Maintenance of Measles Elimination Status in the United States for 20 Years Despite Increasing Challenges
Maintenance of Measles Elimination Status in the United States for 20 Years Despite Increasing Challenges
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DOI：
10.1093/cid/ciab979
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发表时间：
2022-01-08
影响因子：
11.8
通讯作者：
Gastanaduy, Paul A.
中科院分区：
文献类型：
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作者：
Mathis, Adria D.;Clemmons, Nakia S.;Gastanaduy, Paul A.
尽管美国在过去20年中一直保持着消除麻疹的状态，但与未接种疫苗者聚集有关的传播增加的新趋势突出表明，有必要缩小现有的免疫差距，并强调预防疫情的重要性。2000年美国宣布（中断地方性麻疹病毒传播）;然而，近年来病例和疫情的数量有所增加。我们描述了麻疹疫情的流行病学特征和消除后的麻疹传播模式，以确定美国麻疹控制计划中的潜在差距。方法分析2001年1月1日至2019年12月31日全国麻疹报告数据。我们将麻疹感染聚集性定义为单个病例（与其他病例无关的孤立病例）、2例聚集性病例或3例以上相关病例的暴发。我们计算了有效繁殖数（R），以评估遗传性的变化，并回顾了分子流行病学数据。结果2001-2019年，美国共报告了3873例麻疹病例，其中包括747例国际输入病例; 29%的输入病例与疫情有关。在871个聚集性病例中，69%为单一病例，72%没有传播。自2013年以来，报告了更大和更长的集群，包括7次爆发，其中50例病例持续时间>2个月，其中5例发生在已知的免疫不足，联系紧密的社区。没有麻疹谱系在单一传播链中传播超过12个月。近年来，人们注意到R的估计值较高，尽管R仍低于流行阈值1。结论目前的流行病学继续支持中断地方性麻疹病毒在美国的传播。然而，在消除麻疹后的最近几年里，爆发规模更大、时间更长，免疫接种不足的社区出现了传播增加的趋势，这突出表明需要采取有针对性的方法来缩小现有的免疫差距，保持麻疹的消除。
Althoughmeasles elimination has been maintained in the United States for the past 20 years, emerging trends of increased transmission related to clustering of unvaccinated persons highlight the need to close existing immunity gaps and the importance of outbreak preparedness.Background Measles elimination (interruption of endemic measles virus transmission) in the United States was declared in 2000; however, the number of cases and outbreaks have increased in recent years. We characterized the epidemiology of measles outbreaks and measles transmission patterns after elimination to identify potential gaps in the US measles control program. Methods We analyzed national measles notification data from 1 January 2001 to 31 December 2019. We defined measles infection clusters as single cases (isolated cases not linked to additional cases), 2-case clusters, or outbreaks with >= 3 linked cases. We calculated the effective reproduction number (R) to assess changes in transmissibility and reviewed molecular epidemiology data. Results During 2001-2019, a total of 3873 measles cases, including 747 international importations, were reported in the United States; 29% of importations were associated with outbreaks. Among 871 clusters, 69% were single cases and 72% had no spread. Larger and longer clusters were reported since 2013, including 7 outbreaks with >50 cases lasting >2 months, 5 of which occurred in known underimmunized, close-knit communities. No measles lineage circulated in a single transmission chain for >12 months. Higher estimates of R were noted in recent years, although R remained below the epidemic threshold of 1. Conclusions Current epidemiology continues to support the interruption of endemic measles virus transmission in the United States. However, larger and longer outbreaks in recent postelimination years and emerging trends of increased transmission in underimmunized communities emphasize the need for targeted approaches to close existing immunity gaps and maintain measles elimination.