Fig. 4

Correlations between interventions and number of cases. a Probability distribution of number of traced contacts per case over the period August 4, 2014, to February 25, 2015. b Cross-correlation between the average number of contacts included in contact tracing per case at a given time and the incidence of cases observed 0 to 40 days later. The average number of contacts included in contact tracing per case is computed as the sum of followed contacts over 21 days divided by the sum of new cases over the same 21 days (alternative definitions of contact tracing are considered in Additional file 1). The highest absolute value of cross-correlation is obtained for a lag of 17 days. c Red line: daily number of cases (as obtained with a moving average of 15 days, i.e., 1 week previous and 1 week following the data point) over time; blue line: number of traced contacts per case (defined as in b) over time; dotted line: linear model best fitting the number of traced contacts. Scale for blue and dotted curves is on the right axis. d Red line: as in c; blue line: probability of unsafe burials over time computed as the fraction of daily community safe burials over the daily total number of community burials (scale on the right axis); the curve is then obtained by computing a moving average of 15 days, i.e., 1 week previous and 1 week following the data point. e Red line: as in c; blue line: number of admissions to ETUs over time (scale on the right axis); the curve is then obtained by computing a moving average of 15 days, i.e., 1 week previous and 1 week following the data point. Dates in panels c–e refer to the period August 2014 to June 2015