An Attempt to Validate Lots Quality Assurance Sampling Results using Vaccination Tracking System: an Overview of Supplementary Immunization Activities in Kano State

Abstract

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. Also, vaccination team tracking system (VTS) was used to track teams through Global Positioning System (GPS) tracking using underlying geospatial data sets of wards, settlement points and satellite imagery. The aim of this research is to authenticate the association between Lot Quality Assurance Sampling (LQAS) and Vaccination Tracking System (VTS) so as to validate the results of the outcome of each of the immunization coverage measuring tools. The association between LQAS results and VTS-GIS tracking coverage were tested using Chi-square statistic. The LQAS bands were categorized into ≥90% and <90% on one hand and VTS-GIS coverage were categorized into ≥90% and <90% on the other. Each of the 44 LGAs was counted for each cross-tabulation of both measurement tools in a 2×2 contingency table. The results show that one of the assumptions for Chi Square test was violated, the need to use the significance of Fisher’s Exact Test rather than Pearson Chi-Square becomes eminent to avoid loss of statistical power. The Fisher’s Exact Test Significance for the one and two tailed test respectively thus: 0.393, 0.227; 1.000, 0.664; 1.000, 0.603; 0.236, 0.203; and 0.499 and 0.325. All of these values both for one and two tailed significance are greater than 5%, which is evidence that there is no significant association between LQAS results and VTS coverage. To this end, we conclude that since both immunization coverage quality assessment tools are independent at a lower threshold of 90%, it therefore suggests the need for upward review of the lower classification band.