Takaji Wakita, head of the National Institute of Infectious Diseases (NIID), is seen in this file photo. (Mainichi/Toshiki Miyama)

       TOKYO -- Over 75% of children aged 18 or younger who contracted the coronavirus between August and September amid the fifth wave of the epidemic in Japan were infected at home, according to health ministry statistics.

       Summer break appears to be a factor that increased home infections among minors between August and September. Meanwhile, the proportion of infections at school and other places outside the home has been increasing among under-16s in September, as elementary and junior high schools have resumed classes.

       The Ministry of Health, Labor and Welfare aggregated data between Aug. 1 and Sept. 13, using the Health Center Real-time Information-sharing System on COVID-19, or HER-SYS, into which information about COVID-19 patients is inputted. During the period, there were a total of 102,759 infected individuals aged between 3 and 18. Among them, the health ministry analyzed data on 15,619 individuals whose place of infection could be identified, and found that 11,724 infections, or 75.1%, occurred at home -- making this the most common route. Setting aside young children aged from 3 to 5, who use day care centers and other welfare facilities, the ministry found that among children aged between 6 and 18, the older the age group, the larger the proportions of infections at school and other places outside the home.

       Meanwhile, the rate of infections at school and welfare facilities increased from September following the end of summer break. Among the 2,265 children aged 3 to 5 who had COVID-19 in August, 223, or 9.8%, were infected in welfare facilities. The figure for September stood at 101, or 13.6% of the total. Children in the 6-12, and 13-15 age groups, also saw greater percentages of school infections from September.

       As for why home infections exceeded 70%, a councillor of the Cabinet Secretariat in charge of coronavirus countermeasures said that summer break was likely a contributing factor.

       In addition, the health ministry's probe into virus clusters that broke out at elementary schools found that the week between Sept. 6 and 12 saw 32 cases, the highest figure since tallies began to be taken in April.

       As children aged under 12 are not included as individuals eligible for receiving coronavirus vaccines, infections among children may increase further moving forward.

       Takaji Wakita, head of the National Institute of Infectious Diseases (NIID), commented, "Within the home, parents and siblings need to be vaccinated, and the same goes for elementary school employees."

       (Japanese original by Takashi Kokaji, Lifestyle and Medical News Department)

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