情势可能更恶化：去年底成人接种率不足 43%。目前流感活动大幅上升，主要与被称为「超级流感」的新变异株有关，它是常见 H3N2 的突变，现行疫苗与之匹配度偏差；专家指出其可能更能躲避免疫，使更多人变得易感、加速传播，且美国「离高峰仍很远」。
儿童与青少年受冲击尤其严重：在年底最后一周，超过 8% 的急诊就诊与流感相关；其中 5–17 岁儿童超过 20%，4 岁以下为 18%。本季已有 9 名儿童死亡；而死亡常随季节推进而上升，去年全美儿科流感死亡超过 280 例。流感通常先在东南部出现、再向北与向西扩散；目前门诊最高仍集中于美国东部，但加州、俄勒冈与华盛顿等州也在上升，流感季通常到 5 月才趋缓。
So far this flu season in the US, at least 11 million people have been infected and 5,000 have died. The CDC classified the outbreak as “moderately severe” for the first time in the last week of 2025, and doctor and emergency-department visits for flu-like illness are at their highest level since before the pandemic hit in 2020.
The situation may worsen because fewer than 43% of adults were vaccinated by the end of last year. Rising activity is being driven largely by a new “super flu” variant, a mutation of the common H3N2 strain, and current shots appear to be a poor match; experts say it can evade immunity from vaccination or prior infection, leaving a larger susceptible share and speeding spread, with the US still “far from a peak.”
Children and teenagers are being hit hardest: in the last week of the year, more than 8% of emergency-department visits were for influenza, rising to over 20% for ages 5–17 and 18% for children under 4. Nine children have already died this season; deaths typically lag and rose to more than 280 pediatric deaths last year. Flu often starts in the Southeast and spreads north and west; the highest outpatient activity remains in the eastern US, but is climbing in California, Oregon, and Washington, and the season typically winds down by May.
