Ebola virus disease among children in West Africa Agua-Agum, Junerlyn; Ariyarajah, Archchun; Blake, Isobel M ...
The New England journal of medicine,
2015-Mar-26, Letnik:
372, Številka:
13
Journal Article
Despite previous evidence of high level of efficacy, no synthetic metric of yellow fever (YF) vaccine efficacy is currently available. Based on the studies identified in a recent systematic review, ...we conducted a random-effects meta-analysis of the serological response associated with YF vaccination. Eleven studies conducted between 1965 and 2011 representing 4,868 individual observations were included in the meta-analysis. The pooled estimate of serological response was 97.5% (95% confidence interval CI = 82.9-99.7%). There was evidence of between-study heterogeneity (I
= 89.1%), but this heterogeneity did not appear to be related to study size, study design, or seroconversion measurement or definition. Pooled estimates were significantly higher (P < 0.0001) among studies conducted in nonendemic settings (98.9%, 95% CI = 98.2-99.4%) than among those conducted in endemic settings (94.2%, 95% CI = 83.8-98.1%). These results provide background information against which to evaluate the efficacy of fractional doses of YF vaccine that may be used in outbreak situations.
While the number of variant Creutzfeldt-Jakob disease (vCJD) cases continues to decline, concern has been raised that transmission could occur directly from one person to another through routes ...including the transfer of blood and shared use of surgical instruments. Here we firstly present data on the surgical procedures undertaken on vCJD patients prior to onset of clinical symptoms, which supports the hypothesis that cases via this route are possible. We then apply a mathematical framework to assess the potential for self-sustaining epidemics via surgical procedures. Data from hospital episode statistics on the rates of high- and medium-risk procedures in the UK were used to estimate model parameters, and sensitivity to other unknown parameters about surgically transmitted vCJD was assessed. Our results demonstrate that a key uncertainty determining the scale of an epidemic and whether it is self-sustaining is the number of times a single instrument is re-used, alongside the infectivity of contaminated instruments and the effectiveness of cleaning. A survey into the frequency of re-use of surgical instruments would help reduce these uncertainties.
The deterministic limit of a Hopfield-type mutation-selection model in the sequence space approach is investigated. Genotypes are identified with two-letter sequences. Mutation is modelled as a ...Markov process, fitness functions are of Hopfield type, where the fitness of a sequence is determined by the Hamming distances to a number of predefined patterns. Using a maximum principle for the population mean fitness in equilibrium, the error threshold phenomenon is studied for quadratic Hopfield-type fitness functions with small numbers of patterns. Different from previous investigations of the Hopfield model, the system shows error threshold behaviour not for all fitness functions, but only for certain parameter values.
Not all persons infected with Middle East respiratory syndrome coronavirus (MERS-CoV) develop severe symptoms, which likely leads to an underestimation of the number of people infected and an ...overestimation of the severity. To estimate the number of MERS-CoV infections that have occurred in the Kingdom of Saudi Arabia, we applied a statistical model to a line list describing 721 MERS-CoV infections detected between June 7, 2012, and July 25, 2014. We estimated that 1,528 (95% confidence interval (CI): 1,327, 1,883) MERS-CoV infections occurred in this interval, which is 2.1 (95% CI: 1.8, 2.6) times the number reported. The probability of developing symptoms ranged from 11% (95% CI: 4, 25) in persons under 10 years of age to 88% (95% CI: 72, 97) in those 70 years of age or older. An estimated 22% (95% CI: 18, 25) of those infected with MERS-CoV died. MERS-CoV is deadly, but this work shows that its clinical severity differs markedly between groups and that many cases likely go undiagnosed.
Key data for outbreak evaluation: building on the Ebola experience Cori, Anne; Donnelly, Christl A.; Dorigatti, Ilaria ...
Philosophical transactions of the Royal Society of London. Series B. Biological sciences,
05/2017, Letnik:
372, Številka:
1721
Journal Article
Recenzirano
Following the detection of an infectious disease outbreak, rapid epidemiological assessment is critical for guiding an effective public health response. To understand the transmission dynamics and ...potential impact of an outbreak, several types of data are necessary. Here we build on experience gained in the West African Ebola epidemic and prior emerging infectious disease outbreaks to set out a checklist of data needed to: (1) quantify severity and transmissibility; (2) characterize heterogeneities in transmission and their determinants; and (3) assess the effectiveness of different interventions. We differentiate data needs into individual-level data (e.g. a detailed list of reported cases), exposure data (e.g. identifying where/how cases may have been infected) and populationlevel data (e.g. size/demographics of the population(s) affected and when/ where interventions were implemented). A remarkable amount of individuallevel and exposure data was collected during the West African Ebola epidemic, which allowed the assessment of (1) and (2). However, gaps in population-level data (particularly around which interventions were applied when and where) posed challenges to the assessment of (3). Here we highlight recurrent data issues, give practical suggestions for addressing these issues and discuss priorities for improvements in data collection in future outbreaks. This article is part of the themed issue 'The 2013–2016 West African Ebola epidemic: data, decision-making and disease control'.
Long-acting artemisinin-based combination therapy (LACT) offers the potential to prevent recurrent malaria attacks in highly exposed children. However, it is not clear where this advantage will be ...most important, and deployment of these drugs is not rationalized on this basis.
To understand where post-treatment prophylaxis would be most beneficial, the relationship between seasonality, transmission intensity and the interval between malaria episodes was explored using data from six cohort studies in West Africa and an individual-based malaria transmission model. The total number of recurrent malaria cases per 1000 child-years at risk, and the fraction of the total annual burden that this represents were estimated for sub-Saharan Africa.
In settings where prevalence is less than 10 %, repeat malaria episodes constitute a small fraction of the total burden, and few repeat episodes occur within the window of protection provided by currently available drugs. However, in higher transmission settings, and particularly in high transmission settings with highly seasonal transmission, repeat malaria becomes increasingly important, with up to 20 % of the total clinical burden in children estimated to be due to repeat episodes within 4 weeks of a prior attack.
At a given level of transmission intensity and annual incidence, the concentration of repeat malaria episodes in time, and consequently the protection from LACT is highest in the most seasonal areas. As a result, the degree of seasonality, in addition to the overall intensity of transmission, should be considered by policy makers when deciding between ACT that differ in their duration of post-treatment prophylaxis.
The 2013–2016 Ebola outbreak in West Africa is the largest on record with 28 616 confirmed, probable and suspected cases and 11 310 deaths officially recorded by 10 June 2016, the true burden ...probably considerably higher. The case fatality ratio (CFR: proportion of cases that are fatal) is a key indicator of disease severity useful for gauging the appropriate public health response and for evaluating treatment benefits, if estimated accurately. We analysed individual-level clinical outcome data from Guinea, Liberia and Sierra Leone officially reported to the World Health Organization. The overall mean CFR was 62.9% (95% CI: 61.9% to 64.0%) among confirmed cases with recorded clinical outcomes. Age was the most important modifier of survival probabilities, but country, stage of the epidemic and whether patients were hospitalized also played roles. We developed a statistical analysis to detect outliers in CFR between districts of residence and treatment centres (TCs), adjusting for known factors influencing survival and identified eight districts and three TCs with a CFR significantly different from the average. From the current dataset, we cannot determine whether the observed variation in CFR seen by district or treatment centre reflects real differences in survival, related to the quality of care or other factors or was caused by differences in reporting practices or case ascertainment. This article is part of the themed issue 'The 2013–2016 West African Ebola epidemic: data, decision-making and disease control'.
Objective To estimate the economic impact likely to be achieved by efforts to vaccinate against 10 vaccine-preventable diseases between 2001 and 2020 in 73 low- and middle-income countries largely ...supported by Gavi, the Vaccine Alliance. Methods We used health impact models to estimate the economic impact of achieving forecasted coverages for vaccination against Haemophilus influenzae type b, hepatitis B, human papillomavirus, Japanese encephalitis, measles, Neisseria meningitidis serogroup A, rotavirus, rubella, Streptococcus pneumoniae and yellow fever. In comparison with no vaccination, we modelled the costs --expressed in 2010 United States dollars (US$)--of averted treatment, transportation costs, productivity losses of caregivers and productivity losses due to disability and death. We used the value-of-a-life-year method to estimate the broader economic and social value of living longer, in better health, as a result of immunization. Findings We estimated that, in the 73 countries, vaccinations given between 2001 and 2020 will avert over 20 million deaths and save US$ 350 billion in cost of illness. The deaths and disability prevented by vaccinations given during the two decades will result in estimated lifelong productivity gains totalling US$330 billion and US$9 billion, respectively. Over the lifetimes of the vaccinated cohorts, the same vaccinations will save an estimated US$ 5 billion in treatment costs. The broader economic and social value of these vaccinations is estimated at US$820 billion. Conclusion By preventing significant costs and potentially increasing economic productivity among some of the world's poorest countries, the impact of immunization goes well beyond health. Objectif Estimer l'impact economique qui pourrait decouler des efforts de vaccination contre 10 maladies a prevention vaccinale deployes entre 2001 et 2020 dans 73 pays a revenu faible et intermediaire, et largement soutenus par Gavi, I'Alliance du Vaccin. Methodes Nous avons utilise des modeles devaluation de l'impact sur la sante pour estimer l'impact economique qui decoulerait, si le taux de couverture prevu est atteint, des vaccinations contre Haemophilus influenzae type B, l'hepatite B, le papillomavirus humaln, l'encephalite japonaise, la rougeole, Neisseria meningitidis serogroupe A, le rotavirus, la rubeole, Streptococcus pneumoniae et la fievre jaune. Pour etablir une comparaison avec l'absence de vaccination, nous avons modelise les couts--exprimes en dollars des Etats-Unis 2010 (USD)--des traitements evites, les couts de transport, les pertes de productivite des soignants non professionnels et les pertes de productivite pour cause d'invalidite ou de deces. Nous avons utilise une methode permettant d'evaluer la valeur d'une annee de vie pour estimer la valeur economique et sociale au sens large d'une vie plus longue et en meilleure sante grace a la vaccination. Resultats D'apres nos estimations, les vaccinations pratiquees entre 2001 et 2020 dans les 73 pays permettront d'eviter plus de 20 millions de deces et d'economiser 350 milliards de dollars des Etats-Unis en couts sanitaires. Les cas de deces et d'invalidite evites grace a la vaccination pratiquee au cours de ees deux decennies entraineront des gains de productivite permanents respectivement estimes a 330 milliards de dollars des Etats-Unis et 9 milliards de dollars des Etats-Unis. On estime qu'au cours de la vie des cohortes vaccinees, les memes vaccinations permettront d'economiser 5 milliards de dollars des Etats-Unis en couts de traitement. La valeur economique et sociale au sens large de ees vaccinations est estimee a 820 milliards de dollars des Etats-Unis. Conclusion L'impact de la vaccination depasse le domaine de la sante, car il permet d'eviter d'importants couts et une augmentation potentielle de la productivite economique de certains des pays les plus pauvres du monde. Objetivo Estimarei impacto economico que probablemente se logaria con los esfuerzos de vacunar frente a 10 enfermedades evitables mediante la vacunacion entre 2001 y 2020 en 73 paises con ingresos bajos y medios ampliamente respaldados por la Gavi, la Vaccine Alliance. Metodos Se utilizaron modelos de impacto sanitario para estimar el impacto economico de lograr las coberturas previstas de vacunacion frente a Haemophilus influenzae tipo b, hepatitis B, virus del papiloma humano, encefalitis japonesa, sarampion, Neisseria meningitidis serogrupo A, rotavirus, rubeola, Streptococcus pneumoniae y fiebre amarilla. En comparacion con la no vacunacion, se modelaron los costes (expresados en dolares estadounidenses, USD, de 2010) de los tratamientos evitados, los costes de transporte, las perdidas de productividad de los proveedores de salud y las perdidas de productividad debido a la discapacidad y la muerte. Se utilizo el metodo de valor de vida anual para estimar de forma mas amplia el valor economico y social del hecho de vivir mas, con una mejor salud, como resultado de la inmunizacion. Resultados Se estimo que, en los 73 paises, las vacunas suministradas entre 2001 y 2020 evitaran mas de 20 millones de muertes y ahorraran 350 000 millones de USD en costes de enfermedades. Las muertes y las discapacidades evitadas gracias a las vacunas suministradas durante las dos decadas tendran como resultado unas ganancias permanentes estimadas en la productividad de un total de 330 000 millones de USD y 9 000 millones de USD, respectivamente. Durante la vida de las cohortes vacunadas, se estima que las mismas vacunaciones ahorraran 5 000 millones de USD en costes de tratamientos. El valor economico y social mas amplio de estas vacunas se estima en 820 000 millones de USD. Conclusion El impacto de las vacunas es positivo mas alla de la salud, ya que se evitan costes significativos y se aumenta potencialmente la productividad economica entre algunos de los paises mas pobres.
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