Fig. 4.

Sensitivity of the probability of the end of Ebola epidemic to the reproduction number and evaluation of the sequence of declarations.

Vertical axis measures the probability of observing additional cases on or after the specified week, while the horizontal axis measures the weeks since the last case was buried or tested negative twice to Ebola virus. Panels A, C and E examines the sensitivity of the probability to the reproduction number around the end of the epidemic. We used the reproduction numbers during the late stage of the epidemic, taking weighted means using case counts for weighting, dating back for 24 weeks from the week in which the last case was reported. Of the two types of vertical lines, the solid line represents the week in which the end of the epidemic was declared, following a 42-day waiting period as specified by the WHO. The dashed vertical line represents the week in which a recrudescent case was recognized after the first erroneous declaration. The horizontal dashed line measures the probability at 5% below which one may regard that the epidemic is over. Panels B, D and F measure the sensitivity of the probability to different timings at which the last case was observed.