But the last steps to ending this disease are proving the most difficult, particularly with continuing outbreaks of circulating vaccine-derived polio viruses (cVDPVs).
cVDPVs are rare and occur if the weakened strain of the poliovirus contained in the oral polio vaccine (OPV) circulates among under-immunized populations for a long time.
If not enough children are immunized against polio, the weakened virus can pass between individuals and over time genetically revert to a form that can cause paralysis.
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循环的2型疫苗衍生脊灰病毒是目前最流行的疫苗衍生病毒。
Type 2 cVDPVs are currently the most prevalent form of the vaccine-derived virus.
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纳入紧急使用的程序及其如何帮助加速获取未来的COVID-19疫苗
The EUL procedure and how it could help to speed up access to a future COVID-19 vaccine
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紧急使用程序评估尚未获批卫生产品是否适合在脊灰和COVID-19等突发公共卫生事件期间使用。
The EUL procedure assesses the suitability of yet to be licensed health products during public health emergencies, such as polio and COVID.
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目的是使这些药物、疫苗和诊断工具能够更快地投入使用，以应对突发事件。
The objective is to make these medicines, vaccines and diagnostics available faster to address the emergency.
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在评估中，需要依据一整套有力的证据权衡突发事件造成的威胁和使用产品可能带来的好处。
The assessment essentially weighs the threat posed by the emergency against the benefit that would accrue from the use of the product based on a robust body of evidence.
The procedure was introduced during the West Africa Ebola outbreak of 2014-2016, when multiple Ebola diagnostics received emergency use listing; since then, numerous COVID-19 diagnostics have also been listed.
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从那时起，许多COVID-19诊断制剂也已列入清单。
The nOPV2 is the first such listing for a vaccine.