Effectiveness of antiviral prophylaxis coupled with contact tracing in reducing the transmission of the influenza A (H1N1-2009): a systematic review

Abstract

BackgroundDuring the very early stage of the 2009 pandemic, mass chemoprophylaxis was implemented as part of containment measure. The purposes of the present study were to systematically review the retrospective studies that investigated the effectiveness of antiviral prophylaxis during the 2009 pandemic, and to explicitly estimate the effectiveness by employing a mathematical model.MethodsA systematic review identified 17 articles that clearly defined the cases and identified exposed individuals based on contact tracing. Analysing a specific school-driven outbreak, we estimated the effectiveness of antiviral prophylaxis using a renewal equation model. Other parameters, including the reproduction number and the effectiveness of antiviral treatment and school closure, were jointly estimated.ResultsBased on the systematic review, median secondary infection risks (SIRs) among exposed individuals with and without prophylaxis were estimated at 2.1% (quartile: 0, 12.2) and 16.6% (quartile: 8.4, 32.4), respectively. A very high heterogeneity in the SIR was identified with an estimated I2 statistic at 71.8%. From the outbreak data in Madagascar, the effectiveness of mass chemoprophylaxis in reducing secondary transmissions was estimated to range from 92.8% to 95.4% according to different model assumptions and likelihood functions, not varying substantially as compared to other parameters.ConclusionsOnly based on the meta-analysis of retrospective studies with different study designs and exposure settings, it was not feasible to estimate the effectiveness of antiviral prophylaxis in reducing transmission. However, modelling analysis of a single outbreak successfully yielded an estimate of the effectiveness that appeared to be robust to model assumptions. Future studies should fill the data gap that has existed in observational studies and allow mathematical models to be used for the analysis of meta-data.

Crossing the scale from within-host infection dynamics to between-host transmission fitness: a discussion of current assumptions and knowledge

“…While the clinical benefits of NAI in reducing the severity of complications in infected patients remain debated [1][2][3][4], NAI are known to shorten the symptomatic period and reduce virus load [5]. This, in turn, can potentially lead to reduced transmission of those treated with NAI, and therefore, make NAI a potentially important tool in outbreak mitigation or the curtailment of localized transmission [6][7][8][9][10]. However, even though we appreciate the need for quantifying the epidemiological impacts of NAI, obtaining suitable population-level information to do so remains difficult [11][12][13][14][15].…”

Assessing the State of Knowledge Regarding the Effectiveness of Interventions to Contain Pandemic Influenza Transmission: A Systematic Review and Narrative Synthesis

“…Eight [26–33] review the effectiveness of pandemic influenza vaccine in preventing influenza and influenza-like illness (ILI); three [34–36] examine the impact of antivirals; two [32, 37] review the effectiveness of seasonal influenza vaccines in preventing pandemic influenza infection; two evaluate the impact of personal protective measures (hand-washing, mask use) [38, 39]; one [40] analyzes the impact of school closure; and another [41] reviews the efficacy of traditional Chinese medicine (TCM). One review [42] evaluates the economic viability of a wide range of pharmaceutical and non-pharmaceutical measures, concluding that social distancing, antiviral prophylaxis, school closure, and vaccination are likely to be cost-effective in all settings, while quarantine is never cost-effective.…”

“…Three systematic reviews evaluated studies on the role of antiviral prophylaxis and treatment in reducing pandemic influenza infection [34–36]. Fielding et al .…”

“…Mizumoto et al . [36] reported that secondary infection rates generally decreased in situations where mass oseltamivir prophylaxis had been employed, with a median secondary infection risk of 2.1% (relative to 16.6% among those not receiving prophylaxis). In both cases differences in study design, exposure, and treatment strategies precluded pooled estimates of effectiveness.…”

Modeling the obesity epidemic: social contagion and its implications for control

“…The intervention of social contact is intended to prevent person-to-person transmission by suppressing obesity contagion. The practical feasibility of such an intervention is subject to discussion, but in the present study the intervention is theoretically considered as resembling contact tracing of directly transmitted infectious diseases [17,18]. Preventing weight gain among never-obese individuals is to control the diet and enhance physical activities, including the specification of nutrients and restriction of calorie intake [19].…”