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Evaluating temporal factors in combined interventions of workforce shift and school closure for mitigating the spread of influenza.

Zhang T, Fu X, Ma S, Xiao G, Wong L, Kwoh CK, Lees M, Lee GK, Hung T - PLoS ONE (2012)

Bottom Line: It is believed that combined interventions may be more effective than individual interventions in mitigating epidemic.To better understand the problem, we develop an individual-based simulation model running on top of contact networks based on real-life contact data in Singapore.The results of this study are useful to policy makers in deliberating and planning individual and combined interventions.

View Article: PubMed Central - PubMed

Affiliation: Institute of High Performance Computing, A*STAR, Singapore.

ABSTRACT

Background: It is believed that combined interventions may be more effective than individual interventions in mitigating epidemic. However there is a lack of quantitative studies on performance of the combination of individual interventions under different temporal settings.

Methodology/principal findings: To better understand the problem, we develop an individual-based simulation model running on top of contact networks based on real-life contact data in Singapore. We model and evaluate the spread of influenza epidemic with intervention strategies of workforce shift and its combination with school closure, and examine the impacts of temporal factors, namely the trigger threshold and the duration of an intervention. By comparing simulation results for intervention scenarios with different temporal factors, we find that combined interventions do not always outperform individual interventions and are more effective only when the duration is longer than 6 weeks or school closure is triggered at the 5% threshold; combined interventions may be more effective if school closure starts first when the duration is less than 4 weeks or workforce shift starts first when the duration is longer than 4 weeks.

Conclusions/significance: We therefore conclude that identifying the appropriate timing configuration is crucial for achieving optimal or near optimal performance in mitigating the spread of influenza epidemic. The results of this study are useful to policy makers in deliberating and planning individual and combined interventions.

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Related in: MedlinePlus

Mean numbers of contacts at different types of community structures (class contacts refer to the contacts within the same class; school contacts refer to the contacts with the same school but different classes. A ward is a residential section in a hospital for serving hospitalized patients; ward contacts refer to the contacts between the patients in the same wards; and hospital contacts refer to the contacts between the patients in the same hospital but different wards).
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pone-0032203-g001: Mean numbers of contacts at different types of community structures (class contacts refer to the contacts within the same class; school contacts refer to the contacts with the same school but different classes. A ward is a residential section in a hospital for serving hospitalized patients; ward contacts refer to the contacts between the patients in the same wards; and hospital contacts refer to the contacts between the patients in the same hospital but different wards).

Mentions: To lower the computational cost, the contact network is only comprised of 10% of Singapore population: age structure, household size distribution, characteristics of the modeled community structures have been retained proportionally in the simulated population to keep the epidemic trend consistent with that in the whole population. The sizes of communities in the network are obtained proportionally to the statistical numbers in the whole Singapore society. Specifically, a list of households is firstly generated based on the household size distribution. Subsequently, 35 schools are created proportionally according to the total number of students and school size distribution. Then each school is sub-divided into classes based on class size distribution. After that, students are assigned to schools and classes following the “enrollment in the nearby schools” policy, i.e., the students living nearby have a higher chance to be enrolled into the same school or class. Students in the same class may have more contacts (class contacts) and than those between students from the same school but different classes (school contacts), as shown in Figure 1. Similarly, 3 hospitals are constructed with sub-divisions – “wards” (i.e., sections in a hospital for accommodating hospitalized patients) based on hospital and ward size distribution (in term of number of beds) and bed occupation rate. Furthermore, ∼5,300 workplaces (equivalent to companies) are constructed based on the number of working adults, number of companies, and company size distribution, with no further sub-divisions; 10 shopping malls are created according to the survey data including the population size going for shopping, shopping frequency and daily traffic of malls, with no sub-divisions. Finally, a single structure of public transport is created as a single-layer giant component which includes all the commuters in the population.


Evaluating temporal factors in combined interventions of workforce shift and school closure for mitigating the spread of influenza.

Zhang T, Fu X, Ma S, Xiao G, Wong L, Kwoh CK, Lees M, Lee GK, Hung T - PLoS ONE (2012)

Mean numbers of contacts at different types of community structures (class contacts refer to the contacts within the same class; school contacts refer to the contacts with the same school but different classes. A ward is a residential section in a hospital for serving hospitalized patients; ward contacts refer to the contacts between the patients in the same wards; and hospital contacts refer to the contacts between the patients in the same hospital but different wards).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3293885&req=5

pone-0032203-g001: Mean numbers of contacts at different types of community structures (class contacts refer to the contacts within the same class; school contacts refer to the contacts with the same school but different classes. A ward is a residential section in a hospital for serving hospitalized patients; ward contacts refer to the contacts between the patients in the same wards; and hospital contacts refer to the contacts between the patients in the same hospital but different wards).
Mentions: To lower the computational cost, the contact network is only comprised of 10% of Singapore population: age structure, household size distribution, characteristics of the modeled community structures have been retained proportionally in the simulated population to keep the epidemic trend consistent with that in the whole population. The sizes of communities in the network are obtained proportionally to the statistical numbers in the whole Singapore society. Specifically, a list of households is firstly generated based on the household size distribution. Subsequently, 35 schools are created proportionally according to the total number of students and school size distribution. Then each school is sub-divided into classes based on class size distribution. After that, students are assigned to schools and classes following the “enrollment in the nearby schools” policy, i.e., the students living nearby have a higher chance to be enrolled into the same school or class. Students in the same class may have more contacts (class contacts) and than those between students from the same school but different classes (school contacts), as shown in Figure 1. Similarly, 3 hospitals are constructed with sub-divisions – “wards” (i.e., sections in a hospital for accommodating hospitalized patients) based on hospital and ward size distribution (in term of number of beds) and bed occupation rate. Furthermore, ∼5,300 workplaces (equivalent to companies) are constructed based on the number of working adults, number of companies, and company size distribution, with no further sub-divisions; 10 shopping malls are created according to the survey data including the population size going for shopping, shopping frequency and daily traffic of malls, with no sub-divisions. Finally, a single structure of public transport is created as a single-layer giant component which includes all the commuters in the population.

Bottom Line: It is believed that combined interventions may be more effective than individual interventions in mitigating epidemic.To better understand the problem, we develop an individual-based simulation model running on top of contact networks based on real-life contact data in Singapore.The results of this study are useful to policy makers in deliberating and planning individual and combined interventions.

View Article: PubMed Central - PubMed

Affiliation: Institute of High Performance Computing, A*STAR, Singapore.

ABSTRACT

Background: It is believed that combined interventions may be more effective than individual interventions in mitigating epidemic. However there is a lack of quantitative studies on performance of the combination of individual interventions under different temporal settings.

Methodology/principal findings: To better understand the problem, we develop an individual-based simulation model running on top of contact networks based on real-life contact data in Singapore. We model and evaluate the spread of influenza epidemic with intervention strategies of workforce shift and its combination with school closure, and examine the impacts of temporal factors, namely the trigger threshold and the duration of an intervention. By comparing simulation results for intervention scenarios with different temporal factors, we find that combined interventions do not always outperform individual interventions and are more effective only when the duration is longer than 6 weeks or school closure is triggered at the 5% threshold; combined interventions may be more effective if school closure starts first when the duration is less than 4 weeks or workforce shift starts first when the duration is longer than 4 weeks.

Conclusions/significance: We therefore conclude that identifying the appropriate timing configuration is crucial for achieving optimal or near optimal performance in mitigating the spread of influenza epidemic. The results of this study are useful to policy makers in deliberating and planning individual and combined interventions.

Show MeSH
Related in: MedlinePlus