疫苗衍生脊髓灰质炎病毒病例识别及处理

Characterization of an OPV vaccine-derived poliovirus infection

目的分析疫苗衍生脊髓灰质炎病毒(VDPV)病例发病原因并探索控制对策。方法 对发生的VDPV病例进行个案调查,测定免疫功能,采集粪便样本分离病毒,进行病毒核苷酸序列测定和分析;对病例所在地及医院进行急性弛缓性麻痹(AFP)病例主动搜索;对病例所在地及相邻地区开展儿童常规接种率快速评价;对密切接触者和周围健康儿童进行粪便样本带毒率调查。结果病例最终分类诊断为VDPV病例,有11个核苷酸变异;当地口服脊髓灰质炎减毒活疫苗(OPV)接种率高;密切接触者粪便样本未分离到脊髓灰质炎病毒。结论 该病毒未在当地造成循环。为防止VDPV病例发生和VDPV循环,应维持高水平的OPV接种率,保持AFP监测系统的灵敏性,有条件的地区引入脊髓灰质炎灭活疫苗(IPV)。

Objective To characterize an OPV vaccine-derived poliovirus（VDPV） infection and summarize the management practice for preventing from circulating VDPV（cVDPV）.Methods A case of VDPV suspect infection was reported from Jinan by the network of China Infectious Disease Report System.The characterization of the VDPV infection was determined by case investigation,including reviewing the disease history of the patient,patient immunologic function testing,virus isolation of stool specimen,and virus nucleotide sequencing for the isolated virus.Active investigation of acute flaccid paralysis（AFP） cases was performed in areas that the patient was possibly involved,including the location of residence,hospitals and schools,etc.Virus isolation was applied to the stool specimens of people who had direct contact with the patient.The assessment of vaccine safety was completed for the OPV vaccinated children.Results The case VPDV was confirmed by viral isolation and the result of gene sequencing.There were 11 nucleotides differences between the gene sequence of vaccine strain and that of isolated strain.There was no cVDPV case confirmed with a stringent protocol of screening.The investigation verified that the coverage rate of OPV vaccination was between 95.51%（85/89） and 100%（86/86） among the children in the towns close by to the case of VDPV.Conclusion The case of OPV VDPV was characterized and no cVDPV was confirmed.It is essential to maintain the high rate of OPV coverage and sensitive AFP surveillance for preventing cVDPV.Inactivated poliovirus vaccine（IPV） would be optimal for mass vaccination program.