PREDICTING COVID-19 SECOND WAVE SIGNAL IN SELECTED STATES OF SOUTHWEST NIGERIA: A COMPARISON OF CUMULATIVE SUM C2 AND CUMULATIVE SUM C1 EPIDEMIC THRESHOLDS

INTRODUCTION: Epidemic thresholds generated using the conventional historical data is not optimal for COVID-19 because of its short historical trajectory. This study therefore, aimed to develop and compare Cumulative sum C2 and C1 epidemic thresholds for COVID-19 in selected states in southwestern Nigeria. METHODS: This was a retrospective longitudinal analysis of the COVID-19 surveillance data (week 10 - 48) retrieved from the Nigerian Centre for Disease Control (NCDC) database of situation reports as at the 6th of December, 2020. Data was managed with Microsoft excel. The weekly time scale was adopted for developing the CUSUM C2 and C1 epidemic thresholds for three selected southwest states and Nigeria. RESULTS: A total of 236 situation reports were reviewed for each state. For Lagos state, the maximum C2 and C1 estimated was 2326 which was during the peak of the epidemic. From the four most recent surveillance points, the thresholds and the observed confirmed cases appeared to diverge from each other. For Ogun state, the maximum C2 and C1 estimated was 318 during the peak of the epidemic. From the four most recent surveillance points, the thresholds and the observed confirmed cases appeared to converge. For Oyo state, the maximum C2 and C1 estimated was 708 during the peak of the epidemic. From the four most recent surveillance points, the thresholds and the observed confirmed cases appeared to converge and then diverge. CONCLUSION: A closer monitor of the surveillance data for the states is recommended for a possible public health intervention.