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Leung VKY, Wong JY, Barnes R, Kelso J, Milne GJ, Blyth CC, Cowling BJ, Moore HC, Sullivan SG. Excess respiratory mortality and hospitalizations associated with influenza in Australia, 2007-2015. Int J Epidemiol 2021; 51:458-467. [PMID: 34333637 DOI: 10.1093/ije/dyab138] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/25/2021] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Influenza is the most common vaccine-preventable disease in Australia, causing significant morbidity and mortality. We assessed the burden of influenza across all ages in terms of influenza-associated mortality and hospitalizations using national mortality, hospital-discharge and influenza surveillance data. METHODS Influenza-associated excess respiratory mortality and hospitalization rates from 2007 to 2015 were estimated using generalized additive models with a proxy of influenza activity based on syndromic and laboratory surveillance data. Estimates were made for each age group and year. RESULTS The estimated mean annual influenza-associated excess respiratory mortality was 2.6 per 100 000 population [95% confidence interval (CI): 1.8, 3.4 per 100 000 population]. The excess annual respiratory hospitalization rate was 57.4 per 100 000 population (95% CI: 32.5, 82.2 per 100 000 population). The highest mortality rates were observed among those aged ≥75 years (35.11 per 100 000 population; 95% CI: 19.93, 50.29 per 100 000 population) and hospitalization rates were also highest among older adults aged ≥75 years (302.95 per 100 000 population; 95% CI: 144.71, 461.19 per 100 000 population), as well as children aged <6 months (164.02 per 100 000 population; 95% CI: -34.84, 362.88 per 100 000 population). Annual variation was apparent, ranging from 1.0 to 3.9 per 100 000 population for mortality and 24.2 to 94.28 per 100 000 population for hospitalizations. Influenza A contributed to almost 80% of the average excess respiratory hospitalizations and 60% of the average excess respiratory deaths. CONCLUSIONS Influenza causes considerable burden to all Australians. Expected variation was observed among age groups, years and influenza type, with the greatest burden falling to older adults and young children. Understanding the current burden is useful for understanding the potential impact of mitigation strategies, such as vaccination.
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Affiliation(s)
- Vivian K Y Leung
- WHO Collaborating Centre for Reference and Research on Influenza, Royal Melbourne Hospital, at the Peter Doherty Institute for Infection and Immunity, Victoria, Australia
| | - Jessica Y Wong
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, Hong Kong, PR China
| | - Roseanne Barnes
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Perth, Western Australia, Australia
| | - Joel Kelso
- Department of Computer Science, University of Western Australia, Perth, Australia
| | - George J Milne
- Department of Computer Science, University of Western Australia, Perth, Australia
| | - Christopher C Blyth
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Perth, Western Australia, Australia.,School of Medicine, University of Western Australia, Perth, Western Australia, Australia.,PathWest Laboratory Medicine WA, QE11 Medical Centre, Perth, Western Australia, Australia.,Department of Infectious Diseases, Perth Children's Hospital, Perth, Western Australia, Australia
| | - Benjamin J Cowling
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, Hong Kong, PR China
| | - Hannah C Moore
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Perth, Western Australia, Australia
| | - Sheena G Sullivan
- WHO Collaborating Centre for Reference and Research on Influenza, Royal Melbourne Hospital, at the Peter Doherty Institute for Infection and Immunity, Victoria, Australia.,Department of Infectious Diseases, University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Australia.,Department of Epidemiology, University of California, Los Angeles, USA
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2
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Yu Q, Li X, Fan M, Qiu H, Wong AYS, Tian L, Chui CSL, Li PH, Lau LKW, Chan EW, Goggins WB, Ip P, Lum TY, Hung IFN, Cowling BJ, Wong ICK, Jit M. The impact of childhood pneumococcal conjugate vaccine immunisation on all-cause pneumonia admissions in Hong Kong: A 14-year population-based interrupted time series analysis. Vaccine 2021; 39:2628-2635. [PMID: 33858719 DOI: 10.1016/j.vaccine.2021.03.090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 03/25/2021] [Accepted: 03/29/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND Nine years after the introduction of pneumococcal conjugate vaccine (PCV) in the United States, Hong Kong (HK) introduced the vaccine to its universal childhood immunisation programme in 2009. We aimed to assess the impact of childhood PCV immunisation on all-cause pneumonia (ACP) admissions among the overall population of HK. METHODS In this population-based interrupted time series analysis, we used territory-wide population-representative electronic health records in HK to evaluate the vaccine impact. We identified hospitalised patients with a diagnosis of pneumonia from any cause between 2004 and 2017. We applied segmented Poisson regression to assess the gradual change in the monthly incidence of ACP admissions between pre- and post-vaccination periods. Negative outcome control, subgroup and sensitivity analyses were used to test the robustness of the main analysis. FINDINGS Over the 14-year study period, a total of 587,607 ACP episodes were identified among 357,950 patients. The monthly age-standardised incidence of ACP fluctuated between 33.42 and 87.44 per 100,000-persons. There was a marginal decreasing trend in pneumonia admissions after PCV introduction among overall population (incidence rate ratio [IRR]: 0·9965, 95% confidence interval [CI]: 0·9932-0·9998), and older adults (≥65 years, IRR: 0·9928, 95% CI: 0·9904-0·9953) but not in younger age groups. INTERPRETATION There was a marginally declining trend of overall ACP admissions in HK up to eight years after childhood PCV introduction. The significance disappeared when fitting sensitivity analyses. The results indicate the complexities of using non-specific endpoints for measuring vaccine effect and the necessity of enhancing serotype surveillance systems for replacement monitoring. FUNDING Health and Medical Research Fund, Food and Health Bureau of the Government of Hong Kong (Reference number: 18171272).
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Affiliation(s)
- Qiuyan Yu
- Centre for Safe Medication Practice and Research, Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China; Laboratory of Data Discovery for Health (D²4H), Hong Kong, China
| | - Xue Li
- Centre for Safe Medication Practice and Research, Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China; Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong; Laboratory of Data Discovery for Health (D²4H), Hong Kong, China.
| | - Min Fan
- Centre for Safe Medication Practice and Research, Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Hong Qiu
- Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Hong Kong, China
| | - Angel Y S Wong
- Department of Non-communicable Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK
| | - Linwei Tian
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Celine S L Chui
- Laboratory of Data Discovery for Health (D²4H), Hong Kong, China; School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China; School of Nursing, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Philip H Li
- Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Lauren K W Lau
- Centre for Safe Medication Practice and Research, Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Esther W Chan
- Centre for Safe Medication Practice and Research, Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China; Laboratory of Data Discovery for Health (D²4H), Hong Kong, China
| | - William B Goggins
- Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China
| | - Patrick Ip
- Department of Paediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Terry Y Lum
- Department of Social Work and Social Administration, Faculty of Social Sciences, The University of Hong Kong, Hong Kong, China; Sau Po Centre on Ageing, The University of Hong Kong, Hong Kong, China
| | - Ivan F N Hung
- Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Benjamin J Cowling
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Ian C K Wong
- Centre for Safe Medication Practice and Research, Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China; Laboratory of Data Discovery for Health (D²4H), Hong Kong, China; Research Department of Policy and Practice, University College London School of Pharmacy, London, UK
| | - Mark Jit
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China; Centre for Mathematical Modelling of Infectious Diseases, Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
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Lam SC, Chong ACY, Chung JYS, Lam MY, Chan LM, Shum CY, Wong EYN, Mok YM, Lam MT, Chan MM, Tong KY, Chu OL, Siu FK, Cheung JHM. Methodological Study on the Evaluation of Face Mask Use Scale among Public Adult: Cross-Language and Psychometric Testing. ACTA ACUST UNITED AC 2020. [DOI: 10.7475/kjan.2020.32.1.46] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Simon Ching Lam
- Assistant Professor, School of Nursing, The Hong Kong Polytechnic University, Hong Kong SAR
| | - Andy Chun Yin Chong
- Senior Lecturer, School of Nursing and Health Studies, The Open University of Hong Kong, Hong Kong SAR
| | - Jessie Yuk Seng Chung
- Senior Lecturer, School of Nursing and Health Studies, The Open University of Hong Kong, Hong Kong SAR
| | - Ming Yee Lam
- Registered Nurse, Yan Chai Hospital, Hospital Authority, Hong Kong SAR
| | - Lai Man Chan
- Registered Nurse, Caritas Medical Center, Hospital Authority, Hong Kong SAR
| | - Cho Yee Shum
- Registered Nurse, Prince of Wales Hospital, Hospital Authority, Hong Kong SAR
| | - Eliza Yi Ni Wong
- Registered Nurse, Prince of Wales Hospital, Hospital Authority, Hong Kong SAR
| | - Yat Man Mok
- Registered Nurse, Ruttonjee Hospital, Hospital Authority, Hong Kong SAR
| | - Ming Tat Lam
- Registered Nurse, Queen Mary Hospital, Hospital Authority, Hong Kong SAR
| | - Man Man Chan
- Registered Nurse, Prince of Wales Hospital, Hospital Authority, Hong Kong SAR
| | - Ka Ying Tong
- Registered Nurse, St. Paul's Hospital, Hong Kong Island, Hong Kong SAR
| | - Oi Lee Chu
- Registered Nurse, Prince of Wales Hospital, Hospital Authority, Hong Kong SAR
| | - Fong Kiu Siu
- Registered Nurse, Caritas Medical Center, Hospital Authority, Hong Kong SAR
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Sullivan SG, Price OH, Regan AK. Burden, effectiveness and safety of influenza vaccines in elderly, paediatric and pregnant populations. Ther Adv Vaccines Immunother 2019; 7:2515135519826481. [PMID: 30793097 PMCID: PMC6376509 DOI: 10.1177/2515135519826481] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 12/20/2018] [Indexed: 11/17/2022] Open
Abstract
Vaccination is the most practical means available for preventing influenza. Influenza vaccines require frequent updates to keep pace with antigenic drift of the virus, and the effectiveness, and sometimes the safety, of the vaccine can therefore vary from season to season. Three key populations that the World Health Organization recommends should be prioritized for influenza vaccination are pregnant women, children younger than 5 years of age and the elderly. This review discusses the burden of influenza and the safety and effectiveness profile of influenza vaccines recommended for these groups.
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Affiliation(s)
- Sheena G Sullivan
- WHO Collaborating Centre for Reference and Research on Influenza, Peter Doherty Institute for Infection and Immunity, 792 Elizabeth St, Melbourne, Victoria 3000, Australia
| | - Olivia H Price
- WHO Collaborating Centre for Reference and Research on Influenza, Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Annette K Regan
- School of Public Health, Texas A&M University, College Station, TX, United States; School of Public Health, Curtin University, Perth, Western Australia, Australia, and Wesfamers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, Crawley, Western Australia, Australia
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5
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Significant spike in excess mortality in England in winter 2014/15 - influenza the likely culprit. Epidemiol Infect 2018; 146:1106-1113. [PMID: 29743125 DOI: 10.1017/s0950268818001152] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Significant increases in excess all-cause mortality, particularly in the elderly, were observed during the winter of 2014/15 in England. With influenza A(H3N2) the dominant circulating influenza A subtype, this paper determines the contribution of influenza to this excess controlling for weather. A standardised multivariable Poisson regression model was employed with weekly all-cause deaths the dependent variable for the period 2008-2015. Adjusting for extreme temperature, a total of 26 542 (95% CI 25 301-27 804) deaths in 65+ and 1942 (95% CI 1834-2052) in 15-64-year-olds were associated with influenza from week 40, 2014 to week 20, 2015. This is compatible with the circulation of influenza A(H3N2). It is the largest estimated number of influenza-related deaths in England since prior to 2008/09. The findings highlight the potential health impact of influenza and the important role of the annual influenza vaccination programme that is required to protect the population including the elderly, who are vulnerable to a severe outcome.
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Li L, Wong JY, Wu P, Bond HS, Lau EHY, Sullivan SG, Cowling BJ. Heterogeneity in Estimates of the Impact of Influenza on Population Mortality: A Systematic Review. Am J Epidemiol 2018; 187:378-388. [PMID: 28679157 PMCID: PMC5860627 DOI: 10.1093/aje/kwx270] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 06/22/2017] [Accepted: 06/27/2017] [Indexed: 12/15/2022] Open
Abstract
Influenza viruses are associated with a substantial global burden of morbidity and mortality every year. Estimates of influenza-associated mortality often vary between studies due to differences in study settings, methods, and measurement of outcomes. We reviewed 103 published articles assessing population-based influenza-associated mortality through searches of PubMed and Embase, and we identified considerable variation in the statistical methods used across studies. Studies using regression models with an influenza activity proxy applied 4 approaches to estimate influenza-associated mortality. The estimates increased with age and ranged widely, from -0.3-1.3 and 0.6-8.3 respiratory deaths per 100,000 population for children and adults, respectively, to 4-119 respiratory deaths per 100,000 population for older adults. Meta-regression analysis identified that study design features were associated with the observed variation in estimates. The estimates increased with broader cause-of-death classification and were higher for older adults than for children. The multiplier methods tended to produce lower estimates, while Serfling-type models were associated with higher estimates than other methods. No "average" estimate of excess mortality could reliably be made due to the substantial variability of the estimates, partially attributable to methodological differences in the studies. Standardization of methodology in estimation of influenza-associated mortality would permit improved comparisons in the future.
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Affiliation(s)
- Li Li
- WHO Collaborating Center for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, China
- WHO Collaborating Center for Reference and Research on Influenza, Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
- Department of Epidemiology, Fielding School of Public Health, University of California, Los Angeles, Los Angeles, California
| | - Jessica Y Wong
- WHO Collaborating Center for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Peng Wu
- WHO Collaborating Center for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Helen S Bond
- WHO Collaborating Center for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Eric H Y Lau
- WHO Collaborating Center for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Sheena G Sullivan
- WHO Collaborating Center for Reference and Research on Influenza, Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
- Department of Epidemiology, Fielding School of Public Health, University of California, Los Angeles, Los Angeles, California
| | - Benjamin J Cowling
- WHO Collaborating Center for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, China
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7
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Zhang H, Xiong Q, Wu P, Chen Y, Leung NHL, Cowling BJ. Influenza-associated mortality in Yancheng, China, 2011-15. Influenza Other Respir Viruses 2018; 12:98-103. [PMID: 29193690 PMCID: PMC5818359 DOI: 10.1111/irv.12487] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2017] [Indexed: 12/01/2022] Open
Abstract
INTRODUCTION The Yangtze river delta in eastern China, centered on Shanghai, is one of the most populated regions of the world with more than 100 million residents. We examined the impact of influenza on excess mortality in Yancheng, a prefecture-level city with 8.2 million population located 250 km north of Shanghai, during 2011-2015. METHODS We obtained individual data on deaths by date, age, sex, and cause in Yancheng from the Chinese Centers for Disease Control and Prevention, and used these to derive weekly rates of mortality from respiratory causes, respiratory and cardiovascular causes combined, and all causes. We used data on influenza-like illnesses and laboratory detections of influenza to construct a proxy measure of the weekly incidence of influenza virus infections in the community. We used regression models to estimate the association of influenza activity with mortality and excess mortality by age, cause, and influenza type/subtype. RESULTS We estimated that an annual average of 4.59 (95% confidence interval: 3.94, 7.41) excess respiratory deaths per 100 000 persons were associated with influenza, which was 4.6% of all respiratory deaths in the years studied. Almost all influenza-associated excess deaths occurred in persons ≥65 years. Influenza A(H3N2) had the greatest impact on mortality and was associated with around 50% of the influenza-associated respiratory deaths in the 5 years studied. CONCLUSIONS Influenza has a substantial impact on respiratory mortality in Yancheng, mainly in older adults. Influenza vaccination has the potential to reduce disease burden, and cost-effectiveness analysis could be used to compare policy options.
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Affiliation(s)
- Hongjun Zhang
- Yancheng Center for Disease Prevention and ControlYanchengChina
| | - Qian Xiong
- WHO Collaborating Centre for Infectious Disease Epidemiology and ControlSchool of Public Health, Li Ka Shing Faculty of MedicineThe University of Hong KongHong Kong Special Administrative RegionHong KongChina
| | - Peng Wu
- WHO Collaborating Centre for Infectious Disease Epidemiology and ControlSchool of Public Health, Li Ka Shing Faculty of MedicineThe University of Hong KongHong Kong Special Administrative RegionHong KongChina
| | - Yuyun Chen
- WHO Collaborating Centre for Infectious Disease Epidemiology and ControlSchool of Public Health, Li Ka Shing Faculty of MedicineThe University of Hong KongHong Kong Special Administrative RegionHong KongChina
| | - Nancy H. L. Leung
- WHO Collaborating Centre for Infectious Disease Epidemiology and ControlSchool of Public Health, Li Ka Shing Faculty of MedicineThe University of Hong KongHong Kong Special Administrative RegionHong KongChina
| | - Benjamin J. Cowling
- WHO Collaborating Centre for Infectious Disease Epidemiology and ControlSchool of Public Health, Li Ka Shing Faculty of MedicineThe University of Hong KongHong Kong Special Administrative RegionHong KongChina
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8
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Kwok KO, Riley S, Perera RAPM, Wei VWI, Wu P, Wei L, Chu DKW, Barr IG, Malik Peiris JS, Cowling BJ. Relative incidence and individual-level severity of seasonal influenza A H3N2 compared with 2009 pandemic H1N1. BMC Infect Dis 2017; 17:337. [PMID: 28494805 PMCID: PMC5425986 DOI: 10.1186/s12879-017-2432-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 04/28/2017] [Indexed: 12/25/2022] Open
Abstract
Background Two subtypes of influenza A currently circulate in humans: seasonal H3N2 (sH3N2, emerged in 1968) and pandemic H1N1 (pH1N1, emerged in 2009). While the epidemiological characteristics of the initial wave of pH1N1 have been studied in detail, less is known about its infection dynamics during subsequent waves or its severity relative to sH3N2. Even prior to 2009, few data was available to estimate the risk of severe outcomes following infection with one circulating influenza strain relative to another. Methods We analyzed antibodies in quadruples of sera from individuals in Hong Kong collected between July 2009 and December 2011, a period that included three distinct influenza virus epidemics. We estimated infection incidence using these assay data and then estimated rates of severe outcomes per infection using population-wide clinical data. Results Cumulative incidence of infection was high among children in the first epidemic of pH1N1. There was a change towards the older age group in the age distribution of infections for pH1N1 from the first to the second epidemic, with the age distribution of the second epidemic of pH1N1 more similar to that of sH3N2. We found no serological evidence that individuals were infected in both waves of pH1N1. The risks of excess mortality conditional on infection were higher for sH3N2 than for pH1N1, with age-standardized risk ratios of 2.6 [95% CI: 1.8, 3.7] for all causes and 1.5 [95% CI: 1.0, 2.1] for respiratory causes throughout the study period. Conclusions Overall increase in clinical incidence of pH1N1 and higher rates of severity in older adults in post pandemic waves were in line with an age-shift in infection towards the older age groups. The absence of repeated infection is good evidence that waning immunity did not cause the second wave. Despite circulating in humans since 1968, sH3N2 is substantially more severe per infection than the pH1N1 strain. Infection-based estimates of individual-level severity have a role in assessing emerging strains; updating seasonal vaccine components; and optimizing of vaccination programs. Electronic supplementary material The online version of this article (doi:10.1186/s12879-017-2432-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kin On Kwok
- JC School of Public Health and Primary Care, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, Hong Kong, Special Administrative Region of China.,Tanley Ho Centre for Emerging Infectious Diseases, The Chinese University of Hong Kong, Shatin, Hong Kong, Hong Kong, Special Administrative Region of China.,WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, Hong Kong, Special Administrative Region of China
| | - Steven Riley
- MRC Centre for Outbreak Analysis and Modelling, Department for Infectious Disease Epidemiology, Imperial College London, London, UK.
| | - Ranawaka A P M Perera
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, Hong Kong, Special Administrative Region of China
| | - Vivian W I Wei
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, Hong Kong, Special Administrative Region of China
| | - Peng Wu
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, Hong Kong, Special Administrative Region of China
| | - Lan Wei
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, Hong Kong, Special Administrative Region of China
| | - Daniel K W Chu
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, Hong Kong, Special Administrative Region of China
| | - Ian G Barr
- WHO Collaborating Centre for Reference and Research, Melbourne, VIC, Australia.,Department of Microbiology and Immunology, University of Melbourne, Melbourne, VIC, Australia
| | - J S Malik Peiris
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, Hong Kong, Special Administrative Region of China
| | - Benjamin J Cowling
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, Hong Kong, Special Administrative Region of China
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9
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Wu P, Presanis AM, Bond HS, Lau EHY, Fang VJ, Cowling BJ. A joint analysis of influenza-associated hospitalizations and mortality in Hong Kong, 1998-2013. Sci Rep 2017; 7:929. [PMID: 28428558 PMCID: PMC5430505 DOI: 10.1038/s41598-017-01021-x] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 03/23/2017] [Indexed: 12/02/2022] Open
Abstract
Influenza viruses may cause severe human infections leading to hospitalization or death. Linear regression models were fitted to population-based data on hospitalizations and deaths. Surveillance data on influenza virus activity permitted inference on influenza-associated hospitalizations and deaths. The ratios of these estimates were used as a potential indicator of severity. Influenza was associated with 431 (95% CrI: 358–503) respiratory deaths and 12,700 (95% CrI: 11,700–13,700) respiratory hospitalizations per year. Majority of the excess deaths occurred in persons ≥65 y of age. The ratios of deaths to hospitalizations in adults ≥65 y were significantly higher for influenza A(H1N1) and A(H1N1)pdm09 compared to A(H3N2) and B. Substantial disease burden associated with influenza viruses were estimated in Hong Kong particularly among children and elderly in 1998–2013. Infections with influenza A(H1N1) was suggested to be more serious than A(H3N2) in older adults.
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Affiliation(s)
- Peng Wu
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Anne M Presanis
- Medical Research Council Biostatistics Unit, Cambridge Institute of Public Health, Cambridge, UK
| | - Helen S Bond
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Eric H Y Lau
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Vicky J Fang
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Benjamin J Cowling
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.
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10
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Cowling BJ, Caini S, Chotpitayasunondh T, Djauzi S, Gatchalian SR, Huang QS, Koul PA, Lee PI, Muttalif AR, Plotkin S. Influenza in the Asia-Pacific region: Findings and recommendations from the Global Influenza Initiative. Vaccine 2017; 35:856-864. [PMID: 28081970 DOI: 10.1016/j.vaccine.2016.12.064] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 12/15/2016] [Accepted: 12/28/2016] [Indexed: 11/28/2022]
Abstract
The fourth roundtable meeting of the Global Influenza Initiative (GII) was held in Hong Kong, China, in July 2015. An objective of this meeting was to gain a broader understanding of the epidemiology, surveillance, vaccination policies and programs, and obstacles to vaccination of influenza in the Asia-Pacific region through presentations of data from Australia, Hong Kong, India, Indonesia, Malaysia, New Zealand, the Philippines, Taiwan, Thailand, and Vietnam. As well as a need for improved levels of surveillance in some areas, a range of factors were identified that act as barriers to vaccination in some countries, including differences in climate and geography, logistical challenges, funding, lack of vaccine awareness and education, safety concerns, perceived lack of vaccine effectiveness, and lack of inclusion in national guidelines. From the presentations at the meeting, the GII discussed a number of recommendations for easing the burden of influenza and overcoming the current challenges in the Asia-Pacific region. These recommendations encompass the need to improve surveillance and availability of epidemiological data; the development and publication of national guidelines, where not currently available and/or that are in line with those proposed by the World Health Organization; the requirement for optimal timing of vaccination programs according to local or country-specific epidemiology; and calls for advocacy and government support of vaccination programs in order to improve availability and uptake and coverage. In conclusion, in addition to the varied epidemiology of seasonal influenza across this diverse region, there are a number of logistical and resourcing issues that present a challenge to the development of optimally effective vaccination strategies and that need to be overcome to improve access to and uptake of seasonal influenza vaccines. The GII has developed a number of recommendations to address these challenges and improve the control of influenza.
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Affiliation(s)
- Benjamin J Cowling
- School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region.
| | - Saverio Caini
- NIVEL, Dutch Institute for Health Services Research, Utrecht, The Netherlands
| | - Tawee Chotpitayasunondh
- Queen Sirikit National Institute of Child Health, Ministry of Public Health, Bangkok, Thailand
| | | | - Salvacion R Gatchalian
- University of the Philippines Manila, College of Medicine, Philippine General Hospital, Manila City, Philippines
| | - Q Sue Huang
- Institute of Environmental Science and Research (ESR), Wallaceville, Upper Hutt, New Zealand
| | - Parvaiz A Koul
- Sher-i-Kashmir Institute of Medical Sciences, Srinagar, India
| | - Ping-Ing Lee
- National Taiwan University Children's Hospital, Taipei, Taiwan
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11
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Xu C, Fang VJ, Perera RA, Kam AMS, Ng S, Chan YH, Chan KH, Ip DK, Peiris JM, Cowling BJ. Serum 25-Hydroxyvitamin D Was Not Associated with Influenza Virus Infection in Children and Adults in Hong Kong, 2009-2010. J Nutr 2016; 146:2506-2512. [PMID: 27798334 DOI: 10.3945/jn.116.234856] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/09/2016] [Accepted: 09/30/2016] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Some studies have hypothesized that vitamin D may have a role to play in protection against influenza virus infections and illnesses, and that seasonal fluctuation in serum 25-hydroxyvitamin D [25(OH)D] may affect seasonal patterns of influenza virus infections. OBJECTIVE We aimed to investigate whether serum 25(OH)D concentrations were associated with the incidence of influenza virus infections and illnesses in children and adults in Hong Kong. METHODS In 2009-2010, 3030 children and adults of all ages from 796 households in Hong Kong were followed up to identify acute respiratory illnesses. Sera from 2694 participants were collected at baseline and after ∼1 mo, 6 mo, and 12 mo. Influenza virus infections were confirmed by reverse transcriptase-polymerase chain reaction performed on nasal and throat swab samples collected during illness episodes. Serologic evidence of influenza virus infection was measured by hemagglutination inhibition assays in unvaccinated participants. The serum 25(OH)D concentrations were measured after collection of all specimens. Each individual's baseline serum 25(OH)D concentration on 1 January 2010 was predicted by a random-effects linear regression model. RESULTS We found that, in children and adults who had not received a seasonal influenza vaccine, baseline serum 25(OH)D concentrations (<50 nmol/L compared with ≥50 nmol/L) were not statistically significantly associated with serologic evidence of influenza A(H1N1)pdm09 (RR, 1.18; 95% CI: 0.85, 1.65) or seasonal influenza virus infections [including A(H3N2) and B virus] (RR, 1.13; 95% CI: 0.86, 1.49). In all participants, baseline serum 25(OH)D concentrations were not statistically significantly associated with polymerase chain reaction-confirmed influenza virus infection (RR, 1.15; 95% CI: 0.73, 1.83) and influenza-like illness (RR, 1.18; 95% CI: 0.98, 1.43). CONCLUSIONS These findings indicate that lower serum vitamin D concentrations may not contribute to the seasonality of influenza and are not associated with an increased risk of influenza virus infections in persons of all ages in Hong Kong.
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Affiliation(s)
- Cuiling Xu
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Vicky J Fang
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Ranawaka Apm Perera
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Andrea May-Sin Kam
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Sophia Ng
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI
| | - Yap-Hang Chan
- Division of Cardiology, Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Pokfulam, Hong Kong, China; and
| | - Kwok-Hung Chan
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China; and
| | - Dennis Km Ip
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Js Malik Peiris
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Benjamin J Cowling
- WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong, China;
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12
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Chan YK, Wong RY, Ip M, Lee NL, You JH. Economic outcomes of influenza in hospitalized elderly with and without ICU admission. Antivir Ther 2016; 22:173-177. [PMID: 27740538 DOI: 10.3851/imp3102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2016] [Indexed: 10/20/2022]
Abstract
BACKGROUND To describe direct medical costs of influenza in hospitalized elderly, with and without intensive care unit (ICU) admission, during the 2014-2015 season in Hong Kong. METHODS A retrospective study was conducted in 110 inpatients aged ≥65 years with laboratory-confirmed influenza treated by antiviral therapy during season 2014-2015 in a tertiary hospital. Resource utilization of influenza-related diagnostic and laboratory tests, medications for influenza treatment, usage of general medical ward and ICU during the influenza-related length of hospital stay (IR-LOS) were collected. RESULTS There were 18 (16.4%) and 92 (83.4%) cases with and without ICU admission, respectively. The difference in influenza-related mortality rates between patients with (11.1%) and without ICU admission (2.2%) was not statistically significant (P=0.064). Patients with ICU admission reported longer IR-LOS (12.7 ±6.0 days versus 5.5 ±2.7 days; P<0.001) and higher direct costs (36,588 USD ±21,482 versus 5,773 USD ±2,017; P<0.001; 1 USD=7.8 HKD). Male gender (OR=14.50; 95% CI 1.68, 125.07) and respiratory complications (OR=9.61; 95% CI 1.90, 48.50) were positive predictors of ICU admission. Age ≥70 years (OR=0.09; 95% CI 0.02, 0.46) and antiviral therapy initiation within 7 days (OR=0.05; 95% CI 0.003, 0.79) were negative predictors of ICU admission. Influenza B was a positive predictor of high-cost hospitalization in non-ICU survivors (OR=7.33; 95% CI 1.24, 43.29). No predictor of mortality was identified. CONCLUSIONS Hospitalization cost in elderly for seasonal influenza was substantial in Hong Kong. The cost in patients with ICU admission was significantly higher than those without ICU care. Respiratory complications and male gender predicted ICU admission. Influenza B infection predicted high-cost hospitalization in non-ICU survivors.
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Affiliation(s)
- Yik-Kei Chan
- School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Rity Yk Wong
- Divison of Infectious Diseases, Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Margaret Ip
- Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Nelson Ls Lee
- Divison of Infectious Diseases, Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Joyce Hs You
- School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China
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13
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Abstract
BACKGROUND In influenza epidemiology, analysis of paired sera collected from people before and after influenza seasons has been used for decades to study the cumulative incidence of influenza virus infections in populations. However, interpretation becomes challenging when sera are collected after the start or before the end of an epidemic, and do not neatly bracket the epidemic. METHODS Serum samples were collected longitudinally in a community-based study. Most participants provided their first serum after the start of circulation of influenza A(H1N1)pdm09 virus in 2009. We developed a Bayesian hierarchical model to correct for nonbracketing sera and estimate the cumulative incidence of infection from the serological data and surveillance data in Hong Kong. RESULTS We analyzed 4,843 sera from 2,097 unvaccinated participants in the study, collected from April 2009 to December 2010. After accounting for nonbracketing, we estimated that the cumulative incidence of H1N1pdm09 virus infection was 45% (95% credible interval [CI] = 40%, 49%), 17% (95% CI = 13%, 20%), and 11% (95% CI = 6%, 18%) for children ages 0-18 years, adults 19-50 years, and older adults >50 years, respectively. Including all available data substantially increased precision compared with a simpler analysis based only on sera collected at 6-month intervals in a subset of participants. CONCLUSIONS We developed a framework for the analysis of antibody titers that accounted for the timing of sera collection with respect to influenza activity and permitted robust estimation of the cumulative incidence of infection during an epidemic.
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14
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Nicholson EG, Schlegel C, Garofalo RP, Mehta R, Scheffler M, Mei M, Piedra PA. Robust Cytokine and Chemokine Response in Nasopharyngeal Secretions: Association With Decreased Severity in Children With Physician Diagnosed Bronchiolitis. J Infect Dis 2016; 214:649-55. [PMID: 27190183 PMCID: PMC4957440 DOI: 10.1093/infdis/jiw191] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 05/03/2016] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Bronchiolitis causes substantial disease in young children. Previous findings had indicated that a robust innate immune response was not associated with a poor clinical outcome in bronchiolitis. This study tested the hypothesis that increased concentrations of cytokines and chemokines in nasal wash specimens were associated with decreased severity in bronchiolitis. METHODS Children <24 months old who presented to the emergency department with signs and symptoms of bronchiolitis were eligible for enrollment. Nasal wash specimens were analyzed for viral pathogens and cytokine/chemokine concentrations. These results were evaluated with regard to disposition. RESULTS One hundred eleven children with bronchiolitis were enrolled. A viral pathogen was identified in 91.9% of patients (respiratory syncytial virus in 51.4%, human rhinovirus in 11.7%). Higher levels of cytokines and chemokines (interferon [IFN] γ; interleukin [IL] 4, 15, and 17; CXCL10; and eotaxin) were significantly associated with a decreased risk of hospitalization. IL-17, IL-4, IFN-γ, and IFN-γ-inducible protein 10 (CXCL10 or IP-10) remained statistically significant in the multivariate analyses. CONCLUSIONS The cytokines and chemokines significantly associated with decreased bronchiolitis severity are classified in a wide range of functional groups (T-helper 1 and 2, regulatory, and chemoattractant). The involvement of these functional groups suggest that a broadly overlapping cytokine/chemokine response is required for control of virus-mediated respiratory disease in young children.
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Affiliation(s)
| | | | | | - Reena Mehta
- Allergy & Asthma Specialists, Saddle River, New Jersey
| | - Margaret Scheffler
- Department of Pediatrics, Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Minghua Mei
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston
| | - Pedro A Piedra
- Department of Pediatric Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston
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15
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Goldstein E, Greene SK, Olson DR, Hanage WP, Lipsitch M. Estimating the hospitalization burden associated with influenza and respiratory syncytial virus in New York City, 2003-2011. Influenza Other Respir Viruses 2016; 9:225-33. [PMID: 25980600 PMCID: PMC4548992 DOI: 10.1111/irv.12325] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/08/2015] [Indexed: 12/03/2022] Open
Abstract
Background Hospitalization burden associated with influenza and respiratory syncytial virus (RSV) is uncertain due to ambiguity in the inference methodologies employed for its estimation. Objectives Utilization of a new method to quantitate the above burden. Methods Weekly hospitalization rates for several principal diagnoses from 2003 to 2011 in New York City by age group were regressed linearly against incidence proxies for the major influenza subtypes and RSV adjusting for temporal trends and seasonal baselines. Results Average annual rates of influenza-associated respiratory hospitalizations per 100 000 were estimated to be 129 [95% CI (79, 179)] for age <1, 36·3 (21·6, 51·4) for ages 1–4, 10·6 (7·5, 13·7) for ages 5–17, 25·6 (21·3, 29·8) for ages 18–49, 65·5 (54·0, 76·9) for ages 50–64, 125 (105, 147) for ages 65–74, and 288 (244, 331) for ages ≥75. Additionally, influenza had a significant contribution to hospitalization rates with a principal diagnosis of septicemia for ages 5–17 [0·76 (0·1, 1·4)], 18–49 [1·02 (0·3, 1·7)], 50–64 [4·0 (1·7, 6·3)], 65–74 [8·8 (2·2, 15·6)], and ≥75 [38·7 (25·7, 52·9)]. RSV had a significant contribution to the rates of respiratory hospitalizations for age <1 [1900 (1740, 2060)], ages 1–4 [117 (70, 167)], and ≥75 [175 (44, 312)] [including chronic lower respiratory disease, 90 (43, 140)] as well as pneumonia & influenza hospitalizations for ages 18–49 [6·2 (1·1, 11·3)] and circulatory hospitalizations for ages ≥75 [199 (13, 375)]. Conclusions The high burden of RSV hospitalizations among young children and seniors age ≥75 suggests the need for additional control measures such as vaccination to mitigate the impact of annual RSV epidemics. Our estimates for influenza-associated hospitalizations provide further evidence of the burden of morbidity associated with influenza, supporting current guidelines regarding influenza vaccination and antiviral treatment.
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Affiliation(s)
- Edward Goldstein
- Department of Epidemiology, Center for Communicable Disease Dynamics, Harvard School of Public Health, Boston, MA, USA
| | - Sharon K Greene
- Bureau of Communicable Disease, New York City Department of Health and Mental Hygiene, Queens, NY, USA
| | - Donald R Olson
- Bureau of Epidemiology Services, New York City Department of Health and Mental Hygiene, Queens, NY, USA
| | - William P Hanage
- Department of Epidemiology, Center for Communicable Disease Dynamics, Harvard School of Public Health, Boston, MA, USA
| | - Marc Lipsitch
- Department of Epidemiology, Center for Communicable Disease Dynamics, Harvard School of Public Health, Boston, MA, USA.,Department of Immunology and Infectious Disease, Harvard School of Public Health, Boston, MA, USA
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16
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Sheu SM, Tsai CF, Yang HY, Pai HW, Chen SCC. Comparison of age-specific hospitalization during pandemic and seasonal influenza periods from 2009 to 2012 in Taiwan: a nationwide population-based study. BMC Infect Dis 2016; 16:88. [PMID: 26911158 PMCID: PMC4765149 DOI: 10.1186/s12879-016-1438-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 02/16/2016] [Indexed: 02/06/2023] Open
Abstract
Background Determining the age-specific hospitalization burden associated with seasonal influenza and the (H1N1) 2009 pandemic is important for the development of effective vaccine strategies and clinical management. The aim of this study was to investigate age-specific differences in hospitalization rates during the pandemic and seasonal periods. Methods Using the Taiwan National Health Insurance Research Database (NHIRD), we identified hospitalized patients with a principle discharge diagnosis of influenza-related infection (ICD-9-CM 487) between 2009 and 2012. Results Based on the time distribution of influenza-related hospitalizations and previously reported epidemic periods, the first and second waves of the (H1N1) 2009 pandemic (p1 is known as 2009.07-2010.01, and p2 is known as 2010.12-2011.03) and three seasonal periods (s1 is known as 2010.03-2010.11, s2 is known as 2011.10-2012.03, and s3 is known as 2012.04-2012.10) were found. During these five periods, children younger than 7 years of age consistently had the highest hospitalization rate of the studied age groups. In individuals younger than 50 years of age, the seasonal periods were associated with a significantly lower risk of hospitalization than that of p1 (Relative risk (RR) range = 0.18–0.85); however, they had a significantly higher hospitalization risk for adults over 50 years of age (RR = 1.51–3.22). Individuals over 50 years of age also had a higher intensive care unit admission rate and case fatality ratio than individuals under than 50 years of age during the seasonal periods and especially during the pandemic periods. Conclusions In both pandemic and seasonal periods, the highest hospitalization rate was observed for children younger than 7 years of age. Adults over 50 years of age had a higher hospitalization risk during the seasonal periods and a higher clinical severity during the pandemic periods. Those results emphasize that the importance of influenza-related prevention strategies in the younger and older age groups, either seasonal or pandemic periods.
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Affiliation(s)
- Shew-Meei Sheu
- Department of Medical Research, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi City, Taiwan
| | - Ching-Fang Tsai
- Department of Medical Research, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi City, Taiwan
| | - Hsin-Yi Yang
- Department of Medical Research, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi City, Taiwan
| | - Hui-Wen Pai
- Department of Geriatrics, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi City, Taiwan.
| | - Solomon Chih-Cheng Chen
- Department of Medical Research, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi City, Taiwan. .,Department of Pediatrics, School of Medicine, Taipei Medical University, Taipei, Taiwan.
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17
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Abstract
Each year, influenza causes substantial mortality and morbidity worldwide. It is important to understand influenza in the tropics because of the significant burden in the region and its relevance to global influenza circulation. In this review, influenza burden, transmission dynamics, and their determinants in the tropics are discussed. Environmental, cultural, and social conditions in the tropics are very diverse and often differ from those of temperate regions. Theories that account for and predict influenza dynamics in temperate regions do not fully explain influenza epidemic patterns observed in the tropics. Routine surveillance and household studies have been useful in understanding influenza dynamics in the tropics, but these studies have been limited to only some regions; there is still a lack of information regarding influenza burden and transmission dynamics in many tropical countries. Further studies in the tropics will provide useful insight on many questions that remain.
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Affiliation(s)
- Sophia Ng
- Department of Epidemiology, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109 USA
| | - Aubree Gordon
- Department of Epidemiology, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109 USA
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18
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Zhou Y, Cowling BJ, Wu P, Chan WM, Lee SY, Lau EHY, Schooling CM. Adiposity and influenza-associated respiratory mortality: a cohort study. Clin Infect Dis 2015; 60:e49-57. [PMID: 25645211 DOI: 10.1093/cid/civ060] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Accepted: 01/17/2015] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Obesity was first noted as a risk factor for severe illness associated with pandemic H1N1 infection in 2009, but the relationship between obesity and seasonal influenza remains unclear. METHODS We used data from a population-based cohort comprising 66 820 older (≥65 years) participants with a follow-up period from 1998 to 2012. The impact of influenza activity on respiratory mortality rates was estimated using a Cox proportional hazards model adjusted for comorbidities, meteorological factors, and other co-circulating respiratory viruses. We also tested whether the association of influenza with respiratory mortality varied with obesity and/or health status. As a control outcome, we similarly assessed the association of influenza with deaths from external causes, because these deaths should be unrelated to influenza. RESULTS Seasonal influenza activity was associated with higher respiratory mortality (hazard ratio [HR], 1.13 for influenza activity in the influenza season vs noninfluenza season; 95% confidence interval [CI], 1.05-1.22). The effect of seasonal influenza was 19% greater in obese individuals than normal-weight individuals (HR, 1.19; 95% CI, 1.01-1.42). The marginally significant and greater effect modification of obesity status on the association between seasonal influenza and respiratory mortality was also observed among older people in good health (HR, 1.35; 95% CI, .97-1.87). No such relations were observed for death from external causes. CONCLUSIONS Obesity aggravates the effect of seasonal influenza on respiratory mortality. Priority for influenza vaccine should be considered for obese older people to decrease the burden of influenza.
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Affiliation(s)
- Ying Zhou
- Infectious Disease Epidemiology Group, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong
| | - Benjamin J Cowling
- Infectious Disease Epidemiology Group, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong
| | - Peng Wu
- Infectious Disease Epidemiology Group, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong
| | - Wai Man Chan
- Department of Health, Hong Kong Government, Hong Kong Special Administrative Region, China
| | - Siu Yin Lee
- Department of Health, Hong Kong Government, Hong Kong Special Administrative Region, China
| | - Eric H Y Lau
- Infectious Disease Epidemiology Group, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong
| | - C Mary Schooling
- Infectious Disease Epidemiology Group, School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong School of Public Health at Hunter College, City University of New York, New York
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19
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Cowling BJ, Perera RAPM, Fang VJ, Chan KH, Wai W, So HC, Chu DKW, Wong JY, Shiu EY, Ng S, Ip DKM, Peiris JSM, Leung GM. Incidence of influenza virus infections in children in Hong Kong in a 3-year randomized placebo-controlled vaccine study, 2009-2012. Clin Infect Dis 2014; 59:517-24. [PMID: 24825868 DOI: 10.1093/cid/ciu356] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND School-aged children suffer high rates of influenza virus infections and associated illnesses each year, and are a major source of transmission in the community. However, information on the cumulative incidence of infection in specific epidemics is scarce, and there are limited studies with sufficient follow-up to identify the strength and duration of protection against reinfection. METHODS We randomly allocated children 5-17 years of age to receive trivalent inactivated influenza vaccine (TIV) or placebo from September 2009 through January 2010, and then conducted follow-up for 3 years including regular collection of sera, symptom diaries, and collection of nose and throat swabs during illness episodes in participants or their household members. RESULTS Of 796 children initially randomized, 484 continued to participate for all 3 years. In unvaccinated children, cumulative incidence of infection was estimated to be 59% in the first wave of H1N1pdm09 in 2009-2010, and 7%, 14%, 20%, and 31% in subsequent epidemics of H3N2 (2010), H1N1pdm09 (2011), B (2012), and H3N2 (2012), respectively. Infection with H1N1pdm09 in 2009-2010 and H3N2 in 2010 was associated with protection against infection with subsequent epidemics of the same subtype in 2011 and 2012, respectively, but we found no evidence of heterotypic or heterosubtypic protection against infection. CONCLUSIONS We identified substantial incidence of influenza virus infections in children in Hong Kong in 5 major epidemics over a 3-year period, and evidence of homosubtypic but not heterosubtypic protection following infection. CLINICAL TRIALS REGISTRATION NCT00792051.
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Affiliation(s)
| | - Ranawaka A P M Perera
- Division of Public Health Laboratory Sciences, School of Public Health Centre for Influenza Research
| | - Vicky J Fang
- Division of Epidemiology and Biostatistics, School of Public Health
| | | | - Winnie Wai
- Division of Epidemiology and Biostatistics, School of Public Health
| | - Hau Chi So
- Division of Epidemiology and Biostatistics, School of Public Health
| | - Daniel K W Chu
- Division of Public Health Laboratory Sciences, School of Public Health Centre for Influenza Research
| | - Jessica Y Wong
- Division of Epidemiology and Biostatistics, School of Public Health
| | - Eunice Y Shiu
- Division of Epidemiology and Biostatistics, School of Public Health
| | - Sophia Ng
- Department of Ecology and Evolutionary Biology, Princeton University, New Jersey
| | - Dennis K M Ip
- Division of Community Medicine and Public Health Practice, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - J S Malik Peiris
- Division of Public Health Laboratory Sciences, School of Public Health Centre for Influenza Research
| | - Gabriel M Leung
- Division of Community Medicine and Public Health Practice, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
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20
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Tsang TK, Cauchemez S, Perera RAPM, Freeman G, Fang VJ, Ip DKM, Leung GM, Malik Peiris JS, Cowling BJ. Association between antibody titers and protection against influenza virus infection within households. J Infect Dis 2014; 210:684-92. [PMID: 24676208 DOI: 10.1093/infdis/jiu186] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Previous studies have established that antibody titer measured by the hemagglutination-inhibiting (HAI) assay is correlated with protection against influenza virus infection, with an HAI titer of 1:40 generally associated with 50% protection. METHODS We recruited index cases with confirmed influenza virus infection from outpatient clinics, and followed up their household contacts for 7-10 days to identify secondary infections. Serum samples collected from a subset of household contacts were tested by HAI and microneutralization (MN) assays against prevalent influenza viruses. We analyzed the data using an individual hazard-based transmission model that adjusted for age and vaccination history. RESULTS Compared to a reference group with antibody titers <1:10, we found that HAI titers of 1:40 against influenza A(H1N1) and A(H3N2) were associated with 31% (95% confidence interval [CI], 13%-46%) and 31% (CI, 1%-53%) protection against polymerase chain reaction (PCR)-confirmed A(H1N1) and A(H3N2) virus infection, respectively, while an MN titer of 1:40 against A(H3N2) was associated with 49% (95% CI, 7%-81%) protection against PCR-confirmed A(H3N2) virus infection. CONCLUSIONS An HAI titer of 1:40 was associated with substantially less than 50% protection against PCR-confirmed influenza virus infection within households, perhaps because of exposures of greater duration or intensity in that confined setting.
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Affiliation(s)
- Tim K Tsang
- Division of Epidemiology and Biostatistics, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Simon Cauchemez
- Mathematical Modelling of Infectious Diseases Unit, Institut Pasteur, Paris, France
| | - Ranawaka A P M Perera
- Division of Public Health Laboratory Sciences, School of Public Health Centre of Influenza Research
| | - Guy Freeman
- Division of Epidemiology and Biostatistics, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Vicky J Fang
- Division of Epidemiology and Biostatistics, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Dennis K M Ip
- Division of Community Medicine and Public Health Practice, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Gabriel M Leung
- Division of Community Medicine and Public Health Practice, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | | | - Benjamin J Cowling
- Division of Epidemiology and Biostatistics, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
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