日本提前进入流感季

Core Insights - Japan has entered the flu season earlier than usual, with flu cases reported at 1.5 times the previous week, influenced by factors such as increased international travel, decreased preventive awareness, and climate change [1][2] Summary by Sections Flu Season Timing - The flu season in Japan began approximately one month earlier than in previous years, with the Ministry of Health announcing the start on October 3, 2023, which is five weeks earlier than in 2024 and the second earliest since 1999 [1] Case Statistics - From August 11 to 17, the number of weekly new flu cases has increased for seven consecutive weeks, leading to the closure of 620 educational institutions by October 5, 2023, compared to only 99 during the same period last year [1] Contributing Factors - Decreased awareness of infection prevention measures, such as mask-wearing and handwashing, has contributed to the early onset of the flu season [2] - Increased international travel, particularly from Australia, has facilitated the spread of the H3N2 strain of the virus [2] - Climate change and the hot summer may have weakened immune responses, as people spent more time indoors, reducing their exposure to sunlight and vitamin D synthesis [2] - Potential low matching of this year's flu vaccine with circulating strains and the mild symptoms of the current flu may have led to underreporting and easier virus spread [2] Global Implications - The current flu situation in Japan is not expected to evolve into a global pandemic, but there is a risk of transmission to neighboring countries and those with travel links to Japan, especially as winter approaches in other regions [2]