Chinese authorities have greenlit a clinical trial for the world’s first tetravalent vaccine against norovirus, the most common cause of viral gastroenteritis. The vaccine received the clinical research permit from the National Medical Products Administration on May 30, its developer, the Institut Pasteur of Shanghai (IPS) under the Chinese Academy of Sciences, announced at a press conference Tuesday. As the number one cause of acute viral gastroenteritis, the highly contagious and sometimes deadly norovirus infects about 685 million people worldwide annually and has increasingly emerged as a public health issue in China. The vaccine, after four years of development, can theoretically prevent 80 to 90 percent of norovirus infections also known as “stomach flu,” said Huang Zhong, who leads the project at IPS. The norovirus has long eluded the world’s vaccine development, as traditional strategies of inactivation and attenuation fail on the virus that cannot be cultured in vitro on a large scale. This was further complicated by the virus’ many genotypes, regional variations and its propensity to mutate, according to Huang. The clinical trial is expected to last for five years before the vaccine can apply for new drug registration, which will benefit norovirus prevention in both China and abroad, said Tang Hong, researcher with the IPS.