Simulation suggests that rapid activation of social distancing can arrest epidemic development due to a novel strain of Influenza

School of Computer Science and Software Engineering, University of Western Australia, Perth, WA, Australia.
BMC Public Health (Impact Factor: 2.26). 05/2009; 9(1):117. DOI: 10.1186/1471-2458-9-117
Source: PubMed


Social distancing interventions such as school closure and prohibition of public gatherings are present in pandemic influenza preparedness plans. Predicting the effectiveness of intervention strategies in a pandemic is difficult. In the absence of other evidence, computer simulation can be used to help policy makers plan for a potential future influenza pandemic. We conducted simulations of a small community to determine the magnitude and timing of activation that would be necessary for social distancing interventions to arrest a future pandemic.
We used a detailed, individual-based model of a real community with a population of approximately 30,000. We simulated the effect of four social distancing interventions: school closure, increased isolation of symptomatic individuals in their household, workplace nonattendance, and reduction of contact in the wider community. We simulated each of the intervention measures in isolation and in several combinations; and examined the effect of delays in the activation of interventions on the final and daily attack rates.
For an epidemic with an R0 value of 1.5, a combination of all four social distancing measures could reduce the final attack rate from 33% to below 10% if introduced within 6 weeks from the introduction of the first case. In contrast, for an R0 of 2.5 these measures must be introduced within 2 weeks of the first case to achieve a similar reduction; delays of 2, 3 and 4 weeks resulted in final attack rates of 7%, 21% and 45% respectively. For an R0 of 3.5 the combination of all four measures could reduce the final attack rate from 73% to 16%, but only if introduced without delay; delays of 1, 2 or 3 weeks resulted in final attack rates of 19%, 35% or 63% respectively. For the higher R0 values no single measure has a significant impact on attack rates.
Our results suggest a critical role of social distancing in the potential control of a future pandemic and indicate that such interventions are capable of arresting influenza epidemic development, but only if they are used in combination, activated without delay and maintained for a relatively long period.

Download full-text


Available from: Joel Kelso,
  • Source
    • "In particular, the co-evolution of information diffusion as a proxy for effective preventive behavioural changes and epidemiological contagion has been investigated by Funk and colleagues, (e.g., see Funk et al., 2009, 2010 for a review on different investigations on the impacts behavioural changes on epidemiological dynamics). However , these models, as in other deterministic game-theoretical formulation, rely on a rational construction of agents utilizing payoff maximization (e.g., homo-economicus perspective) to trigger preventive behaviours including vaccinations (Fu et al., 2010; Ndeffo Mbah et al., 2012; Perisic and Bauch, 2009; Epstein et al., 2008; Kelso et al., 2009). In Fu et al. (2010) and Ndeffo Mbah et al. (2012), the authors used game-theoretic approach within an in silico to explore the effect of cost-benefit of imitation of vaccination patterns. "

  • Source
    • "At the national level, the most universally recommended two-set measures were frequent hand-washing and availability and use of alcohol-based hand sanitizers; as well as covering sneezes/coughs, and the use of masks, all widely advocated through extensive print, audio, video campaigns conducted throughout virtually all public spaces, airwaves and outlets. Recent theoretical models confirm the legitimacy of these early, sustained, and non-pharmaceutical interventions for influenza containment[7]–[12]. However, there is a severely lacking amount of information about the potential indirect impact of this international crisis on other prevalent diseases. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The 2009 A/H1N1 influenza pandemic has received a great deal of attention from public health authorities. Our study examines whether this pandemic and the resulting public health measures could have impacted acute diarrhea, a prevalent, highly transmissible and historically monitored disease. Using augmentation procedures of national data for the previous five years (2004-2009), we estimated the expected timing and incidence of acute diarrhea in France in 2009-2010 and evaluated differences with the observed. We also reviewed national hand gels for the same period. Number of episodes of acute diarrhea in France in 2009-2010 was significantly lower than expected until the third week of December (-24%, 95% CI [-36%; -9%]), then significantly higher (+40%, 95% CI [22%; 62%]), leading to a surplus of 574,440 episodes. The epidemic was delayed by 5 weeks with a peak 1.3 times higher than expected. Hand-gels sales inversely correlated with incidence of both influenza-like illness and acute diarrheal disease. Among individuals >65 yo, no excess cases of influenza and no excess rebound in acute diarrhea were observed, despite similar delay in the onset of the seasonal diarrheal epidemic. Our results suggest that at least one endemic disease had an unexpected behavior in 2009-2010. Acute diarrhea seems to have been controlled during the beginning of the pandemic in all age groups, but later peaked higher than expected in the younger population. The all-age delay in seasonal onset seems partly attributable to hand-gels use, while the differential magnitude of the seasonal epidemic between young and old, concurrent for both influenza and acute diarrhea, is compatible with disease interaction.
    PLoS ONE 10/2013; 8(10):e75226. DOI:10.1371/journal.pone.0075226 · 3.23 Impact Factor
  • Source
    • "The simulation model used in this study has been used in previous studies to examine various aspects of social distancing and pharmaceutical (antiviral and vaccine) pandemic influenza interventions [4,5,10,11,37,52]. This simulation model shares characteristics with other individual-based pandemic influenza simulation models that have been employed at a variety of scales, including small communities [7,10,13,38,60,61], cities [8,62], countries [6,23,34,63] and whole continents [64]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background The threat of emergence of a human-to-human transmissible strain of highly pathogenic influenza A(H5N1) is very real, and is reinforced by recent results showing that genetically modified A(H5N1) may be readily transmitted between ferrets. Public health authorities are hesitant in introducing social distancing interventions due to societal disruption and productivity losses. This study estimates the effectiveness and total cost (from a societal perspective, with a lifespan time horizon) of a comprehensive range of social distancing and antiviral drug strategies, under a range of pandemic severity categories. Methods An economic analysis was conducted using a simulation model of a community of ~30,000 in Australia. Data from the 2009 pandemic was used to derive relationships between the Case Fatality Rate (CFR) and hospitalization rates for each of five pandemic severity categories, with CFR ranging from 0.1% to 2.5%. Results For a pandemic with basic reproduction number R0 = 1.8, adopting no interventions resulted in total costs ranging from $441 per person for a pandemic at category 1 (CFR 0.1%) to $8,550 per person at category 5 (CFR 2.5%). For severe pandemics of category 3 (CFR 0.75%) and greater, a strategy combining antiviral treatment and prophylaxis, extended school closure and community contact reduction resulted in the lowest total cost of any strategy, costing $1,584 per person at category 5. This strategy was highly effective, reducing the attack rate to 5%. With low severity pandemics costs are dominated by productivity losses due to illness and social distancing interventions, whereas higher severity pandemic costs are dominated by healthcare costs and costs arising from productivity losses due to death. Conclusions For pandemics in high severity categories the strategies with the lowest total cost to society involve rigorous, sustained social distancing, which are considered unacceptable for low severity pandemics due to societal disruption and cost.
    BMC Public Health 03/2013; 13(1):211. DOI:10.1186/1471-2458-13-211 · 2.26 Impact Factor
Show more