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Bisanzio D, Davis AE, Talbird SE, Van Effelterre T, Metz L, Gaudig M, Mathieu VO, Brogan AJ. Targeted preventive vaccination campaigns to reduce Ebola outbreaks: An individual-based modeling study. Vaccine 2023; 41:684-693. [PMID: 36526505 DOI: 10.1016/j.vaccine.2022.11.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 11/16/2022] [Accepted: 11/17/2022] [Indexed: 12/15/2022]
Abstract
INTRODUCTION 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. METHODS 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%). RESULTS 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. CONCLUSIONS 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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Affiliation(s)
- Donal Bisanzio
- RTI International, 701 13th St NW #750, Washington, DC 20005, USA
| | - Ashley E Davis
- RTI Health Solutions, 3040 East Cornwallis Road, Research Triangle Park, NC 27709, USA
| | - Sandra E Talbird
- RTI Health Solutions, 3040 East Cornwallis Road, Research Triangle Park, NC 27709, USA
| | | | - Laurent Metz
- Johnson & Johnson Global Public Health, One Johnson and Johnson Plaza, New Brunswick, NJ 08901, USA
| | - Maren Gaudig
- Johnson & Johnson Global Public Health, One Johnson and Johnson Plaza, New Brunswick, NJ 08901, USA
| | | | - Anita J Brogan
- RTI Health Solutions, 3040 East Cornwallis Road, Research Triangle Park, NC 27709, USA.
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Kelly JD, Frankfurter RG, Tavs JM, Barrie MB, McGinnis T, Kamara M, Freeman A, Quiwah K, Davidson MC, Dighero-Kemp B, Gichini H, Elliott E, Reilly C, Hensley LE, Lane HC, Weiser SD, Porco TC, Rutherford GW, Richardson ET. Association of Lower Exposure Risk With Paucisymptomatic/Asymptomatic Infection, Less Severe Disease, and Unrecognized Ebola Virus Disease: A Seroepidemiological Study. Open Forum Infect Dis 2022; 9:ofac052. [PMID: 35265726 PMCID: PMC8900924 DOI: 10.1093/ofid/ofac052] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 01/31/2022] [Indexed: 01/12/2023] Open
Abstract
Background It remains unclear if there is a dose-dependent relationship between exposure risk to Ebola virus (EBOV) and severity of illness. Methods From September 2016 to July 2017, we conducted a cross-sectional, community-based study of Ebola virus disease (EVD) cases and household contacts of several transmission chains in Kono District, Sierra Leone. We analyzed 154 quarantined households, comprising both reported EVD cases and their close contacts. We used epidemiological surveys and blood samples to define severity of illness as no infection, pauci-/asymptomatic infection, unrecognized EVD, reported EVD cases who survived, or reported EVD decedents. We determine seropositivity with the Filovirus Animal Nonclinical Group EBOV glycoprotein immunoglobulin G antibody test. We defined levels of exposure risk from 8 questions and considered contact with body fluid as maximum exposure risk. Results Our analysis included 76 reported EVD cases (both decedents and survivors) and 421 close contacts. Among these contacts, 40 were seropositive (22 paucisymptomatic and 18 unrecognized EVD), accounting for 34% of the total 116 EBOV infections. Higher exposure risks were associated with having had EBOV infection (maximum risk: adjusted odds ratio [AOR], 12.1 [95% confidence interval {CI}, 5.8-25.4; trend test: P < .001) and more severe illness (maximum risk: AOR, 25.2 [95% CI, 6.2-102.4]; trend test: P < .001). Conclusions This community-based study of EVD cases and contacts provides epidemiological evidence of a dose-dependent relationship between exposure risk and severity of illness, which may partially explain why pauci-/asymptomatic EBOV infection, less severe disease, and unrecognized EVD occurs.
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Affiliation(s)
- J Daniel Kelly
- Department of Epidemiology and Biostatistics, University of California, San Francisco, California, USA
- Institute for Global Health Sciences, University of California, San Francisco, California, USA
- F. I. Proctor Foundation, University of California, San Francisco, California, USA
- Partners In Health, Freetown, Sierra Leone
| | | | - Jacqueline M Tavs
- F. I. Proctor Foundation, University of California, San Francisco, California, USA
| | - Mohamed Bailor Barrie
- Department of Epidemiology and Biostatistics, University of California, San Francisco, California, USA
- Institute for Global Health Sciences, University of California, San Francisco, California, USA
- Partners In Health, Freetown, Sierra Leone
| | - Timothy McGinnis
- Department of Global Health and Social Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | | | | | | | - Michelle C Davidson
- School of Medicine, University of California, San Francisco, California, USA
| | - Bonnie Dighero-Kemp
- Integrated Research Facility, National Institute of Allergy and Infectious Diseases, Fort Detrick, Maryland, USA
| | - Harrison Gichini
- Integrated Research Facility, National Institute of Allergy and Infectious Diseases, Fort Detrick, Maryland, USA
| | - Elizabeth Elliott
- Integrated Research Facility, National Institute of Allergy and Infectious Diseases, Fort Detrick, Maryland, USA
| | - Cavan Reilly
- Division of Biostatistics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Lisa E Hensley
- Integrated Research Facility, National Institute of Allergy and Infectious Diseases, Fort Detrick, Maryland, USA
| | - H Clifford Lane
- Integrated Research Facility, National Institute of Allergy and Infectious Diseases, Fort Detrick, Maryland, USA
| | - Sheri D Weiser
- Division of HIV, Infectious Disease, and Global Medicine, Department of Medicine, University of California, San Francisco, San Francisco, California, USA
| | - Travis C Porco
- Department of Epidemiology and Biostatistics, University of California, San Francisco, California, USA
- F. I. Proctor Foundation, University of California, San Francisco, California, USA
| | - George W Rutherford
- Department of Epidemiology and Biostatistics, University of California, San Francisco, California, USA
- Institute for Global Health Sciences, University of California, San Francisco, California, USA
| | - Eugene T Richardson
- Partners In Health, Freetown, Sierra Leone
- Department of Global Health and Social Medicine, Harvard Medical School, Boston, Massachusetts, USA
- Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, USA
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Abstract
Infectious diseases emerge via many routes and may need to overcome stepwise bottlenecks to burgeon into epidemics and pandemics. About 60% of human infections have animal origins, whereas 40% either co-evolved with humans or emerged from non-zoonotic environmental sources. Although the dynamic interaction between wildlife, domestic animals, and humans is important for the surveillance of zoonotic potential, exotic origins tend to be overemphasized since many zoonoses come from anthropophilic wild species (for example, rats and bats). We examine the equivocal evidence of whether the appearance of novel infections is accelerating and relate technological developments to the risk of novel disease outbreaks. Then we briefly compare selected epidemics, ancient and modern, from the Plague of Athens to COVID-19.
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Affiliation(s)
- Robin A Weiss
- Division of Infection & Immunity, University College London, London, UK
| | - Neeraja Sankaran
- The Descartes Centre for the History and Philosophy of the Sciences and the Humanities, Utrecht University, Utrecht, The Netherlands
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