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

In order to produce model outbreak trajectories consistent with the case counts reported more recently in the outbreak, it was necessary to make the filtering step of the model more tolerant to variation in counts in order to accommodate the rapidly rising count. This was because higher transmission rates in late September and early October were necessary to generate case counts of that size than were consistent with the earlier counts. Thus, this model embodies a set of assumptions that transmission rates are overall gradually declining from the start of the outbreak to its end, though possibly with a high level of variability in transmission rate between cases and between simulations. When the tolerance of the filter on case counts is small, quenching of transmission through time must closely track case counts, while when tolerance is high, fluctuations in the rate of generation of new cases can reflect a pattern of ongoing quenching of transmission more loosely and on the long term, while being more insensitive to short-term up and down fluctuations in transmission rates reflected in the true case counts.