An analysis of swine flu cases reported to health care institutions shows that patients in their early teens have been catching the virus in increasing numbers since schools and nurseries reopened after the summer break, a government institute said Tuesday.
A researcher at the National Institute of Infectious Diseases said the H1N1 virus may be in the initial stage of a domestic outbreak, citing patterns for seasonal influenzas that typically hit specific regions and age groups in the early stage.
Between July 6 and Sept. 20, about 70 percent of the flu patients reported by around 5,000 institutions throughout the nation were aged 5 to 19. A breakdown showed those aged 5 to 9 accounted for about 24 percent, 10 to 14 around 28 percent and 15 to 19 some 16 percent.
In the week up to Sept. 20 alone, people aged 10 to 14 accounted for a sharply increased 40 percent of all patients, according to the institute.
By region, reported cases in Okinawa Prefecture have been on the decline, but infections have been growing in metropolitan areas, including Tokyo, Aichi, Osaka, Hyogo and Fukuoka, in addition to Hokkaido and Miyagi prefectures.
