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Cong B, Dighero I, Zhang T, Chung A, Nair H, Li Y. Understanding the age spectrum of respiratory syncytial virus associated hospitalisation and mortality burden based on statistical modelling methods: a systematic analysis. BMC Med 2023; 21:224. [PMID: 37365569 DOI: 10.1186/s12916-023-02932-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Accepted: 06/08/2023] [Indexed: 06/28/2023] Open
Abstract
BACKGROUND Statistical modelling studies based on excess morbidity and mortality are important for understanding RSV disease burden for age groups that are less frequently tested for RSV. We aimed to understand the full age spectrum of RSV morbidity and mortality burden based on statistical modelling studies, as well as the value of modelling studies in RSV disease burden estimation. METHODS The databases Medline, Embase and Global Health were searched to identify studies published between January 1, 1995, and December 31, 2021, reporting RSV-associated excess hospitalisation or mortality rates of any case definitions using a modelling approach. All reported rates were summarised using median, IQR (Interquartile range) and range by age group, outcome and country income group; where applicable, a random-effects meta-analysis was conducted to combine the reported rates. We further estimated the proportion of RSV hospitalisations that could be captured in clinical databases. RESULTS A total of 32 studies were included, with 26 studies from high-income countries. RSV-associated hospitalisation and mortality rates both showed a U-shape age pattern. Lowest and highest RSV acute respiratory infection (ARI) hospitalisation rates were found in 5-17 years (median: 1.6/100,000 population, IQR: 1.3-18.5) and < 1 year (2235.7/100,000 population, 1779.1-3552.5), respectively. Lowest and highest RSV mortality rates were found in 18-49 years (0.1/100,000 population, 0.06-0.2) and ≥ 75 years (80.0/100,000 population, 70.0-90.0) for high-income countries, respectively, and in 18-49 years (0.3/100,000 population, 0.1-2.4) and < 1 year (143.4/100,000 population, 143.4-143.4) for upper-middle income countries. More than 70% of RSV hospitalisations in children < 5 years could be captured in clinical databases whereas less than 10% of RSV hospitalisations could be captured in adults, especially for adults ≥ 50 years. Using pneumonia and influenza (P&I) mortality could potentially capture half of all RSV mortality in older adults but only 10-30% of RSV mortality in children. CONCLUSIONS Our study provides insights into the age spectrum of RSV hospitalisation and mortality. RSV disease burden using laboratory records alone could be substantially severely underreported for age groups ≥ 5 years. Our findings confirm infants and older adults should be prioritised for RSV immunisation programmes. TRIAL REGISTRATION PROSPERO CRD42020173430.
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Affiliation(s)
- Bingbing Cong
- Department of Epidemiology, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Izzie Dighero
- Centre for Global Health, Usher Institute, University of Edinburgh, Edinburgh, UK
| | - Tiantian Zhang
- Department of Epidemiology, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Alexandria Chung
- Centre for Global Health, Usher Institute, University of Edinburgh, Edinburgh, UK
| | - Harish Nair
- Department of Epidemiology, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
- Centre for Global Health, Usher Institute, University of Edinburgh, Edinburgh, UK
- MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - You Li
- Department of Epidemiology, School of Public Health, Nanjing Medical University, Nanjing, 211166, China.
- Centre for Global Health, Usher Institute, University of Edinburgh, Edinburgh, UK.
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Firdaus MAM, Mohd Yunus R, Hairi NN, Choo WY, Hairi F, Suddin LS, Sooryanarayana R, Ismail N, Peramalah D, Ali ZM, Ahmad SN, Razak IA, Othman S, Bulgiba A. Elder abuse and hospitalization in rural Malaysia. PLoS One 2022; 17:e0270163. [PMID: 35749384 PMCID: PMC9231721 DOI: 10.1371/journal.pone.0270163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 06/03/2022] [Indexed: 11/19/2022] Open
Abstract
Our study aims to describe and determine factors associated with hospitalization among victims of elder abuse and neglect (EAN) in rural Malaysia. A cross sectional study based on the baseline data of the Malaysian Elder Mistreatment Project (MAESTRO) collected from November 2013 until July 2014 involving 1927 older adults in Kuala Pilah, Negeri Sembilan was conducted. EAN was determined using the modified Conflict Tactics Scale (CTS) and hospitalization rates were determined based on self-report. The prevalence of overall EAN was 8.1% (95%CI 6.9–9.3). Among male respondents, 9.5% revealed history of abuse and among female respondents, 7.2% reported experiencing EAN. The annual hospitalization rates per 100 persons within the past one year among EAN victims and non-victims were 18 per 100 persons (SD = 46.1) and 15 per 100 persons (SD = 64.1) respectively. Among respondents with history of EAN, 16.0% (n = 21) had been hospitalized in the past 12 months while among respondents with no EAN experience, 10.2% (n = 153) were hospitalized. Multivariable analyses using Poisson regression did not show any significant association between EAN and hospitalization. This could be due to the complex interactions between medical and social circumstances that play a role in hospital admissions, factors affecting the health care system, and access to health care among EAN victims.
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Affiliation(s)
| | - Raudah Mohd Yunus
- Department of Public Health Medicine, Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh, Malaysia
- Department of Social and Preventive Medicine, Centre for Epidemiology and Evidence-Based Practice, University of Malaya, Kuala Lumpur, Malaysia
| | - Noran Naqiah Hairi
- Department of Social and Preventive Medicine, Centre for Epidemiology and Evidence-Based Practice, University of Malaya, Kuala Lumpur, Malaysia
- Health and Well-being Research Cluster, Institute of Research Management and Monitoring, Research Management and Innovation Complex, University of Malaya, Kuala Lumpur, Malaysia
- Faculty of Public Health, Universitas Airlangga, Surabaya, Indonesia
- * E-mail:
| | - Wan Yuen Choo
- Department of Social and Preventive Medicine, Centre for Epidemiology and Evidence-Based Practice, University of Malaya, Kuala Lumpur, Malaysia
- Department of Social and Preventive Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Farizah Hairi
- Department of Social and Preventive Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Leny Suzana Suddin
- Department of Public Health Medicine, Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh, Malaysia
| | - Rajini Sooryanarayana
- Family Health Development Division, Ministry of Health Malaysia, Putrajaya, Malaysia
| | - Norliana Ismail
- Disease Control Division, Tobacco Control Unit, Ministry of Health Malaysia, Putrajaya, Malaysia
| | - Devi Peramalah
- Department of Social and Preventive Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Zainudin M. Ali
- Negeri Sembilan Health State Department, Seremban, Negeri Sembilan, Malaysia
| | - Sharifah N. Ahmad
- Negeri Sembilan Health State Department, Seremban, Negeri Sembilan, Malaysia
| | - Inayah A. Razak
- Negeri Sembilan Health State Department, Seremban, Negeri Sembilan, Malaysia
| | | | - Awang Bulgiba
- Department of Social and Preventive Medicine, Centre for Epidemiology and Evidence-Based Practice, University of Malaya, Kuala Lumpur, Malaysia
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An Evidence Synthesis Approach to Estimating the Proportion of Influenza Among Influenza-like Illness Patients. Epidemiology 2018; 28:484-491. [PMID: 28252453 DOI: 10.1097/ede.0000000000000646] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Estimation of the national-level incidence of seasonal influenza is notoriously challenging. Surveillance of influenza-like illness is carried out in many countries using a variety of data sources, and several methods have been developed to estimate influenza incidence. Our aim was to obtain maximally informed estimates of the proportion of influenza-like illness that is true influenza using all available data. METHODS We combined data on weekly general practice sentinel surveillance consultation rates for influenza-like illness, virologic testing of sampled patients with influenza-like illness, and positive laboratory tests for influenza and other pathogens, applying Bayesian evidence synthesis to estimate the positive predictive value (PPV) of influenza-like illness as a test for influenza virus infection. We estimated the weekly number of influenza-like illness consultations attributable to influenza for nine influenza seasons, and for four age groups. RESULTS The estimated PPV for influenza in influenza-like illness patients was highest in the weeks surrounding seasonal peaks in influenza-like illness rates, dropping to near zero in between-peak periods. Overall, 14.1% (95% credible interval [CrI]: 13.5%, 14.8%) of influenza-like illness consultations were attributed to influenza infection; the estimated PPV was 50% (95% CrI: 48%, 53%) for the peak weeks and 5.8% during the summer periods. CONCLUSIONS The model quantifies the correspondence between influenza-like illness consultations and influenza at a weekly granularity. Even during peak periods, a substantial proportion of influenza-like illness-61%-was not attributed to influenza. The much lower proportion of influenza outside the peak periods reflects the greater circulation of other respiratory pathogens relative to influenza.
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Schanzer DL, Saboui M, Lee L, Nwosu A, Bancej C. Burden of influenza, respiratory syncytial virus, and other respiratory viruses and the completeness of respiratory viral identification among respiratory inpatients, Canada, 2003-2014. Influenza Other Respir Viruses 2017; 12:113-121. [PMID: 29243369 PMCID: PMC5818333 DOI: 10.1111/irv.12497] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/09/2017] [Indexed: 12/01/2022] Open
Abstract
Background A regression‐based study design has commonly been used to estimate the influenza burden; however, these estimates are not timely and many countries lack sufficient virological data. Alternative approaches that would permit a timelier assessment of the burden, including a sentinel surveillance approach recommended by the World Health Organization (WHO), have been proposed. We aimed to estimate the hospitalization burden attributable to influenza, respiratory syncytial virus (RSV), and other respiratory viruses (ORV) and to assess both the completeness of viral identification among respiratory inpatients in Canada and the implications of adopting other approaches. Methods Respiratory inpatient records were extracted from the Canadian Discharge Abstract Database from 2003 to 2014. A regression model was used to estimate excess respiratory hospitalizations attributable to influenza, RSV, and ORV by age group and diagnostic category and compare these estimates with the number with a respiratory viral identification. Results An estimated 33 (95% CI: 29, 38), 27 (95% CI: 22, 33), and 27 (95% CI: 18, 36) hospitalizations per 100 000 population per year were attributed to influenza, RSV, and ORV, respectively. An influenza virus was identified in an estimated 78% (95% CI: 75, 81) and 17% (95% CI: 15, 21) of respiratory hospitalizations attributed to influenza for children and adults, respectively, and 75% of influenza‐attributed hospitalizations had an ARI diagnosis. Conclusions Hospitalization rates with respiratory viral identification still underestimate the burden. Approaches based on acute respiratory case definitions will likely underestimate the burden as well, although each proposed method should be compared with regression‐based estimates of influenza‐attributed burden as a way of assessing their validity.
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Affiliation(s)
- Dena L Schanzer
- Infectious Disease Prevention and Control Branch, Public Health Agency of Canada, Ottawa, ON, Canada
| | - Myriam Saboui
- Infectious Disease Prevention and Control Branch, Public Health Agency of Canada, Ottawa, ON, Canada
| | - Liza Lee
- Infectious Disease Prevention and Control Branch, Public Health Agency of Canada, Ottawa, ON, Canada
| | - Andrea Nwosu
- Infectious Disease Prevention and Control Branch, Public Health Agency of Canada, Ottawa, ON, Canada
| | - Christina Bancej
- Infectious Disease Prevention and Control Branch, Public Health Agency of Canada, Ottawa, ON, Canada
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5
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Liu XX, Qin G, Li X, Zhang J, Zhao K, Hu M, Wang XL. Excess mortality associated with influenza after the 2009 H1N1 pandemic in a subtropical city in China, 2010–2015. Int J Infect Dis 2017; 57:54-60. [DOI: 10.1016/j.ijid.2017.01.039] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 01/25/2017] [Accepted: 01/27/2017] [Indexed: 11/17/2022] Open
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Matias G, Taylor R, Haguinet F, Schuck-Paim C, Lustig R, Shinde V. Estimates of hospitalization attributable to influenza and RSV in the US during 1997-2009, by age and risk status. BMC Public Health 2017; 17:271. [PMID: 28320361 PMCID: PMC5359836 DOI: 10.1186/s12889-017-4177-z] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Accepted: 03/07/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Estimates of influenza and respiratory syncytial virus (RSV) burden must be periodically updated to inform public health strategies. We estimated seasonal influenza- and RSV-attributable hospitalizations in the US from 1997 to 2009 according to age and risk status (NCT01599390). METHODS Multiple linear regression modelling was used to attribute hospitalizations to influenza or RSV using virological surveillance and hospitalization data. Hospitalization data were obtained from the US Nationwide Inpatient Sample and virology data were obtained from FluView (Centers for Disease Control and Prevention). Outcomes included any mention of ICD-coded respiratory disease and cardiorespiratory disease diagnoses. We also explored a broader definition of respiratory disease that included mention of relevant respiratory sign/symptoms and viral infection ("respiratory broad"). RESULTS Applying the respiratory broad outcome, our model attributed ~300,000 and ~200,000 hospitalizations to influenza and RSV, respectively. Influenza A/H3N2 was the predominant cause of influenza-related hospitalizations in most seasons, except in three seasons when influenza B was dominant; likewise, A/H3N2 caused most influenza-related hospitalizations in all age segments, except in children <18 years where the relative contribution of A/H3N2 and B was similar. Most influenza A- and B-related hospitalizations occurred in seniors while approximately one half and one third of all RSV-related events occurred in children 0-4 years and seniors 65+ years, respectively. High-risk status was associated with higher risk of both influenza- and RSV-attributable hospitalizations in adults, but not in children. CONCLUSIONS Our study assessed the burden of influenza and RSV, information that is important for both cost effectiveness studies and for prioritization of the development of antivirals and vaccines. For seniors, we found that the burdens of influenza and RSV were both substantial. Among children <18 years, about half of all influenza hospitalizations were due to influenza B, most occurring in children without noted risk conditions. RSV hospitalizations among children were confined to those 0-4 years. Our study also demonstrated the importance of the outcome used to estimate hospitalization burden. Our findings highlight the burden of influenza among children regardless of risk status and underscore the prevalence of RSV infections among both young children and older adults.
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Affiliation(s)
| | | | | | | | | | - Vivek Shinde
- GSK, King of Prussia, USA.,Present Address: Novavax Vaccines, Washington, DC, USA
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FLEMING DM, TAYLOR RJ, HAGUINET F, SCHUCK-PAIM C, LOGIE J, WEBB DJ, LUSTIG RL, MATIAS G. Influenza-attributable burden in United Kingdom primary care. Epidemiol Infect 2016; 144:537-47. [PMID: 26168005 PMCID: PMC4714299 DOI: 10.1017/s0950268815001119] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 04/01/2015] [Accepted: 05/06/2015] [Indexed: 11/16/2022] Open
Abstract
Influenza is rarely laboratory-confirmed and the outpatient influenza burden is rarely studied due to a lack of suitable data. We used the Clinical Practice Research Datalink (CPRD) and surveillance data from Public Health England in a linear regression model to assess the number of persons consulting UK general practitioners (GP episodes) for respiratory illness, otitis media and antibiotic prescriptions attributable to influenza during 14 seasons, 1995-2009. In CPRD we ascertained influenza vaccination status in each season and risk status (conditions associated with severe influenza outcomes). Seasonal mean estimates of influenza-attributable GP episodes in the UK were 857 996 for respiratory disease including 68 777 for otitis media, with wide inter-seasonal variability. In an average season, 2·4%/0·5% of children aged <5 years and 1·3%/0·1% of seniors aged ⩾75 years had a GP episode for respiratory illness attributed to influenza A/B. Two-thirds of influenza-attributable GP episodes were estimated to result in prescription of antibiotics. These estimates are substantially greater than those derived from clinically reported influenza-like illness in surveillance programmes. Because health service costs of influenza are largely borne in general practice, these are important findings for cost-benefit assessment of influenza vaccination programmes.
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Affiliation(s)
- D. M. FLEMING
- 9 Dowles Close,
Birmingham, UK(independent consultant)
| | | | | | | | - J. LOGIE
- GSK R&D,
Uxbridge, Middlesex, UK
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8
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Fleming DM, Taylor RJ, Lustig RL, Schuck-Paim C, Haguinet F, Webb DJ, Logie J, Matias G, Taylor S. Modelling estimates of the burden of Respiratory Syncytial virus infection in adults and the elderly in the United Kingdom. BMC Infect Dis 2015; 15:443. [PMID: 26497750 PMCID: PMC4618996 DOI: 10.1186/s12879-015-1218-z] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 10/14/2015] [Indexed: 12/12/2022] Open
Abstract
Background Growing evidence suggests respiratory syncytial virus (RSV) is an important cause of respiratory disease in adults. However, the adult burden remains largely uncharacterized as most RSV studies focus on children, and population-based studies with laboratory-confirmation of infection are difficult to implement. Indirect modelling methods, long used for influenza, can further our understanding of RSV burden by circumventing some limitations of traditional surveillance studies that rely on direct linkage of individual-level exposure and outcome data. Methods Multiple linear time-series regression was used to estimate RSV burden in the United Kingdom (UK) between 1995 and 2009 among the total population and adults in terms of general practice (GP) episodes (counted as first consultation ≥28 days following any previous consultation for same diagnosis/diagnostic group), hospitalisations, and deaths for respiratory disease, using data from Public Health England weekly influenza/RSV surveillance, Clinical Practice Research Datalink, Hospital Episode Statistics, and Office of National Statistics. The main outcome considered all ICD-listed respiratory diseases and, for GP episodes, related symptoms. Estimates were adjusted for non-specific seasonal drivers of disease using secular cyclical terms and stratified by age and risk group (according to chronic conditions indicating severe influenza risk as per UK recommendations for influenza vaccination). Trial registration NCT01706302. Registered 11 October 2012. Results Among adults aged 18+ years an estimated 487,247 GP episodes, 17,799 hospitalisations, and 8,482 deaths were attributable to RSV per average season. Of these, 175,070 GP episodes (36 %), 14,039 hospitalisations (79 %) and 7,915 deaths (93 %) were in persons aged 65+ years. High- versus low-risk elderly were two-fold more likely to have a RSV-related GP episode or death and four-fold more likely be hospitalised for RSV. In most seasons since 2001, more GP episodes, hospitalisations and deaths were attributable to RSV in adults than to influenza. Conclusion RSV is associated with a substantial disease burden in adults comparable to influenza, with most of the hospitalisation and mortality burden in the elderly. Treatment options and measures to prevent RSV could have a major impact on the burden of RSV respiratory disease in adults, especially the elderly. Electronic supplementary material The online version of this article (doi:10.1186/s12879-015-1218-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Douglas M Fleming
- Independent Consultant, 9 Dowles Close, Birmingham, B29 4LE, United Kingdom.
| | - Robert J Taylor
- Sage Analytica, 4550 Montgomery Ave., Suite 4915 St. Elmo Ave, Ste. 205, Bethesda, MD 20814, USA.
| | - Roger L Lustig
- Sage Analytica, 4550 Montgomery Ave., Suite 4915 St. Elmo Ave, Ste. 205, Bethesda, MD 20814, USA.
| | - Cynthia Schuck-Paim
- Sage Analytica, 4550 Montgomery Ave., Suite 4915 St. Elmo Ave, Ste. 205, Bethesda, MD 20814, USA.
| | - François Haguinet
- GSK Vaccines, Av Fleming 20, Parc de la Noire Epine, 1300, Wavre, Belgium.
| | - David J Webb
- GSK Pharmaceuticals, Stockley Park West, 1-3 Ironbridge Road, Heathrow, Uxbridge, Middlesex, UB11 1B S, United Kingdom.
| | - John Logie
- GSK Pharmaceuticals, Stockley Park West, 1-3 Ironbridge Road, Heathrow, Uxbridge, Middlesex, UB11 1B S, United Kingdom.
| | - Gonçalo Matias
- GSK Vaccines, Av Fleming 20, Parc de la Noire Epine, 1300, Wavre, Belgium.
| | - Sylvia Taylor
- GSK Vaccines, Av Fleming 20, Parc de la Noire Epine, 1300, Wavre, Belgium.
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Alonso WJ, McCormick BJJ, Miller MA, Schuck-Paim C, Asrar GR. Beyond crystal balls: crosscutting solutions in global health to prepare for an unpredictable future. BMC Public Health 2015; 15:955. [PMID: 26400682 PMCID: PMC4581487 DOI: 10.1186/s12889-015-2285-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 09/15/2015] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Efforts in global heath need to deal not only with current challenges, but also to anticipate new scenarios, which sometimes unfold at lightning speed. Predictive modeling is frequently used to assist planning, but outcomes depend heavily on a subset of critical assumptions, which are mostly hampered by our limited knowledge about the many factors, mechanisms and relationships that determine the dynamics of disease systems, by a lack of data to parameterize and validate models, and by uncertainties about future scenarios. DISCUSSION We propose a shift from a focus on the prediction of individual disease patterns to the identification and mitigation of broader fragilities in public health systems. Modeling capabilities should be used to perform "stress tests" on how interrelated fragilities respond when faced with a range of possible or plausible threats of different nature and intensity. This system should be able to reveal crosscutting solutions with the potential to address not only one threat, but multiple areas of vulnerability to future health risks. Actionable knowledge not based on a narrow subset of threats and conditions can better guide policy, build societal resilience and ensure effective prevention in an uncertain world.
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Affiliation(s)
- Wladimir Jimenez Alonso
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland, 20892, USA.
- Origem Scientifica, São Paulo, São Paulo, Brazil.
| | | | - Mark A Miller
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland, 20892, USA.
| | | | - Ghassem R Asrar
- Joint Global Change Research Institute, University of Maryland, College Park, MD, 20740, USA.
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Wang XL, Yang L, Chan KH, Chan KP, Cao PH, Lau EHY, Peiris JSM, Wong CM. Age and Sex Differences in Rates of Influenza-Associated Hospitalizations in Hong Kong. Am J Epidemiol 2015. [PMID: 26219977 DOI: 10.1093/aje/kwv068] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Few studies have explored age and sex differences in the disease burden of influenza, although men and women probably differ in their susceptibility to influenza infections. In this study, quasi-Poisson regression models were applied to weekly age- and sex-specific hospitalization numbers of pneumonia and influenza cases in the Hong Kong SAR, People's Republic of China, from 2004 to 2010. Age and sex differences were assessed by age- and sex-specific rates of excess hospitalization for influenza A subtypes A(H1N1), A(H3N2), and A(H1N1)pdm09 and influenza B, respectively. We found that, in children younger than 18 years, boys had a higher excess hospitalization rate than girls, with the male-to-female ratio of excess rate (MFR) ranging from 1.1 to 2.4. MFRs of hospitalization associated with different types/subtypes were less than 1.0 for adults younger than 40 years except for A(H3N2) (MFR = 1.6), while all the MFRs were equal to or higher than 1.0 in adults aged 40 years or more except for A(H1N1)pdm09 in elderly persons aged 65 years or more (MFR = 0.9). No MFR was found to be statistically significant (P < 0.05) for hospitalizations associated with influenza type/subtype. There is some limited evidence on age and sex differences in hospitalization associated with influenza in the subtropical city of Hong Kong.
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Savard N, Bédard L, Allard R, Buckeridge DL. Using age, triage score, and disposition data from emergency department electronic records to improve Influenza-like illness surveillance. J Am Med Inform Assoc 2015; 22:688-96. [PMID: 25725005 DOI: 10.1093/jamia/ocu002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 10/19/2014] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVE Markers of illness severity are increasingly captured in emergency department (ED) electronic systems, but their value for surveillance is not known. We assessed the value of age, triage score, and disposition data from ED electronic records for predicting influenza-related hospitalizations. MATERIALS AND METHODS From June 2006 to January 2011, weekly counts of pneumonia and influenza (P&I) hospitalizations from five Montreal hospitals were modeled using negative binomial regression. Over lead times of 0-5 weeks, we assessed the predictive ability of weekly counts of 1) total ED visits, 2) ED visits with influenza-like illness (ILI), and 3) ED visits with ILI stratified by age, triage score, or disposition. Models were adjusted for secular trends, seasonality, and autocorrelation. Model fit was assessed using Akaike information criterion, and predictive accuracy using the mean absolute scaled error (MASE). RESULTS Predictive accuracy for P&I hospitalizations during non-pandemic years was improved when models included visits from patients ≥65 years old and visits resulting in admission/transfer/death (MASE of 0.64, 95% confidence interval (95% CI) 0.54-0.80) compared to overall ILI visits (0.89, 95% CI 0.69-1.10). During the H1N1 pandemic year, including visits from patients <18 years old, visits with high priority triage scores, or visits resulting in admission/transfer/death resulted in the best model fit. DISCUSSION Age and disposition data improved model fit and moderately reduced the prediction error for P&I hospitalizations; triage score improved model fit only during the pandemic year. CONCLUSION Incorporation of age and severity measures available in ED records can improve ILI surveillance algorithms.
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Affiliation(s)
- Noémie Savard
- Department of Biostatistics, Epidemiology and Occupational Health, McGill University, Montréal, Québec, Canada
| | - Lucie Bédard
- Direction de santé publique de l'Agence de la santé et des services sociaux de Montréal, Montréal, Québec, Canada Department of Social and Preventive Medicine, University of Montréal, Montréal, Québec, Canada
| | - Robert Allard
- Department of Biostatistics, Epidemiology and Occupational Health, McGill University, Montréal, Québec, Canada Direction de santé publique de l'Agence de la santé et des services sociaux de Montréal, Montréal, Québec, Canada
| | - David L Buckeridge
- Department of Biostatistics, Epidemiology and Occupational Health, McGill University, Montréal, Québec, Canada Direction de santé publique de l'Agence de la santé et des services sociaux de Montréal, Montréal, Québec, Canada
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Ortiz JR, Neuzil KM, Cooke CR, Neradilek MB, Goss CH, Shay DK. Influenza pneumonia surveillance among hospitalized adults may underestimate the burden of severe influenza disease. PLoS One 2014; 9:e113903. [PMID: 25423025 PMCID: PMC4244176 DOI: 10.1371/journal.pone.0113903] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 11/02/2014] [Indexed: 01/10/2023] Open
Abstract
Background Studies seeking to estimate the burden of influenza among hospitalized adults often use case definitions that require presence of pneumonia. The goal of this study was to assess the extent to which restricting influenza testing to adults hospitalized with pneumonia could underestimate the total burden of hospitalized influenza disease. Methods We conducted a modelling study using the complete State Inpatient Databases from Arizona, California, and Washington and regional influenza surveillance data acquired from CDC from January 2003 through March 2009. The exposures of interest were positive laboratory tests for influenza A (H1N1), influenza A (H3N2), and influenza B from two contiguous US Federal Regions encompassing the study area. We identified the two outcomes of interest by ICD-9-CM code: respiratory and circulatory hospitalizations, as well as critical illness hospitalizations (acute respiratory failure, severe sepsis, and in-hospital death). We linked the hospitalization datasets with the virus surveillance datasets by geographic region and month of hospitalization. We used negative binomial regression models to estimate the number of influenza-associated events for the outcomes of interest. We sub-categorized these events to include all outcomes with or without pneumonia diagnosis codes. Results We estimated that there were 80,834 (95% CI 29,214–174,033) influenza-associated respiratory and circulatory hospitalizations and 26,760 (95% CI 14,541–47,464) influenza-associated critical illness hospitalizations. When a pneumonia diagnosis was excluded, the estimated number of influenza-associated respiratory and circulatory hospitalizations was 24,816 (95% CI 6,342–92,624). The estimated number of influenza-associated critical illness hospitalizations was 8,213 (95% CI 3,764–20,799). Around 30% of both influenza-associated respiratory and circulatory hospitalizations, as well as influenza-associated critical illness hospitalizations did not have pneumonia diagnosis codes. Conclusions Surveillance studies which only consider hospitalizations that include a diagnosis of pneumonia may underestimate the total burden of influenza hospitalizations.
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Affiliation(s)
- Justin R. Ortiz
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
- Vaccine Access and Delivery Global Program, PATH, Seattle, Washington, United States of America
- * E-mail:
| | - Kathleen M. Neuzil
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
- Vaccine Access and Delivery Global Program, PATH, Seattle, Washington, United States of America
| | - Colin R. Cooke
- Department of Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Moni B. Neradilek
- The Mountain-Whisper-Light Statistics, Seattle, Washington, United States of America
| | - Christopher H. Goss
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
| | - David K. Shay
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
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Gilca R, Amini R, Douville-Fradet M, Charest H, Dubuque J, Boulianne N, Skowronski DM, De Serres G. Other respiratory viruses are important contributors to adult respiratory hospitalizations and mortality even during peak weeks of the influenza season. Open Forum Infect Dis 2014; 1:ofu086. [PMID: 25734152 PMCID: PMC4281811 DOI: 10.1093/ofid/ofu086] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 09/01/2014] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND During peak weeks of seasonal influenza epidemics, severe respiratory infections without laboratory confirmation are typically attributed to influenza. METHODS In this prospective study, specimens and demographic and clinical data were collected from adults admitted with respiratory symptoms to 4 hospitals during the 8-10 peak weeks of 2 influenza seasons. Specimens were systematically tested for influenza and 13 other respiratory viruses (ORVs) by using the Luminex RVP FAST assay. RESULTS At least 1 respiratory virus was identified in 46% (21% influenza, 25% noninfluenza; 2% coinfection) of the 286 enrolled patients in 2011-2012 and in 62% (46% influenza, 16% noninfluenza; 3% coinfection) of the 396 enrolled patients in 2012-2013. Among patients aged ≥75 years, twice as many ORVs (32%) as influenza viruses (14%) were detected in 2011-2012. During both seasons, the most frequently detected ORVs were enteroviruses/rhinoviruses (7%), respiratory syncytial virus (6%), human metapneumovirus (5%), coronaviruses (4%), and parainfluenza viruses (2%). Disease severity was similar for influenza and ORVs during both seasons. CONCLUSIONS Although ORV contribution relative to influenza varies by age and season, during the peak weeks of certain influenza seasons, ORVs may be a more frequent cause of elderly hospitalization than influenza.
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Affiliation(s)
- Rodica Gilca
- Biological, Environmental and Occupational Risks , Institut national de santé publique du Québec ; Public Health Research Unit , Centre Hospitalier Universitaire de Québec ; Faculty of Medicine , Laval University , Québec City
| | - Rachid Amini
- Biological, Environmental and Occupational Risks , Institut national de santé publique du Québec
| | - Monique Douville-Fradet
- Biological, Environmental and Occupational Risks , Institut national de santé publique du Québec
| | - Hugues Charest
- Laboratoire de Santé Publique du Québec , Institut national de santé publique du Québec
| | - Josée Dubuque
- Ministère de la Santé et des Services sociaux, Montreal, Québec
| | - Nicole Boulianne
- Biological, Environmental and Occupational Risks , Institut national de santé publique du Québec ; Public Health Research Unit , Centre Hospitalier Universitaire de Québec
| | - Danuta M Skowronski
- Influenza and Emerging Respiratory Pathogens , British Columbia Centre for Disease Control , Vancouver , Canada
| | - Gaston De Serres
- Biological, Environmental and Occupational Risks , Institut national de santé publique du Québec ; Public Health Research Unit , Centre Hospitalier Universitaire de Québec ; Faculty of Medicine , Laval University , Québec City
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Quinn E, Jit M, Newall AT. Key issues and challenges in estimating the impact and cost-effectiveness of quadrivalent influenza vaccination. Expert Rev Pharmacoecon Outcomes Res 2014; 14:425-35. [PMID: 24734967 DOI: 10.1586/14737167.2014.908713] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Evidence has shown that quadrivalent influenza vaccines containing all four subtypes are safe and immunogenic. However, to date there have been few published studies exploring the population-level clinical and economic impact of quadrivalent compared to trivalent influenza vaccines. Economic evaluation studies need to be conducted in order to inform country-level decision making about whether (and how to) introduce and replace the current trivalent influenza vaccines with quadrivalent influenza vaccination programs. Several key issues associated with estimating the clinical and economic impact of the trivalent versus quadrivalent vaccines are discussed in this article, particularly the complexities involved in estimating the incremental preventable disease and economic burden. Other factors, such as the indirect (herd) protection from quadrivalent influenza vaccination and the timing of the replacement of trivalent influenza vaccination programs are also discussed.
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Affiliation(s)
- Emma Quinn
- NSW Ministry of Health , Sydney , Australia
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Chan KP, Wong CM, Chiu SSS, Chan KH, Wang XL, Chan ELY, Peiris JSM, Yang L. A robust parameter estimation method for estimating disease burden of respiratory viruses. PLoS One 2014; 9:e90126. [PMID: 24651832 PMCID: PMC3961249 DOI: 10.1371/journal.pone.0090126] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 01/26/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Poisson model has been widely applied to estimate the disease burden of influenza, but there has been little success in providing reliable estimates for other respiratory viruses. METHODS We compared the estimates of excess hospitalization rates derived from the Poisson models with different combinations of inference methods and virus proxies respectively, with the aim to determine the optimal modeling approach. These models were validated by comparing the estimates of excess hospitalization attributable to respiratory viruses with the observed rates of laboratory confirmed paediatric hospitalization for acute respiratory infections obtained from a population based study. RESULTS The Bayesian inference method generally outperformed the classical likelihood estimation, particularly for RSV and parainfluenza, in terms of providing estimates closer to the observed hospitalization rates. Compared to the other proxy variables, age-specific positive counts provided better estimates for influenza, RSV and parainfluenza, regardless of inference methods. The Bayesian inference combined with age-specific positive counts also provided valid and reliable estimates for excess hospitalization associated with multiple respiratory viruses in both the 2009 H1N1 pandemic and interpandemic period. CONCLUSIONS Poisson models using the Bayesian inference method and virus proxies of age-specific positive counts should be considered in disease burden studies on multiple respiratory viruses.
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Affiliation(s)
- King Pan Chan
- School of Publish Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Chit Ming Wong
- School of Publish Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Susan S. S. Chiu
- Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Kwok Hung Chan
- Department of Microbiology, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Xi Ling Wang
- School of Publish Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Eunice L. Y. Chan
- Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - J. S. Malik Peiris
- School of Publish Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
- HKU - Pasteur Research Centre, Hong Kong Special Administrative Region, China
| | - Lin Yang
- School of Publish Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
- Squina International Centre for Infection Control, School of Nursing, The Hong Kong Polytechnic University, Hong Kong Special Administrative Region, China
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Cromer D, van Hoek AJ, Jit M, Edmunds WJ, Fleming D, Miller E. The burden of influenza in England by age and clinical risk group: a statistical analysis to inform vaccine policy. J Infect 2013; 68:363-71. [PMID: 24291062 DOI: 10.1016/j.jinf.2013.11.013] [Citation(s) in RCA: 165] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 11/05/2013] [Accepted: 11/19/2013] [Indexed: 11/19/2022]
Abstract
OBJECTIVES To assess the burden of influenza by age and clinical status and use this to inform evaluations of the age and risk-based influenza vaccination policy in the United Kingdom. METHODS Weekly laboratory reports for influenza and 7 other respiratory pathogens were extracted from the national database and used in a regression model to estimate the proportion of acute respiratory illness outcomes attributable to each pathogen. RESULTS Influenza accounted for ∼10% of the attributed respiratory admissions and deaths in hospital. Healthy children under five had the highest influenza admission rate (1.9/1000). The presence of co-morbidities increased the admission rate by 5.7 fold for 5-14 year olds (from 0.1 to 0.56/1000), the relative risk declining to 1.8 fold in 65+ year olds (from 0.46 to 0.84/1000). The majority (72%) of influenza-attributable deaths in hospital occurred in 65+ year olds with co-morbidities. Mortality in children under 15 years was low with around 12 influenza-attributable deaths in hospital per year in England; the case fatality rate was substantially higher in risk than non-risk children. Infants under 6 months had the highest consultation and admission rates, around 70/1000 and 3/1000 respectively. CONCLUSIONS Additional strategies are needed to reduce the remaining morbidity and mortality in the high-risk and elderly populations, and to protect healthy children currently not offered the benefits of vaccination.
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Affiliation(s)
- Deborah Cromer
- Complex Systems in Biology Group, Centre for Vascular Research, University of New South Wales, Sydney, Australia.
| | | | - Mark Jit
- Public Health England, London, United Kingdom; Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - W John Edmunds
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Douglas Fleming
- Research and Surveillance Unit, Royal College of General Practitioners, Birmingham, United Kingdom
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Abstract
Background Poisson regression modelling has been widely used to estimate the disease burden attributable to influenza, though not without concerns that some of the excess burden could be due to other causes. This study aims to provide annual estimates of the mortality and hospitalization burden attributable to both seasonal influenza and the 2009 A/H1N1 pandemic influenza for Canada, and to discuss issues related to the reliability of these estimates. Methods Weekly time-series for all-cause mortality and regression models were used to estimate the number of deaths in Canada attributable to influenza from September 1992 to December 2009. To assess their robustness, the annual estimates derived from different parameterizations of the regression model for all-cause mortality were compared. In addition, the association between the annual estimates for mortality and hospitalization by age group, underlying cause of death or primary reason for admission and discharge status is discussed. Results The crude influenza-attributed mortality rate based on all-cause mortality and averaged over 17 influenza seasons prior to the 2009 A/H1N1 pandemic was 11.3 (95%CI, 10.5 - 12.1) deaths per 100 000 population per year, or an average of 3,500 (95%CI, 3,200 - 3,700) deaths per year attributable to seasonal influenza. The estimated annual rates ranged from undetectable at the ecological level to more than 6000 deaths per year over the three A/Sydney seasons. In comparison, we attributed an estimated 740 deaths (95%CI, 350–1500) to A(H1N1)pdm09. Annual estimates from different model parameterizations were strongly correlated, as were estimates for mortality and morbidity; the higher A(H1N1)pdm09 burden in younger age groups was the most notable exception. Interpretation With the exception of some of the Serfling models, differences in the ecological estimates of the disease burden attributable to influenza were small in comparison to the variation in disease burden from one season to another.
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Ortiz JR, Neuzil KM, Rue TC, Zhou H, Shay DK, Cheng PY, Cooke CR, Goss CH. Population-based incidence estimates of influenza-associated respiratory failure hospitalizations, 2003 to 2009. Am J Respir Crit Care Med 2013; 188:710-5. [PMID: 23855650 DOI: 10.1164/rccm.201212-2341oc] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE The incidence of influenza-associated acute respiratory failure is unknown. OBJECTIVES To estimate the population-based incidence of influenza-associated acute respiratory failure hospitalizations. METHODS This is a cohort study from January 2003 through March 2009 using hospitalization databases for Arizona, California, and Washington from the Healthcare Cost and Utilization Project and influenza surveillance data for regions encompassing these states. Acute respiratory failure requiring mechanical ventilation was defined by International Classification of Diseases-9-CM code. We used negative-binomial regression modeling to estimate the incidence of influenza-associated events. MEASUREMENTS AND MAIN RESULTS The incidence of influenza-associated acute respiratory failure was 2.7 per 100,000 person-years (95% confidence interval, 0.2-23.5), and during the influenza season, 3.8% of all respiratory failure hospitalizations were attributable to influenza. Compared with adults aged 18-49 years, the incidence rate ratio for influenza-associated acute respiratory failure was lower among children aged 1-4 (0.9) and 5-17 years (0.3); however, it was higher among adults aged 50-64 (4.8), 65-74 (10.4), 75-84 (19.9), and 85 years and older (33.7). Results were similar with more sensitive and specific outcome definitions and in a sensitivity analysis using only Arizona-specific outcome and surveillance data. CONCLUSIONS Our data indicate that influenza was an important contributor to respiratory failure hospitalizations during 2003-2009. Clinicians should maintain a high index of suspicion for influenza among hospitalized patients with acute respiratory illness when influenza is circulating in a community. Influenza has a greater effect on respiratory failure in the elderly, for whom better prevention measures are needed.
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Schanzer DL, McGeer A, Morris K. Statistical estimates of respiratory admissions attributable to seasonal and pandemic influenza for Canada. Influenza Other Respir Viruses 2013; 7:799-808. [PMID: 23122189 PMCID: PMC3796862 DOI: 10.1111/irv.12011] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND The number of admissions to hospital for which influenza is laboratory confirmed is considered to be a substantial underestimate of the true number of admissions due to an influenza infection. During the 2009 pandemic, testing for influenza in hospitalized patients was a priority, but the ascertainment rate remains uncertain. METHODS The discharge abstracts of persons admitted with any respiratory condition were extracted from the Canadian Discharge Abstract Database, for April 2003-March 2010. Stratified, weekly admissions were modeled as a function of viral activity, seasonality, and trend using Poisson regression models. RESULTS An estimated 1 out of every 6.4 admissions attributable to seasonal influenza (2003-April 2009) were coded to J10 (influenza virus identified). During the 2009 pandemic (May-March 2010), the influenza virus was identified in 1 of 1.6 admissions (95% CI, 1.5-1.7) attributed to the pandemic strain. Compared with previous H1N1 seasons (2007/08, 2008/09), the influenza-attributed hospitalization rate for persons <65 years was approximately six times higher during the 2009 H1N1 pandemic, whereas for persons 75 years or older, the pandemic rate was approximately fivefold lower. CONCLUSIONS Case ascertainment was much improved during the pandemic period, with under ascertainment of admissions due to H1N1/2009 limited primarily to patients with a diagnosis of pneumonia.
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Affiliation(s)
- Dena L Schanzer
- Infectious Disease Prevention and Control Branch, Public Health Agency of Canada, Ottawa, ON, Canada.
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20
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Estimates of excess medically attended acute respiratory infections in periods of seasonal and pandemic influenza in Germany from 2001/02 to 2010/11. PLoS One 2013; 8:e64593. [PMID: 23874380 PMCID: PMC3712969 DOI: 10.1371/journal.pone.0064593] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 04/16/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The number of patients seeking health care is a central indicator that may serve several different purposes: (1) as a proxy for the impact on the burden of the primary care system; (2) as a starting point to estimate the number of persons ill with influenza; (3) as the denominator data for the calculation of case fatality rate and the proportion hospitalized (severity indicators); (4) for economic calculations. In addition, reliable estimates of burden of disease and on the health care system are essential to communicate the impact of influenza to health care professionals, public health professionals and to the public. METHODOLOGY/PRINCIPAL FINDINGS Using German syndromic surveillance data, we have developed a novel approach to describe the seasonal variation of medically attended acute respiratory infections (MAARI) and estimate the excess MAARI attributable to influenza. The weekly excess inside a period of influenza circulation is estimated as the difference between the actual MAARI and a MAARI-baseline, which is established using a cyclic regression model for counts. As a result, we estimated the highest ARI burden within the last 10 years for the influenza season 2004/05 with an excess of 7.5 million outpatient visits (CI95% 6.8-8.0). In contrast, the pandemic wave 2009 accounted for one third of this burden with an excess of 2.4 million (CI95% 1.9-2.8). Estimates can be produced for different age groups, different geographic regions in Germany and also in real time during the influenza waves.
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Nguyen AM, Noymer A. Influenza mortality in the United States, 2009 pandemic: burden, timing and age distribution. PLoS One 2013; 8:e64198. [PMID: 23717567 PMCID: PMC3661470 DOI: 10.1371/journal.pone.0064198] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Accepted: 04/09/2013] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND In April 2009, the most recent pandemic of influenza A began. We present the first estimates of pandemic mortality based on the newly-released final data on deaths in 2009 and 2010 in the United States. METHODS We obtained data on influenza and pneumonia deaths from the National Center for Health Statistics (NCHS). Age- and sex-specific death rates, and age-standardized death rates, were calculated. Using negative binomial Serfling-type methods, excess mortality was calculated separately by sex and age groups. RESULTS In many age groups, observed pneumonia and influenza cause-specific mortality rates in October and November 2009 broke month-specific records since 1959 when the current series of detailed US mortality data began. Compared to the typical pattern of seasonal flu deaths, the 2009 pandemic age-specific mortality, as well as influenza-attributable (excess) mortality, skewed much younger. We estimate 2,634 excess pneumonia and influenza deaths in 2009-10; the excess death rate in 2009 was 0.79 per 100,000. CONCLUSIONS Pandemic influenza mortality skews younger than seasonal influenza. This can be explained by a protective effect due to antigenic cycling. When older cohorts have been previously exposed to a similar antigen, immune memory results in lower death rates at older ages. Age-targeted vaccination of younger people should be considered in future pandemics.
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Affiliation(s)
- Ann M. Nguyen
- Palomar Health, Escondido, California, United States of America
| | - Andrew Noymer
- Department of Population Health and Disease Prevention, University of California Irvine, Irvine, California, United States of America
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Schanzer DL, Schwartz B. Impact of seasonal and pandemic influenza on emergency department visits, 2003-2010, Ontario, Canada. Acad Emerg Med 2013; 20:388-97. [PMID: 23701347 PMCID: PMC3748786 DOI: 10.1111/acem.12111] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 09/30/2012] [Accepted: 10/06/2012] [Indexed: 01/07/2023]
Abstract
Objectives Weekly influenza-like illness (ILI) consultation rates are an integral part of influenza surveillance. However, in most health care settings, only a small proportion of true influenza cases are clinically diagnosed as influenza or ILI. The primary objective of this study was to estimate the number and rate of visits to the emergency department (ED) that are attributable to seasonal and pandemic influenza and to describe the effect of influenza on the ED by age, diagnostic categories, and visit disposition. A secondary objective was to assess the weekly “real-time” time series of ILI ED visits as an indicator of the full burden due to influenza. Methods The authors performed an ecologic analysis of ED records extracted from the National Ambulatory Care Reporting System (NARCS) database for the province of Ontario, Canada, from September 2003 to March 2010 and stratified by diagnostic characteristics (International Classification of Diseases, 10th Revision [ICD-10]), age, and visit disposition. A regression model was used to estimate the seasonal baseline. The weekly number of influenza-attributable ED visits was calculated as the difference between the weekly number of visits predicted by the statistical model and the estimated baseline. Results The estimated rate of ED visits attributable to influenza was elevated during the H1N1/2009 pandemic period at 1,000 per 100,000 (95% confidence interval [CI] = 920 to 1,100) population compared to an average annual rate of 500 per 100,000 (95% CI = 450 to 550) for seasonal influenza. ILI or influenza was clinically diagnosed in one of 2.6 (38%) and one of 14 (7%) of these visits, respectively. While the ILI or clinical influenza diagnosis was the diagnosis most specific to influenza, only 87% and 58% of the clinically diagnosed ILI or influenza visits for pandemic and seasonal influenza, respectively, were likely directly due to an influenza infection. Rates for ILI ED visits were highest for younger age groups, while the likelihood of admission to hospital was highest in older persons. During periods of seasonal influenza activity, there was a significant increase in the number of persons who registered with nonrespiratory complaints, but left without being seen. This effect was more pronounced during the 2009 pandemic. The ratio of influenza-attributed respiratory visits to influenza-attributed ILI visits varied from 2.4:1 for the fall H1N1/2009 wave to 9:1 for the 2003/04 influenza A(H3N2) season and 28:1 for the 2007/08 H1N1 season. Conclusions Influenza appears to have had a much larger effect on ED visits than was captured by clinical diagnoses of influenza or ILI. Throughout the study period, ILI ED visits were strongly associated with excess respiratory complaints. However, the relationship between ILI ED visits and the estimated effect of influenza on ED visits was not consistent enough from year to year to predict the effect of influenza on the ED or downstream in-hospital resource requirements.
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Affiliation(s)
- Dena L. Schanzer
- Centre for Communicable Diseases and Infection Control Infectious Disease Prevention and Control Branch Public Health Agency of Canada Ottawa Ontario
| | - Brian Schwartz
- Public Health Ontario and the Department of Family and Community Medicine University of Toronto Toronto Ontario Canada
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Wong CM, Yang L, Chan KP, Chan WM, Song L, Lai HK, Thach TQ, Ho LM, Chan KH, Lam TH, Peiris JSM. Cigarette smoking as a risk factor for influenza-associated mortality: evidence from an elderly cohort. Influenza Other Respir Viruses 2012; 7:531-9. [PMID: 22813463 PMCID: PMC5855151 DOI: 10.1111/j.1750-2659.2012.00411.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Please cite this paper as: Wong et al. (2012) Cigarette smoking as a risk factor for influenza‐associated mortality: evidence from an elderly cohort. Influenza and Other Respiratory Viruses 7(4), 531–539. Background The effects of individual lifestyle factors on the mortality risk after influenza infection have not been explored. Objectives In this study, we assessed the modifying effects of cigarette smoking on mortality risks associated with influenza in a cohort of Hong Kong elders with a follow‐up period of 1998–2009. Methods We used the Cox proportional hazards model with time‐dependent covariates of weekly proportions of specimens positive for influenza (termed as influenza virus activity), to calculate the hazard ratio of mortality associated with a 10% increase in influenza virus activity for never, ex‐ and current smokers. Other individual lifestyle and socioeconomic factors as well as seasonal confounders were also added into the models. Results The overall hazard ratio associated with influenza was 1·028 (95% confidence interval, 1·006, 1·051) for all natural cause mortality and 1·035 (1·003, 1·068) for cardiovascular and respiratory mortality. We found that influenza‐associated hazard ratio was greater in current and ex‐smokers than in never smokers for mortality of all natural causes, cardiovascular and respiratory diseases. Conclusions The findings suggest that smoking might increase influenza‐associated mortality risks among elders.
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Affiliation(s)
- Chit M Wong
- School of Public Health, The University of Hong Kong, Hong Kong, China
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Wang XL, Yang L, Chan KP, Chiu SS, Chan KH, Peiris JSM, Wong CM. Model selection in time series studies of influenza-associated mortality. PLoS One 2012; 7:e39423. [PMID: 22745751 PMCID: PMC3380027 DOI: 10.1371/journal.pone.0039423] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 05/21/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Poisson regression modeling has been widely used to estimate influenza-associated disease burden, as it has the advantage of adjusting for multiple seasonal confounders. However, few studies have discussed how to judge the adequacy of confounding adjustment. This study aims to compare the performance of commonly adopted model selection criteria in terms of providing a reliable and valid estimate for the health impact of influenza. METHODS We assessed four model selection criteria: quasi Akaike information criterion (QAIC), quasi bayesian information criterion (QBIC), partial autocorrelation functions of residuals (PACF), and generalized cross-validation (GCV), by separately applying them to select the Poisson model best fitted to the mortality datasets that were simulated under the different assumptions of seasonal confounding. The performance of these criteria was evaluated by the bias and root-mean-square error (RMSE) of estimates from the pre-determined coefficients of influenza proxy variable. These four criteria were subsequently applied to an empirical hospitalization dataset to confirm the findings of simulation study. RESULTS GCV consistently provided smaller biases and RMSEs for the influenza coefficient estimates than QAIC, QBIC and PACF, under the different simulation scenarios. Sensitivity analysis of different pre-determined influenza coefficients, study periods and lag weeks showed that GCV consistently outperformed the other criteria. Similar results were found in applying these selection criteria to estimate influenza-associated hospitalization. CONCLUSIONS GCV criterion is recommended for selection of Poisson models to estimate influenza-associated mortality and morbidity burden with proper adjustment for confounding. These findings shall help standardize the Poisson modeling approach for influenza disease burden studies.
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Affiliation(s)
- Xi-Ling Wang
- School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Lin Yang
- School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
- * E-mail:
| | - King-Pan Chan
- School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Susan S. Chiu
- Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Kwok-Hung Chan
- Department of microbiology, Queen Mary Hospital, Hong Kong Special Administrative Region, China
| | - J. S. Malik Peiris
- School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
- The University of Hong Kong Pasteur Research Center, Hong Kong Special Administrative Region, China
| | - Chit-Ming Wong
- School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
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Zhou H, Thompson WW, Viboud CG, Ringholz CM, Cheng PY, Steiner C, Abedi GR, Anderson LJ, Brammer L, Shay DK. Hospitalizations associated with influenza and respiratory syncytial virus in the United States, 1993-2008. Clin Infect Dis 2012; 54:1427-36. [PMID: 22495079 DOI: 10.1093/cid/cis211] [Citation(s) in RCA: 429] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Age-specific comparisons of influenza and respiratory syncytial virus (RSV) hospitalization rates can inform prevention efforts, including vaccine development plans. Previous US studies have not estimated jointly the burden of these viruses using similar data sources and over many seasons. METHODS We estimated influenza and RSV hospitalizations in 5 age categories (<1, 1-4, 5-49, 50-64, and ≥65 years) with data for 13 states from 1993-1994 through 2007-2008. For each state and age group, we estimated the contribution of influenza and RSV to hospitalizations for respiratory and circulatory disease by using negative binomial regression models that incorporated weekly influenza and RSV surveillance data as covariates. RESULTS Mean rates of influenza and RSV hospitalizations were 63.5 (95% confidence interval [CI], 37.5-237) and 55.3 (95% CI, 44.4-107) per 100000 person-years, respectively. The highest hospitalization rates for influenza were among persons aged ≥65 years (309/100000; 95% CI, 186-1100) and those aged <1 year (151/100000; 95% CI, 151-660). For RSV, children aged <1 year had the highest hospitalization rate (2350/100000; 95% CI, 2220-2520) followed by those aged 1-4 years (178/100000; 95% CI, 155-230). Age-standardized annual rates per 100000 person-years varied substantially for influenza (33-100) but less for RSV (42-77). CONCLUSIONS Overall US hospitalization rates for influenza and RSV are similar; however, their age-specific burdens differ dramatically. Our estimates are consistent with those from previous studies focusing either on influenza or RSV. Our approach provides robust national comparisons of hospitalizations associated with these 2 viral respiratory pathogens by age group and over time.
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Affiliation(s)
- Hong Zhou
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA
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Yang L, Chen PY, He JF, Chan KP, Ou CQ, Deng AP, Malik Peiris JS, Wong CM. Effect modification of environmental factors on influenza-associated mortality: a time-series study in two Chinese cities. BMC Infect Dis 2011; 11:342. [PMID: 22168284 PMCID: PMC3265445 DOI: 10.1186/1471-2334-11-342] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 12/14/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Environmental factors have been associated with transmission and survival of influenza viruses but no studies have ever explored the role of environmental factors on severity of influenza infection. METHODS We applied a Poisson regression model to the mortality data of two Chinese metropolitan cities located within the subtropical zone, to calculate the influenza associated excess mortality risks during the periods with different levels of temperature and humidity. RESULTS The results showed that high absolute humidity (measured by vapor pressure) was significantly (p < 0.05) associated with increased risks of all-cause and cardiorespiratory deaths, but not with increased risks of pneumonia and influenza deaths. The association between absolute humidity and mortality risks was found consistent among the two cities. An increasing pattern of influenza associated mortality risks was also found across the strata of low to high relative humidity, but the results were less consistent for temperature. CONCLUSIONS These findings highlight the need for people with chronic cardiovascular and respiratory diseases to take extra caution against influenza during hot and humid days in the subtropics and tropics.
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Affiliation(s)
- Lin Yang
- Department of Community Medicine, School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, 5/F William Mong Block, 21 Sassoon Road, Hong Kong, China
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Excess mortality associated with the 2009 pandemic of influenza A(H1N1) in Hong Kong. Epidemiol Infect 2011; 140:1542-50. [DOI: 10.1017/s0950268811002238] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
SUMMARYReliable estimates of the burden of 2009 pandemic influenza A(pH1N1) cannot be easily obtained because only a small fraction of infections were confirmed by laboratory tests in a timely manner. In this study we developed a Poisson prediction modelling approach to estimate the excess mortality associated with pH1N1 in 2009 and seasonal influenza in 1998–2008 in the subtropical city Hong Kong. The results suggested that there were 127 all-cause excess deaths associated with pH1N1, including 115 with cardiovascular and respiratory disease, and 22 with pneumonia and influenza. The excess mortality rates associated with pH1N1 were highest in the population aged ⩾65 years. The mortality burden of influenza during the whole of 2009 was comparable to those in the preceding ten inter-pandemic years. The estimates of excess deaths were more than twofold higher than the reported fatal cases with laboratory-confirmed pH1N1 infection.
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Yang L, Ma S, Chen PY, He JF, Chan KP, Chow A, Ou CQ, Deng AP, Hedley AJ, Wong CM, Peiris JM. Influenza associated mortality in the subtropics and tropics: results from three Asian cities. Vaccine 2011; 29:8909-14. [PMID: 21959328 PMCID: PMC7115499 DOI: 10.1016/j.vaccine.2011.09.071] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 08/12/2011] [Accepted: 09/16/2011] [Indexed: 11/19/2022]
Abstract
Influenza has been well documented to significantly contribute to winter increase of mortality in the temperate countries, but its severity in the subtropics and tropics was not recognized until recently and geographical variations of disease burden in these regions remain poorly understood. In this study, we applied a standardized modeling strategy to the mortality and virology data from three Asian cities: subtropical Guangzhou and Hong Kong, and tropical Singapore, to estimate the disease burden of influenza in these cities. We found that influenza was associated with 10.6, 13.4 and 8.3 deaths per 100,000 population in Guangzhou, Hong Kong and Singapore, respectively. The annual rates of excess deaths in the elders were estimated highest in Guangzhou and lowest in Singapore. The excess death rate attributable to A/H1N1 subtype was found slightly higher than the rates attributable to A/H3N2 during the study period of 2004-2006 based on the data from Hong Kong and Guangzhou. Our study revealed a geographical variation in the disease burden of influenza in these subtropical and tropical cities. These results highlight a need to explore the determinants for severity of seasonal influenza.
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Affiliation(s)
- Lin Yang
- Department of Community Medicine and School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Stefan Ma
- Epidemiology & Disease Control Division, Ministry of Health, Singapore
| | - Ping Yan Chen
- Department of Biostatistics, School of Public Health and Tropical Medicine, Southern Medical University, China
| | - Jian Feng He
- Guangdong Provincial Center for Disease Control and Prevention, China
| | - King Pan Chan
- Department of Community Medicine and School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Angela Chow
- Communicable Disease Centre, Tan Tock Seng Hospital, Singapore
| | - Chun Quan Ou
- Department of Biostatistics, School of Public Health and Tropical Medicine, Southern Medical University, China
| | - Ai Ping Deng
- Guangdong Provincial Center for Disease Control and Prevention, China
| | - Anthony J. Hedley
- Department of Community Medicine and School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Chit Ming Wong
- Department of Community Medicine and School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - J.S. Malik Peiris
- Department of Microbiology, The University of Hong Kong, Hong Kong Special Administrative Region, China
- HKU Pasteur Research Center, Hong Kong Special Administrative Region, China
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