About 25 million people, or some 20 percent of the population in Japan, are expected to become infected with the new H1N1 strain of influenza A, the Health, Labor and Welfare Ministry said Friday. Some 380,000 people, or 1.5 percent of the anticipated cases, are expected to be hospitalized and 40,000 people, or 0.15 percent, are expected to develop serious symptoms like encephalopathy or need to be aided by respirators, according to the ministry's estimates.
The ministry anticipates that the peak of the epidemic will come around late September to early October in Japan. Some regions, including urban areas where the population is concentrated and rural areas with many elderly people, may see more than 30 percent of their populations infected, according to the estimates. In those areas, the rate of hospitalization may hit 2.5 percent and the percentage of serious cases of infections may reach 0.5 percent.
''The figures do not take into consideration the effects of vaccinations. Actual figures will be affected largely by contact between people in each community and weather conditions,'' a ministry official said. ''But the situation may turn worse if the virus becomes more virulent.'' Also on Friday, the ministry instructed prefectural governments to expedite preparations to deal with the epidemic. The ministry expects the rate of new-flu infections to be about twice as much as seasonal flu. Including infections with no symptoms or very mild symptoms, the total number of infections may be as high as around 63 million people, roughly half the population.
Judging from the cases of seasonal flu reported in the past five years, the ministry thinks it will take about 19 weeks before the end of the new-flu epidemic in Japan. A full epidemic is believed to have begun in mid-August and the peak is estimated to come in the ninth week -- late September through early October. During the anticipated peak period, about 760,000 people are likely to develop new-flu infections per day. The number of patients likely to be hospitalized is expected to peak in the 10th week at 46,400 people. Of the 46,400 people, 3,500 are expected to be toddlers aged 5 or younger, 11,800 between ages 6 and 15, 20,000 between 16 and 64, and 11,100 at 65 and older.
