美国麻疹感染人数已达到35年来的最高水平[1]。截至2026年7月中旬，美国共报告麻疹病例2,321例[1]，这一数字已经超过了2025年全年的2,286例[1]。专家警告称，美国可能失去自2000年以来保持的麻疹消除状态，因为病毒正在接种不足的社区内传播[1]。
麻疹对患者构成严重健康威胁。约五分之一的患者需要住院治疗[1]，每1,000名感染儿童中约有1名发生脑炎[1]，而1至3名儿童可能因呼吸或神经并发症而死亡[1]。更令人担忧的是，麻疹甚至可能在原始感染后5至10年引发亚急性硬化性全脑炎[1]。儿童在症状出现前约四天就已具有传染性[1]。
疫苗接种率下降和公众对麻疹危害的认识淡漠是疫情扩散的主要原因[1]。根据约翰斯·霍普金斯大学流行病学家威廉·莫斯的评估，病毒现已开始在美国易感社区间传播，而不再仅限于境外输入病例[1]。
The United States is experiencing a significant resurgence in measles infections, with cumulative cases reaching 2,321 by mid-July 2026—already surpassing the entire 2025 annual total of 2,286 cases [1]. This alarming trend threatens to undermine the country's measles elimination status maintained since 2000, as public health experts warn that waning vaccination rates and diminished awareness of the disease's dangers are enabling the virus to spread through under-immunized communities [1].
The severity of measles-related complications underscores the urgency of the outbreak. Approximately one in five measles patients requires hospitalization, while about one in 1,000 infected children develops encephalitis [1]. More gravely, between one and three in 1,000 infected children may die from respiratory or neurological complications [1]. Additionally, measles can trigger subacute sclerotizing panencephalitis—a severe brain inflammation—five to ten years after the initial infection [1]. Children become contagious approximately four days before symptoms appear, complicating early containment efforts [1].
According to Johns Hopkins epidemiologist William Moss, the virus is now spreading within vulnerable American communities rather than remaining limited to imported cases [1]. This shift in transmission patterns reflects the erosion of herd immunity and highlights the critical role that vaccination coverage plays in disease prevention.