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Browsing by Author "Lipsitch, Marc"

Now showing 1 - 4 of 4
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    Enhancing disease surveillance with novel data streams: challenges and opportunities
    Althouse, Benjamin M.; Scarpino, Samuel V.; Meyers, Lauren Ancel; Ayers, John W.; Bargsten, Marisa; Baumbach, Joan; Brownstein, John S.; Castro, Lauren; Clapham, Hannah; Cummings, Derek A. T.; Del Valle, Sara; Eubank, Stephen; Fairchild, Geoffrey; Finelli, Lyn; Generous, Nicholas; George, Dylan; Harper, David R.; Hebert-Dufresne, Laurent; Johansson, Michael A.; Konty, Kevin; Lipsitch, Marc; Millinovich, Gabriel; Miller, Joseph D.; Nsoesie, Elaine O.; Olson, Donald R.; Paul, Michael; Priedhorsky, Reid; Read, Jonathan M.; Rodriguez-Barraquer, Isabel; Smith, Derek J.; Stefansen, Christian; Swerdlow, David L.; Thompson, Deborah; Vespignani, Alessandro; Wesolowski, Amy; Polgreen, Philip M. (Springer, 2015)
    Novel data streams (NDS), such as web search data or social media updates, hold promise for enhancing the capabilities of public health surveillance. In this paper, we outline a conceptual framework for integrating NDS into current public health surveillance. Our approach focuses on two key questions: What are the opportunities for using NDS and what are the minimal tests of validity and utility that must be applied when using NDS? Identifying these opportunities will necessitate the involvement of public health authorities and an appreciation of the diversity of objectives and scales across agencies at different levels (local, state, national, international). We present the case that clearly articulating surveillance objectives and systematically evaluating NDS and comparing the performance of NDS to existing surveillance data and alternative NDS data is critical and has not sufficiently been addressed in many applications of NDS currently in the literature.
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    Limited available evidence supports theoretical predictions of reduced vaccine efficacy at higher exposure dose
    Langwig, Kate E.; Gomes, M. Gabriela M.; Clark, Mercedes D.; Kwitny, Molly; Yamada, Steffany A.; Wargo, Andrew R.; Lipsitch, Marc (Nature, 2019)
    Understanding the causes of vaccine failure is important for predicting disease dynamics in vaccinated populations and planning disease interventions. Pathogen exposure dose and heterogeneity in host susceptibility have both been implicated as important factors that may reduce overall vaccine efficacy and cause vaccine failure. Here, we explore the effect of pathogen dose and heterogeneity in host susceptibility in reducing efficacy of vaccines. Using simulation-based methods, we find that increases in pathogen exposure dose decrease vaccine efficacy, but this effect is modified by heterogeneity in host susceptibility. In populations where the mode of vaccine action is highly polarized, vaccine efficacy decreases more slowly with exposure dose than in populations with less variable protection. We compared these theoretical results to empirical estimates from a systematic literature review of vaccines tested over multiple exposure doses. We found that few studies (nine of 5,389) tested vaccine protection against infection over multiple pathogen challenge doses, with seven studies demonstrating a decrease in vaccine efficacy with increasing exposure dose. Our research demonstrates that pathogen dose has potential to be an important determinant of vaccine failure, although the limited empirical data highlight a need for additional studies to test theoretical predictions on the plausibility of reduced host susceptibility and high pathogen dose as mechanisms responsible for reduced vaccine efficacy in high transmission settings.
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    Quantifying Interhospital Patient Sharing as a Mechanism for Infectious Disease Spread
    Huang, Susan S.; Avery, Takuser R.; Song, Yeohan H.; Elkins, Kristen R.; Nguyen, Christopher C.; Nutter, Sandra K.; Nafday, Alaka. A.; Condon, Curtis J.; Chang, Michael T.; Chrest, David; Boos, John; Bobashev, Georgiy; Wheaton, William; Frank, Steven A.; Platt, Richard; Lipsitch, Marc; Bush, Robin M.; Eubank, Stephen; Burke, Donald S.; Lee, Bruce Y. (University of Chicago Press, 2010-11)
    BACKGROUND. Assessments of infectious disease spread in hospitals seldom account for interfacility patient sharing. This is particularly important for pathogens with prolonged incubation periods or carrier states. METHODS. We quantified patient sharing among all 32 hospitals in Orange County (OC), California, using hospital discharge data. Same-day transfers between hospitals were considered "direct" transfers, and events in which patients were shared between hospitals after an intervening stay at home or elsewhere were considered "indirect" patient-sharing events. We assessed the frequency of readmissions to another OC hospital within various time points from discharge and examined interhospital sharing of patients with Clostridium difficile infection. RESULTS. In 2005, OC hospitals had 319,918 admissions. Twenty-nine percent of patients were admitted at least twice, with a median interval between discharge and readmission of 53 days. Of the patients with 2 or more admissions, 75% were admitted to more than 1 hospital. Ninety-four percent of interhospital patient sharing occurred indirectly. When we used 10 shared patients as a measure of potential interhospital exposure, 6 (19%) of 32 hospitals "exposed" more than 50% of all OC hospitals within 6 months, and 17 (53%) exposed more than 50% within 12 months. Hospitals shared 1 or more patient with a median of 28 other hospitals. When we evaluated patients with C. difficile infection, 25% were readmitted within 12 weeks; 41% were readmitted to different hospitals, and less than 30% of these readmissions were direct transfers. CONCLUSIONS. In a large metropolitan county, interhospital patient sharing was a potential avenue for transmission of infectious agents. Indirect sharing with an intervening stay at home or elsewhere composed the bulk of potential exposures and occurred unbeknownst to hospitals.
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    Vaccine Effects on Heterogeneity in Susceptibility and Implications for Population Health Management
    Langwig, Kate E.; Jones, Darbi R.; Rutan, Barbara J.; Viss, Jessie R.; Wargo, Andrew R.; Egan, Nicholas A.; Sá-Guimarães, Pedro; Kim, Min Sun; Kurath, Gael; Gomes, M. Gabriela M.; Lipsitch, Marc (American Society for Microbiology, 2017-11-21)
    Heterogeneity in host susceptibility is a key determinant of infectious disease dynamics but is rarely accounted for in assessment of disease control measures. Understanding how susceptibility is distributed in populations, and how control measures change this distribution, is integral to predicting the course of epidemics with and without interventions. Using multiple experimental and modeling approaches, we show that rainbow trout have relatively homogeneous susceptibility to infection with infectious hematopoietic necrosis virus and that vaccination increases heterogeneity in susceptibility in a nearly all-or-nothing fashion. In a simple transmission model with an R0 of 2, the highly heterogeneous vaccine protection would cause a 35 percentage-point reduction in outbreak size over an intervention inducing homogenous protection at the same mean level. More broadly, these findings provide validation of methodology that can help to reduce biases in predictions of vaccine impact in natural settings and provide insight into how vaccination shapes population susceptibility.