In Japan, based on the National Epidemiological Surveillance of Infectious Diseases (NESID) Program, influenza cases from ~5,000 sentinel sites are monitored weekly as part of influenza surveillance (as number of influenza cases/sentinel site). One limitation is that the number of influenza tests conducted is not reported. Separately, the National Hospital Organization (NHO), with ~140 hospitals, routinely publishes three indicators: number of influenza tests, influenza-positive case counts, and test positivity. We used NESID and NHO data from April 2011 to June 2022 to assess the usefulness of multiple indicators to monitor influenza activity. Temporal trends of the NHO and NESID indicators were similar, and NHO indicator levels well-correlated with those of the NESID indicator. Influenza positivity in the NHO data, however, showed an earlier rise and peak time compared to the NESID indicator. Importantly, through the non-epidemic summer periods and the coronavirus disease 2019 pandemic, a sizable number of influenza tests continued to be done at NHO hospitals, with results showing considerably low case counts and test positivity. These data show that a relatively small number of sentinel sites is sufficient to monitor influenza activity nationally, and, that utilizing multiple indicators can increase our confidence in situational awareness and data interpretations.

在日本，根据国家传染病流行病学监测 (NESID) 计划，每周监测约 5,000 个哨点的流感病例，作为流感监测的一部分（作为流感病例/哨点的数量）。一个限制是没有报告进行的流感检测的数量。另外，拥有约 140 家医院的国家医院组织 (NHO) 定期发布三项指标：流感检测数量、流感阳性病例数和检测阳性率。我们使用 2011 年 4 月至 2022 年 6 月的 NESID 和 NHO 数据来评估多个指标监测流感活动的有用性。 NHO 和 NESID 指标的时间趋势相似，NHO 指标水平与 NESID 指标水平相关性良好。然而，与 NESID 指标相比，NHO 数据中的流感阳性率显示出更早的上升和峰值时间。重要的是，在非流行的夏季和 2019 年冠状病毒病大流行期间，NHO 医院继续进行了大量流感检测，结果显示病例数和检测阳性率相当低。这些数据表明，相对较少的哨点足以监测全国范围内的流感活动，并且利用多个指标可以增加我们对态势感知和数据解释的信心。