scholarly journals The global burden of yellow fever

2020 ◽  
Author(s):  
Katy A. M. Gaythorpe ◽  
Arran T. P. Hamlet ◽  
Kevin Jean ◽  
Daniel Garkauskas Ramos ◽  
Laurence Cibrelus ◽  
...  
Keyword(s):  
South America ◽  
Yellow Fever ◽  
Mass Vaccination ◽  
Global Burden ◽  
Short Supply ◽  
Tropical Regions ◽  
Force Of Infection ◽  
Viral Haemorrhagic Fever ◽  
Vaccination Campaigns ◽  
The Impact

AbstractBackgroundYellow fever (YF) is a viral haemorrhagic fever endemic in tropical regions of Africa and South America. Current intervention policies, namely the Eliminate Yellow fever Epidemics (EYE) strategy are actioned through vaccination. However, the stockpiles and production mean that vaccination can be in short supply. As such, intervention strategies need to be optimised; one of the tools for doing this is mathematical modelling.MethodsWe fit a generalised linear model of YF reports to occurrence data available from 1987 to 2019 in Africa and South America and available serology survey data to estimate the force of infection across the continents. Then, using demographic and vaccination data, we examine the impact of interventions.FindingsWe estimate that in 2018 there were approximately 51,000 (95%CrI [31,000 - 82,000]) deaths due to YF in Africa and South America. When we examine the impact of mass vaccination campaigns in Africa, these amount to approximately 10,000 (95%CrI [6,000 - 17,000]) deaths averted in 2018 due to mass vaccination activities in Africa; this corresponds to a 47% reduction (95%CrI [10% - 77%]).InterpretationWe find that the majority, 92% (95%CrI [89% - 95%]), of global burden occurs in Africa and that mass vaccination activities have significantly reduced the current deaths per year due to YF. This methodology allows us to evaluate the effectiveness of vaccination campaigns past, present and future and illustrates the need for continued vigilance and surveillance of YF.FundingBMGF and MRC

scholarly journals The global burden of yellow fever

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Katy AM Gaythorpe ◽  
Arran Hamlet ◽  
Kévin Jean ◽  
Daniel Garkauskas Ramos ◽  
Laurence Cibrelus ◽  
...  
Keyword(s):  
South America ◽  
Yellow Fever ◽  
Viral Vector ◽  
Credible Interval ◽  
Endemic Region ◽  
Tropical Regions ◽  
Modelling Framework ◽  
Severe Infections ◽  
Vector Borne ◽  
The Impact

Yellow fever (YF) is a viral, vector-borne, haemorrhagic fever endemic in tropical regions of Africa and South America. The vaccine for YF is considered safe and effective, but intervention strategies need to be optimised; one of the tools for this is mathematical modelling. We refine and expand an existing modelling framework for Africa to account for transmission in South America. We fit to YF occurrence and serology data. We then estimate the subnational forces of infection for the entire endemic region. Finally, using demographic and vaccination data, we examine the impact of vaccination activities. We estimate that there were 109,000 (95% credible interval [CrI] [67,000–173,000]) severe infections and 51,000 (95% CrI [31,000–82,000]) deaths due to YF in Africa and South America in 2018. We find that mass vaccination activities in Africa reduced deaths by 47% (95% CrI [10%–77%]). This methodology allows us to evaluate the effectiveness of vaccination and illustrates the need for continued vigilance and surveillance of YF.

scholarly journals Assessing the impact of preventive mass vaccination campaigns on yellow fever outbreaks in Africa : a population-level self-controlled case-series study

2020 ◽  
Author(s):  
Kevin Jean ◽  
Hanaya Raad ◽  
Katy A. M. Gaythorpe ◽  
Arran Hamlet ◽  
Judith E. Mueller ◽  
...  
Keyword(s):  
Yellow Fever ◽  
Case Series ◽  
Public Health Intervention ◽  
Population Level ◽  
Mass Vaccination ◽  
Sensitivity Analyses ◽  
Endemic Region ◽  
Case Series Study ◽  
Vaccination Campaigns ◽  
The Impact

Introduction: The Eliminate Yellow fever Epidemics (EYE) strategy was launched in 2017 in response to the resurgence of yellow fever in Africa and the Americas. The strategy relies on several vaccination activities, including preventive mass vaccination campaigns (PMVCs). However, by how much PMVCs decrease the risk of outbreak to occur has not yet been quantified. Methods: We used the self-controlled case series (SCCS) method to assess the association between the occurrence of yellow fever outbreaks and the implementation of PMVCs at the province level in the African endemic region. As all time-invariant confounders are implicitly controlled for, the SCCS method is an alternative to classical cohort or case-control study designs when the risk of residual confounding is high. The location and dates of outbreaks were identified from international epidemiological records, and information on PMVCs was provided by coordinators of vaccination activities and international funders. The study sample consisted of provinces that were both affected by an outbreak and targeted for a PMVC between 2005 and 2018. We compared the relative incidence of outbreaks before and after the implementation of a PMVC. The sensitivity of our estimates to a range of assumptions was explored, and the results of the SCCS method were compared to those obtained through a retrospective cohort study design. We further derived the number of yellow fever outbreaks that have been prevented by PMVCs. Results: The study sample consisted of 33 African provinces. Among these, outbreaks occurred during the pre-PMVC period in 26 (78.8%) provinces versus 7 (21.2%) occurring in the post-PMVC period. This corresponded to a significantly reduced incidence rate ratio of 0.14 (95% Confidence interval 0.06 to 0.34) for the post-PMVC versus pre-PMVC period. This estimate was robust across a range of sensitivity analyses, while the results of the cohort-style analyses were highly sensitive to the choice of covariates included in the model. Based on the SCCS results, we estimated that PMVCs have reduced the number of outbreaks by 34% (22% to 45%) in Africa over the study period. Conclusion: Our estimates provide new empirical evidence of the high preventive impact of PMVCs on yellow fever outbreaks. This study illustrates that the SCCS method can be advantageously applied at the population level in order to evaluate a public health intervention.

scholarly journals Assessing the impact of preventive mass vaccination campaigns on yellow fever outbreaks in Africa: A population-level self-controlled case series study

PLoS Medicine ◽  
2021 ◽  
Vol 18 (2) ◽  
pp. e1003523
Author(s):  
Kévin Jean ◽  
Hanaya Raad ◽  
Katy A. M. Gaythorpe ◽  
Arran Hamlet ◽  
Judith E. Mueller ◽  
...  
Keyword(s):  
Yellow Fever ◽  
Case Series ◽  
Population Level ◽  
Mass Vaccination ◽  
Sensitivity Analyses ◽  
Environmental Drivers ◽  
Case Series Study ◽  
Vaccination Campaigns ◽  
The Impact ◽  
Province Level

Background The Eliminate Yellow fever Epidemics (EYE) strategy was launched in 2017 in response to the resurgence of yellow fever in Africa and the Americas. The strategy relies on several vaccination activities, including preventive mass vaccination campaigns (PMVCs). However, to what extent PMVCs are associated with a decreased risk of outbreak has not yet been quantified. Methods and findings We used the self-controlled case series (SCCS) method to assess the association between the occurrence of yellow fever outbreaks and the implementation of PMVCs at the province level in the African endemic region. As all time-invariant confounders are implicitly controlled for in the SCCS method, this method is an alternative to classical cohort or case–control study designs when the risk of residual confounding is high, in particular confounding by indication. The locations and dates of outbreaks were identified from international epidemiological records, and information on PMVCs was provided by coordinators of vaccination activities and international funders. The study sample consisted of provinces that were both affected by an outbreak and targeted for a PMVC between 2005 and 2018. We compared the incidence of outbreaks before and after the implementation of a PMVC. The sensitivity of our estimates to a range of assumptions was explored, and the results of the SCCS method were compared to those obtained through a retrospective cohort study design. We further derived the number of yellow fever outbreaks that have been prevented by PMVCs. The study sample consisted of 33 provinces from 11 African countries. Among these, the first outbreak occurred during the pre-PMVC period in 26 (79%) provinces, and during the post-PMVC period in 7 (21%) provinces. At the province level, the post-PMVC period was associated with an 86% reduction (95% CI 66% to 94%, p < 0.001) in the risk of outbreak as compared to the pre-PMVC period. This negative association between exposure to PMVCs and outbreak was robustly observed across a range of sensitivity analyses, especially when using quantitative estimates of vaccination coverage as an alternative exposure measure, or when varying the observation period. In contrast, the results of the cohort-style analyses were highly sensitive to the choice of covariates included in the model. Based on the SCCS results, we estimated that PMVCs were associated with a 34% (95% CI 22% to 45%) reduction in the number of outbreaks in Africa from 2005 to 2018. A limitation of our study is the fact that it does not account for potential time-varying confounders, such as changing environmental drivers of yellow fever and possibly improved disease surveillance. Conclusions In this study, we provide new empirical evidence of the high preventive impact of PMVCs on yellow fever outbreaks. This study illustrates that the SCCS method can be advantageously applied at the population level in order to evaluate a public health intervention.

scholarly journals Cutaneous lesions caused by the yellow fever vaccine – have you ever seen them?

2018 ◽  
Vol 64 (6) ◽  
pp. 498-500 ◽  
Author(s):  
Michelle Larissa Zini Lise ◽  
Michael Laurence Zini Lise
Keyword(s):  
Side Effects ◽  
South America ◽  
Skin Rash ◽  
Yellow Fever ◽  
Yellow Fever Virus ◽  
Fever Virus ◽  
Yellow Fever Vaccine ◽  
Cutaneous Lesions ◽  
Tropical Regions

SUMMARY The Yellow Fever virus was isolated in 1927 and the disease is considered endemic and epidemic in tropical regions of South America and Africa, with thousands of new cases reported annually. Several side effects of the vaccine have already been reported. Although reports of skin rash secondary to the vaccine range from 0 to 15%, no image or detailed description of the lesions were found in the literature. Here we describe a rash on a toddler vaccinated to travel.

scholarly journals Technical viability of the YF MAC-HD ELISA kit for use in yellow fever-endemic regions

2021 ◽  
Vol 15 (6) ◽  
pp. e0009417
Author(s):  
Christin H. Goodman ◽  
Maurice Demanou ◽  
Mick Mulders ◽  
Jairo Mendez-Rico ◽  
Alison Jane Basile
Keyword(s):  
South America ◽  
Yellow Fever ◽  
Accurate Diagnosis ◽  
Immunoglobulin M ◽  
Enzyme Linked Immunosorbent Assay ◽  
Elisa Kit ◽  
Wash Buffer ◽  
Antibody Capture ◽  
Vaccination Campaigns ◽  
Arboviral Disease

Yellow fever (YF), an arboviral disease, affects an estimated 200,000 people and causes 30,000 deaths per year and recently has caused major epidemics in Africa and South America. Timely and accurate diagnosis of YF is critical for managing outbreaks and implementing vaccination campaigns. A YF immunoglobulin M (IgM) antibody-capture (MAC) enzyme-linked immunosorbent assay (ELISA) kit, the YF MAC-HD, was successfully introduced starting in 2018 to laboratories in Africa and South America. The YF MAC-HD kit can be performed in 3.5 hours, test up to 24 samples, and includes all reagents necessary to perform the test, except for water used to dilute wash buffer. In 2018 and 2019, a total of 56 laboratory personnel from 39 countries in Africa and South America were trained to use the kit during workshops, followed by take-home YF IgM proficiency testing (PT) exercises. Participants received either a 10- or 20-sample YF PT panel and performed testing using the YF MAC-HD kit. All countries obtained 90% or higher correct results. These results verified the technical viability and transferability of YF MAC-HD kit use for laboratories in YF-endemic countries.

scholarly journals Mathematical modeling of endemic cholera transmission

2021 ◽  
Author(s):  
Dennis L Chao
Keyword(s):  
Mathematical Modeling ◽  
Herd Immunity ◽  
Population Level ◽  
Additional Benefit ◽  
Mass Vaccination ◽  
The Cost ◽  
Vaccination Campaigns ◽  
The Impact ◽  
Indirect Protection ◽  
Endemic Cholera

Abstract Mathematical modeling can be used to project the impact of mass vaccination on cholera transmission. Here, we discuss two examples for which indirect protection from mass vaccination needs to be considered. In the first, we show that non-vaccinees can be protected by mass vaccination campaigns. This additional benefit of indirect protection improves the cost-effectiveness of mass vaccination. In the second, we model the use of mass vaccination to eliminate cholera. In this case, a high population level of immunity, including contributions from infection and vaccination, is required to reach the “herd immunity” threshold needed to stop transmission and achieve elimination.

scholarly journals Impact of COVID-19-related disruptions to measles, meningococcal A, and yellow fever vaccination in 10 countries

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Katy A M Gaythorpe ◽  
Kaja Abbas ◽  
John Huber ◽  
Andromachi Karachaliou ◽  
Niket Thakkar ◽  
...  
Keyword(s):  
Yellow Fever ◽  
Health Impact ◽  
Vaccination Programs ◽  
Preventive Vaccination ◽  
Catch Up ◽  
Yellow Fever Vaccination ◽  
Gates Foundation ◽  
Measles Outbreaks ◽  
Vaccination Campaigns ◽  
The Impact

Background: Childhood immunisation services have been disrupted by COVID-19. WHO recommends considering outbreak risk using epidemiological criteria when deciding whether to conduct preventive vaccination campaigns during the pandemic. Methods: We used 2-3 models per infection to estimate the health impact of 50% reduced routine vaccination coverage and delaying campaign vaccination for measles, meningococcal A and yellow fever vaccination in 3-6 high burden countries per infection. Results: Reduced routine coverage in 2020 without catch-up vaccination may increase measles and yellow fever disease burden in the modelled countries. Delaying planned campaigns may lead to measles outbreaks and increases in yellow fever burden in some countries. For meningococcal A vaccination, short term disruptions in 2020 are unlikely to have a significant impact. Conclusion: The impact of COVID-19-related disruption to vaccination programs varies between infections and countries. Funding: Bill and Melinda Gates Foundation and Gavi, the Vaccine Alliance.

Expansion of the Distribution of Aedes albopictus (Diptera: Culicidae): New Records in Northern Argentina and Their Implications From an Epidemiological Perspective

2020 ◽  
Vol 57 (4) ◽  
pp. 1310-1313
Author(s):  
S Goenaga ◽  
A Chuchuy ◽  
M V Micieli ◽  
B Natalini ◽  
J Kuruc ◽  
...  
Keyword(s):  
South America ◽  
Yellow Fever ◽  
Aedes Albopictus ◽  
Nonhuman Primates ◽  
New Records ◽  
Mosquito Species ◽  
Vector Surveillance ◽  
Misiones Province ◽  
The Impact ◽  
First Time

Abstract Since the last yellow fever (YF) outbreak was detected in Argentina in 2009, vector surveillance and studies of arbovirus infections are carried out intermittently specifically in areas where nonhuman primates of the Alouatta genus are present. We report in these areas of Corrientes province the detection of Haemagogus leucocelaenus (Dyar and Shannon) (Diptera: Culicidae) and Sabethes albiprivus (Theobald) (Diptera: Culicidae), both species involved in the forest YF cycle, and also the presence of Aedes albopictus (Skuse) in new areas in Argentina, which represents the southernmost citation for this species in South America. Aedes albopictus, a mosquito species native to Asia, was reported for the first time in Argentina in 1998, in Misiones province. Since then, no other report has indicated the extension of the distribution of this mosquito. This report shows the importance of performing continual entomological and arboviruses surveillance and highlights the impact that could result from the expansion of Ae. albopictus across Argentina.

scholarly journals What Does the Future Hold for Yellow Fever Virus? (II)

2018 ◽  
Author(s):  
Raphaëlle Klitting ◽  
Carlo Fischer ◽  
Jan F. Drexler ◽  
Ernest A. Gould ◽  
David Roiz ◽  
...  
Keyword(s):  
South America ◽  
Yellow Fever ◽  
Yellow Fever Virus ◽  
Virus Transmission ◽  
Fever Virus ◽  
Control Measures ◽  
World Health ◽  
Epidemiological Surveillance ◽  
Tropical Regions ◽  
Vaccination Recommendation

As revealed by the recent resurgence of yellow fever virus (YFV) activity in the tropical regions of Africa and South America, YFV control measures need urgent rethinking. Over the last decade, most reported outbreaks occurred in, or eventually reached, areas of low vaccination coverage but suitable for virus transmission, with an unprecedented risk of expansion to densely populated territories in Africa, South America and Asia. As reflected in the World Health Organization&rsquo;s initiative launched in 2017, it is high time to strengthen epidemiological surveillance to monitor accurately, viral dissemination and redefine vaccination recommendation areas. Vector-control and immunisation measures need to be adapted and vaccine manufacturing must be reconciled with an increasing demand. We will have to face more YF cases in the upcoming years hence, improving disease management through the development of efficient treatments will prove most beneficial. Undoubtedly, these developments will require in-depth descriptions of YFV biology at molecular, physiological and ecological levels. This second section of the two-part review describes the current state of knowledge and gaps regarding the molecular biology of YFV, along with an overview of the tools that can be used to manage the disease at the individual, local and global levels.

scholarly journals The impact of reactive mass vaccination campaigns on measles outbreaks in the Katanga region, Democratic Republic of Congo

2019 ◽  
Author(s):  
Sebastian Funk ◽  
Saki Takahashi ◽  
Joel Hellewell ◽  
Kartini Gadroen ◽  
Isidro Carrion-Martin ◽  
...  
Keyword(s):  
Vaccination Coverage ◽  
Democratic Republic ◽  
Democratic Republic Of Congo ◽  
Vaccination Campaign ◽  
Effective Means ◽  
Mass Vaccination ◽  
Republic Of Congo ◽  
Measles Outbreaks ◽  
Vaccination Campaigns ◽  
The Impact

AbstractThe Katanga region in the Democratic Republic of Congo (DRC) has been struck by repeated epidemics of measles, with large outbreaks occurring in 2010–13 and 2015. In many of the affected health zones, reactive mass vaccination campaigns were conducted in response to the outbreaks. Here, we attempted to determine how effective the vaccination campaigns in 2015 were in curtailing the ongoing outbreak. We further sought to establish whether the risk of large measles outbreaks in different health zones could have been determined in advance to help prioritise areas for vaccination campaign and speed up the response. In doing so, we first attempted to identify factors that could have been used in 2015 to predict in which health zones the greatest outbreaks would occur. Administrative vaccination coverage was not a good predictor of the size of outbreaks in different health zones. Vaccination coverage derived from surveys, on the other hand, appeared to give more reliable estimates of health zones of low vaccination coverage and, consequently, large outbreaks. On a coarser geographical scale, the provinces most affected in 2015 could be predicted from the outbreak sizes in 2010–13. This, combined with the fact that the vast majority of reported cases were in under-5 year olds, would suggest that there are systematic issues of undervaccination. If this was to continue, outbreaks would be expected to continue to occur in the affected health zones at regular intervals, mostly concentrated in under-5 year olds. We further used a model of measles transmission to estimate the impact of the vaccination campaigns, by first fitting a model to the data including the campaigns and then re-running this without vaccination. We estimated the reactive campaigns to have reduced the size of the overall outbreak by approximately 21,000 (IQR: 16,000–27,000; 95% CI: 8300–38,000) cases. There was considerable heterogeneity in the impact of campaigns, with campaigns started earlier after the start of an outbreak being more impactful. Taken together, these findings suggest that while a strong routine vaccination regime remains the most effective means of measles control, it might be possible to improve the effectiveness of reactive campaigns by considering predictive factors to trigger a more targeted vaccination response.

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