Centre of Mathematical Modelling of Infectious Diseases, London School of Hygiene and Tropical Medicine, London, UK.
Polio Eradication, World Health Organization, Geneva, Switzerland.
Science. 2020 Apr 24;368(6489):401-405. doi: 10.1126/science.aba1238. Epub 2020 Mar 19.
Although there have been no cases of serotype 2 wild poliovirus for more than 20 years, transmission of serotype 2 vaccine-derived poliovirus (VDPV2) and associated paralytic cases in several continents represent a threat to eradication. The withdrawal of the serotype 2 component of oral poliovirus vaccine (OPV2) was implemented in April 2016 to stop VDPV2 emergence and secure eradication of all serotype 2 poliovirus. Globally, children born after this date have limited immunity to prevent transmission. Using a statistical model, we estimated the emergence date and source of VDPV2s detected between May 2016 and November 2019. Outbreak response campaigns with monovalent OPV2 are the only available method to induce immunity to prevent transmission. Yet our analysis shows that using monovalent OPV2 is generating more paralytic VDPV2 outbreaks with the potential for establishing endemic transmission. A novel OPV2, for which two candidates are currently in clinical trials, is urgently required, together with a contingency strategy if this vaccine does not materialize or perform as anticipated.
虽然已经有 20 多年没有出现 2 型野生脊灰病毒病例，但在几个大洲，2 型疫苗衍生脊灰病毒（VDPV2）的传播及其相关麻痹病例仍然构成对消灭脊灰的威胁。2016 年 4 月停止使用 2 型口服脊灰疫苗（OPV2），以阻止 VDPV2 的出现，并确保消灭所有 2 型脊灰病毒。自那以后出生的儿童，其预防传播的 2 型免疫力有限。我们使用统计模型估计了 2016 年 5 月至 2019 年 11 月期间检测到的 VDPV2 的出现日期和来源。含有单价 2 型 OPV 的暴发应对活动是诱导免疫力以预防传播的唯一可用方法。然而，我们的分析表明，使用单价 OPV2 会导致更多的具有建立地方性传播潜力的麻痹性 VDPV2 暴发。目前正在临床试验中开发两种候选疫苗的新型 OPV2 已迫在眉睫，如果这种疫苗不能实现或不能按预期发挥作用，还需要制定应急战略。
