Data_Sheet_1_Detection of the Onset of the Epidemic Period of Respiratory Syncytial Virus Infection in Japan.ZIP

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infection in young children worldwide. An annual epidemic of RSV infection generally begins around autumn, reaching a peak at the end of year in Japan, but in 2017 it started in early July and peaked in September. As the onset timing of RSV season varies, it is important to detect the beginning of an epidemic, to enable the implementation of preventive measures. However, there are currently no specified criteria or methods to determine the onset of RSV season in a timely manner. Therefore, we developed a model to detect the epidemic onset, based on data from the Infectious Diseases Weekly Report from 2012 to 2017. The 47 prefectures of Japan span 11 climate zones, which affect the timing of epidemic onset. Therefore, the onset of RSV season was assessed separately in each prefecture. Non-linear regression analysis was performed to generate a mathematical model of the annual epidemic cycle for each prefecture. A search index was used to determine the onset of RSV season, which was estimated using the number of RSV reports per week within an epidemic period (RSV-reports/w) and the number of reported cases included within an epidemic period relative to the total number of RSV reports (capture rate). A number of RSV-reports/w, which was used as a threshold (a number at onset line) to determine the condition of the onset of RSV season, was then estimated based on the search index. The mean number at the onset of RSV season for 47 prefectures was 29.7 reports/week (median 21.0, range 6.0–121.0 reports/ week). The model also showed that the onset of RSV season in 2017 was more than 1 month earlier than the previous year. In conclusion, the model detected epidemic cycles and their onset conditions in all prefectures, despite the 11 climate zones of Japan. The results are expected to contribute to infant medical care by allowing medical personnel to take preventive measures promptly at the beginning of the epidemic RSV season.

呼吸道合胞病毒（Respiratory syncytial virus, RSV）是全球范围内引发幼儿下呼吸道感染的首要病因。RSV感染的年度流行通常于秋季左右启动，日本的流行高峰一般出现在年末，但2017年的流行却于7月初便开始，并在9月达到峰值。由于RSV流行季的启动时间存在显著差异，及时检测流行起始点以落实预防措施至关重要。然而当前尚无能够及时确定RSV流行季启动的明确标准或方法。为此，研究团队基于2012年至2017年《传染病周报》（Infectious Diseases Weekly Report）的数据，开发了一款流行起始检测模型。日本的47个都道府县横跨11个气候区，而气候区会影响流行启动的时间，因此研究人员针对每个都道府县分别评估RSV流行季的启动情况。通过非线性回归分析，为每个都道府县构建了年度流行周期的数学模型。研究采用搜索索引结合两项指标确定RSV流行季的启动情况：一是流行期内每周RSV报告数（RSV-reports/w），二是流行期内报告病例数占总RSV报告数的比例（捕获率，capture rate）。随后基于搜索索引，估算出作为RSV流行季启动阈值（启动线数值）的每周RSV报告数。日本47个都道府县的RSV流行季启动平均阈值为29.7份报告/周（中位数21.0，范围6.0–121.0份报告/周）。模型分析还显示，2017年的RSV流行季启动时间较前一年提前了一个多月。综上，尽管日本存在11个气候区，该模型仍成功检测出所有都道府县的流行周期及其启动条件。研究结果有望帮助医护人员在RSV流行季初期及时采取预防措施，从而为婴幼儿医疗照护工作提供支持。