Containing Ebola at the Source with Ring Vaccination

• Published in: PLoS neglected tropical diseases Vol. 10; no. 11; p. e0005093
• Main Authors: Merler, Stefano, Ajelli, Marco, Fumanelli, Laura, Parlamento, Stefano, Pastore y Piontti, Ana, Dean, Natalie E., Putoto, Giovanni, Carraro, Dante, Longini, Ira M., Halloran, M. Elizabeth, Vespignani, Alessandro
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 02.11.2016; Public Library of Science (PLoS)
• Subjects: Biology and Life Sciences; Colleges & universities; Earth Sciences; Ebola hemorrhagic fever; Ebola Vaccines - administration & dosage; Ebolavirus - physiology; Epidemics; Guinea - epidemiology; Health aspects; Hemorrhagic Fever, Ebola - epidemiology; Hemorrhagic Fever, Ebola - prevention & control; Humans; Immunization; Infectious diseases; Medicine and Health Sciences; Models, Biological; Outbreaks; People and Places; Prevention; Public health; Sensitivity analysis; Sierra Leone - epidemiology; Social Sciences; Tropical diseases; Vaccination; Vaccines; Viral vaccines; United States; Italy; Sierra Leone; Florida; Guinea; United States > US; Massachusetts; West Africa
• ISSN: 1935-2735; 1935-2727; 1935-2735
• DOI: 10.1371/journal.pntd.0005093

Interim results from the Guinea Ebola ring vaccination trial suggest high efficacy of the rVSV-ZEBOV vaccine. These findings open the door to the use of ring vaccination strategies in which the contacts and contacts of contacts of each index case are promptly vaccinated to contain future Ebola virus disease outbreaks. To provide a numerical estimate of the effectiveness of ring vaccination strategies we introduce a spatially explicit agent-based model to simulate Ebola outbreaks in the Pujehun district, Sierra Leone, structurally similar to previous modelling approaches. We find that ring vaccination can successfully contain an outbreak for values of the effective reproduction number up to 1.6. Through an extensive sensitivity analysis of parameters characterising the readiness and capacity of the health care system, we identify interventions that, alongside ring vaccination, could increase the likelihood of containment. In particular, shortening the time from symptoms onset to hospitalisation to 2-3 days on average through improved contact tracing procedures, adding a 2km spatial component to the vaccination ring, and decreasing human mobility by quarantining affected areas might contribute increase our ability to contain outbreaks with effective reproduction number up to 2.6. These results have implications for future control of Ebola and other emerging infectious disease threats.