不同流感样病例定义对住院儿童流感监测结果的影响

  目的   了解不同流感样病例定义对住院儿童流感监测结果的影响。   方法   利用2017年10月-2018年5月苏州大学附属儿童医院呼吸道疾病综合监测的病原学和临床症状等数据, 计算符合中国、欧盟疾病预防控制中心(European center for disease prevention and control, ECDC)和世界卫生组织(world health organization, WHO)的流感样病例定义时的流感病毒检出率, 以流感病毒检出为金标准, 分别分析三种流感样病例定义确诊的灵敏度、特异度、阳性预测值、阴性预测值与受试者工作特征曲线(receiver operator characteristic curve, ROC)下面积, 并采用多因素Logistic回归分析模型分析流感病毒阳性率的相关因素。   结果   研究共纳入1 459例呼吸道感染住院病例, 其中流感病毒阳性者204例, 阳性率14.0%。ECDC定义的灵敏度最高(91.7%, 95% CI:87.9%~95.5%), 但其特异度最低(44.6%, 95% CI:41.9%~47.4%); WHO定义的灵敏度最低(70.6%, 95% CI:64.3%~76.8%); 中国定义的灵敏度(91.2%, 95% CI:87.3%~95.1%)和特异度(51.5%, 95% CI:48.8%~54.3%)均较高, 且其ROC曲线下面积最大(71.2%, 95% CI:67.9%~74.5%)。多因素分析发现有发热症状(≥38℃)患儿的流感病毒检出率高于不发热患儿(OR=7.03, 95% CI:3.89~12.70)。   结论   在住院儿童中开展流感监测时, 采用中国流感监测的流感样病例定义可以获得较好的效果。     

Influenza in Refugees on the Thailand�CMyanmar Border, May�COctober 2009

We describe the epidemiology of influenza virus infections in refugees in a camp in rural Southeast Asia during May–October 2009, the first 6 months after identification of pandemic (H1N1) 2009 in Thailand. Influenza A viruses were detected in 20% of patients who had influenza-like illness and in 23% of those who had clinical pneumonia. Seasonal influenza A (H1N1) was the predominant virus circulating during weeks 26–33 (June 25–August 29) and was subsequently replaced by the pandemic strain. A review of passive surveillance for acute respiratory infection did not show an increase in acute respiratory tract infection incidence associated with the arrival of pandemic (H1N1) 2009 in the camp.     

Estimating influenza vaccine effectiveness: Evolution of methods to better understand effects of confounding in older adults

Older adults are at high risk for serious complications of influenza illness and loss of vaccine-mediated protection. It is increasingly recognized that in addition to age, multiple chronic conditions and associated frailty contribute to the decline in vaccine effectiveness in this population. However, observational studies have been fraught with issues of confounding related to the degree of frailty and functional decline, measures of which are not included in standard administrative health care databases that are used to calculate vaccine effectiveness. This issue has led to the identification of confounding by indication or from “healthy vaccinee” bias, which respectively lead to underestimates or overestimates of influenza vaccine effectiveness. In addition, the sensitivity and specificity of the criteria used to define influenza-like illness declines with increasing age due to atypical presentations of illness and the inability to distinguish between influenza and other respiratory viruses. The test-negative case:control design has emerged as a method to estimate influenza vaccine effectiveness by comparing vaccination rates in those with laboratory-confirmed influenza to those with other acute viral respiratory illnesses. This review provides a perspective on how test-negative case:control study designs and new insights into mechanisms of protection have considerably strengthened influenza vaccination policy decisions for older adults that have historically been undermined by the conclusions of observational studies.     

流感样病例定义对流感监测结果影响的比较分析

目的 比较不同临床症状的流感样病例流感检出情况的差异,探讨采用不同流感样病例定义对流感监测结果的影响。方法 根据2015年上海市2家国家级流感监测哨点医院的流感病原学监测数据和病例临床症状,计算不同临床症状（有咳嗽咽痛、仅咳嗽、仅咽痛）的流感样病例流感病毒检出情况,并通过多因素Logistic回归分析流感病毒检出情况的影响因素。结果 2 010例流感样病例中,有咳嗽咽痛者1 105例、仅有咳嗽者270例、仅有咽痛者635例,流感阳性率分别为36.2%、39.3%和15.9%,经分析,有咳嗽咽痛者、仅有咳嗽者的流感阳性检出率均高于仅有咽痛者（均有P<0.05）。对于发病3 d内采样的流感样病例,有咳嗽咽痛、仅有咳嗽者的流感阳性检出率均高于仅咽痛者（均有P<0.05）。多因素Logistic回归分析结果显示,流感病毒检出情况与病例体温（≥ 39℃）（OR=1.719,95%CI：1.389~2.127）、咳嗽（OR=3.046,95%CI：2.377~3.905）有关。结论 建议以"发热（体温≥ 38℃）伴咳嗽症状者"作为流感监测中的流感样病例定义。     

2017-2018年青岛地区儿童急性上呼吸道感染病毒谱与流行特征

目的  了解2017年3月-2018年3月青岛地区儿童急性上呼吸道感染病毒谱与流行特征。 方法  随机抽选青岛地区符合国家流感监测方案诊断标准的流感监测病例中的儿童流感样病例（influenza-like illness,ILI）作为研究对象,共检测359例。采集患儿咽拭子,采用多重实时荧光逆转录-聚合酶链反应进行核酸检测的方法,对9种呼吸道病毒进行筛查。 结果  359例标本中200例至少有1种病毒检测结果为阳性,阳性率为55.71%（200/359）。其中,阳性最多的是流感病毒B型（Influenza Virus B,IVB）Yamagata亚型29.50%（59/200）,其次是肠道病毒（Human Enterovirus,HEV）15.00%（30/200）,呼吸道腺病毒（Adenovirus,AdV）13.50%（27/200）,呼吸道合胞病毒A型（Respiratory Syncytial Virus A,RSVA）12.50%（25/200）,流感病毒A型（Influenza Virus A,IVA）H1N1亚型10.00%（20/200）等。2例3种病毒混合感染,1例4种病毒混合感染。 结论  2017年3月-2018年3月9种呼吸道病毒在青岛地区均有流行,IVB Yamagata亚型、HEV、AdV、RSVA亚型、IVA H1N1亚型为主要流行病毒。其中流感病毒、HEV、RSV、偏肺病毒（Human metapneumovirus,HMPV）具有明显的季节性分布。9种病毒在各病毒流行月份存在混合感染。     

A comparison of data sources for the surveillance of seasonal and pandemic influenza in Victoria

Understanding the characteristics of available influenza or influenza-like illness (ILI) surveillance systems is important for seasonal influenza surveillance and pandemic preparedness. We compared five influenza or ILI data sources in Victoria: notifications of laboratory-confirmed influenza to the Victorian Department of Human Services; hospital emergency presentations and hospital admissions; sentinel general practitioner surveillance; and medical locum service surveillance. Seasonal trends for influenza and ILI activity were similar for all data sources. Community ILI surveillance, operating as sentinel GP, locum service or hospital emergency department surveillance, in conjunction with notification of laboratory-confirmed influenza, would provide adequate inter-pandemic surveillance for influenza in Victoria and, by extension, in any Australian jurisdiction. Other surveillance systems would be needed for early pandemic case or cluster detection, while pandemic monitoring would be better achieved by a more automated system.     

Establishing thresholds for influenza surveillance in Victoria

Objective: We aimed to review the proportion of influenza-like illness (ILI) that could be attributed to influenza infection over five consecutive influenza seasons in Victoria, to compare ILI activity with hospital admissions for influenza, and to develop thresholds that would indicate when ILI activity may coincide with increases in influenza hospitalisations.
Methods: Combined nose/throat swabs from patients with ILI selected from sentinel general practices were tested for influenza and other respiratory viruses at the Victorian Infectious Diseases Reference Laboratory. The proportion of ILI attributed to laboratory-confirmed influenza was evaluated for five consecutive surveillance seasons, from 1998 to 2002. The seasonal patterns of ILI and laboratory-confirmed influenza were compared for 2000–02. ILI surveillance from sentinel general practices between 1997 and 2000 was compared with hospital admissions for influenza extracted from the Victorian Admitted Episodes Dataset between 1994 and 2000.
Results: Approximately 41% of all ILI cases from sentinel general practices were confirmed to have an influenza infection between 1998 and 2002. The seasonal pattern of ILI and confirmed influenza among patients selected from sentinel general practices was very similar over three influenza seasons. The trends for ILI rates in sentinel general practices appeared to correlate remarkably well with those of hospital admissions for influenza. Thresholds for ILI were defined as: baseline <0.25 ILI cases/100 patients/week; normal seasonal activity 0.25–1.5; above normal seasonal activity >1.5–3.5; and epidemic activity above 3.5.
Conclusion: ILI rates from sentinel general practices correspond with hospital admissions coded as influenza and allow the use of threshold levels to describe seasonal influenza activity.     

Annual report of the National Influenza Surveillance Scheme, 2006

Influenza surveillance in Australia is based on laboratory isolation of influenza viruses, sentinel general practitioner reports of influenza-like illness, and absenteeism data from a major national employer. In 2006, 3,130 cases of laboratory-confirmed influenza were reported to the National Notifiable Diseases Surveillance System, which was one-third lower than in 2005. The influenza season started in mid-June, with peak activity in late August. Influenza A was the predominant type notified (71%), however influenza B activity continued to increase as a proportion of reported cases. Reports of influenza-like illness from sentinel general practitioners showed a slow but steady increase throughout the first half of the year to peak in late August. In 2006, 657 influenza isolates from Australia were antigenically analysed: 402 were A(H3N2), 24 were A(H1N1) and 231 were influenza B viruses. Continued antigenic drift was seen with the A(H3N2) viruses from the previous reference strains (A/California/7/2004 and A/New York/55/2004) and drift was also noted in some of the A(H1N1) strains from the reference/ vaccine strain A/New Caledonia/20/99, although very few A(H1N1) viruses were isolated in Australia in 2006. The B viruses isolated were predominately of the B/Victoria-lineage and similar to the reference/vaccine strain B/Malaysia/2506/2004.     

Community influenza activity and risk of acute influenza-like illness episodes among healthy unvaccinated pregnant and postpartum women

This study investigated the relation between weekly levels of influenza activity and the risk of acute influenza-like illness episodes among 8,323 healthy pregnant and postpartum women enrolled in a Puget Sound region, Washington, health maintenance organization, Group Health Cooperative, between June 1991 and December 1997. The authors classified weeks between October and May for isolate activity level based on surveillance data for influenza, respiratory syncytial virus, parainfluenza, and adenovirus infection. Influenza-like illness episodes were identified from medical encounters assigned a diagnostic code consistent with a symptomatic influenza infection. The authors compared the occurrence of influenza-like illness episodes within each pregnancy stage for periods with varying levels of influenza isolate detection in the community. Repeated-measures logistic regression methods accounted for time-dependent factors. The adjusted strength of association between influenza exposure and influenza-like illness episodes increased as the pregnancy stage progressed (first trimester odds ratio = 1.12, 95% confidence interval: 0.79, 1.59; second trimester odds ratio = 1.30, 95% confidence interval: 0.97, 1.73; third trimester odds ratio = 1.84, 95% confidence interval: 1.31, 2.59; postpartum period odds ratio = 2.28, 95% confidence interval: 1.42, 3.68). Pregnancy stage modified the association between influenza activity and influenza-like illness episodes. Findings estimate that 20-43 pregnant/postpartum women would need to be vaccinated with an 80% effective vaccine to prevent one influenza-like illness episode.     

Effectiveness of virosomal subunit influenza vaccine in preventing influenza-related illnesses and its social and economic consequences in children aged 3-14 years: a prospective cohort study

To evaluate the effectiveness of a virosomal subunit influenza vaccine in preventing influenza-related illnesses and its social and economic consequences in children aged 3-14 years, a prospective cohort study was carried out during the 2004-2005 influenza season in 11 private pediatric clinics in the Barcelona metropolitan area. One dose of a virosomal subunit inactivated influenza vaccine (Inflexal V Berna) was given during September and October 2004 to healthy children aged 3-14 years attended in 5 of the 11 clinics. Who comprised the vaccinated cohort (n=966). The non-vaccinated cohort (n=985) was comprised of children attended in the other six clinics. Informed consent was obtained from all parents. The follow up was performed between 1 November 2004 and 31 March 2005. Using a self-administered questionnaire, information was collected from parents or guardians on any type of acute, febrile respiratory illness suffered by their children during the study period, including antibiotic use, and absence from school or work-loss of parents as a result of the illness. RT-PCR (influenza A+B+C) was carried out on pharyngeal and nasal samples obtained from children attended by pediatricians during this period in these clinics with the following symptoms: fever> or =38.5 degrees lasting at least 72h, cough or sore throat (influenza-like illness). Adjusted vaccination effectiveness was 58.6% (95% CI 49.2-66.3) in preventing acute febrile respiratory illnesses, 75.1% (95% CI 61.0-84.1) in preventing cases of influenza-like illnesses and 88.4% (95% CI 49.2-97.3) in preventing laboratory-confirmed cases of influenza A. The adjusted vaccination effectiveness in reducing antibiotic use (18.6%, 95% CI -4.2 to 3.64), absence from school (57.8%, 95% CI 47.9-65.9) and work-loss of parents (33.3%, 95% CI 8.9-51.2) in children affected by an acute febrile respiratory illness was somewhat lower. Vaccination of children aged 3-14 years in pediatric practices with one dose of virosomal subunit inactivated influenza vaccine has the potential to considerably reduce the health and social burdens caused by influenza-related illnesses.     

应用多重PCR技术快速检测临床标本中常见呼吸道病毒

[目的]应用多重PCR技术快速检测流感样病例和不明原因肺炎病例呼吸道标本中的常见呼吸道病毒,为急性病毒性呼吸道感染的监测和应急处理提供快速诊断手段。[方法]提取标本中病毒核酸RNA/DNA,反转录合成cDNA,多重PCR扩增目的基因,电泳检测扩增产物。[结果]从30份呼吸道标本中检出甲型流感病毒、乙型流感病毒、副流感病毒3型和呼吸道合胞病毒A型。[结论]本研究初步验证了该多重PCR技术能用于快速检测流感样病例和不明原因肺炎病例呼吸道标本中的常见呼吸道病毒。     

Annual report of the National Influenza Surveillance Scheme, 2005

Surveillance of influenza in Australia is based on laboratory isolation of influenza viruses, sentinel general-practitioner reports of influenza-like illness, and absenteeism data from a major national employer. In 2005, 4,575 cases of laboratory-confirmed influenza-like illness were reported, which was 115 per cent higher than in 2004. The influenza season started in the first week of June, with peak activity in early August, a month earlier than in 2004. Influenza A was the predominant type notified (73%), while influenza B activity continued to increase compared to previous years. During 2005, the influenza notification rate amongst persons aged over 65 years (22 cases per 100,000 population) was 70 per cent higher than the mean rate of the last four years. One thousand one hundred and seventy-four influenza isolates from Australia were antigenically analysed: 689 were A(H3N2), 210 were A(H1N1) strains and 275 were influenza B viruses. Continued antigenic drift was seen with the A(H3N2) viruses from the previous reference strains with approximately one quarter of isolates being distinguishable from A/Wellington/1/2004-like viruses and more closely matched to A/California/7/2004-like viruses.     

Effectiveness of seasonal influenza vaccine in Australia, 2015: An epidemiological,antigenic and phylogenetic assessment

BackgroundA record number of laboratory-confirmed influenza cases were notified in Australia in 2015, during which type A(H3) and type B Victoria and Yamagata lineages co-circulated. We estimated effectiveness of the 2015 inactivated seasonal influenza vaccine against specific virus lineages and clades.MethodsThree sentinel general practitioner networks conduct surveillance for laboratory-confirmed influenza amongst patients presenting with influenza-like illness in Australia. Data from the networks were pooled to estimate vaccine effectiveness (VE) for seasonal trivalent influenza vaccine in Australia in 2015 using the case test-negative study design.ResultsThere were 2443 eligible patients included in the study, of which 857 (35%) were influenza-positive. Thirty-three and 19% of controls and cases respectively were reported as vaccinated. Adjusted VE against all influenza was 54% (95% CI: 42, 63). Antigenic characterisation data suggested good match between vaccine and circulating strains of A(H3); however VE for A(H3) was low at 44% (95% CI: 21, 60). Phylogenetic analysis indicated most circulating viruses were from clade 3C.2a, rather than the clade included in the vaccine (3C.3a). VE point estimates were higher against B/Yamagata lineage influenza (71%; 95% CI: 57, 80) than B/Victoria (42%, 95% CI: 13, 61), and in younger people.ConclusionsOverall seasonal vaccine was protective against influenza infection in Australia in 2015. Higher VE against the B/Yamagata lineage included in the trivalent vaccine suggests that more widespread use of quadrivalent vaccine could have improved overall effectiveness of influenza vaccine. Genetic characterisation suggested lower VE against A(H3) influenza was due to clade mismatch of vaccine and circulating viruses.     

Influenza vaccine effectiveness among adult patients in a University of Lyon hospital (2004-2009)

The aim of this study was to estimate influenza vaccine effectiveness (IVE) against laboratory-confirmed influenza among hospitalized patients. A case-control investigation was based on the prospective surveillance of influenza-like illness (ILI) during five flu seasons. We compared influenza-positive cases and influenza-negative controls. Unadjusted overall IVE was 62% (95% confidence interval 24% to 81%). We found that IVE was lower during the 2004-05 flu season (11%; 95% CI −232% to 76%) when the vaccine and circulating viruses were mismatched. Expansion of the study to other hospitals could provide IVE estimates earlier in the season, for different age groups and emerging virus strains.     

Effectiveness of the 2003-2004 influenza vaccine among U.S. military basic trainees: a year of suboptimal match between vaccine and circulating strain

Effectiveness of the 2003-2004 influenza vaccine was evaluated at five military basic training centers throughout the United States. Data from surveillance conducted in December and January 2003-2004 in this highly vaccinated population were evaluated. During this period, 10.6% (37/350) of specimens were positive for influenza A. A 14-day period after vaccination was considered the period prior to immune protection; vaccine effectiveness (VE) was calculated based on febrile respiratory illness presentation and laboratory confirmation of influenza before or after this 14-day period. Thirty-two cases presented within 14 days of vaccination, and five cases presented beyond 14 days from vaccination. VE in this population was estimated to be 94.4% for laboratory-confirmed influenza. In contrast, VE was only 13.9% for influenza-like illness (ILI) without a laboratory confirmation.     

Creating a model program for influenza surveillance in California: results from the 2005-2006 influenza season

BACKGROUND: Influenza surveillance is valuable for monitoring trends in influenza-related morbidity and mortality. Using the 2005-2006 influenza season as an example, this paper describes a comprehensive influenza surveillance program used by the California Department of Public Health (CDPH). METHODS: Data collected from patients evaluated for acute respiratory illness in a given week were reported and summarized the following week, including (1) electronic hospital pneumonia and influenza admission and antiviral usage records from Kaiser Permanente, (2) sentinel provider influenza-like illness (ILI) reports, (3) severe pediatric influenza case reports (e.g., children either hospitalized in intensive care or expired), (4) school clinic ILI evaluations, and (5) positive influenza test results from a network of academic, hospital, commercial, and public health laboratories and the state CDPH Viral and Rickettsial Disease Laboratory. RESULTS: Influenza activity in California in the 2005-2006 season was moderate in severity; all clinical and laboratory markers rose and fell consistently. Extensive laboratory characterization identified the predominant circulating virus strain as A/California/7/2004(H3N2), which was a component of the 2005-2006 influenza vaccine; 96% of samples tested showed adamantane resistance. CONCLUSIONS: By using multiple, complementary surveillance methods coupled with a strong laboratory component, the CDPH has developed a simple, flexible, stable, and widely accepted influenza surveillance system that can monitor trends in statewide influenza activity, ascertain the correlation between circulating strains with vaccine strains, and assist with detection of new strain variants. The methods described can serve as a model for influenza surveillance in other states.     

中国10省(市)2009－2014年15岁以下儿童流感确诊住院病例严重急性呼吸道感染临床特征及其危险因素分析

目的 探讨我国<15岁儿童流感确诊病例严重急性呼吸道感染(SARI)临床特征及感染危险因素。方法 分析10省市2009年12月至2014年6月SARI哨点监测系统纳入的<15岁儿童流感实验室确诊住院病例。通过调查表收集病例人口学、既往疾病史、临床症状和体征、治疗和结局等信息,描述临床特征及流感感染危险因素。结果 纳入的2 937例儿童SARI住院病例中,190例(6.5%)为流感确诊病例。流感确诊病例中,男性123例(64.7%),<5岁儿童139例(73.2%),年龄M=3.0(IQR:1.0～5.0)岁。20例(10.5%)至少有一种慢性基础性疾病,其中慢性心血管疾病(3.2%)、免疫抑制性疾病(3.2%)和肿瘤(2.6%)最常见。发热(92.6%)和咳嗽(88.8%)是最常见的临床症状,肺部听诊异常(51.1%)和X线表现肺部异常(36.1%)是最常见的临床体征。29例(15.8%)出现并发症,以肺炎(15.3%)为最常见的并发症。16例(8.6%)服用抗病毒药物,4例(2.2%)收入ICU治疗。危险因素分析提示,<6月龄是流感病毒感染的保护因素(OR=0.406,95%CI:0.203～0.815),5～9岁是流感病毒感染的危险因素(OR=2.535,95%CI:1.059～6.066)。结论 流感确诊病例主要集中在<5岁儿童,不同年龄组病例感染流感病毒的风险存在差异。     

Incidence of influenza-like illness and severe acute respiratory infection during three influenza seasons in Bangladesh, 2008-2010

Objective

To determine how much influenza contributes to severe acute respiratory illness (SARI), a leading cause of death in children, among people of all ages in Bangladesh.

Methods

Physicians obtained nasal and throat swabs to test for influenza virus from patients who were hospitalized within 7 days of the onset of severe acute respiratory infection (SARI) or who consulted as outpatients for influenza-like illness (ILI). A community health care utilization survey was conducted to determine the proportion of hospital catchment area residents who sought care at study hospitals and calculate the incidence of influenza using this denominator.

Findings

The estimated incidence of SARI associated with influenza in children ConclusionInfluenza-like illness is a frequent cause of consultation in the outpatient setting in Bangladesh. Children aged less than?5 years are hospitalized for influenza in greater proportions than children in other age groups.     

Frailty is associated with impairment of vaccine-induced antibody response and increase in post-vaccination influenza infection in community-dwelling older adults

Annual immunization with a trivalent inactivated vaccine (TIV) is considered efficacious for prevention of seasonal influenza in older adults. However, significant controversy exists in the current literature regarding the clinical effectiveness of TIV immunization in this highly heterogeneous population. Frailty is an important geriatric syndrome characterized by decreased physiologic reserve and increased vulnerability to stressors. Using a validated set of frailty criteria, we conducted a prospective observational study to evaluate TIV-induced strain-specific hemagglutination inhibition (HI) antibody titers and post-vaccination rates of influenza-like illness (ILI) and infection in frail and nonfrail older adults. The results indicate that frailty was associated with significant impairment in TIV-induced strain-specific HI titers and increased rates of ILI and laboratory-confirmed influenza infection. These findings suggest that assessing frailty status in the elderly may identify those who are less likely to respond to TIV immunization and be at higher risk for seasonal influenza and its complications.     

一起甲型H1N1和H3N2流感病毒混合感染调查研究

目的 从病例临床特征、抗体变化规律及病原学检测等多角度分析一起由甲型H1N1和H3N2流感病毒混合感染引起暴发疫情的流行特征,为有效控制疾病的发生与蔓延提供科学依据.方法 采用回顾性调查和现场流行病学调查方法进行问卷调查,利用RT-PCR和血凝抑制试验分别进行流感病毒和血清抗体检测.结果 45例流感样病例中,确诊40例,其中22例为甲型H1N1流感、12例为季节性H3N2型流感、6例为H1N1和H3N2病毒混合感染.不同病毒感染病例的临床表现差异无统计学意义.序列比对分析显示,混合病毒感染和单一病毒感染者的甲型H1N1和季节性H3N2病毒基因序列没有差异.同时分析表明,所有流感病例的病毒株均对金刚烷胺耐药,对奥司他韦(达菲)有效.患者的双份血清血凝抑制试验检测表明,暴发由甲型H1N1和H3N2流感病毒混合感染引起.结论 这是一起由甲型H1N1和H3N2流感病毒混合感染引起的疫情,甲型H1N1病毒在传播过程中可能较H3N2更具有优势.