Alexis Robert1, Anton Camacho2, W John Edmunds1, Marc Baguelin3, Jean-Jacques Muyembe Tamfum4, Alicia Rosello5, Sakoba Kéïta6, Rosalind M Eggo7. 1. London School of Hygiene & Tropical Medicine, Keppel St. London. WC1E 7HT UK. 2. London School of Hygiene & Tropical Medicine, Keppel St. London. WC1E 7HT UK; Epicentre, Paris, France. 3. London School of Hygiene & Tropical Medicine, Keppel St. London. WC1E 7HT UK; Public Health England, 61 Colindale Avenue, London, NW9 5EQ, UK. 4. Institut National de Recherche Biomédicale, Congo. 5. Public Health England, 61 Colindale Avenue, London, NW9 5EQ, UK; Institute of Health Informatics, Farr Institute of Health Informatics Research, UCL, London NW1 2DA, UK. 6. Ebola Response, Ministry of Health, Conakry, Guinea. 7. London School of Hygiene & Tropical Medicine, Keppel St. London. WC1E 7HT UK. Electronic address: r.eggo@lshtm.ac.uk.
Abstract
BACKGROUND: Health care workers (HCW) are at risk of infection during Ebola virus disease outbreaks and therefore may be targeted for vaccination before or during outbreaks. The effect of these strategies depends on the role of HCW in transmission which is understudied. METHODS: To evaluate the effect of HCW-targeted or community vaccination strategies, we used a transmission model to explore the relative contribution of HCW and the community to transmission. We calibrated the model to data from multiple Ebola outbreaks. We quantified the impact of ahead-of-time HCW-targeted strategies, and reactive HCW and community vaccination. RESULTS: We found that for some outbreaks (we call "type 1″) HCW amplified transmission both to other HCW and the community, and in these outbreaks prophylactic vaccination of HCW decreased outbreak size. Reactive vaccination strategies had little effect because type 1 outbreaks ended quickly. However, in outbreaks with longer time courses ("type 2 outbreaks"), reactive community vaccination decreased the number of cases, with or without prophylactic HCW-targeted vaccination. For both outbreak types, we found that ahead-of-time HCW-targeted strategies had an impact at coverage of 30%. CONCLUSIONS: The vaccine strategies tested had a different impact depending on the transmission dynamics and previous control measures. Although we will not know the characteristics of a new outbreak, ahead-of-time HCW-targeted vaccination can decrease the total outbreak size, even at low vaccine coverage.
BACKGROUND: Health care workers (HCW) are at risk of infection during Ebola virus disease outbreaks and therefore may be targeted for vaccination before or during outbreaks. The effect of these strategies depends on the role of HCW in transmission which is understudied. METHODS: To evaluate the effect of HCW-targeted or community vaccination strategies, we used a transmission model to explore the relative contribution of HCW and the community to transmission. We calibrated the model to data from multiple Ebola outbreaks. We quantified the impact of ahead-of-time HCW-targeted strategies, and reactive HCW and community vaccination. RESULTS: We found that for some outbreaks (we call "type 1″) HCW amplified transmission both to other HCW and the community, and in these outbreaks prophylactic vaccination of HCW decreased outbreak size. Reactive vaccination strategies had little effect because type 1 outbreaks ended quickly. However, in outbreaks with longer time courses ("type 2 outbreaks"), reactive community vaccination decreased the number of cases, with or without prophylactic HCW-targeted vaccination. For both outbreak types, we found that ahead-of-time HCW-targeted strategies had an impact at coverage of 30%. CONCLUSIONS: The vaccine strategies tested had a different impact depending on the transmission dynamics and previous control measures. Although we will not know the characteristics of a new outbreak, ahead-of-time HCW-targeted vaccination can decrease the total outbreak size, even at low vaccine coverage.