An evaluation of the Zambia influenza sentinel surveillance system, 2011–2017

Simusika, Paul; Tempia, Stefano; Chentulo, Edward; Polansky, Lauren; Mazaba, Mazyanga Lucy; Ndumba, Idah; Mbewe, Quinn K.; Monze, Mwaka

For each quantitative indicator we first obtained the proportion (expressed as percentage) of the outcome of interest over the total [18] [19] [20] [21] . For instance, for the indicator on completeness of laboratory testing (one of the indicators used to evaluate the data quality and completeness attribute) we divided the number of samples with available influenza results by the total number of samples collected and received by the laboratory. Subsequently, similar to other influenza surveillance evaluations conducted in Africa, we used a scale from 1 to 3 to provide a score for each quantitative indicator as follows: < 60% (as obtained in the example above) scored 1 (weak performance); 60-79% scored 2 (moderate performance); ≥80% scored 3 (good performance) [18] [19] [20] [21] . For indicators for which a proportion over a total could not be obtained (qualitative indicators) a score was assigned based on the same scale using expert consensus. Thereafter, the scores assigned to each indicator were averaged for all indicators evaluated within each attribute to provide an overall score for each surveillance attribute assessed in this study. An overall score for the surveillance system was obtained by averaging the scores of all evaluated indicators as previously described [18] [19] [20] [21] . All data generated by the surveillance system during the review period were included in the evaluation. The analysis was implemented using Stata version 14.2 (Sta-taCorp, College Station, Texas, USA).