch Rotarix in additional Latin American countries, as well as Asia Pacific countries, during the course of 2005.