The Diet has passed revisions to the Infectious Disease Law and the Quarantine Law to effectively cope with a possible outbreak of new types of influenza. There is fear that deadly new types of influenza will emerge, since the H5N1 bird flu is spreading mainly in Southeast Asia and bird-to-human infection is increasing. If a bird flu virus mutates into one capable of human-to-human transmission, a large number of people are expected to die. The government estimates that a new type of flu with the same lethality rate as the 1918 Spanish flu could kill up to 640,000 Japanese.

The law revisions will enable the government to segregate or forcibly hospitalize those who have developed symptoms of, are infected with, or are suspected of being infected with new types of flu. The government can prohibit such people from going to work.

The government has also decided to conduct a clinical test this fiscal year in which some 6,000 doctors, quarantine inspectors, other medical and health professionals and immigration and customs officials will be inoculated with stockpiled "pre-pandemic" vaccine based on the H5N1 virus strain. It also will inoculate 120 children at least 6 months old and younger than 20 with the same vaccine. If the vaccination proves safe and effective, it plans to vaccinate 10 million people whose work is related to maintaining basic functions of society.