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Eliminating yellow fever epidemics in Africa: Vaccine demand forecast and impact modelling.
- Source :
-
PLoS neglected tropical diseases [PLoS Negl Trop Dis] 2020 May 07; Vol. 14 (5), pp. e0008304. Date of Electronic Publication: 2020 May 07 (Print Publication: 2020). - Publication Year :
- 2020
-
Abstract
- Background: To counter the increasing global risk of Yellow fever (YF), the World Health Organisation initiated the Eliminate Yellow fever Epidemics (EYE) strategy. Estimating YF burden, as well as vaccine impact, while accounting for the features of urban YF transmission such as indirect benefits of vaccination, is key to informing this strategy.<br />Methods and Findings: We developed two model variants to estimate YF burden in sub-Saharan Africa, assuming all infections stem from either the sylvatic or the urban cycle of the disease. Both relied on an ecological niche model fitted to the local presence of any YF reported event in 34 African countries. We calibrated under-reporting using independent estimates of transmission intensity provided by 12 serological surveys performed in 11 countries. We calculated local numbers of YF infections, deaths and disability-adjusted life years (DALYs) lost based on estimated transmission intensity while accounting for time-varying vaccination coverage. We estimated vaccine demand and impact of future preventive mass vaccination campaigns (PMVCs) according to various vaccination scenarios. Vaccination activities conducted in Africa between 2005 and 2017 were estimated to prevent from 3.3 (95% CI 1.2-7.7) to 6.1 (95% CI 2.4-13.2) millions of deaths over the lifetime of vaccinees, representing extreme scenarios of none or maximal herd effects, respectively. By prioritizing provinces based on the risk of urban YF transmission in future PMVCs, an average of 37.7 million annual doses for PMVCs over eight years would avert an estimated 9,900,000 (95% CI 7,000,000-13,400,000) infections and 480,000 (180,000-1,140,000) deaths over the lifetime of vaccinees, corresponding to 1.7 (0.7-4.1) deaths averted per 1,000 vaccine doses.<br />Conclusions: By estimating YF burden and vaccine impact over a range of spatial and temporal scales, while accounting for the specificity of urban transmission, our model can be used to inform the current EYE strategy.<br />Competing Interests: KJ, AH and TG received personal fees from the World Health Organization for consultancy on the topic. All other authors declare no competing interest.
- Subjects :
- Adolescent
Adult
Africa epidemiology
Aged
Aged, 80 and over
Child
Child, Preschool
Epidemiologic Methods
Female
Humans
Infant
Infant, Newborn
Male
Middle Aged
Models, Statistical
Yellow Fever Vaccine immunology
Young Adult
Cost of Illness
Disease Transmission, Infectious prevention & control
Epidemics prevention & control
Yellow Fever epidemiology
Yellow Fever prevention & control
Yellow Fever Vaccine administration & dosage
Subjects
Details
- Language :
- English
- ISSN :
- 1935-2735
- Volume :
- 14
- Issue :
- 5
- Database :
- MEDLINE
- Journal :
- PLoS neglected tropical diseases
- Publication Type :
- Academic Journal
- Accession number :
- 32379756
- Full Text :
- https://doi.org/10.1371/journal.pntd.0008304