Projections of epidemic transmission and estimation of vaccination impact during an ongoing Ebola virus disease outbreak in Northeastern Democratic Republic of Congo, as of Feb. 25, 2019

Worden, Lee; Wannier, Rae; Hoff, Nicole A.; Musene, Kamy; Selo, Bernice; Mossoko, Mathias; Okitolonda-Wemakoy, Emile; Muyembe Tamfum, Jean Jacques; Rutherford, George W.; Lietman, Thomas M.; Rimoin, Anne W.; Porco, Travis C.; Kelly, J. Daniel

As of February 25, 2019, with 875 cases reported to date, most of our model projections were concentrated in a range up to about 300 additional cases overall, and even the Gott's rule forecast, whose prediction intervals are especially wide, placed low probability on outcomes on the scale of the West African outbreak. The current outbreak, however, has so far behaved unpredictably, possibly due to complex social circumstances, and could continue to be unpredictable and render our projections inaccurate. EVD has never before been introduced into a conflict zone with such political instability, potential disease mobility and community impenetrability [2] . In October, WHO reported that up to 80% of contacts were not being traced [3] . At present, the most reliable data source of EBOV transmission has been the weekly case counts that can be found in the WHO situation reports. Despite such situations of data scarcity and new outbreak circumstances, our models generated relatively accurate short-term projections of outbreak size in the months of January and February 2019, suggesting that short-term projections made in real time can be useful in decision making and resource allocation.