Abstract：
BACKGROUND: Measles, mumps, and rubella(MMR) vaccination is critical to measles outbreak responses. However, vaccine reactions and detection of measles vaccine RNA in recently immunized persons may complicate case classification especially in those presenting with another respiratory viral illness. We aim to characterize cases of measles vaccine shedding in recently vaccinated children presenting with respiratory viral symptoms.
METHODS: Children who were tested with a multiplex respiratory panel <30 days after receiving MMR were identified. Remnant nasopharyngeal(NP) samples were tested for measles vaccine by PCR. Medical records were reviewed for demographics, presenting symptoms, and test results.
RESULTS: From January 2022 to March 2023, 127 NP from children who received MMR were tested. Ninety-six NP were collected after the first dose, of which 33(34.4 %) were positive for vaccine RNA. The median interval between MMR and detection was 11.0 days. Thirty-one NP were collected after the second MMR and 1(3.2 %) was positive; time between the vaccination and detection was 18.9 days. Median cycle threshold(Ct) value of the measles PCR for vaccine shedding was significantly higher than median Ct in children with wild-type infection.
CONCLUSIONS: Shedding of measles vaccine RNA is not uncommon and vaccine RNA can be detected up to 29 days post MMR; the amount of vaccine RNA shedding is low indicated by high Ct values. Clinicians and public health officials should consider performing measles vaccine testing on those testing positive for measles within one month of MMR vaccination, especially if the Ct value is high and definitive epidemiological links are absent.
METHODS: Children who were tested with a multiplex respiratory panel <30 days after receiving MMR were identified. Remnant nasopharyngeal(NP) samples were tested for measles vaccine by PCR. Medical records were reviewed for demographics, presenting symptoms, and test results.
RESULTS: From January 2022 to March 2023, 127 NP from children who received MMR were tested. Ninety-six NP were collected after the first dose, of which 33(34.4 %) were positive for vaccine RNA. The median interval between MMR and detection was 11.0 days. Thirty-one NP were collected after the second MMR and 1(3.2 %) was positive; time between the vaccination and detection was 18.9 days. Median cycle threshold(Ct) value of the measles PCR for vaccine shedding was significantly higher than median Ct in children with wild-type infection.
CONCLUSIONS: Shedding of measles vaccine RNA is not uncommon and vaccine RNA can be detected up to 29 days post MMR; the amount of vaccine RNA shedding is low indicated by high Ct values. Clinicians and public health officials should consider performing measles vaccine testing on those testing positive for measles within one month of MMR vaccination, especially if the Ct value is high and definitive epidemiological links are absent.
摘要：
背景：麻疹，腮腺炎,风疹（MMR）疫苗接种对麻疹疫情的应对至关重要。然而,在最近接受免疫的人中，疫苗反应和麻疹疫苗RNA的检测可能会使病例分类复杂化，尤其是在患有其他呼吸道病毒性疾病的人中。我们旨在描述最近接种疫苗并出现呼吸道病毒症状的儿童麻疹疫苗脱落的病例。
方法：在接受MMR后<30天进行多重呼吸测试的儿童被鉴定。通过PCR测试剩余的鼻咽（NP）样品的麻疹疫苗。对医疗记录进行了人口统计学审查，出现症状，和测试结果。
结果：从2022年1月到2023年3月，对接受MMR的儿童的127个NP进行了测试。在第一次给药后收集到96个NP，其中33例（34.4%）疫苗RNA阳性。MMR和检测之间的中位间隔为11.0天。在第二次MMR后收集31个NP,1个(3.2%)为阳性;接种和检测之间的时间为18.9天。麻疹PCR疫苗脱落的中位周期阈值（Ct）值明显高于野生型感染儿童的中位Ct值。
结论：麻疹疫苗RNA脱落并不少见，MMR后29天可以检测到疫苗RNA；高Ct值表明疫苗RNA脱落量低。临床医生和公共卫生官员应考虑在MMR疫苗接种后一个月内对麻疹检测呈阳性的人进行麻疹疫苗检测，特别是如果Ct值很高，并且没有明确的流行病学联系。
方法：在接受MMR后<30天进行多重呼吸测试的儿童被鉴定。通过PCR测试剩余的鼻咽（NP）样品的麻疹疫苗。对医疗记录进行了人口统计学审查，出现症状，和测试结果。
结果：从2022年1月到2023年3月，对接受MMR的儿童的127个NP进行了测试。在第一次给药后收集到96个NP，其中33例（34.4%）疫苗RNA阳性。MMR和检测之间的中位间隔为11.0天。在第二次MMR后收集31个NP,1个(3.2%)为阳性;接种和检测之间的时间为18.9天。麻疹PCR疫苗脱落的中位周期阈值（Ct）值明显高于野生型感染儿童的中位Ct值。
结论：麻疹疫苗RNA脱落并不少见，MMR后29天可以检测到疫苗RNA；高Ct值表明疫苗RNA脱落量低。临床医生和公共卫生官员应考虑在MMR疫苗接种后一个月内对麻疹检测呈阳性的人进行麻疹疫苗检测，特别是如果Ct值很高，并且没有明确的流行病学联系。
