Assessing the Dynamics and Control of Droplet- and Aerosol-Transmitted Influenza Using an Indoor Positioning System

There is increasing evidence that aerosol transmission is a major contributor to the spread of influenza. Despite this, virtually all studies assessing the dynamics and control of influenza assume that it is transmitted solely through direct contact and large droplets, requiring close physical proximity. Here, we use wireless sensors to measure simultaneously both the location and close proximity contacts in the population of a US high school. This dataset, highly resolved in space and time, allows us to model both droplet and aerosol transmission either in isolation or in combination. In particular, it allows us to computationally quantify the potential effectiveness of overlooked mitigation strategies such as improved ventilation that are available in the case of aerosol transmission. Our model suggests that recommendation-abiding ventilation could be as effective in mitigating outbreaks as vaccinating approximately half of the population. In simulations using empirical transmission levels observed in households, we find that bringing ventilation to recommended levels had the same mitigating effect as a vaccination coverage of 50% to 60%. Ventilation is an easy-to-implement strategy that has the potential to support vaccination efforts for effective control of influenza spread

Optimizing targeted vaccination across cyber-physical networks: an empirically based mathematical simulation study

Targeted vaccination, whether to minimize the forward transmission of infectious diseases or their clinical impact, is one of the ‘holy grails’ of modern infectious disease outbreak response, yet it is difficult to achieve in practice due to the challenge of identifying optimal targets in real time. If interruption of disease transmission is the goal, targeting requires knowledge of underlying person-to-person contact networks. Digital communication networks may reflect not only virtual but also physical interactions that could result in disease transmission, but the precise overlap between these cyber and physical networks has never been empirically explored in real-life settings. Here, we study the digital communication activity of more than 500 individuals along with their person-to-person contacts at a 5-min temporal resolution. We then simulate different disease transmission scenarios on the person-to-person physical contact network to determine whether cyber communication networks can be harnessed to advance the goal of targeted vaccination for a disease spreading on the network of physical proximity. We show that individuals selected on the basis of their closeness centrality within cyber networks (what we call ‘cyber-directed vaccination’) can enhance vaccination campaigns against diseases with short-range (but not full-range) modes of transmission

Influence of Contact Definitions in Assessment of the Relative Importance of Social Settings in Disease Transmission Risk

BACKGROUND: Realistic models of disease transmission incorporating complex population heterogeneities require input from quantitative population mixing studies. We use contact diaries to assess the relative importance of social settings in respiratory pathogen spread using three measures of person contact hours (PCH) as proxies for transmission risk with an aim to inform bipartite network models of respiratory pathogen transmission. METHODS AND FINDINGS: Our survey examines the contact behaviour for a convenience sample of 65 adults, with each encounter classified as occurring in a work, retail, home, social, travel or "other" setting. The diary design allows for extraction of PCH-interaction (cumulative time in face-face conversational or touch interaction with contacts)--analogous to the contact measure used in several existing surveys--as well as PCH-setting (product of time spent in setting and number of people present) and PCH-reach (product of time spent in setting and number of people in close proximity). Heterogeneities in day-dependent distribution of risk across settings are analysed using partitioning and cluster analyses and compared between days and contact measures. Although home is typically the highest-risk setting when PCH measures isolate two-way interactions, its relative importance compared to social and work settings may reduce when adopting a more inclusive contact measure that considers the number and duration of potential exposure events. CONCLUSIONS: Heterogeneities in location-dependent contact behaviour as measured by contact diary studies depend on the adopted contact definition. We find that contact measures isolating face-face conversational or touch interactions suggest that contact in the home dominates, whereas more inclusive contact measures indicate that home and work settings may be of higher importance. In the absence of definitive knowledge of the contact required to facilitate transmission of various respiratory pathogens, it is important for surveys to consider alternative contact measures

The Role of the industrial hygienist in a pandemic. 2nd edition

Provides resources, information, and tools to advise and assist general workers, health care workers, and management to protect workers in the case of a pandemic.Published September 1, 2021. Edits on pages 9, 34, and 36 made on December 1, 2021. Refer to Errata page for original text.This document is sponsored and maintained by the American Industrial Hygiene Association\u2019s (AIHA\u2019s) Biosafety and Environmental Microbiology Committee Project Team. This collaborative effort included members of the Biosafety and Environmental Microbiology Committee, Indoor Environmental Quality Committee, Healthcare Working Group, the Emergency Preparedness & Response Committee, and the Chair of the American Conference of Governmental Industrial Hygienists (ACGIH) Pandemic Response Task Force. The Centers for Disease Control and Prevention provided grant support for this work through the National Office of the American Industrial Hygiene Association, Fairfax, VA, Grant # CDC-RFA-CK20-2003. AIHA committee members and other volunteers received no compensation for the writing or editing of this document.This educational initiative was funded by a cooperative agreement with the Centers for Disease Control and Prevention (Grant # 1 NU50CK000583-01-00) to the American Industrial Hygiene Association (AIHA). The Centers for Disease Control and Prevention is an agency within the Department of Health and Human Services (HHS). The contents of this resource center do not necessarily represent the policies or views of CDC or HHS and should not be considered an endorsement by the Federal Government.STOCK NUMBER: SEPG21-711Role-of-the-Industrial-Hygienist-in-a-Pandemic-2nd-edition.pdf2021Grant # CDC-RFA-CK20-2003Centers for Disease Control and Prevention Grant # 1 NU50CK000583-01-00)978-1-950286-01-01081

Report on Scientific advice to TfL on bus driver assault screen modifications due to the Covid-19 pandemic

In April 2020 Transport for London (TfL) commissioned the UCL Department of Civil, Environmental and Geomatic Engineering (CEGE) to explore measures to mitigate the occupational risk posed to London bus drivers from the COVID-19 pandemic, following the tragic deaths of a number of drivers among bus operators within London. A separate study undertaken by UCL’s Institute of Health Equality has examined more comprehensively a number of other risk factors affecting bus drivers, including beyond their occupational risk. Phase one of that study was published on the 27th July 2020 and has determined that “there is evidence that among bus drivers those aged 65 and over, those from BAME backgrounds and those with pre-existing hypertension are at a higher risk of COVID-19 mortality and this should be taken into accounts in efforts by TfL and bus companies to reduce risks”. TfL asked UCL CEGE to explore the nature of this occupational risk in relation to the interaction between passengers and the bus driver, and the effects arising as a result of the design of the bus itself, in particular the assault screen. The assault screen is a pre-existing transparent polycarbonate fixture designed to resist physical attacks, such as stabbings, while allowing the driver to have both a clear view through the screen, access the electronic ticket machine and provide receipts when required, and the ability to be able to hear and speak to passengers as the need arises. It was not originally designed to keep the driver completely isolated from the passengers. A set of detailed models was created of the front part of a typical London bus, including both front and central doors, the driver’s cabin and a detailed dynamic model of the bus driver, and then detailed CFD simulations were carried out. These calculated the motion of aerosols emanating from a passenger who is coughing and breathing in a number of positions relative to the driver’s cabin under a variety of design and operational scenarios in order to identify appropriate interventions. A typical screen and bus design were chosen for the simulations, that addressed all the relevant design issues - gaps, door and window operations - as a representative case for all buses. The original (pre-COVID) designs of polycarbonate dividers or screens were only marginally protective against aerosols and were not sufficient on their own to protect against airborne transmission of SARS-CoV-2. A set of recommendations has been made with the aim of reducing this risk to London drivers in particular as much as is practically possible, further to interventions already initiated by TfL. Buses in large cities are a unique indoor environment that is confined and often crowded at rush hour or in tourist season and, if poorly ventilated there is potential for airborne transmission of infectious diseases which may pose a risk to drivers due to their prolonged exposure times. Further work is required to determine if there may be a risk to passengers too, if they are on board for long journeys. Regardless of any mechanical or physical interventions to reduce risk, it is recommended that in the medium-term, targets for Indoor Air Quality (IAQ) standards on public transport are developed and adopted. This, due to the high number of daily passengers, some of whom have long journey durations (>1hr if commuting from zones 4 and beyond) and the prevalence of infectious diseases such as influenza and the common cold in the population every winter season, which carry large economic costs and also cost lives. The emergence of highly infectious and more dangerous diseases in the UK and around the world in the past two decades, such as SARS-CoV-2, SARS, H1N1 (swine flu) or MERS, all indicate that it is very timely to invest efforts towards maintaining healthy and safe indoor air on public transport

Gastrointestinal parasite infections in Chacma baboons (Papio ursinus) of the Cape Peninsula, South Africa : the influence of individual, group and anthropogenic factors

Includes abstract.Includes bibliographical references (p. 146-168).This study investigates whether anthropogenic changes in the Cape Peninsula, South Africa, have affected gastrointestinal parasite infections in a free-living population of chacma baboons (Papio ursinus). Data on parasite diversity and prevalence were obtained from 616 faecal samples collected from over 350 individuals in eight troops (six from the Cape Peninsula, one from Pringle Bay, and one from Wildcliff Nature Reserve) between July 2006 and August 2007

Synthesising and Assessing the Public Health Risks of SARS-CoV-2 in Animals

Background: SARS-CoV-2 is zoonotic in origin and has retained the capacity to infect animals. If susceptible animal species can readily transmit the virus to other animals or humans, this could extend the pandemic. To assess animal host susceptibility and the potential outcomes of animal-human interactions, I had the following objectives: 1) identify which animal species are susceptible to SARS-CoV-2, 2) determine the risks of SARS-CoV-2 exposure to humans from infected wildlife in North America; and 3) describe how the risks of SARS-CoV-2 in wildlife could be effectively communicated. Methods: For objective 1), a scoping review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews, which identified animal families considered highly susceptible to SARS-CoV-2. For objective 2, a rapid qualitative risk assessment using the World Organization for Animal Health framework was applied to assess risks of human exposure to SARS-CoV-2 from selected taxonomic families of wildlife in North America. For objective 3, positive and negative instances of risk communication were identified from personal experiences, and suggestions for communicating risks were provided. Results: The scoping review identified 97 source manuscripts investigating 649 animal species from eight different classes. Four different methods were used to evaluate susceptibility: in silico, in vitro, in vivo, and epidemiological analyses. From the identified sources, animal species varied in their evaluated susceptibilities. The risk assessment identified four families that pose a risk to humans: cervids, cricetid rodents, felids, and mustelids. While the likelihood of a human becoming exposed to a wild animal currently shedding SARS-CoV-2 was minimal, the consequences of such an event could be severe. Risk communication can be improved by understanding the characteristics of the target audience and the context in which they will perceive the information. Conclusions: This thesis identified animal families that posed higher risk to humans, and critically evaluated different methods of determining animal susceptibility, emphasizing the importance of epidemiological and in vivo studies. Finally, this thesis emphasized the need for careful and effective communication to lessen confusion and misinformation surrounding SARS-CoV-2, remaining uncertainties, and the need for additional research regarding SARS-CoV-2 in animals

Early detection and control of potential pandemics.

Over the centuries, human beings have been inflicted with a variety of contagious diseases, resulting in tens of millions of respiratory illnesses and deaths worldwide. Early detection of disease spread facilitates timely responses that can greatly reduce its impact on a population. Therefore, this early information is a major public health objective and is crucial for policy makers and public health officials responsible for protecting the public from the spread of contagious diseases. Current indicators of the spread of contagious outbreaks lag behind its actual spread, leaving no time for a planned response. The studies of Christakis et al. in 2010 have shown that social networks can provide more timely information for prediction. However, the reported social network methods used to monitor disease spread do not consider contact patterns of individuals over space and time, such as during their movement from place to place. In this dissertation we propose a more effective way to chart the spread of contagious outbreaks, in a spatio-temporal sense, using “contact networks”. This enables more effective control of the spread of contagious outbreaks in their early stages so as to “nip a potential pandemic in the bud.” In order to enhance the prediction model developed we introduce factors to consider the intensity of exposure to the disease, and the susceptibility of the individual. This would involve the consideration of both space and time factors, since diseases caused by either viruses or bacteria involve some type of contact, either direct (e.g. shaking hands) or through the atmosphere (e.g. coughing or sneezing) between the susceptible and infected individuals. In this dissertation, we apply data mining methodologies and predictive modeling technologies, such as logistic regression, decision trees and neural networks to estimate the infection risk based on an individual’s demographic information and health status. The information used in the models can be obtained from a wide variety of data sources, including historical medical records from hospitals and clinics. Early information on the presence of a potential disease outbreak can be obtained from sensors , such as, First Watch and EARS (Early Aberration Response Systems) and central individuals in “contact” networks