Study population and setting
This study examines the age-distribution of confirmed cases of SARS-CoV-2 between January and March 2020 in Japan. Age-specific attack rates were also calculated.
Summary of Main Findings
There were a total of 313 domestically-acquired cases emerging from 2496 suspected cases with close contacts and confirmed via RT-PCR, as of March 7, 2020 in Japan. Overall, there was a higher proportion of cases that were male (55.2%). A total of ten cases (3%) were among those 0-19 years old, while 131 cases were among those 60 years or older (42%). The attack rate for those 0-19 years old was 7.2% (95% CI: 3.0%, 14.3%) among males and 3.8% (95% CI: 0.8%, 10.6%) among females. The highest attack rate was seen among those 50-59 year old for both males (22.2%) and females (21.9%).
This study provides initial descriptive data for Japan that reinforces age-related data observed in other settings.
This is a relatively small study with limited information about the suspected index cases or testing information about contacts which prevent understanding of infection risk (versus disease).
This small study provides additional evidence that supports that children may be less likely to be diagnosed as cases, and that even given documented exposure, the risk of children acquiring the disease is low.