Lot Quality Assurance Sampling to Monitor Supplemental Immunization Activity Quality: An Essential Tool for Improving Performance in Polio Endemic Countries
Monitoring the quality of supplementary immunization activities (SIAs) is a key tool for polio eradication. Regular monitoring data, however, are often unreliable, showing high coverage levels in virtually all areas, including those with ongoing virus circulation. To address this challenge, lot quality assurance sampling (LQAS) was introduced in 2009 as an additional tool to monitor SIA quality. Now used in 8 countries, LQAS provides a number of programmatic benefits: identifying areas of weak coverage quality with statistical reliability, differentiating areas of varying coverage with greater precision, and allowing for trend analysis of campaign quality. LQAS also accommodates changes to survey format, interpretation thresholds, evaluations of sample size, and data collection through mobile phones to improve timeliness of reporting and allow for visualization of campaign quality. LQAS becomes increasingly important to address remaining gaps in SIA quality and help focus resources on high-risk areas to prevent the continued transmission of wild poliovirus.
Figure 4. Two options for visualizing LQAS results collected on mobile phones. A, Coverage at the cluster level. This figure, for LQAS survey in April 2013, demonstrates the classification of clusters according to their number of unvaccinated individuals. Raw data from the magpi.com server are exported to the local computer and the number of unvaccinated children in each cluster is calculated and then uploaded to ESRI ArcGIS software for visualization. B, Coverage at the LGA level. This figure represents the overall lot-level (LGA-level) classification for all LGAs in which LQAS was conducted in Nigeria in March 2013. Worst performing areas (“not accepted at 60%”) are clearly visible on these maps. Color-coded national maps reflect the geographic distribution of the poorest lots in the country, clearly demarcating areas in need of continued vaccination campaign support. Abbreviations: LGA, local government area; LQAS, lot quality assurance sampling.