2025年，日本正式進入流感大流行期，引起社會各界高度關注。根據日本國立健康危機管理研究機構最新數據顯示，截至10月5日，日本已報告6,013例流感感染病例，初步判斷可能由H3N2甲型流感病毒株引發。專家指出，由於日本疫情出現快速增長趨勢，流感很可能擴散至周邊國家。

從疫情發展來看，9月29日至10月5日這一周，日本全國報告的流感病例數比上一周增加1.5倍。多重因素共同作用，使今年的流感季比往年提前約一個月。其中，海外旅行活躍、居民防護意識下降以及氣候變化，是導致疫情提前爆發的主要原因之一。根據日本的標準，如果平均每家定點醫療機構每周報告病例數超過1例，即標誌著正式進入流感季。按照這一標準，9月22日至28日當周，日本每家定點醫療機構平均報告病例1.04例，厚生勞動省於10月3日正式宣布全國進入流感季，較2024年提前了 5周，同時這也是自1999年採用現行統計方法以來的第二早紀錄。

自8月11日至17日以來，日本每周新增流感病例數已連續7周增長。受疫情影響，截至本月5日，日本全國已有620所保育園、幼兒園、中小學 出現全校停課或部分年級、班級停課情況。其中，僅在9月29日至10月5日這一周，就有 209所教育機構停課或部分停課，而去年同期僅有 99所，顯示疫情擴散速度明顯加快，對教育與社會生活造成廣泛影響。

關於今年流感季提前的原因，專家指出有多方面因素。首先，日本民眾戴口罩、勤洗手等防感染意識有所下降，降低流感防控效果。其次，跨國旅行活動頻繁，增加了病毒傳播機會。根據英國《自然》雜誌報導，世界衛生組織官員伊恩·巴爾指出，H3N2病毒株在過去兩個月主要在澳大利亞與新西蘭流行，而大量澳大利亞人近期前往日本，這使病毒在南北半球之間的傳播風險顯著提高。此外，氣候變化帶來的溫度和濕度波動，也可能促進病毒的活躍與傳播速度。

綜合來看，日本流感季提前爆發，不僅對公共衛生系統提出挑戰，也對教育、社會活動與跨國交流產生影響。專家建議民眾應加強個人防護措施，及時接種流感疫苗，並密切關注疫情動態，以降低感染風險並控制疫情擴散。

In 2025, Japan has officially entered its influenza outbreak season, drawing widespread attention across the country. According to the latest data from the National Institute of Health Crisis Management, as of October 5, Japan had reported 6,013 influenza cases, preliminarily linked to the H3N2 strain of Influenza A. Experts warn that given the rapid increase in cases, the outbreak could potentially spread to neighboring countries.

During the week of September 29 to October 5, the number of reported influenza cases nationwide increased by 1.5 times compared to the previous week. Multiple factors contributed to this early surge, including high levels of overseas travel, decreased public vigilance regarding infection prevention, and climate variations, causing Japan’s flu season to begin roughly one month earlier than usual. By Japanese standards, an average of more than one case per reporting medical institution per week marks the official start of the influenza season. In the week of September 22–28, the average number of cases per medical reporting site was 1.04, prompting the Ministry of Health, Labour and Welfare to officially declare the start of the flu season on October 3—five weeks earlier than in 2024 and the second earliest since 1999 under current statistical methods.

Since the week of August 11–17, Japan has experienced seven consecutive weeks of increasing influenza cases. The outbreak has had a significant impact on education: as of October 5, 620 kindergartens, elementary, and secondary schools nationwide have either closed entirely or suspended certain grades or classes. In just the week of September 29 to October 5 alone, 209 educational institutions implemented closures or partial closures, compared with only 99 during the same period last year, reflecting the rapid spread of the virus and its broad social impact.

Experts attribute the early flu season to several factors. Firstly, many Japanese citizens have reduced preventative behaviors such as mask-wearing and hand hygiene, weakening protective measures. Secondly, cross-border travel remains highly active, increasing opportunities for virus transmission. According to an article in the British journal Nature, citing WHO official Ian Barr, the H3N2 strain had been prevalent in Australia and New Zealand over the past two months, and the large influx of Australian visitors to Japan heightened the risk of viral transmission between the southern and northern hemispheres. Additionally, climate fluctuations, including temperature and humidity changes, may have further promoted the virus’s activity and transmission speed.

In summary, Japan’s early influenza season in 2025 poses challenges for public health, education, and social activities, as well as potential implications for international travel. Experts recommend that citizens strengthen personal protection, get vaccinated against influenza, and closely monitor the evolving situation to reduce infection risk and help contain the outbreak.