A cynomolgus macaque (Macaca fascicularis) with a pre-existing, undiagnosed, subclinical but severe cerebral hydrocephalus was enrolled in a study of long-term immunogenicity of the IRES/CHIK vaccine. The animal began showing signs of neurological dysfunction post-vaccination, which progressed and ultimately resulted in euthanasia. The underlying brain abnormality was revealed at necropsy and was subsequently investigated with gross and microscopic examination. This becomes the first reported case of an adverse event following administration of a live attenuated vaccine and suggests the possibility of an increased susceptibility risk of unwanted adverse outcome associated with vaccination in populations with pre-existing conditions such as hydrocephalus.

中文翻译：

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食蟹猴猕猴中的减毒活减毒基孔肯雅热疫苗接种后出现的不良事件。

猕猴（猕猴）具有预先存在，未诊断，亚临床但严重的脑积水被纳入研究IRES / CHIK疫苗的长期免疫原性。该动物在接种疫苗后开始表现出神经功能障碍的迹象，这种疾病进展并最终导致安乐死。尸检发现潜在的脑部异常，随后进行肉眼和显微镜检查。这成为首次报道的减毒活疫苗接种后发生不良事件的病例，并提示在已有疾病（例如脑积水）的人群中，与疫苗接种相关的不良不良后果的易感性风险增加。