美国流感季提前到来：变异H1N1毒株扩散 CDC估计已170万人感染
美国流感季今年来得比往年早。美国疾病控制与预防中心（CDC）的数据显示，流感活动自 8 月底至 9 月初开始上升，10 月的活动水平已达到通常 12 月或 1 月才出现的程度。截至 10 月 30 日，CDC 估计本季流感已造成 170 万人患病、2.5 万人住院、1400 人死亡。
截至 11 月 5 日的 CDC 预测显示，40 个州的流感感染人数呈上升趋势，没有一个州呈下降趋势。废水监测数据显示，10 月的流感活动水平已达到往年 12 月或 1 月的程度。截至 10 月 31 日的一周内，全国 51351 份流感检测中有 4694 份呈阳性，阳性率为 9.14%。
本季流感以甲型 H1N1 流感病毒为主，最常见的毒株为基因亚分支 D.3.1.1，系 H1N1 的变异版本。有专家警告，该毒株可能导致流感季提前或延长。一项发表于预印本平台 bioRxiv 的研究指出这一毒株的传播特点，该研究尚未完成同行评议。
世界卫生组织、CDC 与其他公共卫生机构表示，预防重症流感最有效的方法是接种疫苗。
U.S. Flu Season Arrives Early: Mutated H1N1 Spreading, CDC Estimates 1.7 Million Illnesses
The flu season arrived early in the United States this year. According to the Centers for Disease Control and Prevention (CDC), flu activity began increasing in parts of the country in late August and early September, reaching an activity level in October not usually seen until December or January. The CDC estimates 1.7 million illnesses, 25,000 hospitalizations and 1,400 deaths from flu so far this season as of October 30.
As of November 5, CDC projections found that flu infections were on the rise in 40 states and declining in none. Wastewater data showed flu activity in October at a level typically observed in December or January. In the week through October 31, about 9.14 percent (4,694) of the 51,351 flu tests administered that week were reported positive to the National Respiratory and Enteric Virus Surveillance System.
H1N1, a type of influenza A, is the primary virus behind this season so far. The most common H1N1 strain currently is the genetic subgroup known as subclade D.3.1.1, a mutated version of H1N1, with some experts warning that it could play a hand in an earlier or longer season. The finding was published in a study on the preprint server bioRxiv, meaning the research has not yet completed peer review.
The most effective way to prevent serious illness from the flu is vaccination, according to the World Health Organization, the CDC and other public health institutions.
来源：美国疾病控制与预防中心
发布：GSM·美国（发布链接）
图片来源：图：美国疾病控制与预防中心总部（GSM 固定图库）。CDC headquarters. (GSM asset library)
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