Targeted preventive vaccination campaigns to reduce Ebola outbreaks: An individual-based modeling study.

Nonpharmaceutical interventions (NPI) and ring vaccination (i.e., vaccination that primarily targets contacts and contacts of contacts of Ebola cases) are currently used to reduce the spread of Ebola during outbreaks. Because these measures are typically initiated after an outbreak is declared, they are limited by real-time implementation challenges. Preventive vaccination may provide a complementary option to help protect communities against unpredictable outbreaks. This study aimed to assess the impact of preventive vaccination strategies when implemented in conjunction with NPI and ring vaccination. A spatial-explicit, individual-based model (IBM) that accounts for heterogeneity of human contact, human movement, and timing of interventions was built to represent Ebola transmission in the Democratic Republic of the Congo. Simulated preventive vaccination strategies targeted healthcare workers (HCW), frontline workers (FW), and the general population (GP) with varying levels of coverage (lower coverage: 30% of HCW/FW, 5% of GP; higher coverage: 60% of HCW/FW, 10% of GP) and efficacy (lower efficacy: 60%; higher efficacy: 90%). The IBM estimated that the addition of preventive vaccination for HCW reduced cases, hospitalizations, and deaths by ∼11 % to ∼25 % compared with NPI + ring vaccination alone. Including HCW and FW in the preventive vaccination campaign yielded ∼14 % to ∼38 % improvements in epidemic outcomes. Further including the GP yielded the greatest improvements, with ∼21 % to ∼52 % reductions in epidemic outcomes compared with NPI + ring vaccination alone. In a scenario without ring vaccination, preventive vaccination reduced cases, hospitalizations, and deaths by ∼28 % to ∼59 % compared with NPI alone. In all scenarios, preventive vaccination reduced Ebola transmission particularly during the initial phases of the epidemic, resulting in flatter epidemic curves. The IBM showed that preventive vaccination may reduce Ebola cases, hospitalizations, and deaths, thus safeguarding the healthcare system and providing more time to implement additional interventions during an outbreak.

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Déclaration de conflit d'intérêts

Declaration of Competing Interest This work was funded by Johnson & Johnson Global Public Health: Johnson and Johnson Services, Inc., One Johnson & Johnson Plaza, New Brunswick, NJ 08933, USA. D.B. is a full-time employee of RTI International, and A.D., S.T., and A.B. are full-time employees of RTI Health Solutions, which are independent research organizations that received funding from Johnson and Johnson Services, Inc. to support the conduct of this study. T.V.E. is a full-time employee of Janssen Pharmaceutica N.V., is a Johnson & Johnson stockholder, and declares ownership of shares in GlaxoSmithKline. L.M. was an employee of Johnson & Johnson Global Public Health at the time of this study. M.G. is a full-time employee of Johnson & Johnson Global Public Health and V.O.M. is a full-time employee of Janssen Vaccines & Prevention B.V., and both may hold shares of Johnson & Johnson. Janssen Pharmaceutica N.V., Johnson & Johnson Global Public Health, and Janssen Vaccines & Prevention B.V. are companies of Johnson & Johnson.