Impact of the Protracted War in Yemen on the Acute Flaccid Paralysis Surveillance System: Retrospective Descriptive Analysis.

BACKGROUND: Highly sensitive acute flaccid paralysis (AFP) surveillance, which includes immediate case investigation and specimen collection, is critical for achieving global polio eradication. In Yemen, the Acute Flaccid Paralysis Surveillance System (AFPSS) was launched in 1998 to achieve the polio eradication target. Although Yemen was certified as a polio-free country in 2009, the protracted war since 2015 has placed the country at risk for polio reemergence. OBJECTIVE: The objectives of this analysis were to evaluate the performance of the Yemen AFPSS at both the national and governorate levels, and to assess the impact of the ongoing war on the performance. METHODS: Retrospective descriptive analysis was performed on Yemen secondary AFP surveillance data for the years 2014 (before the war) and 2015-2017 (during the war). Data comprising all children <15 years old reported as having AFP were included in the analysis. AFP surveillance performance was evaluated using World Health Organization-specified AFP surveillance indicators. RESULTS: At the national level, all indicators were met before and after the war except for "lab results received within ≤28 days," which was unmet since the war erupted. Furthermore, the indicator "stool specimens arriving at a central level within ≤3 days" was unmet after the war but only in 2017. At the governorate level, although the indicators "adequacy" and "stool specimens arriving at the laboratory in good condition" were met before the war in all governorates, the former indicator was unmet in 9 (41%) governorates since the war erupted and the latter indicator was also unmet in 9 governorates (41%) but only in 2017. CONCLUSIONS: The findings show that some AFP surveillance indicators were negatively impacted by eruption of the war in Yemen due to closure of the Sana'a capital airport and postponement of sample shipment to the reference laboratory, which remained under long-term poor storage conditions. To ensure rapid detection of polio cases, improving specimen collection, storage, and transportation, together with proper and timely shipment of specimens to the reference laboratory should be considered.