Extracting key information from historical data to quantify the transmission dynamics of smallpox

Nishiura, Hiroshi; Brockmann, Stefan; Eichner, Martin

doi:10.1186/1742-4682-5-20

Cited by 23 publications

(15 citation statements)

References 90 publications

(97 reference statements)

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“…The aim of this paper is to better understand the conditions under which the inclusion of contact repetition and clustering is relevant in models of disease spread compared to a reference case assuming random mixing. This is pertinent, as many researchers still use the random mixing assumption without thoroughly discussing its adequacy for the respective case study [17][18][19][20][21]. In particular, we test and discuss the influence of transmission probability, number of contacts per day, duration of the infectious period, clustering and proportion of repetitive contacts on the total outbreak size of a disease.…”

Section: Introductionmentioning

confidence: 99%

Models of epidemics: when contact repetition and clustering should be included

Smieszek

Fiebig

Scholz

2009

Theor Biol Med Model

107

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Background: The spread of infectious disease is determined by biological factors, e.g. the duration of the infectious period, and social factors, e.g. the arrangement of potentially contagious contacts. Repetitiveness and clustering of contacts are known to be relevant factors influencing the transmission of droplet or contact transmitted diseases. However, we do not yet completely know under what conditions repetitiveness and clustering should be included for realistically modelling disease spread.

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Section: Introductionmentioning

confidence: 99%

Models of epidemics: when contact repetition and clustering should be included

Smieszek

Fiebig

Scholz

2009

Theor Biol Med Model

107

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“…In agreement with many other mathematical models, 19 we have assumed a case fatality rate of 30%. However, case fatality has been shown to vary with virulence; for example, given exposure to highly virulent strains that were imported to Europe, Mack and others 20 previously reported that the crude case fatality rate was as high as 52% among unvaccinated individuals.…”

Section: Great Britain Districtsmentioning

confidence: 73%

Stamping Out Fires! Controlling Smallpox with Targeted Mass Vaccination

Egan¹,

Hall²

2010

Med Decis Making

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. Reactive nationwide mass vaccination remains a suboptimal strategy for controlling an expanding smallpox outbreak in all but the most extreme circumstances. Rather, targeted mass vaccination of affected areas is likely to result in fewer deaths. The vaccines administered are also likely to be much fewer because they would probably be distributed to a much smaller number of districts, thus relieving pressure on potentially stretched public health systems.

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“…This leads to (1 − q )(1 − v f ) R 0 < 1 (or (1 − q ) R 0 < 1 due to v f = 0). In the absence of intervention, R 0 is crudely assumed to be 5 which is in line with the goal of vaccination coverage during the Intensified Smallpox Eradication Programme without accounting for other interventions [16] and also with the published estimate of 6.85 if accompanied by contact tracing [17,18]. The protective effect of contact tracing, q is arbitrarily assumed as 0.8 due to an assumption of sub-critical process ( i.e.…”

Section: Methodsmentioning

confidence: 99%

“…One should remember that these arbitrarily allocated R 0 and q are very influential in discussing the feasibility of containment (using Equation (3)). Under these assumptions, we vary the combined effect of vaccination, denoted by α s α i α m α d , while we adopt a fixed value of α s at 0.8 given that a historical household data with probably limited vaccine potency indicates that susceptibility is reduced by a factor of 0.69 [16]. Varying the combined effect of vaccination from 0 to 2, we calculate the estimate of the effective reproduction number, the expected total number of cases, the probability of extinction, and the expected duration of an outbreak.…”

Section: Methodsmentioning

confidence: 99%

Vaccination and Clinical Severity: Is the Effectiveness of Contact Tracing and Case Isolation Hampered by Past Vaccination?

Mizumoto

Ejima

Yamamoto

et al. 2013

IJERPH

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While contact tracing and case isolation are considered as the first choice of interventions against a smallpox bioterrorist event, their effectiveness under vaccination is questioned, because not only susceptibility of host and infectiousness of case but also the risk of severe clinical manifestations among cases is known to be reduced by vaccine-induced immunity, thereby potentially delaying the diagnosis and increasing mobility among vaccinated cases. We employed a multi-type stochastic epidemic model, aiming to assess the feasibility of contact tracing and case isolation in a partially vaccinated population and identify data gaps. We computed four epidemiological outcome measures, i.e., (i) the threshold of a major epidemic under the interventions; (ii) the expected total number of cases; (iii) the probability of extinction, and (iv) the expected duration of an outbreak, demonstrating that all of these outcomes critically depend on the clinical impact of past vaccination on the diagnosis and movement of vaccinated cases. We discuss that, even in the absence of smallpox in the present day, one should consider the way to empirically quantify the delay in case detection and an increase in the frequency of contacts among previously vaccinated cases compared to unvaccinated during the early stage of an epidemic so that the feasibility of contact tracing and case isolation in a vaccinated population can be explicitly assessed.

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Extracting key information from historical data to quantify the transmission dynamics of smallpox

Cited by 23 publications

References 90 publications

Models of epidemics: when contact repetition and clustering should be included

Models of epidemics: when contact repetition and clustering should be included

Stamping Out Fires! Controlling Smallpox with Targeted Mass Vaccination

Vaccination and Clinical Severity: Is the Effectiveness of Contact Tracing and Case Isolation Hampered by Past Vaccination?

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