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Taniguchi K, Ikeda S, Hagiwara Y, Tsuzuki D, Klai M, Sakai Y, Crawford B, Nealon J. Epidemiology and burden of illness of seasonal influenza among the elderly in Japan: A systematic literature review and vaccine effectiveness meta-analysis. Influenza Other Respir Viruses 2021; 15:293-314. [PMID: 32997395 PMCID: PMC7902263 DOI: 10.1111/irv.12814] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 08/27/2020] [Accepted: 08/30/2020] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Elderly populations are particularly vulnerable to influenza and often require extensive clinical support. In Japan, nationwide passive surveillance monitors seasonal influenza but does not capture the full disease burden. We synthesized existing evidence on the epidemiology, vaccine effectiveness (VE), and economic burden of seasonal influenza in the elderly population. METHODS PubMed, EMBASE, and ICHUSHI were searched for articles on seasonal influenza in Japan, published between 1997 and 2018, in English or Japanese. Grey literature was also assessed. A random-effects meta-analysis characterized VE of influenza vaccines among studies reporting this information. RESULTS Of 1,147 identified articles, 143 met inclusion criteria. Reported incidence rates varied considerably depending on study design, season, study setting and, most importantly, case definition. In nursing homes, the maximum reported attack rate was 55.2% and in the 16 articles reporting mortality rates, case fatality rates varied from 0.009% to 14.3%. Most hospitalizations were in people aged >60; healthcare costs were partially mitigated by vaccine administration. Meta-analysis estimated overall VE of 19.1% (95% CI: 2.3% - 33.0%) with a high proportion of heterogeneity (I2 : 89.1%). There was a trend of lower VE in older people (40.1% [-57.3-77.2] in the <65 group; 12.9% [-8.0-29.8] in those 65; P = .21). CONCLUSIONS Despite differences between studies that make comparisons challenging, the influenza burden in elderly Japanese is significant. While vaccines are effective, current vaccination programs offer suboptimal protection. Health economic data and cost-effectiveness analyses were limited and represent areas for policy-relevant future research.
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Affiliation(s)
| | - Shunya Ikeda
- Department of Public HealthSchool of MedicineInternational University of Health and WelfareNaritaJapan
| | - Yuriko Hagiwara
- Sanofi PasteurTokyoJapan
- Department of Health Economics and Outcomes ResearchGraduate School of Pharmaceutical SciencesThe University of TokyoTokyoJapan
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Miyashita K, Nakatani E, Hozumi H, Sato Y, Miyachi Y, Suda T. Risk Factors for Pneumonia and Death in Adult Patients With Seasonal Influenza and Establishment of Prediction Scores: A Population-Based Study. Open Forum Infect Dis 2021; 8:ofab068. [PMID: 33738319 PMCID: PMC7953663 DOI: 10.1093/ofid/ofab068] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 02/01/2021] [Indexed: 01/12/2023] Open
Abstract
Background Seasonal influenza remains a global health problem; however, there are limited data on the specific relative risks for pneumonia and death among outpatients considered to be at high risk for influenza complications. This population-based study aimed to develop prediction models for determining the risk of influenza-related pneumonia and death. Methods We included patients diagnosed with laboratory-confirmed influenza between 2016 and 2017 (main cohort, n = 25 659), those diagnosed between 2015 and 2016 (validation cohort 1, n = 16 727), and those diagnosed between 2017 and 2018 (validation cohort 2, n = 34 219). Prediction scores were developed based on the incidence and independent predictors of pneumonia and death identified using multivariate analyses, and patients were categorized into low-, medium-, and high-risk groups based on total scores. Results In the main cohort, age, gender, and certain comorbidities (dementia, congestive heart failure, diabetes, and others) were independent predictors of pneumonia and death. The 28-day pneumonia incidence was 0.5%, 4.1%, and 10.8% in the low-, medium-, and high-risk groups, respectively (c-index, 0.75); the 28-day mortality was 0.05%, 0.7%, and 3.3% in the low-, medium-, and high-risk groups, respectively (c-index, 0.85). In validation cohort 1, c-indices for the models for pneumonia and death were 0.75 and 0.87, respectively. In validation cohort 2, c-indices for the models were 0.74 and 0.87, respectively. Conclusions We successfully developed and validated simple-to-use risk prediction models, which would promptly provide useful information for treatment decisions in primary care settings.
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Affiliation(s)
- Koichi Miyashita
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan.,Research Support Center, Shizuoka General Hospital, Shizuoka, Japan
| | - Eiji Nakatani
- Research Support Center, Shizuoka General Hospital, Shizuoka, Japan
| | - Hironao Hozumi
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Yoko Sato
- Research Support Center, Shizuoka General Hospital, Shizuoka, Japan
| | - Yoshiki Miyachi
- Research Support Center, Shizuoka General Hospital, Shizuoka, Japan
| | - Takafumi Suda
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
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3
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Tsuzuki S, Yoshihara K. The characteristics of influenza-like illness management in Japan. BMC Public Health 2020; 20:568. [PMID: 32345248 PMCID: PMC7189553 DOI: 10.1186/s12889-020-08603-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 03/27/2020] [Indexed: 11/10/2022] Open
Abstract
Background This study aimed to make a quantitative assessment of the management of influenza-like illnesses (ILI) in Japanese healthcare settings. Methods We analysed participants’ healthcare-seeking behaviour and physicians’ practice in January 2019 using an online survey of 200 households in Japan. Quality of life score, quality-adjusted life years lost, the duration of symptoms, and the duration of absence from work were compared between the influenza ILI group and the non-influenza ILI group with one-to-one propensity score matching. Missing data were imputed using multiple imputation. Results In total, 261 of the 600 (43.5%) participants had at least one episode of influenza-like illness during January 2019. Of these, 194 (75.5%) visited healthcare facilities, 167 (86.1%) within 2 days of onset of symptoms. A total of 169 out of 191 (88.5%) received a rapid influenza diagnostic test and 101 were diagnosed with influenza, of whom 95.0% were treated with antivirals. The median quality-adjusted life-years (QALYs) lost was 0.0055 (interquartile range, IQR 0.0040–0.0072) and median absence from work for a single episode of influenza-like illness was 2 days (IQR 1–5 days). Albeit QALYs lost per episode was not different between two groups, the influenza ILI group showed longer duration of absence from work (5 days, IQR 4–6 days) than the non-influenza ILI group (2 days, IQR 1–3 days). Conclusions In Japan, most people with influenza-like illnesses visit healthcare facilities soon after symptoms first occur and receive a diagnostic test. Those with influenza are usually treated with antivirals. Absence from work was longer for influenza than other similar illnesses.
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Affiliation(s)
- Shinya Tsuzuki
- Department of Paediatric Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, 852-8523, Japan. .,AMR Clinical Reference Center, Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan. .,Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium.
| | - Keisuke Yoshihara
- Department of Paediatric Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, 852-8523, Japan
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4
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Chua H, Feng S, Lewnard JA, Sullivan SG, Blyth CC, Lipsitch M, Cowling BJ. The Use of Test-negative Controls to Monitor Vaccine Effectiveness: A Systematic Review of Methodology. Epidemiology 2020; 31:43-64. [PMID: 31609860 PMCID: PMC6888869 DOI: 10.1097/ede.0000000000001116] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND The test-negative design is an increasingly popular approach for estimating vaccine effectiveness (VE) due to its efficiency. This review aims to examine published test-negative design studies of VE and to explore similarities and differences in methodological choices for different diseases and vaccines. METHODS We conducted a systematic search on PubMed, Web of Science, and Medline, for studies reporting the effectiveness of any vaccines using a test-negative design. We screened titles and abstracts and reviewed full texts to identify relevant articles. We created a standardized form for each included article to extract information on the pathogen of interest, vaccine(s) being evaluated, study setting, clinical case definition, choices of cases and controls, and statistical approaches used to estimate VE. RESULTS We identified a total of 348 articles, including studies on VE against influenza virus (n = 253), rotavirus (n = 48), pneumococcus (n = 24), and nine other pathogens. Clinical case definitions used to enroll patients were similar by pathogens of interest but the sets of symptoms that defined them varied substantially. Controls could be those testing negative for the pathogen of interest, those testing positive for nonvaccine type of the pathogen of interest, or a subset of those testing positive for alternative pathogens. Most studies controlled for age, calendar time, and comorbidities. CONCLUSIONS Our review highlights similarities and differences in the application of the test-negative design that deserve further examination. If vaccination reduces disease severity in breakthrough infections, particular care must be taken in interpreting vaccine effectiveness estimates from test-negative design studies.
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Affiliation(s)
- Huiying Chua
- From the World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Shuo Feng
- From the World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Joseph A Lewnard
- Division of Epidemiology, School of Public Health, University of California, Berkeley, Berkeley, CA
| | - Sheena G Sullivan
- WHO Collaborating Centre for Reference and Research on Influenza, Royal Melbourne Hospital, and Doherty Department, University of Melbourne, at the 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, CA
- Centre for Epidemiology and Biostatistics, School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Christopher C Blyth
- Division of Paediatrics, School of Medicine, Faculty of Health and Medical Sciences, The University of Western Australia, Perth, Western Australia, Australia
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, Perth, Western Australia, Australia
- Department of Infectious Diseases, Perth Children's Hospital, Perth, Western Australia, Australia
| | - Marc Lipsitch
- Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA
- Center for Communicable Disease Dynamics, Harvard T. H. Chan School of Public Health, Boston, MA
| | - Benjamin J Cowling
- From the World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
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5
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Yokomichi H, Mochizuki M, Lee JJ, Kojima R, Yokoyama T, Yamagata Z. Incidence of hospitalisation for severe complications of influenza virus infection in Japanese patients between 2012 and 2016: a cross-sectional study using routinely collected administrative data. BMJ Open 2019; 9:e024687. [PMID: 30782739 PMCID: PMC6340484 DOI: 10.1136/bmjopen-2018-024687] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
OBJECTIVE To calculate the incidence of hospitalisation due to acute respiratory failure, pneumonia, acute respiratory distress syndrome (ARDS), febrile seizures and encephalitis/encephalopathy among influenza-positive patients in Japan, where point-of-care tests are routinely used to diagnose influenza. DESIGN A cross-sectional study using routinely collected data. SETTING Japanese clinics and hospitals between 2012 and 2016. PARTICIPANTS Japanese patients aged 0-74 years diagnosed with influenza by a rapid test in employment-related health insurance records. PRIMARY OUTCOME MEASURES Incidence of hospitalisation per 100 000 influenza-positive episodes. RESULTS We included over 16 million influenza-positive episodes, 1.0% of whom were hospitalised. Of these, 3361 were acute respiratory failure, 27 253 pneumonia, 18 ARDS, 2603 febrile seizure and 159 encephalitis/encephalopathy. The percentage of hospitalisations by age was 2.96% of patients aged 0-1 years, 0.77% aged 2-5, 0.51% aged 6-12, 0.78% aged 13-18, 1.36% aged 19-44, 1.19% aged 45-64, and 2.21% aged 65-74. The incidence of hospitalisations from these five complications combined was highest in influenza-positive patients aged 0-1 years (943 per 100 000) compared with 307 in those aged 2-5 years and 271 in those aged 65-74 years. For pneumonia, the incidence was highest for influenza-positive patients aged 0-5 years and 65 years or more. There were statistically significant decreasing trends over the years in the incidence of all-cause hospitalisations, pneumonia and febrile seizures. CONCLUSIONS Japanese administrative data revealed that 1.0% of influenza-positive patients aged under 75 years were hospitalised. Male patients had a higher incidence of pulmonary complications and febrile seizures. Children aged 0-5 years and adults aged 65-74 years were at high risk of being admitted to hospital for pneumonia.
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Affiliation(s)
- Hiroshi Yokomichi
- Department of Health Sciences, University of Yamanashi, Chuo City, Japan
| | - Mie Mochizuki
- Department of Pediatrics, University of Yamanashi, Chuo City, Japan
| | - Joseph Jonathan Lee
- Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK
| | - Reiji Kojima
- Department of Health Sciences, University of Yamanashi, Chuo City, Japan
| | - Tetsuji Yokoyama
- Department of Health Promotion, National Institute of Public Health, Wako City, Japan
| | - Zentaro Yamagata
- Department of Health Sciences, University of Yamanashi, Chuo City, Japan
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Foppa IM, Ferdinands JM, Chaves SS, Haber MJ, Reynolds SB, Flannery B, Fry AM. The case test-negative design for studies of the effectiveness of influenza vaccine in inpatient settings. Int J Epidemiol 2018; 45:2052-2059. [PMID: 26979985 PMCID: PMC5025336 DOI: 10.1093/ije/dyw022] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/20/2016] [Indexed: 01/11/2023] Open
Abstract
Background: The test-negative design (TND) to evaluate influenza vaccine effectiveness is based on patients seeking care for acute respiratory infection, with those who test positive for influenza as cases and the test-negatives serving as controls. This design has not been validated for the inpatient setting where selection bias might be different from an outpatient setting. Methods: We derived mathematical expressions for vaccine effectiveness (VE) against laboratory-confirmed influenza hospitalizations and used numerical simulations to verify theoretical results exploring expected biases under various scenarios. We explored meaningful interpretations of VE estimates from inpatient TND studies. Results: VE estimates from inpatient TND studies capture the vaccine-mediated protection of the source population against laboratory-confirmed influenza hospitalizations. If vaccination does not modify disease severity, these estimates are equivalent to VE against influenza virus infection. If chronic cardiopulmonary individuals are enrolled because of non-infectious exacerbation, biased VE estimates (too high) will result. If chronic cardiopulmonary disease status is adjusted for accurately, the VE estimates will be unbiased. If chronic cardiopulmonary illness cannot be adequately be characterized, excluding these individuals may provide unbiased VE estimates. Conclusions: The inpatient TND offers logistic advantages and can provide valid estimates of influenza VE. If highly vaccinated patients with respiratory exacerbation of chronic cardiopulmonary conditions are eligible for study inclusion, biased VE estimates will result unless this group is well characterized and the analysis can adequately adjust for it. Otherwise, such groups of subjects should be excluded from the analysis.
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Affiliation(s)
- Ivo M Foppa
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA.,Battelle Memorial Institute, Atlanta, GA, USA and
| | - Jill M Ferdinands
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA.,Battelle Memorial Institute, Atlanta, GA, USA and
| | - Sandra S Chaves
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Michael J Haber
- Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | - Sue B Reynolds
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA.,Battelle Memorial Institute, Atlanta, GA, USA and
| | - Brendan Flannery
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Alicia M Fry
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA
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7
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Darvishian M, van den Heuvel ER, Bissielo A, Castilla J, Cohen C, Englund H, Gefenaite G, Huang WT, la Bastide-van Gemert S, Martinez-Baz I, McAnerney JM, Ntshoe GM, Suzuki M, Turner N, Hak E. Effectiveness of seasonal influenza vaccination in community-dwelling elderly people: an individual participant data meta-analysis of test-negative design case-control studies. THE LANCET RESPIRATORY MEDICINE 2017; 5:200-211. [PMID: 28189522 DOI: 10.1016/s2213-2600(17)30043-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 11/21/2016] [Accepted: 11/29/2016] [Indexed: 01/24/2023]
Abstract
BACKGROUND Several aggregate data meta-analyses have provided estimates of the effectiveness of influenza vaccination in community-dwelling elderly people. However, these studies ignored the effects of patient-level confounders such as sex, age, and chronic diseases that could bias effectiveness estimates. We aimed to assess the confounder-adjusted effectiveness of influenza vaccines on laboratory-confirmed influenza among elderly people by conducting a global individual participant data meta-analysis. METHODS In this individual participant data meta-analysis, we considered studies included in a previously conducted aggregate data meta-analysis that included test-negative design case-control studies published up to July 13, 2014. We contacted all authors of the included studies on Dec 1, 2014, to request individual participant data. Patients were excluded if their unique identifier was missing, their vaccination status was unknown, their outcome status was unknown, or they had had suspected influenza infection more than once in the same influenza season. Cases were patients with influenza-like illness symptoms who tested positive for at least one of A H1N1, A H1N1 pdm09, A H3N2, or B viruses; controls were patients with influenza-like illness symptoms who tested negative for these virus types or subtypes. Influenza vaccine effectiveness against overall and subtype-specific laboratory-confirmed influenza were the primary and secondary outcomes. We used a generalised linear mixed model to calculate adjusted vaccine effectiveness according to vaccine match to the circulating strains of influenza virus and intensity of the virus activity (epidemic or non-epidemic). Vaccine effectiveness was defined as the relative reduction in risk of laboratory-confirmed influenza in vaccinated patients compared with unvaccinated patients. We did subgroup analyses to estimate vaccine effectiveness according to hemisphere, age category, and health status. FINDINGS We received 23 of the 53 datasets included in the aggregate data meta-analysis. Furthermore, six additional datasets were provided by data collaborators, which resulted in individual participant data for a total of 5210 participants. A total of 4975 patients had the required data for analysis. Of these, 3146 (63%) were controls and 1829 (37%) were cases. Influenza vaccination was significantly effective during epidemic seasons irrespective of vaccine match status (matched adjusted vaccine effectiveness 44·38%, 95% CI 22·63-60·01; mismatched adjusted vaccine effectiveness 20·00%, 95% CI 3·46-33·68; analyses in the imputed dataset). Seasonal influenza vaccination did not show significant effectiveness during non-epidemic seasons. We found substantial variation in vaccine effectiveness across virus types and subtypes, with the highest estimate for A H1N1 pdm09 (53·19%, 10·25-75·58) and the lowest estimate for B virus types (-1·52%, -39·58 to 26·16). Although we observed no significant differences between subgroups in each category (hemisphere, age, and health status), influenza vaccination showed a protective effect among elderly people with cardiovascular disease, lung disease, or aged 75 years and younger. INTERPRETATION Influenza vaccination is moderately effective against laboratory-confirmed influenza in elderly people during epidemic seasons. More research is needed to investigate factors affecting vaccine protection (eg, brand-specific or type-specific vaccine effectiveness and repeated annual vaccination) in elderly people. FUNDING University Medical Center Groningen.
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Affiliation(s)
- Maryam Darvishian
- Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands; Unit of Pharmacoepidemiology & Pharmacoeconomics (PE2), Department of Pharmacy, University of Groningen, Groningen, Netherlands; British Columbia Centre for Disease Control, Vancouver, BC, Canada; School of Population and Public Health, University of British Columbia, Vancouver, BC, Canada.
| | | | - Ange Bissielo
- Institute of Environmental Science and Research, Wallaceville, New Zealand
| | - Jesus Castilla
- Instituto de Salud Pública, Navarra Institute for Health Research (IdiSNA), Pamplona, Spain; CIBER Epidemiología y Salud Pública, Spain
| | - Cheryl Cohen
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa; School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Helene Englund
- Unit for Vaccination Programs, Department of Monitoring and Evaluation, Public Health Agency of Sweden, Solna, Sweden
| | | | | | - Sacha la Bastide-van Gemert
- Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Iván Martinez-Baz
- Instituto de Salud Pública, Navarra Institute for Health Research (IdiSNA), Pamplona, Spain; CIBER Epidemiología y Salud Pública, Spain
| | - Johanna M McAnerney
- National Institute for Communicable Diseases of the National Health Laboratory Services, Johannesburg, South Africa
| | - Genevie M Ntshoe
- Division of Public Health Surveillance and Response, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
| | - Motoi Suzuki
- Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Japan
| | - Nikki Turner
- Department of General Practice and Primary Care, University of Auckland, New Zealand
| | - Eelko Hak
- Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands; Unit of Pharmacoepidemiology & Pharmacoeconomics (PE2), Department of Pharmacy, University of Groningen, Groningen, Netherlands
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8
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Saito N, Komori K, Suzuki M, Morimoto K, Kishikawa T, Yasaka T, Ariyoshi K. Negative impact of prior influenza vaccination on current influenza vaccination among people infected and not infected in prior season: A test-negative case-control study in Japan. Vaccine 2016; 35:687-693. [PMID: 28043738 DOI: 10.1016/j.vaccine.2016.11.024] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 11/07/2016] [Accepted: 11/07/2016] [Indexed: 11/15/2022]
Abstract
BACKGROUND Accumulating evidences indicate that repeated influenza vaccination has negative impact on the vaccine effectiveness (VE). However no published studies considered past influenza infection when assessing the VE of repeated vaccination. METHODS Prospective surveillance was conducted from 2009 to 2012 at a community hospital on a small island in Japan. The study included all outpatients with an influenza-like illness (ILI) who attended the hospital, and a rapid diagnostic test (RDT) was used to diagnose influenza A/B infection. The VE of trivalent inactivated influenza vaccine (TIV) against medically attended influenza A (MA-fluA) was estimated using a test-negative case-control study design. The influence of TIV in the prior season on VE in the current season was investigated in the context of MA-fluA during the prior season. RESULTS During the three influenza seasons, 5838 ILI episodes (4127 subjects) were analysed. Subjects who had an episode of MA-fluA in the prior season were at a significantly lower risk of MA-fluA in the current season (adjusted odds ratio: 0.38, 95% CI: 0.30-0.50). The overall adjusted VE was 28% (95% CI, 14-40). VE was substantially lower in subjects vaccinated in the prior season compared to those who had not been vaccinated in prior season (19%; 95% CI: 0-35 vs 46%; 95% CI: 26-60, test for interaction, P value <0.05). In subjects who did not have MA-fluA in the prior season showed the attenuation of VE due to repeated vaccination (13%; 95% CI: -7 to 30 vs 44%; 95% CI: 24-59, test for interaction, P<0.05). However this effect was not detected in subjects who had contracted MA-fluA in the prior season. CONCLUSIONS Negative effects of repeated vaccination were significant among those without history of MA-fluA in the prior season.
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Affiliation(s)
- Nobuo Saito
- Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki, Japan; Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | | | - Motoi Suzuki
- Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki, Japan
| | - Kounosuke Morimoto
- Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki, Japan
| | | | | | - Koya Ariyoshi
- Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki, Japan; Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
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9
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Hara M, Hanaoka T, Maeda K, Kase T, Ohfuji S, Fukushima W, Hirota Y. Immunogenicity and Efficacy of A/H1N1pdm Vaccine Among Subjects With Severe Motor and Intellectual Disability in the 2010/11 Influenza Season. J Epidemiol 2016; 26:300-6. [PMID: 26780860 PMCID: PMC4884898 DOI: 10.2188/jea.je20150036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Background While the immunogenicity and effectiveness of seasonal influenza vaccines among subjects with severe motor and intellectual disability (SMID) are known to be diminished, the efficacy of the A/H1N1pdm vaccine has not been evaluated. Methods We prospectively evaluated 103 subjects with SMID (mean age, 41.7 years) who received trivalent inactivated influenza vaccine during the 2010/11 influenza season. The hemagglutination inhibition (HI) antibody titer was measured in serum samples collected pre-vaccination (S0), post-vaccination (S1), and end-of-season (S2) to evaluate subjects’ immunogenicity capacity. Vaccine efficacy was assessed based on antibody efficacy and achievement proportion. Results The proportions of seroprotection and seroconversion, and the geometric mean titer (GMT) ratio (GMT at S1/GMT at S0) for A/H1N1pdm were 46.0%, 16.0%, and 1.8, respectively—values which did not meet the European Medicines Evaluation Agency criteria. The achievement proportion was 26%. During follow-up, 11 of 43 subjects with acute respiratory illness were diagnosed with type A influenza according to a rapid influenza diagnostic test (RIDT), and A/H1N1pdm strains were isolated from the throat swabs of 5 of those 11 subjects. When either or both RIDT-diagnosed influenza or serologically diagnosed influenza (HI titer at S2/HI titer at S1 ≥2) were defined as probable influenza, subjects with A/H1N1pdm seroprotection were found to have a lower incidence of probable influenza (odds ratio, 0.31; antibody efficacy, 69%; vaccine efficacy, 18%). Conclusions In the present seasonal assessment, antibody efficacy was moderate against A/H1N1pdm among SMID subjects, but vaccine efficacy was low due to the reduced immunogenicity of SMID subjects.
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Affiliation(s)
- Megumi Hara
- Department of Preventive Medicine, Faculty of Medicine, Saga University
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10
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Lytras T, Kossyvakis A, Melidou A, Exindari M, Gioula G, Pogka V, Malisiovas N, Mentis A. Influenza vaccine effectiveness against laboratory confirmed influenza in Greece during the 2013–2014 season: A test-negative study. Vaccine 2015; 33:367-73. [DOI: 10.1016/j.vaccine.2014.11.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 10/24/2014] [Accepted: 11/06/2014] [Indexed: 11/25/2022]
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11
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Sullivan SG, Feng S, Cowling BJ. Potential of the test-negative design for measuring influenza vaccine effectiveness: a systematic review. Expert Rev Vaccines 2014; 13:1571-91. [PMID: 25348015 PMCID: PMC4277796 DOI: 10.1586/14760584.2014.966695] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND The test-negative design is a variant of the case-control study being increasingly used to study influenza vaccine effectiveness (VE). In these studies, patients with influenza-like illness are tested for influenza. Vaccine coverage is compared between those testing positive versus those testing negative to estimate VE. OBJECTIVES We reviewed features in the design, analysis and reporting of 85 published test-negative studies. DATA SOURCES Studies were identified from PubMed, reference lists and email updates. Study eligibility: All studies using the test-negative design reporting end-of-season estimates were included. STUDY APPRAISAL Design features that may affect the validity and comparability of reported estimates were reviewed, including setting, study period, source population, case definition, exposure and outcome ascertainment and statistical model. RESULTS There was considerable variation in the analytic approach, with 68 unique statistical models identified among the studies. CONCLUSION Harmonization of analytic approaches may improve the potential for pooling VE estimates.
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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 VIC 3000, Australia
| | - Shuo Feng
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Benjamin J Cowling
- 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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Darvishian M, Bijlsma MJ, Hak E, van den Heuvel ER. Effectiveness of seasonal influenza vaccine in community-dwelling elderly people: a meta-analysis of test-negative design case-control studies. THE LANCET. INFECTIOUS DISEASES 2014; 14:1228-39. [PMID: 25455990 DOI: 10.1016/s1473-3099(14)70960-0] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND The application of test-negative design case-control studies to assess the effectiveness of influenza vaccine has increased substantially in the past few years. The validity of these studies is predicated on the assumption that confounding bias by risk factors is limited by design. We aimed to assess the effectiveness of influenza vaccine in a high-risk group of elderly people. METHODS We searched the Cochrane library, Medline, and Embase up to July 13, 2014, for test-negative design case-control studies that assessed the effectiveness of seasonal influenza vaccine against laboratory confirmed influenza in community-dwelling people aged 60 years or older. We used generalised linear mixed models, adapted for test-negative design case-control studies, to estimate vaccine effectiveness according to vaccine match and epidemic conditions. FINDINGS 35 test-negative design case-control studies with 53 datasets met inclusion criteria. Seasonal influenza vaccine was not significantly effective during local virus activity, irrespective of vaccine match or mismatch to the circulating viruses. Vaccination was significantly effective against laboratory confirmed influenza during sporadic activity (odds ratio [OR] 0·69, 95% CI 0·48-0·99) only when the vaccine matched. Additionally, vaccination was significantly effective during regional (match: OR 0·42, 95% CI 0·30-0·60; mismatch: OR 0·57, 95% CI 0·41-0·79) and widespread (match: 0·54, 0·46-0·62; mismatch: OR 0·72, 95% CI 0·60-0·85) outbreaks. INTERPRETATION Our findings show that in elderly people, irrespective of vaccine match, seasonal influenza vaccination is effective against laboratory confirmed influenza during epidemic seasons. Efforts should be renewed worldwide to further increase uptake of the influenza vaccine in the elderly population. FUNDING None.
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Affiliation(s)
- Maryam Darvishian
- Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands; Unit of PharmacoEpidemiology and PharmacoEconomics (PE2), Department of Pharmacy, University of Groningen, Groningen, Netherlands
| | - Maarten J Bijlsma
- Unit of PharmacoEpidemiology and PharmacoEconomics (PE2), Department of Pharmacy, University of Groningen, Groningen, Netherlands
| | - Eelko Hak
- Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands; Unit of PharmacoEpidemiology and PharmacoEconomics (PE2), Department of Pharmacy, University of Groningen, Groningen, Netherlands
| | - Edwin R van den Heuvel
- Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands; Department of Mathematics and Computer Science, Eindhoven University of Technology, Eindhoven, Netherlands.
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Gordon SB, Bruce NG, Grigg J, Hibberd PL, Kurmi OP, Lam KBH, Mortimer K, Asante KP, Balakrishnan K, Balmes J, Bar-Zeev N, Bates MN, Breysse PN, Buist S, Chen Z, Havens D, Jack D, Jindal S, Kan H, Mehta S, Moschovis P, Naeher L, Patel A, Perez-Padilla R, Pope D, Rylance J, Semple S, Martin WJ. Respiratory risks from household air pollution in low and middle income countries. THE LANCET RESPIRATORY MEDICINE 2014; 2:823-60. [PMID: 25193349 DOI: 10.1016/s2213-2600(14)70168-7] [Citation(s) in RCA: 511] [Impact Index Per Article: 51.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A third of the world's population uses solid fuel derived from plant material (biomass) or coal for cooking, heating, or lighting. These fuels are smoky, often used in an open fire or simple stove with incomplete combustion, and result in a large amount of household air pollution when smoke is poorly vented. Air pollution is the biggest environmental cause of death worldwide, with household air pollution accounting for about 3·5-4 million deaths every year. Women and children living in severe poverty have the greatest exposures to household air pollution. In this Commission, we review evidence for the association between household air pollution and respiratory infections, respiratory tract cancers, and chronic lung diseases. Respiratory infections (comprising both upper and lower respiratory tract infections with viruses, bacteria, and mycobacteria) have all been associated with exposure to household air pollution. Respiratory tract cancers, including both nasopharyngeal cancer and lung cancer, are strongly associated with pollution from coal burning and further data are needed about other solid fuels. Chronic lung diseases, including chronic obstructive pulmonary disease and bronchiectasis in women, are associated with solid fuel use for cooking, and the damaging effects of exposure to household air pollution in early life on lung development are yet to be fully described. We also review appropriate ways to measure exposure to household air pollution, as well as study design issues and potential effective interventions to prevent these disease burdens. Measurement of household air pollution needs individual, rather than fixed in place, monitoring because exposure varies by age, gender, location, and household role. Women and children are particularly susceptible to the toxic effects of pollution and are exposed to the highest concentrations. Interventions should target these high-risk groups and be of sufficient quality to make the air clean. To make clean energy available to all people is the long-term goal, with an intermediate solution being to make available energy that is clean enough to have a health impact.
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Affiliation(s)
- Stephen B Gordon
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK.
| | - Nigel G Bruce
- Department of Public Health and Policy, University of Liverpool, Liverpool, UK
| | - Jonathan Grigg
- Centre for Paediatrics, Blizard Institute, Queen Mary, University of London, London, UK
| | - Patricia L Hibberd
- Division of Global Health, Department of Pediatrics, Massachusetts General Hospital, and Harvard Medical School, Boston, MA, USA
| | - Om P Kurmi
- Clinical Trials Service Unit and Epidemiological Studies Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK
| | - Kin-bong Hubert Lam
- Institute of Occupational and Environmental Medicine, School of Health and Population Sciences, University of Birmingham, Birmingham, UK
| | - Kevin Mortimer
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Kwaku Poku Asante
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA
| | - Kalpana Balakrishnan
- Department of Environmental Health Engineering, Sri Ramachandra University, Chennai, India
| | - John Balmes
- Department of Medicine, University of California San Francisco, San Francisco, CA, USA; Environmental Health Sciences, School of Public Health, University of California, Berkeley, CA, USA
| | - Naor Bar-Zeev
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, College of Medicine, University of Malawi, Blantyre, Malawi; Institute of Infection and Global Health, University of Liverpool, Liverpool, UK
| | - Michael N Bates
- Divisions of Epidemiology and Environmental Health Sciences, School of Public Health, University of California, Berkeley, CA, USA
| | - Patrick N Breysse
- Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Sonia Buist
- Oregon Health and Science University, Portland, OR, USA
| | - Zhengming Chen
- Clinical Trials Service Unit and Epidemiological Studies Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK
| | - Deborah Havens
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Darby Jack
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA
| | | | - Haidong Kan
- School of Public Health, Fudan University, Shanghai, China
| | - Sumi Mehta
- Health Effects Institute, Boston, MA, USA
| | - Peter Moschovis
- Division of Global Health, Department of Pediatrics, Massachusetts General Hospital, and Harvard Medical School, Boston, MA, USA
| | - Luke Naeher
- The University of Georgia, College of Public Health, Department of Environmental Health Science, Athens, GA, USA
| | | | | | - Daniel Pope
- Department of Public Health and Policy, University of Liverpool, Liverpool, UK
| | - Jamie Rylance
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Sean Semple
- University of Aberdeen, Scottish Centre for Indoor Air, Division of Applied Health Sciences, Royal Aberdeen Children's Hospital, Aberdeen, UK
| | - William J Martin
- Division of Environmental Health Sciences, College of Public Health, The Ohio State University, Columbus, OH, USA.
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Yang P, Thompson MG, Ma C, Shi W, Wu S, Zhang D, Wang Q. Influenza vaccine effectiveness against medically-attended influenza illness during the 2012-2013 season in Beijing, China. Vaccine 2014; 32:5285-9. [PMID: 25092635 DOI: 10.1016/j.vaccine.2014.07.083] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 07/08/2014] [Accepted: 07/22/2014] [Indexed: 12/23/2022]
Abstract
BACKGROUND Influenza vaccine coverage remains low in China, and there is limited information on the preventive value of local vaccination programs. METHODS As part of influenza virological surveillance in Beijing, China during the 2012-2013 influenza season, we assessed the vaccine effectiveness (VE) of one or more doses of trivalent inactivated influenza vaccine (IIV3) in preventing medically-attended influenza-like-illness (ILI) associated with laboratory-confirmed influenza virus infection using a test-negative case-control design. Influenza vaccination was determined based on self-report by adult patients or the parents of child patients. RESULTS Of 1998 patients with ILI, 695 (35%) tested positive for influenza viruses, including 292 (42%) A(H3N2), 398 (57%) A(H1N1)pdm09, and 5 (1%) not (sub)typed influenza viruses. The rate of influenza vaccination among all patients was 4% (71/1998). Among influenza positive patients, 2% (57/1303) were vaccinated compared to 4% (14/695) among influenza negative patients, resulting in VE for one or more doses of vaccine (adjusted for age, sex, week, and days since illness onset) against all circulating influenza viruses of 52% (95% CI=12-74%). A significant adjusted VE for one or more doses of vaccine for all ages against A(H1N1)pdm09 of 59% (95% CI, 8-82%) was observed; however, the VE against A(H3N2) was 43% (95% CI, -30% to 75%). The point estimate of VE was 59% (95% CI, 19-79%) for those aged <60 years, but a negative VE point estimate without statistical significance was observed among those aged ≥60 years. CONCLUSIONS IIV3 conferred moderate protection against medically-attended influenza in Beijing, China during the 2012-2013 season, especially against the A(H1N1)pdm09 strain and among those aged <60 years old.
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Affiliation(s)
- Peng Yang
- Beijing Center for Disease Prevention and Control, Beijing, China; Beijing Research Center for Preventive Medicine, Beijing, China
| | - Mark G Thompson
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Chunna Ma
- Beijing Center for Disease Prevention and Control, Beijing, China; Beijing Research Center for Preventive Medicine, Beijing, China
| | - Weixian Shi
- Beijing Center for Disease Prevention and Control, Beijing, China; Beijing Research Center for Preventive Medicine, Beijing, China
| | - Shuangsheng Wu
- Beijing Center for Disease Prevention and Control, Beijing, China; Beijing Research Center for Preventive Medicine, Beijing, China
| | - Daitao Zhang
- Beijing Center for Disease Prevention and Control, Beijing, China; Beijing Research Center for Preventive Medicine, Beijing, China
| | - Quanyi Wang
- Beijing Center for Disease Prevention and Control, Beijing, China; Beijing Research Center for Preventive Medicine, Beijing, China.
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Vaccine effectiveness against medically attended laboratory-confirmed influenza in Japan, 2011-2012 Season. PLoS One 2014; 9:e88813. [PMID: 24551167 PMCID: PMC3923823 DOI: 10.1371/journal.pone.0088813] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 01/16/2014] [Indexed: 11/19/2022] Open
Abstract
The objective of this study was to estimate influenza vaccine effectiveness (VE) against medically attended, laboratory-confirmed influenza during the 2011-2012 season in Japan using a test-negative case-control study design. The effect of co-circulating non-influenza respiratory viruses (NIRVs) on VE estimates was also explored. Nasopharyngeal swab samples were collected from outpatients with influenza-like illnesses (ILIs) in a community hospital in Nagasaki, Japan. Thirteen respiratory viruses (RVs), including influenza A and B, were identified from the samples using a multiplex polymerase chain reaction. The difference in VE point estimates was assessed using three different controls: ILI patients that tested negative for influenza, those that tested negative for all RVs, and those that tested positive for NIRVs. The adjusted VE against medically attended, laboratory-confirmed influenza using all influenza-negative controls was 5.3% (95% confidence interval [CI], -60.5 to 44.1). The adjusted VEs using RV-negative and NIRV-positive controls were -1.5% (95% CI, -74.7 to 41) and 50% (95% CI, -43.2 to 82.5), respectively. Influenza VE was limited in Japan during the 2011-2012 season. Although the evidence is not conclusive, co-circulating NIRVs may affect influenza VE estimates in test-negative case-control studies.
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Dawood FS, Prapasiri P, Areerat P, Ruayajin A, Chittaganpitch M, Muangchana C, Baggett HC, Olsen SJ. Effectiveness of the 2010 and 2011 Southern Hemisphere trivalent inactivated influenza vaccines against hospitalization with influenza-associated acute respiratory infection among Thai adults aged ≥ 50 years. Influenza Other Respir Viruses 2014; 8:463-8. [PMID: 24490684 PMCID: PMC4181806 DOI: 10.1111/irv.12233] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2013] [Indexed: 01/08/2023] Open
Abstract
Background Inactivated influenza vaccine (IIV) effectiveness has been evaluated among older adults in high-income countries, but data on IIV effectiveness in low- and middle-income countries remain sparse. We conducted a test-negative case–control analysis to estimate 2010 and 2011 trivalent IIV effectiveness against hospitalization with influenza-associated acute respiratory infection (ARI) among persons aged ≥50 years in rural Thailand. Methods During 2010–2011, active surveillance for ARI hospitalization was conducted in two provinces; patients were tested for influenza viruses by real-time RT-PCR. Vaccination status was obtained from vaccine registries. Case and control patients were patients with nasopharyngeal swabs positive and negative for influenza viruses, respectively. Vaccine effectiveness (VE) was estimated for the 6 months after vaccination began. Logistic regression was used to evaluate the association between case status and vaccination while adjusting for age, province, medical conditions, and time. Results During 2010–2011, there were 1545 patients with ARI, of whom 279 (18%) were influenza-positive case patients and 1266 (82%) were influenza-negative control patients. Of the 279 case patients, 247 (89%) had influenza A and 32 (11%) had influenza B. Fourteen of 279 (5%) case patients and 108 of 1266 (9%) control patients were vaccinated against influenza. The unadjusted IIV effectiveness against hospitalization with influenza-associated ARI was 43% (95% CI: 0–68%); adjusted VE was 47% (95% CI: 5–71%). Conclusion The 2010 and 2011 IIVs were moderately effective against hospitalization with influenza-associated ARI among Thais aged ≥50 years, but IIV coverage was low. Additional efforts are warranted in Thailand to improve IIV uptake in this target group.
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Affiliation(s)
- Fatimah S Dawood
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA
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Fu C, He Q, Li Z, Xu J, Li Y, Lu J, Li K, Yang Q, Dong Z, Liu X, Wen S, Hu W, Zhang D, Lv J, Zhu W, Wang M. Seasonal influenza vaccine effectiveness among children, 2010-2012. Influenza Other Respir Viruses 2013; 7:1168-74. [PMID: 23981250 PMCID: PMC4634265 DOI: 10.1111/irv.12157] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/26/2013] [Indexed: 11/26/2022] Open
Abstract
Background The annual differences in the seasonal influenza vaccine and the circulating strains make it necessary to assess influenza vaccine effectiveness (VE) yearly. We assessed the effectiveness of the trivalent inactivated influenza vaccine for the 2010–2011 and 2011–2012 influenza seasons among children in Guangzhou, China. Methods We conducted a 1:2 matched case–control study based on date of birth (±7 days), gender, and area of residence. The influenza cases from surveillance sites in Guangzhou were laboratory‐confirmed during the 2010–2012 seasons. The controls were randomly selected from children aged 6–59 months in the Children's Expanded Programmed Immunization Administrative Computerized System. The influenza vaccination information for both cases and controls was retrieved from this system. Results We analyzed the vaccination information for 1255 influenza cases and 2510 matched controls in 2 influenza seasons in Guangzhou, China. We found that the VE for vaccination during the 2010–2011 and 2011–2012 seasons of virus circulation was 73·2% (95% confidence interval (CI), 52·2–85·0%) and 52·9% (95% CI, 42·1–61·7%), respectively. The VE decreased from 68·9% (95% CI, 57·5–77·2%) in the period between January and March to 48·4% (95% CI, 33·8–59·7%) in the period between April and June. Conclusions This post‐licensing study of VE found moderate protection against influenza for vaccinated children aged 6–59 months. Although the influenza vaccine strains for the 2010–2011 and the 2011–2012 seasons were the same, our study indicated that annual vaccination is recommended even for those who received the vaccine during the previous season.
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Affiliation(s)
- Chuanxi Fu
- Guangzhou Center for Disease Control and Prevention, Guangzhou, China
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