National Immunization Program, Chinese Center for Disease Control and Prevention, Beijing, China.
Sichuan Provincial Center for Disease Control and Prevention, Chengdu, China.
JAMA Netw Open. 2023 Jan 3;6(1):e2249710. doi: 10.1001/jamanetworkopen.2022.49710.
The Sabin-strain inactivated poliovirus vaccine (IPV) may be a tool for polio outbreak response in certain situations.
To investigate the response to a type 2 vaccine-derived poliovirus (VDPV2) outbreak.
DESIGN, SETTING, AND PARTICIPANTS: This case series was conducted in China after a VDPV2 was detected in stool specimens from a child with acute flaccid paralysis (AFP) in Sichuan Province in 2019, 3 years after the global withdrawal of live, attenuated type 2 oral poliovirus vaccine (OPV). Investigation followed National Health Commission and World Health Organization guidance and included searching hospitals for unreported AFP cases; testing stool specimens from the child, his contacts, and local children; enhanced environmental surveillance for VDPV2s in wastewater; and measuring vaccination coverage. Sabin-strain IPV campaigns were conducted in a wide geographic area.
Any VDPV2 detection after completion of the supplementary immunization activities.
A 28-nucleotide-change VDPV2 was isolated from a young boy. Three VDPV2s were detected in healthy children; 2 were contacts of the original child, and none had paralysis. A search of 31 million hospital records found 10 unreported AFP cases; none were polio. No type 2 polioviruses were found in wastewater. Prior to the event, polio vaccine coverage was 65% among children younger than 5 years. Sabin-strain IPV campaigns reached more than 97% of targeted children, administering 1.4 million doses. No transmission source was identified. More than 1 year of enhanced poliovirus environmental and AFP surveillance detected no additional VDPVs.
These findings suggest that the circulating VPDV2 outbreak in 2019 was associated with low vaccine coverage. An investigation discovered 3 infected but otherwise healthy children and no evidence of the virus in wastewater. Following Sabin-strain IPV-only campaigns expanding from county to prefecture, the poliovirus was not detected, and the outbreak response was considered by an expert panel and the World Health Organization to have been successful. This success suggests that the Sabin-strain IPV may be a useful tool for responding to circulating VDPV2 outbreaks when high-quality supplementary immunization activities can be conducted and carefully monitored in settings with good sanitation.
Sabin 株灭活脊髓灰质炎病毒疫苗（IPV）可能是应对某些情况下脊髓灰质炎暴发的一种工具。
调查对 2 型疫苗衍生脊髓灰质炎病毒（VDPV2）暴发的反应。
设计、地点和参与者：本病例系列研究在中国进行，此前在 2019 年四川省 1 名急性弛缓性麻痹（AFP）患儿的粪便标本中检测到 1 例 VDPV2，这是在全球停用活、减毒 2 型口服脊髓灰质炎疫苗（OPV）3 年后发生的。调查遵循国家卫生健康委员会和世界卫生组织的指导，包括在医院中搜索未报告的 AFP 病例；检测患儿、其接触者和当地儿童的粪便标本；加强废水中 VDPV2 的环境监测；以及测量疫苗接种覆盖率。在广泛的地理区域开展了 Sabin 株 IPV 运动。
补充免疫活动完成后任何 VDPV2 的检测结果。
从一名年轻男孩中分离出 1 株具有 28 个核苷酸变化的 VDPV2。在 3 名健康儿童中检测到 3 株 VDPV2；其中 2 例是原始患儿的接触者，均无麻痹。对 3100 万份医院记录的搜索发现 10 例未报告的 AFP 病例；均非脊髓灰质炎。废水中未发现 2 型脊灰病毒。在该事件发生之前，5 岁以下儿童的脊髓灰质炎疫苗覆盖率为 65%。Sabin 株 IPV 运动覆盖了超过 97%的目标儿童，接种了 140 万剂疫苗。未确定传播源。超过 1 年的加强脊灰病毒环境和 AFP 监测未发现其他 VDPV。
这些发现表明，2019 年循环 VPDV2 暴发与疫苗接种率低有关。一项调查发现 3 例感染但无症状的儿童，且未在废水中发现该病毒。在扩大到县一级的 Sabin 株 IPV 单剂运动后，未检测到脊灰病毒，专家组和世界卫生组织认为此次暴发应对成功。这一成功表明，当能够开展高质量的补充免疫活动，并在卫生条件良好的环境中进行仔细监测时，Sabin 株 IPV 可能是应对循环 VDPV2 暴发的有用工具。
