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Demers J, Fagan WF, Potluri S, Calabrese JM. The relationship between controllability, optimal testing resource allocation, and incubation-latent period mismatch as revealed by COVID-19. Infect Dis Model 2023; 8:514-538. [PMID: 37250860 PMCID: PMC10186984 DOI: 10.1016/j.idm.2023.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 04/21/2023] [Accepted: 04/25/2023] [Indexed: 05/31/2023] Open
Abstract
The severe shortfall in testing supplies during the initial COVID-19 outbreak and ensuing struggle to manage the pandemic have affirmed the critical importance of optimal supply-constrained resource allocation strategies for controlling novel disease epidemics. To address the challenge of constrained resource optimization for managing diseases with complications like pre- and asymptomatic transmission, we develop an integro partial differential equation compartmental disease model which incorporates realistic latent, incubation, and infectious period distributions along with limited testing supplies for identifying and quarantining infected individuals. Our model overcomes the limitations of typical ordinary differential equation compartmental models by decoupling symptom status from model compartments to allow a more realistic representation of symptom onset and presymptomatic transmission. To analyze the influence of these realistic features on disease controllability, we find optimal strategies for reducing total infection sizes that allocate limited testing resources between 'clinical' testing, which targets symptomatic individuals, and 'non-clinical' testing, which targets non-symptomatic individuals. We apply our model not only to the original, delta, and omicron COVID-19 variants, but also to generically parameterized disease systems with varying mismatches between latent and incubation period distributions, which permit varying degrees of presymptomatic transmission or symptom onset before infectiousness. We find that factors that decrease controllability generally call for reduced levels of non-clinical testing in optimal strategies, while the relationship between incubation-latent mismatch, controllability, and optimal strategies is complicated. In particular, though greater degrees of presymptomatic transmission reduce disease controllability, they may increase or decrease the role of non-clinical testing in optimal strategies depending on other disease factors like transmissibility and latent period length. Importantly, our model allows a spectrum of diseases to be compared within a consistent framework such that lessons learned from COVID-19 can be transferred to resource constrained scenarios in future emerging epidemics and analyzed for optimality.
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Affiliation(s)
- Jeffery Demers
- Center for Advanced Systems Understanding (CASUS), Helmholtz-Zentrum Dresden-Rosendorf (HZDR), Görlitz, Germany
- Dept. of Biology, University of Maryland, College Park, MD, USA
| | - William F Fagan
- Dept. of Biology, University of Maryland, College Park, MD, USA
| | - Sriya Potluri
- Dept. of Biology, University of Maryland, College Park, MD, USA
| | - Justin M Calabrese
- Center for Advanced Systems Understanding (CASUS), Helmholtz-Zentrum Dresden-Rosendorf (HZDR), Görlitz, Germany
- Dept. of Biology, University of Maryland, College Park, MD, USA
- Dept. of Ecological Modelling, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
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2
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Lovell-Read FA, Funk S, Obolski U, Donnelly CA, Thompson RN. Interventions targeting non-symptomatic cases can be important to prevent local outbreaks: SARS-CoV-2 as a case study. J R Soc Interface 2021; 18:20201014. [PMID: 34006127 PMCID: PMC8131940 DOI: 10.1098/rsif.2020.1014] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 04/22/2021] [Indexed: 12/22/2022] Open
Abstract
During infectious disease epidemics, an important question is whether cases travelling to new locations will trigger local outbreaks. The risk of this occurring depends on the transmissibility of the pathogen, the susceptibility of the host population and, crucially, the effectiveness of surveillance in detecting cases and preventing onward spread. For many pathogens, transmission from pre-symptomatic and/or asymptomatic (together referred to as non-symptomatic) infectious hosts can occur, making effective surveillance challenging. Here, by using SARS-CoV-2 as a case study, we show how the risk of local outbreaks can be assessed when non-symptomatic transmission can occur. We construct a branching process model that includes non-symptomatic transmission and explore the effects of interventions targeting non-symptomatic or symptomatic hosts when surveillance resources are limited. We consider whether the greatest reductions in local outbreak risks are achieved by increasing surveillance and control targeting non-symptomatic or symptomatic cases, or a combination of both. We find that seeking to increase surveillance of symptomatic hosts alone is typically not the optimal strategy for reducing outbreak risks. Adopting a strategy that combines an enhancement of surveillance of symptomatic cases with efforts to find and isolate non-symptomatic infected hosts leads to the largest reduction in the probability that imported cases will initiate a local outbreak.
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Affiliation(s)
| | - Sebastian Funk
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Uri Obolski
- Porter School of the Environment and Earth Sciences, Tel Aviv University, Tel Aviv, Israel
- School of Public Health, Tel Aviv University, Tel Aviv, Israel
| | - Christl A. Donnelly
- Department of Statistics, University of Oxford, Oxford, UK
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Robin N. Thompson
- Mathematical Institute, University of Oxford, Oxford, UK
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene and Tropical Medicine, London, UK
- Mathematics Institute, University of Warwick, Coventry, UK
- The Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, University of Warwick, Coventry, UK
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3
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da Costa VG, Saivish MV, Santos DER, de Lima Silva RF, Moreli ML. Comparative epidemiology between the 2009 H1N1 influenza and COVID-19 pandemics. J Infect Public Health 2020; 13:1797-1804. [PMID: 33121906 PMCID: PMC7553061 DOI: 10.1016/j.jiph.2020.09.023] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 09/20/2020] [Accepted: 09/25/2020] [Indexed: 12/28/2022] Open
Abstract
In a short time, humanity has experienced two pandemics: the influenza A virus pandemic (pH1N1) in 2009 and the coronavirus disease 2019 (COVID-19) pandemic in 2020. Therefore, it is likely that the general population will erroneously seek to compare the two pandemics and adopt similar attitudes in facing them. However, the two pandemics have their intrinsic characteristics that distinguish them considerably; for example, the virulence of the infectious agents and the availability of treatment and vaccine. Consequently, given this knowledge gap between the pH1N1 and COVID-19 pandemics, we conducted this review to clarify and summarize, above all, the epidemiological historical aspects of these two viruses of great importance to global public health.
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Affiliation(s)
- Vivaldo Gomes da Costa
- Department of Cellular Biology, University of Brasília, Brasília, DF, Brazil; Special Academic Unit of Health Sciences, Federal University of Jataí, Jataí, GO, Brazil.
| | | | | | | | - Marcos Lázaro Moreli
- Special Academic Unit of Health Sciences, Federal University of Jataí, Jataí, GO, Brazil
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4
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Auvinen R, Nohynek H, Syrjänen R, Ollgren J, Kerttula T, Mäntylä J, Ikonen N, Loginov R, Haveri A, Kurkela S, Skogberg K. Comparison of the clinical characteristics and outcomes of hospitalized adult COVID-19 and influenza patients - a prospective observational study. Infect Dis (Lond) 2020; 53:111-121. [PMID: 33170050 DOI: 10.1080/23744235.2020.1840623] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND We compared the clinical characteristics, findings, and outcomes of hospitalized patients with coronavirus disease 2019 (COVID-19) or influenza to detect relevant differences. METHODS From December 2019 to April 2020, we recruited all eligible hospitalized adults with respiratory infection to a prospective observational study at a tertiary care hospital in Finland. Influenza and SARS-CoV-2 infections were confirmed by RT-PCR. Follow-up lasted for 3 months from admission. RESULTS We included 61 patients, of whom 28 were COVID-19 and 33 influenza patients with median ages of 53 and 56 years. Majority of both COVID-19 and influenza patients were men (61% vs. 67%) and had at least one comorbidity (68% vs. 85%). Pulmonary diseases and current smoking were less common among COVID-19 than influenza patients (5 [18%] vs. 15 [45%], p=.03 and 1 [4%] vs. 10 [30%], p=.008). In chest X-ray at admission, ground-glass opacities (GGOs) and consolidations were more frequent among COVID-19 than influenza patients (19 [68%] and 7 [21%], p<.001). Severe disease and intensive care unit (ICU) admission occurred more often among COVID-19 than influenza patients (26 [93%] vs. 19 [58%], p=.003 and 8 [29%] vs. 2 [6%], p=.034). COVID-19 patients were hospitalized longer than influenza patients (six days [IQR 4-21] vs. 3 [2-4], p<.001). CONCLUSIONS Bilateral GGOs and consolidations in chest X-ray may help to differentiate COVID-19 from influenza. Hospitalized COVID-19 patients had more severe disease, required longer hospitalization and were admitted to ICU more often than influenza patients, which has important implications for public health policies.
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Affiliation(s)
- Raija Auvinen
- Internal Medicine and Rehabilitation, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.,Department of Health Security, Infectious Disease Control and Vaccinations Unit, Finnish Institute for Health and Welfare, Helsinki, Finland
| | - Hanna Nohynek
- Department of Health Security, Infectious Disease Control and Vaccinations Unit, Finnish Institute for Health and Welfare, Helsinki, Finland
| | - Ritva Syrjänen
- Department of Public Health Solutions, Public Health Projection and Evaluation Unit, Finnish Institute for Health and Welfare, Helsinki, Finland
| | - Jukka Ollgren
- Department of Health Security, Infectious Disease Control and Vaccinations Unit, Finnish Institute for Health and Welfare, Helsinki, Finland
| | - Tuija Kerttula
- HUS Medical Imaging Center, Radiology, Helsinki University Hospital and University of Helsinki, Helsinki, Finland
| | - Jarkko Mäntylä
- Heart and Lung Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Niina Ikonen
- Department of Health Security, Expert Microbiology Unit, Finnish Institute for Health and Welfare, Helsinki, Finland
| | - Raisa Loginov
- HUS Diagnostic Center, HUSLAB, Clinical Microbiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Anu Haveri
- Department of Health Security, Expert Microbiology Unit, Finnish Institute for Health and Welfare, Helsinki, Finland
| | - Satu Kurkela
- HUS Diagnostic Center, HUSLAB, Clinical Microbiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Kirsi Skogberg
- Inflammation Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
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Shimizu K, Negita M. Lessons Learned from Japan's Response to the First Wave of COVID-19: A Content Analysis. Healthcare (Basel) 2020; 8:E426. [PMID: 33114264 PMCID: PMC7711542 DOI: 10.3390/healthcare8040426] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 10/21/2020] [Accepted: 10/21/2020] [Indexed: 12/22/2022] Open
Abstract
While the epidemiological impact of the coronavirus disease 2019 (COVID-19) pandemic has been relatively moderate in East-Asian countries, the pandemic has significantly impacted on citizens' lives and livelihoods, and Japan is no exception. In the early phase of the COVID-19 pandemic, Japan managed unprecedented quarantines and realized the difficulty of controlling COVID-19, finally recording a relatively high number of deaths per million in the Western Pacific region. However, scant research has highlighted the distinctive features of Japan's reaction and the challenges encountered. To clarify these points and examine Japan's first response to COVID-19, we performed a content analysis. Minutes of expert meetings were analyzed from multiple viewpoints, including epidemiology, health systems, border control, and health communication. The obscure evolution of the testing strategy, the usefulness of retrospective contact tracing, the rapid scientific risk assessment, a sluggish expansion of health system capacity and response in border control, and misunderstanding between risk communication and crisis communication are made evident by our analysis. Examining previous responses and gathering lessons learned in each country will improve global responses to COVID-19 and strengthen regional health security. Therefore, while investing in public health and ensuring transparency, Japan needs to clarify the previous decision-making process of each countermeasure towards COVID-19.
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Affiliation(s)
- Kazuki Shimizu
- Department of Health Policy, London School of Economics and Political Science, Cowdray House, Houghton Street, London WC2A 2AE, UK
- Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
- Graduate School of Medicine, Hokkaido University, Kita 15 Nishi 7, Kita-ku, Sapporo 060-8638, Japan
| | - Masashi Negita
- Department of Surgery, Komaki City Hospital, 1-20, Jobushi, Aichi, Komaki 485-8520, Japan;
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Kyriakopoulos AM, Papaefthymiou A, Georgilas N, Doulberis M, Kountouras J. The Potential Role of Super Spread Events in SARS-COV-2 Pandemic; a Narrative Review. ARCHIVES OF ACADEMIC EMERGENCY MEDICINE 2020; 8:e74. [PMID: 33134970 PMCID: PMC7587986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Coronaviruses, members of Coronaviridae family, cause extensive epidemics of vast diseases like severe acute respiratory syndrome (SARS) and Coronavirus Disease-19 (COVID-19) in animals and humans. Super spread events (SSEs) potentiate early outbreak of the disease and its constant spread in later stages. Viral recombination events within species and across hosts lead to natural selection based on advanced infectivity and resistance. In this review, the importance of containment of SSEs was investigated with emphasis on stopping COVID-19 spread and its socio-economic consequences. A comprehensive search was conducted among literature available in multiple electronic sources to find articles that addressed the "potential role of SSEs on severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) pandemic" and were published before 20th of August 2020. Overall, ninety-eight articles were found eligible and reviewed. Specific screening strategies within potential super spreading host groups can also help to efficiently manage severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) epidemics, in contrast to the partially effective general restriction measures. The effect of SSEs on previous SARS epidemics has been documented in detail. However, the respective potential impact of SSEs on SARS-COV-2 outbreak is composed and presented in the current review, thereby implying the warranted effort required for effective SSE preventive strategies, which may lead to overt global community health benefits. This is crucial for SARS-COV-2 pandemic containment as the vaccine(s) development process will take considerable time to safely establish its potential usefulness for future clinical usage.
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Affiliation(s)
- Anthony M. Kyriakopoulos
- Department of Research and Development, Nasco AD Biotechnology Laboratory, Piraeus 18536, Greece. ,Corresponding author: Anthony M. Kyriakopoulos; Department of Research and Development, Nasco AD Biotechnology Laboratory, 11 Sachtouri Str, Piraeus 18536, Greece. , Fax : 00309210818032
| | - Apostolis Papaefthymiou
- Department of Gastroenterology, University Hospital of Larisa, Larisa 41110, Greece.,Department of Internal Medicine, Second Medical Clinic, Ippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, 54642 Macedonia, Greece
| | - Nikolaos Georgilas
- Department of Nephrology, Agios Pavlos Hospital of Thessaloniki, Thessaloniki 55134, Macedonia, Greece
| | - Michael Doulberis
- Department of Internal Medicine, Second Medical Clinic, Ippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, 54642 Macedonia, Greece.,Division of Gastroenterology and Hepatology, University Medical Department Kantonsspital Aarau, Aarau 5001, Switzerland
| | - Jannis Kountouras
- Department of Internal Medicine, Second Medical Clinic, Ippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, 54642 Macedonia, Greece
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7
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Wu Z, Harrich D, Li Z, Hu D, Li D. The unique features of SARS-CoV-2 transmission: Comparison with SARS-CoV, MERS-CoV and 2009 H1N1 pandemic influenza virus. Rev Med Virol 2020; 31:e2171. [PMID: 33350025 PMCID: PMC7537046 DOI: 10.1002/rmv.2171] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 09/01/2020] [Accepted: 09/03/2020] [Indexed: 01/10/2023]
Abstract
From 2002 to 2019, three deadly human coronaviruses (hCoVs), severe acute respiratory syndrome coronavirus (SARS‐CoV), Middle Eastern respiratory syndrome coronavirus (MERS‐CoV) and severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) emerged to produce outbreaks of SARS, MERS and coronavirus disease 2019 (Covid‐19), respectively. All three hCoVs are members of the Betacoronavirus genus in the subfamily Orthocoronavirinae and share many similarities in virology and epidemiology. However, the pattern and scale of Covid‐19 global spread is similar to 2009 pandemic H1N1 influenza (H1N1pdm09), rather than SARS or MERS. Covid‐19 exhibits high viral shedding in the upper respiratory tract at an early stage of infection, and has a high proportion of transmission competent individuals that are pre‐symptomatic, asymptomatic and mildly symptomatic, characteristics seen in H1N1pdm09 but not in SARS or MERS. These two traits of Covid‐19 and H1N1pdm09 result in reduced efficiency in identification of transmission sources by symptomatic screening and play important roles in their ability to spread unchecked to cause pandemics. To overcome these attributes of Covid‐19 in community transmission, identifying the transmission source by testing for virus shedding and interrupting chains of transmission by social distancing and public masking are required.
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Affiliation(s)
- Zhonglan Wu
- Ningxia Center for Disease Control and Prevention, Yinchuan, Ningxia, China.,College of Public Health, Ningxia Medical University, Yinchuan, Ningxia, China
| | - David Harrich
- Department of Cell and Molecular Biology, QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Zhongyang Li
- Eastern Health Library Service Maroondah Hospital, Box Hill, Victoria, Australia
| | - Dongsheng Hu
- Department of Epidemiology and Health Statistics, College of Public Health, Zhengzhou University, Zhengzhou, Henan, China
| | - Dongsheng Li
- Department of Cell and Molecular Biology, QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
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8
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Lo C, Mertz D, Loeb M. Assessing the reporting quality of influenza outbreaks in the community. Influenza Other Respir Viruses 2017; 11:556-563. [PMID: 29054122 PMCID: PMC5705690 DOI: 10.1111/irv.12516] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2017] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND High-quality reporting of outbreak characteristics is fundamental to understand the behaviour of various strains of influenza virus and the impact of outbreak management strategies. However, few studies have systematically evaluated the quality of outbreak reporting. OBJECTIVES To conduct a systematic analysis and assessment for reporting quality of influenza outbreaks based on a modified version of the STROBE statement, and to examine characteristics associated with reporting quality. METHODS A literature search was conducted across 3 online databases (PubMed, Web of Science, MEDLINE) for reports of influenza outbreaks (pandemic H1N1, avian, seasonal). The quality of reports meeting our eligibility criteria was assessed using the Modified STROBE criteria and assigned a score of 30. Mean differences (MD) and 95% confidence intervals (CI) were reported for comparisons of study characteristics. RESULTS Sixty-four outbreak reports were available for analyses. The average Modified STROBE score was 20/30. Peer-reviewed articles were associated with a better quality of reporting (MD 2.79, 95% CI 0.79-4.78). Likewise, reports from authors affiliated with public health agencies were associated with better quality than those from academic institutions (MD 1.65, 95% CI-0.27-3.56). CONCLUSIONS The development of explicit reporting guidelines specifically geared towards reporting of outbreak investigations proved to be useful. Providing information on patient characteristics, investigation details in introduction and results, as well as addressing limitations that could have biased the findings, were frequently missing in the published reports.
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Affiliation(s)
- Calvin Lo
- Department of Pathology and Molecular MedicineMcMaster UniversityHamiltonONCanada
| | - Dominik Mertz
- Department of Pathology and Molecular MedicineMcMaster UniversityHamiltonONCanada
- Department of MedicineMcMaster UniversityHamiltonONCanada
- Department of Health Research Methods, Evidence and ImpactMcMaster UniversityHamiltonONCanada
- Michael G. DeGroote Institute for Infectious Diseases ResearchMcMaster UniversityHamiltonONCanada
| | - Mark Loeb
- Department of Pathology and Molecular MedicineMcMaster UniversityHamiltonONCanada
- Department of Health Research Methods, Evidence and ImpactMcMaster UniversityHamiltonONCanada
- Michael G. DeGroote Institute for Infectious Diseases ResearchMcMaster UniversityHamiltonONCanada
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Transmission of the First Influenza A(H1N1)pdm09 Pandemic Wave in Australia Was Driven by Undetected Infections: Pandemic Response Implications. PLoS One 2015; 10:e0144331. [PMID: 26692335 PMCID: PMC4687009 DOI: 10.1371/journal.pone.0144331] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 10/15/2015] [Indexed: 02/03/2023] Open
Abstract
Background During the first wave of influenza A(H1N1)pdm09 in Victoria, Australia the rapid increase in notified cases and the high proportion with relatively mild symptoms suggested that community transmission was established before cases were identified. This lead to the hypothesis that those with low-level infections were the main drivers of the pandemic. Methods A deterministic susceptible-infected-recovered model was constructed to describe the first pandemic wave in a population structured by disease severity levels of asymptomatic, low-level symptoms, moderate symptoms and severe symptoms requiring hospitalisation. The model incorporated mixing, infectivity and duration of infectiousness parameters to calculate subgroup-specific reproduction numbers for each severity level. Results With stratum-specific effective reproduction numbers of 1.82 and 1.32 respectively, those with low-level symptoms, and those with asymptomatic infections were responsible for most of the transmission. The effective reproduction numbers for infections resulting in moderate symptoms and hospitalisation were less than one. Sensitivity analyses confirmed the importance of parameters relating to asymptomatic individuals and those with low-level symptoms. Conclusions Transmission of influenza A(H1N1)pdm09 was largely driven by those invisible to the health system. This has implications for control measures–such as distribution of antivirals to cases and contacts and quarantine/isolation–that rely on detection of infected cases. Pandemic plans need to incorporate milder scenarios, with a graded approach to implementation of control measures.
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10
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Protecting the frontline: designing an infection prevention platform for preventing emerging respiratory viral illnesses in healthcare personnel. Infect Control Hosp Epidemiol 2015; 36:336-45. [PMID: 25695176 DOI: 10.1017/ice.2014.52] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Healthcare personnel often find themselves on the frontlines of any epidemic, and may be at particularly high risk of acquiring respiratory viral illnesses when compared to the general population. Many aspects dictate how respiratory viruses spread both inside the hospital and out: Elements to consider include the specific type of virus being targeted for prevention, as well as environmental conditions and host factors, such as age and immune status. Due to the diverse nature of these agents, multiple modes of transmission, including contact, droplet, aerosol, and transocular, must be considered when designing an effective infection prevention program. In this review, we examine the data behind current theories of respiratory virus transmission and key elements of any respiratory illness prevention program. We also highlight other influences that may come into play, such as the cost-effectiveness of choosing one respiratory protection strategy over another.
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11
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Le MQ, Horby P, Fox A, Nguyen HT, Le Nguyen HK, Hoang PMV, Nguyen KC, de Jong MD, Jeeninga RE, Rogier van Doorn H, Farrar J, Wertheim HFL. Subclinical avian influenza A(H5N1) virus infection in human, Vietnam. Emerg Infect Dis 2014; 19:1674-7. [PMID: 24047510 PMCID: PMC3810763 DOI: 10.3201/eid1910.130730] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Laboratory-confirmed cases of subclinical infection with avian influenza A(H5N1) virus in humans are rare, and the true number of these cases is unknown. We describe the identification of a laboratory-confirmed subclinical case in a woman during an influenza A(H5N1) contact investigation in northern Vietnam.
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12
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Laskowski M, Greer AL, Moghadas SM. Antiviral strategies for emerging influenza viruses in remote communities. PLoS One 2014; 9:e89651. [PMID: 24586937 PMCID: PMC3931825 DOI: 10.1371/journal.pone.0089651] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 01/27/2014] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Due to the lack of timely access to resources for critical care, strategic use of antiviral drugs is crucial for mitigating the impact of novel influenza viruses with pandemic potential in remote and isolated communities. We sought to evaluate the effect of antiviral treatment and prophylaxis of close contacts in a Canadian remote northern community. METHODS We used an agent-based, discrete-time simulation model for disease spread in a remote community, which was developed as an in-silico population using population census data. Relative and cumulative age-specific attack rates, and the total number of infections in simulated model scenarios were obtained. RESULTS We found that early initiation of antiviral treatment is more critical for lowering attack rates in a remote setting with a low population-average age compared to an urban population. Our results show that a significant reduction in the relative, age-specific attack rates due to increasing treatment coverage does not necessarily translate to a significant reduction in the overall arrack rate. When treatment coverage varies from low to moderate, targeted prophylaxis has a very limited impact in reducing attack rates and should be offered at a low level (below 10%) to avoid excessive waste of drugs. CONCLUSIONS In contrast to previous work, for conservative treatment coverages, our results do not provide any convincing evidence for the implementation of targeted prophylaxis. The findings suggest that public health strategies in remote communities should focus on the wider availability (higher coverage) and timely distribution of antiviral drugs for treatment of clinically ill individuals.
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Affiliation(s)
- Marek Laskowski
- Bartlett School of Graduate Studies, University College London, London, United Kingdom
- Agent-Based Modelling Laboratory, York University, Toronto, Ontario, Canada
| | - Amy L. Greer
- Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Seyed M. Moghadas
- Agent-Based Modelling Laboratory, York University, Toronto, Ontario, Canada
- * E-mail:
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13
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Pandemic influenza A(H1N1)pdm09: risk of infection in primary healthcare workers. Br J Gen Pract 2014; 63:e416-22. [PMID: 23735413 DOI: 10.3399/bjgp13x668212] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Healthcare workers in primary care are at risk of infection during an influenza pandemic. The 2009 influenza pandemic provided an opportunity to assess this risk. AIM To measure the prevalence of seropositivity to influenza A(H1N1)pdm09 among primary healthcare workers in Canterbury, New Zealand, following the 2009 influenza pandemic, and to examine associations between seropositivity and participants' sociodemographic characteristics, professional roles, work patterns, and seasonal influenza vaccination status. DESIGN AND SETTING An observational study involving a questionnaire and testing for influenza A(H1N1)pdm09 seropositivity in all primary healthcare workers in Canterbury, New Zealand between December 2009 and February 2010. Method Participants completed a questionnaire that recorded sociodemographic and professional data, symptoms of influenza-like illness, history of seasonal influenza vaccination, and work patterns. Serum samples were collected and haemagglutination inhibition antibody titres to influenza A(H1N1)pdm09 measured. RESULTS Questionnaires and serum samples were received from 1027 participants, from a workforce of 1476 (response rate 70%). Seropositivity was detected in 224 participants (22%). Receipt of seasonal influenza vaccine (odds ratio [OR] = 2.0, 95% confidence interval [CI] = 1.2 to 3.3), recall of influenza (OR = 1.9, 95% CI = 1.3 to 2.8), and age ≤45 years (OR = 1.4, 95% CI = 1.0 to 1.9) were associated with seropositivity. CONCLUSION A total of 22% of primary care healthcare workers were seropositive. Younger participants, those who recalled having influenza, and those who had been vaccinated against seasonal influenza were more likely to be seropositive. Working in a dedicated influenza centre was not associated with an increased risk of seropositivity.
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Thai PQ, Mai LQ, Welkers MRA, Hang NLK, Thanh LT, Dung VTV, Yen NTT, Duong TN, Hoa LNM, Thoang DD, Trang HTH, de Jong MD, Wertheim H, Hien NT, Horby P, Fox A. Pandemic H1N1 virus transmission and shedding dynamics in index case households of a prospective Vietnamese cohort. J Infect 2014; 68:581-90. [PMID: 24491598 PMCID: PMC4031397 DOI: 10.1016/j.jinf.2014.01.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 01/21/2014] [Accepted: 01/24/2014] [Indexed: 11/29/2022]
Abstract
Objectives Influenza household transmission studies are required to guide prevention strategies but most passively recruit index cases that seek healthcare. We investigated A(H1N1)pdm09 transmission in a household-based cohort during 2009. Methods Health-workers visited 270 households weekly, and collected swabs from influenza-like-illness cases. If A(H1N1)pdm09 was RT-PCR-confirmed, all household members had symptoms assessed and swabs collected daily for 10–15 days. Viral RNA was quantified and sequenced and serology performed on pre-pandemic sera. Results Index cases were detected in 20 households containing 81 people. 98.5% lacked A(H1N1)pdm09 neutralizing antibodies in pre-pandemic sera. Eleven (18.6%, 95% CI 10.7–30.4%) of 59 contacts were infected. Virus genetic diversity within households was negligible and less than between households. Index and secondary cases were distributed between mothers, daughters and sons, and had similar virus-RNA shedding and symptom dynamics. Fathers were rarely infected. Five secondary cases (45%) had no apparent symptoms and three shed virus before symptoms. Secondary infection was associated with index case wet cough (OR 1.56, 95% CI 1.22–1.99). Conclusions In this cohort of A(H1N1)pdm09 susceptible persons, virus sequencing was capable of discriminating household from community transmission. Household transmission involved mothers and children but rarely fathers. Asymptomatic or pre-symptomatic shedding was common.
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Affiliation(s)
- Pham Quang Thai
- National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
| | - Le Quynh Mai
- National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
| | - Matthijs R A Welkers
- Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | | | - Le Thi Thanh
- National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
| | - Vu Tien Viet Dung
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Viet Nam
| | | | - Tran Nhu Duong
- National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
| | - Le Nguyen Minh Hoa
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Viet Nam
| | | | - Hoang Thi Huyen Trang
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Viet Nam
| | - Menno D de Jong
- Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Heiman Wertheim
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Viet Nam; Center for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | | | - Peter Horby
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Viet Nam; Center for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Annette Fox
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Viet Nam; Center for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK; Department of Microbiology and Immunology, University of Melbourne, Australia.
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Abstract
The threat of a virulent, highly transmissible pandemic virus has motivated an escalating research effort to identify the transmissible genotypes of animal viruses that cross over into the human population (animal–human transmission) and sustain human–human transmission. In addition to the pursuit of the viral genotype, a greater understanding of the host-virus phenotype of infectiousness, transmissibility and susceptibility will be required. This review examines experimental animal transmission of influenza for insights into human influenza transmission. Transmission is viewed as sequential steps that the virus must pass critical thresholds to achieve transmission and ultimately survival in the human host. In particular, a quantitative understanding in animal models of viral replication efficiency, airway viral load, exhaled viral aerosol load, environmental virus survival and host susceptibility will likely yield important insights. Computational modeling will enhance animal model data, as well as guide the use of pandemic mitigation strategies.
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Affiliation(s)
- Frederick Koster
- Department of Computer Science, University of New Mexico, Albuquerque, NM, USA and The Lovelace Respiratory Research Institute, Albuquerque, NM, USA
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16
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Freitas FTM, Cabral APS, Barros ENC, Burigo MJO, Prochnow RD, Silva LA, Widdowson MA, Sobel J. Pre-symptomatic transmission of pandemic influenza H1N1 2009: investigation of a family cluster, Brazil. Epidemiol Infect 2013; 141:763-6. [PMID: 22793788 PMCID: PMC9151876 DOI: 10.1017/s0950268812001501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 06/08/2012] [Accepted: 06/10/2012] [Indexed: 11/07/2022] Open
Abstract
We investigated the first cluster of pandemic influenza H1N1 2009 reported in Brazil in May 2009. The index case-patient had travelled from the USA and had contact with 11 relatives before she presented with symptoms. We conducted face-to-face or telephone interviews with the index case-patient and all suspect cases. We found evidence of pre-symptomatic transmission of the virus to four of her contacts. This finding has public health implications because it indicates that viral transmission in communities may not be prevented solely by isolating symptomatic case-patients.
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Affiliation(s)
- F T M Freitas
- Secretariat of Health Surveillance, Brazilian Ministry of Health, Brasilia, Brazil.
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Robinson M, Stilianakis NI. A model for the emergence of drug resistance in the presence of asymptomatic infections. Math Biosci 2013; 243:163-77. [PMID: 23524247 PMCID: PMC7094625 DOI: 10.1016/j.mbs.2013.03.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Revised: 02/22/2013] [Accepted: 03/01/2013] [Indexed: 11/08/2022]
Abstract
We model the emergence of drug resistance in the presence of asymptomatic cases. The absence of a preclinical state leads to an overestimation of peak incidence. Two reproduction numbers, for drug sensitive or resistant strains, are identified. Drug resistant and sensitive strains can coexist in the population.
An analysis of a mathematical model, which describes the dynamics of an aerially transmitted disease, and the effects of the emergence of drug resistance after the introduction of treatment as an intervention strategy is presented. Under explicit consideration of asymptomatic and symptomatic infective individuals for the basic model without intervention the analysis shows that the dynamics of the epidemic is determined by a basic reproduction number R0. A disease-free and an endemic equilibrium exist and are locally asymptotically stable when R0<1 and R0>1 respectively. When treatment is included the system has a basic reproduction number, which is the largest of the two reproduction numbers that characterise the drug-sensitive (R1) or resistant (R2) strains of the infectious agent. The system has a disease-free equilibrium, which is stable when both R1 and R2 are less than unity. Two endemic equilibria also exist and are associated with treatment and the development of drug resistance. An endemic equilibrium where only the drug-resistant strain persists exists and is stable when R2>1 and R1<R2. A second endemic equilibrium exists when R1>1 and R1>R2 and both drug-sensitive and drug-resistant strains are present. The analysis of the system provides insights about the conditions under which the infection will persist and whether sensitive and resistant strains will coexist or not.
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19
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Suess T, Remschmidt C, Schink SB, Schweiger B, Heider A, Milde J, Nitsche A, Schroeder K, Doellinger J, Braun C, Haas W, Krause G, Buchholz U. Comparison of shedding characteristics of seasonal influenza virus (sub)types and influenza A(H1N1)pdm09; Germany, 2007-2011. PLoS One 2012; 7:e51653. [PMID: 23240050 PMCID: PMC3519848 DOI: 10.1371/journal.pone.0051653] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 11/05/2012] [Indexed: 01/25/2023] Open
Abstract
Background Influenza viral shedding studies provide fundamental information for preventive strategies and modelling exercises. We conducted a prospective household study to investigate viral shedding in seasonal and pandemic influenza between 2007 and 2011 in Berlin and Munich, Germany. Methods Study physicians recruited index patients and their household members. Serial nasal specimens were obtained from all household members over at least eight days and tested quantitatively by qRT-PCR for the influenza virus (sub)type of the index patient. A subset of samples was also tested by viral culture. Symptoms were recorded daily. Results We recruited 122 index patients and 320 household contacts, of which 67 became secondary household cases. Among all 189 influenza cases, 12 were infected with seasonal/prepandemic influenza A(H1N1), 19 with A(H3N2), 60 with influenza B, and 98 with A(H1N1)pdm09. Nine (14%) of 65 non-vaccinated secondary cases were asymptomatic/subclinical (0 (0%) of 21 children, 9 (21%) of 44 adults; p = 0.03). Viral load among patients with influenza-like illness (ILI) peaked on illness days 1, 2 or 3 for all (sub)types and declined steadily until days 7–9. Clinical symptom scores roughly paralleled viral shedding dynamics. On the first day prior to symptom onset 30% (12/40) of specimens were positive. Viral load in 6 asymptomatic/subclinical patients was similar to that in ILI-patients. Duration of infectiousness as measured by viral culture lasted approximately until illness days 4–6. Viral load did not seem to be influenced by antiviral therapy, age or vaccination status. Conclusion Asymptomatic/subclinical infections occur infrequently, but may be associated with substantial amounts of viral shedding. Presymptomatic shedding may arise in one third of cases, and shedding characteristics appear to be independent of (seasonal or pandemic) (sub)type, age, antiviral therapy or vaccination; however the power to find moderate differences was limited.
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Affiliation(s)
- Thorsten Suess
- Department of Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany
| | - Cornelius Remschmidt
- Department of Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany
| | - Susanne B. Schink
- Department of Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany
| | - Brunhilde Schweiger
- National Reference Centre for Influenza, Robert Koch Institute, Berlin, Germany
| | - Alla Heider
- National Reference Centre for Influenza, Robert Koch Institute, Berlin, Germany
| | - Jeanette Milde
- National Reference Centre for Influenza, Robert Koch Institute, Berlin, Germany
| | - Andreas Nitsche
- Centre for Biological Security, Division of Highly-Pathogenic Viruses (ZBS1), Robert Koch Institute, Berlin, Germany
| | - Kati Schroeder
- Centre for Biological Security, Division of Highly-Pathogenic Viruses (ZBS1), Robert Koch Institute, Berlin, Germany
| | - Joerg Doellinger
- Centre for Biological Security, Division of Highly-Pathogenic Viruses (ZBS1), Robert Koch Institute, Berlin, Germany
| | - Christian Braun
- Department of Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany
| | - Walter Haas
- Department of Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany
| | - Gérard Krause
- Department of Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany
| | - Udo Buchholz
- Department of Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany
- * E-mail:
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Roberts KL, Shelton H, Stilwell P, Barclay WS. Transmission of a 2009 H1N1 pandemic influenza virus occurs before fever is detected, in the ferret model. PLoS One 2012; 7:e43303. [PMID: 22952661 PMCID: PMC3430703 DOI: 10.1371/journal.pone.0043303] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 07/19/2012] [Indexed: 12/25/2022] Open
Abstract
During the early phase of the 2009 influenza pandemic, attempts were made to contain the spread of the virus. Success of reactive control measures may be compromised if the proportion of transmission that occurs before overt clinical symptoms develop is high. In this study we investigated the timing of transmission of an early prototypic strain of pandemic H1N1 2009 influenza virus in the ferret model. Ferrets are the only animal model in which this can be assessed because they display typical influenza-like clinical signs including fever and sneezing after infection. We assessed transmission from infected animals to sentinels that were placed either in direct contact or in adjacent cages, the latter reflecting the respiratory droplet (RD) transmission route. We found that pre-symptomatic influenza transmission occurred via both contact and respiratory droplet exposure before the earliest clinical sign, fever, developed. Three of 3 animals exposed in direct contact between day 1 and 2 after infection of the donor animals became infected, and 2/3 of the animals exposed at this time period by the RD route acquired the infection, with the third animal becoming seropositive indicating either a low level infection or significant exposure. Moreover, this efficient transmission did not temporally correlate with respiratory symptoms, such as coughs and sneezes, but rather with the peak viral titre in the nose. Indeed respiratory droplet transmission did not occur late in infection, even though this was when sneezing and coughing were most apparent. None of the 3 animals exposed at this time by the RD route became infected and these animals remained seronegative at the end of the experiment. These data have important implications for pandemic planning strategies and suggest that successful containment is highly unlikely for a human-adapted influenza virus that transmits efficiently within a population.
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Affiliation(s)
| | | | | | - Wendy S. Barclay
- Section of Virology, Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, United Kingdom
- * E-mail:
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