The World Health Organisation today said, the swine flu virus had not yet mutated into a more serious disease and the development of vaccines was proceeding on track. WHO Director-General Margaret Chan said at the Hongkong Western Pacific meeting that the vaccines for (A) H1N1 influenza produced so far have been very effective. She said, three billion doses of vaccines could be produced worldwide annually and noted that China had already begun to vaccinate people. She also said the Hong Kong government could relax its measures against the swine flu outbreak step-by-step, to focus resources on saving patients and reducing the number of serious cases. Chan said that only high-risk patients such as the elderly, the obese and those with underlying illnesses would be severely affected by the disease. <br/><br/>