On April 24, 2023, the American Samoa Department of Health (ASDoH) declared a public health emergency amid concern about a possible measles outbreak given low 2-dose vaccination coverage at the time. ASDoH had received two positive measles immunoglobulin (Ig) M test results after Flag Day festivities 1 week earlier from vaccinated children. ASDoH performed active case finding, took actions to mitigate transmission, and requested technical assistance from CDC. ASDoH implemented a vaccination campaign to improve suboptimal coverage. Confirmatory molecular testing of specimens from these initial persons under investigation (PUIs) was not possible, but subsequent testing of specimens from additional PUIs by Hawaii State Laboratories Division and CDC ruled out measles. In settings with low measles prevalence, measles antibody testing results have low positive predictive value and can lead to difficulties with interpreting results. Testing for additional pathogens revealed a variety of viruses known to cause common childhood viral exanthems. Both molecular and serologic testing should be performed for all suspected measles cases. To decrease the probability of false-positive IgM results, testing should be reserved for cases that meet the Council of State and Territorial Epidemiologists measles case definition, especially those in persons with no evidence of immunity and with a history of recent international travel. In addition, maintaining high measles vaccination coverage can prevent future outbreaks.

中文翻译：

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初始麻疹免疫球蛋白 M 抗体检测结果呈阳性的小儿皮疹病爆发 - 美属萨摩亚，2023 年 3 月至 7 月。


2023 年 4 月 24 日，美属萨摩亚卫生部 （ASDoH） 宣布进入公共卫生紧急状态，因为当时 2 剂疫苗接种覆盖率低，人们担心可能会爆发麻疹疫情。ASDoH 在 1 周前的国旗日庆祝活动后收到了两名接种疫苗的儿童的阳性麻疹免疫球蛋白 （Ig） M 检测结果。ASDoH 进行了积极的病例发现，采取行动减轻传播，并请求 CDC 提供技术援助。ASDoH 实施了一项疫苗接种活动，以提高次优覆盖率。无法对这些初始被调查者 （PUI） 的标本进行确认性分子检测，但夏威夷州立实验室部门和 CDC 随后对来自其他 PUI 的标本进行检测，排除了麻疹。在麻疹患病率低的环境中，麻疹抗体检测结果的阳性预测值较低，可能导致结果解释困难。对其他病原体的检测揭示了已知会导致常见儿童病毒疹的各种病毒。应对所有疑似麻疹病例进行分子和血清学检测。为了降低 IgM 假阳性结果的可能性，应仅对符合美国国务委员会和地区流行病学家麻疹病例定义的病例进行检测，尤其是那些没有免疫证据且近期有国际旅行史的病例。此外，保持较高的麻疹疫苗接种覆盖率可以防止未来的疫情暴发。