Harnessing Case Isolation and Ring Vaccination to Control Ebola

Chad Wells*, Dan Yamin, Martial L. Ndeffo-Mbah, Natasha Wenzel, Stephen G. Gaffney, Jeffrey P. Townsend, Lauren Ancel Meyers, Mosoka Fallah, Tolbert G. Nyenswah, Frederick L. Altice, Katherine E. Atkins, Alison P. Galvani

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


As a devastating Ebola outbreak in West Africa continues, non-pharmaceutical control measures including contact tracing, quarantine, and case isolation are being implemented. In addition, public health agencies are scaling up efforts to test and deploy candidate vaccines. Given the experimental nature and limited initial supplies of vaccines, a mass vaccination campaign might not be feasible. However, ring vaccination of likely case contacts could provide an effective alternative in distributing the vaccine. To evaluate ring vaccination as a strategy for eliminating Ebola, we developed a pair approximation model of Ebola transmission, parameterized by confirmed incidence data from June 2014 to January 2015 in Liberia and Sierra Leone. Our results suggest that if a combined intervention of case isolation and ring vaccination had been initiated in the early fall of 2014, up to an additional 126 cases in Liberia and 560 cases in Sierra Leone could have been averted beyond case isolation alone. The marginal benefit of ring vaccination is predicted to be greatest in settings where there are more contacts per individual, greater clustering among individuals, when contact tracing has low efficacy or vaccination confers post-exposure protection. In such settings, ring vaccination can avert up to an additional 8% of Ebola cases. Accordingly, ring vaccination is predicted to offer a moderately beneficial supplement to ongoing non-pharmaceutical Ebola control efforts.

Original languageEnglish
Article numbere0003794
JournalPLoS Neglected Tropical Diseases
Issue number5
StatePublished - 29 May 2015
Externally publishedYes


FundersFunder number
National Institutes of HealthU01 GM105627, NIH U01 GM087719
National Institute on Drug AbuseK24DA017072


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