Chinese scientists have developed a new vaccine for poultry and mammals to prevent the spread of bird flu, according to state media. The new jab is thought to protect chickens for at least 10 months, four months longer than existing drugs. Bird flu has killed 45 people in Asia in the past year - mostly in Vietnam. But the World Health Organization has warned that 100 million people could die if the virus mutated into a form that could pass easily between humans. A spokesman for the WHO in Manila said the benefits of vaccinating poultry were still unproven, because in certain cases vaccines could mask the symptoms of disease in sick birds.
