South Carolina's measles outbreak jumped to Washington state 5 times in 2 weeks

Since measles was declared eliminated in the US in 2000, the country’s occasional cases have come mainly from international travelers—visitors from far-flung places where the virus still spreads freely — or unvaccinated US residents who return from abroad with a highly infectious souvenir. But as vaccination rates have slipped nationwide in recent years and outbreaks grow bigger and more frequent, domestic travel now poses a greater risk than international incursions.

自2000年美国宣布消除麻疹以来，该国偶尔出现的病例主要来自国际旅客——即来自病毒仍在自由传播的遥远地区的访客，或是从国外带回高传染性“纪念品”的未接种疫苗的美国居民。然而，随着近年来全国疫苗接种率的下滑以及疫情规模的扩大和频率的增加，国内旅行现在构成的风险已超过了国际输入。

In a study published this week in NEJM Evidence, Washington state health officials highlight that risk, detailing how an explosive outbreak in South Carolina reached their distant state through five distinct importation events over two weeks in January. In all, the introductions led to 26 cases among residents before officials stamped out the spread.

在本周发表于《新英格兰医学杂志·证据》（NEJM Evidence）的一项研究中，华盛顿州的卫生官员强调了这一风险，详细描述了南卡罗来纳州的一次爆发性疫情如何在1月份的两周内，通过五次不同的输入事件传播到了遥远的华盛顿州。总计，这些输入事件导致当地居民中出现了26例病例，随后官员们扑灭了疫情的蔓延。

South Carolina’s measles outbreak began on October 2, 2025, and was declared over on April 26, 2026. Officials confirmed 997 cases in the state during the outbreak. At the time, it was the largest measles outbreak recorded since the virus was declared eliminated, but Pennsylvania’s ongoing outbreak has since surpassed it.

南卡罗来纳州的麻疹疫情始于2025年10月2日，并于2026年4月26日宣布结束。官员们确认该州在疫情期间共有997例病例。在当时，这是自宣布消除该病毒以来记录的最大规模麻疹疫情，但宾夕法尼亚州目前正在进行的疫情规模已经超过了它。

The study in Washington relied heavily on epidemiological data, linking cases among contacts and exposure sites. But also key to the work was whole genome sequencing, which made clear that cases didn’t just stem from one single introduction of the virus from South Carolina that then spread among Washington residents; instead, it revealed five separate introductions.

华盛顿州的研究在很大程度上依赖于流行病学数据，将接触者和暴露地点的病例联系起来。但这项工作的关键还在于全基因组测序，它明确指出病例并非仅仅源于南卡罗来纳州病毒的单次输入并在华盛顿州居民中传播；相反，它揭示了五次独立的输入事件。

“As public health jurisdictions prepare to respond to increased measles importations linked to domestic measles outbreaks, while remaining vigilant for international importations, timely whole-genome sequencing can supplement epidemiologic information to help differentiate distinct importations from local transmission and inform outbreak response,” the authors conclude.

作者总结道：“随着公共卫生管辖区准备应对与国内麻疹疫情相关的日益增加的麻疹输入，同时对国际输入保持警惕，及时的全基因组测序可以补充流行病学信息，帮助区分不同的输入与本地传播，并为疫情应对提供参考。”

In their analysis, health officials identified the first importation in a resident who fell ill with the telltale rash on January 12 after returning from a trip to South Carolina, where they were exposed to a person sick with measles. Genome sequencing found that the virus closely matched sequences from South Carolina cases. One close contact of the Washington case fell ill and was isolated. No other cases were linked to this importation.

在分析中，卫生官员确定了第一起输入病例，该居民在从南卡罗来纳州旅行归来后，于1月12日出现了典型的皮疹症状，此前他在该州接触过一名麻疹患者。基因组测序发现，该病毒与南卡罗来纳州的病例序列高度匹配。该华盛顿州病例的一名密切接触者随后发病并被隔离。没有其他病例与此次输入有关。

In a second importation event, South Carolina residents visited public places while infectious. As a result, four residents with close contact with the South Carolina visitors fell ill. While infectious, the four residents visited schools, healthcare facilities, and a church. Nine of their contacts and one person exposed in a public location fell ill, leading to a total cluster of 14 cases that spanned January 15 to February 17.

在第二起输入事件中，南卡罗来纳州的居民在具有传染性期间访问了公共场所。结果，四名与这些南卡罗来纳州访客有密切接触的当地居民发病。在具有传染性期间，这四名居民曾前往学校、医疗机构和教堂。他们的九名接触者以及一名在公共场所暴露的人员发病，导致从1月15日到2月17日期间共出现了14例病例。

In the third importation event, two state residents returned from South Carolina and fell ill on January 15 to 16. No additional cases were linked to these residents. Similarly, a fourth importation event occurred when a resident returned from travel. The person adhered to isolation and quarantine recommendations, and no cases were linked to this one.

在第三起输入事件中，两名州居民从南卡罗来纳州返回，并于1月15日至16日发病。没有其他病例与这些居民有关。同样，第四起输入事件发生在一居民旅行归来时。此人遵守了隔离和检疫建议，没有病例与此相关。

In the fifth importation event, a Washington state resident returned from out-of-state travel where they had contact with ill contacts and fell ill themselves on January 19. While contagious, they visited a school and a healthcare facility. Six close contacts fell ill. In all, this cluster of seven cases spanned January 19 to January 29. The genome sequences from five of the cases were nearly identical to those seen in South Carolina. Officials credit basic public health work of quarantines, isolation, and contact tracing with keeping the virus from spreading farther than it did.

在第五起输入事件中，一名华盛顿州居民从外州旅行归来，期间接触过患病者，并于1月19日发病。在具有传染性期间，他们访问了一所学校和一家医疗机构。六名密切接触者发病。总计，这一由七例病例组成的集群发生在1月19日至1月29日之间。其中五例病例的基因组序列与南卡罗来纳州所见的序列几乎完全相同。官员们认为，检疫、隔离和接触者追踪等基础公共卫生工作防止了病毒进一步扩散。

While the study highlights how readily this virus can spread among states amid declining vaccination, it also contradicts a common talking point from Health Secretary Robert F. Kennedy Jr. Kennedy, a prominent anti-vaccine advocate, has downplayed the current measles surge in the US and aggressively defended against suggestions that his decades of anti-vaccine misinformation and disinformation have contributed to the surge in cases and drop in vaccination.

虽然这项研究强调了在疫苗接种率下降的情况下，这种病毒在各州之间传播的容易程度，但它也反驳了卫生部长小罗伯特·F·肯尼迪（Robert F. Kennedy Jr.）的一个常见论点。作为著名的反疫苗倡导者，肯尼迪一直淡化美国当前麻疹病例激增的情况，并极力反驳有关他数十年来散布的反疫苗错误信息和虚假信息导致病例激增和疫苗接种率下降的说法。

Instead, Kennedy claims that there is a “global outbreak” and the US is “doing a better job than any country in the world at controlling the measles outbreak.” Both claims are false. Dozens of other countries have lower case rates than the US. While some countries, including neighboring Canada and Mexico, are also seeing large increases in cases, the soaring case tally in the US is not being driven by international imports, but by domestic spread in under-vaccinated communities.

相反，肯尼迪声称存在“全球性爆发”，而美国在控制麻疹疫情方面“做得比世界上任何国家都好”。这两个说法都是错误的。其他几十个国家的病例率都低于美国。虽然包括邻国加拿大和墨西哥在内的一些国家病例也在大幅增加，但美国病例数的飙升并非由国际输入驱动，而是由疫苗接种不足社区内的国内传播所致。

According to data from the Centers for Disease Control and Prevention, only 18 of the country’s 4,588 confirmed measles cases this year were reported among international visitors. Of all the cases, 4,404 (96 percent) are linked to a domestic outbreak. The US has had 43 new outbreaks this year.

根据美国疾病控制与预防中心（CDC）的数据，今年全国4,588例确诊麻疹病例中，只有18例是国际访客。在所有病例中，有4,404例（96%）与国内疫情有关。美国今年已出现了43起新的疫情。