A quantitative framework to define the end of an outbreak: application to Ebola Virus Disease

Bimandra A Djaafara; Natsuko Imai; Esther Hamblion; Benido Impouma; Christl A Donnelly; Anne Cori

The copyright holder for this preprint . https://doi.org/10.1101/2020.02. 17.20024042 doi: medRxiv preprint declare the EO for EVD. Our simulations show that in most scenarios considered, the current WHO criterion corresponds to a probability of cases arising in the future well above 5%. The corresponding probability is <5% only when the onset-to-outcome delay period is very long (at least two or three weeks, which is unusual) and the reporting rate is high, although with low value, high overdispersion or optimistic transmission the probability reaches <5% in more parameter combinations. Once again, misspecification of the value of in the 'decline' period strongly affected these results (Web Figure 5 & 6 ). An additional analysis, accounting for the 90-day period of enhanced surveillance after the EO declaration of EVD (8) shows that the probability of cases arising in the future for most of simulation scenarios are <5% at the end of the 132-day period (42 + 90 days) except when the value of is high (Web Figure 7 ).