Influenza surveillance in Victoria, 2006

The Victorian influenza season in 2006 remained within normal seasonal activity thresholds and was relatively mild compared with recent years. The season peaked in mid-August, with influenza-like illness (ILI) rates from general practitioner sentinel surveillance and the Melbourne Medical Locum Service (MMLS), and cases of laboratory-confirmed influenza notified to the Department of Human Services, reaching their zeniths within one week of each other. A total of 74 general practitioners (GPs) participated in the sentinel surveillance in 2006, reporting a total of 136,732 consultations during the surveillance period from May to September inclusive. Participating GPs reported a total of 765 patients with an ILI; an average ILI rate of 5.6 cases per 1,000 consultations. The average ILI rate from the MMLS in the same period was 8.5 cases per 1,000 call-outs. Eighty-two per cent of laboratory-confirmed influenza notifications during the surveillance period were type A; the remainder were type B. Typing indicated circulation of two predominant strains during the season: A/Wisconsin/67/2005(H3N2)-like virus and B/Malaysia/2506/2004-like virus. The influenza vaccine for 2006 contained A/New Caledonia/20/ 99(H1N1)-like virus, A/California/7/2004(H3N2)-like virus and B/Malaysia/2506/2004-like virus.     

Influenza surveillance in Victoria, 2005

Influenza activity remained within normal seasonal activity with a well-defined peak at week 29 (beginning 18 July) during the Victorian influenza season from May to September 2005. Surveillance was based on sentinel general practice influenza-like illness (ILI) notifications with laboratory confirmation, medical locum service ILI notifications and laboratory notification of influenza detections. One thousand and eighty-seven consultations for ILI were reported from 38 general practices, while medical practitioners from the locum service reported 317 consultations for ILI. The average weekly rate of ILI from sentinel surveillance was 7.3 per 1,000 consultations. Similar numbers of influenza A subtypes H1N1 and H3N2 were detected; 45 per cent of which were A/California/7/2004-like (H3), 44 per cent were A/New Caledonia/20/99-like (H1) and 11 per cent were A/Wellington/1/2004 (H3). Of the influenza B samples, 67 per cent were B/Hong Kong/330/2001-like and 33 per cent were B/Shanghai/361/2002-like. The influenza vaccine for 2005 contained: A/New Caledonia/20/99(H1N1)-like virus, A/Wellington/ 1/2004(H3N2)-like virus, and B/Shanghai/361/2002-like virus. Although the predominant H3 and B circulating strains were not included in the vaccine, there was reasonable serological cross protection between vaccine and circulating strains.     

Influenza surveillance in Victoria, 2004.

Influenza activity during the traditional Victorian influenza season from May to October 2004 was low with no well-defined peak. Surveillance was based on sentinel general practice influenza-like illness (ILI) notification with laboratory confirmation, locum service ILI notification and laboratory reporting of influenza detections. Eight hundred and fifteen consultations for ILI were reported from 38 general practices and 216 consultations for ILI were reported from the locum service. The average weekly rate of influenza-like-illness from sentinel surveillance was 5.4 cases per 1,000 consultations, representing normal seasonal activity. Influenza A (H3N2) was the predominant circulating sub-type, 88 per cent of which were identified as A/Fujian/411/2002-like and 12 per cent as A/Wellington/1/2004. All influenza B was B/Shanghai/361/2002-like. There was some mismatch with the 2004 influenza vaccine, which contained A/New Caledonia/20/99(H1N1)-like virus, A/Fujian/411/2002(H3N2)-like virus, and B/Hong Kong/330/2001-like virus.     

Higher than normal seasonal influenza activity in Victoria, 2003.

Influenza surveillance in Victoria comprises surveillance of patients with influenza-like illness (ILI) from sentinel general practices and laboratory based reporting of influenza detections, predominantly from hospital inpatients. Surveillance of patients with ILI seen by the Melbourne Medical Locum Service (MMLS) was conducted for the first time in 2003, when the influenza season was characterised by a late onset with higher than normal seasonal activity. Influenza A (H3N2) was the predominant circulating influenza virus type, with 99 per cent of sub-typed viruses identified as a drifted strain, A/Fujian/411/2002-like. Sentinel and hospital laboratory surveillance both indicated low levels of circulating influenza A (H1N1) and influenza B. Although the proportion of patients with ILI detected through MMLS surveillance was greater than the proportion from sentinel general practices, the ILI pattern was comparable between the two surveillance systems.     

郴州市2004年流行性感冒监测结果分析

目的通过监测,了解郴州市流行性感冒流行情况及流行株,为国家流感监测网提供科学数据。方法对市区两所医院的儿科、内科门诊设流感样病例(ILI)监测点,定期上报数据,同时监测全市ILI暴发疫情,采集ILI标本进行实验室病毒分离鉴定。结果两所医院全年报告ILI 2 640例,占门诊就诊者的1%。儿童ILI 2 014例,占ILI总数的76.3%,儿童ILI病例占儿童就诊者总数的1.66%,成人ILI占成人就诊者总数的0.73%。从两起暴发ILI疫情中采集标本23份,分离到甲3型流感病毒A(H3N2)亚型4株。结论郴州市ILI全年均有发生,但3~8月为流行高峰,流行株为A(H3N2)亚型。     

2007-2016年湖南省流感监测结果分析

目的 了解2007-2016年湖南省流感流行规律,为今后的流感防控工作提供科学依据。方法 运用描述流行病学方法对2007-2016年湖南省流感样病例(influenza like illness, ILI)数据、流感毒株分离数据和流感暴发疫情数据进行分析。 结果 2007-2016年哨点医院共报告ILI病例1 520 652例,占就诊病人总数的百分比(ILI%)为4.82%。0~岁、5~岁、15~岁、25~岁和60~岁五个年龄组的ILI人数分别占ILI病例总数的65.98%、20.77%、4.49%、6.68%和2.08%;湖南省流感流行呈现冬春季和夏季双高峰;共分离到流感病毒8 788株,分离率为5.99%,毒株分型为H1N1 476株、 新甲型(H1N1)pdm09(新甲H1) 2 422株、H3N2 2 985株、B型 Yamagata系(BY)1 361株和Victorian系(BV)1 532株、未定型12株,不同型别毒株每隔1~2年成为优势毒株;共报告ILI暴发疫情264起,230起发生在中、小学校,占总疫情的87.12%。结论 冬春季和夏季是湖南省的流感流行高峰;H3、新甲型H1和B型流感毒株每隔1~2年交替成为优势毒株;中小学校是流感暴发疫情的高发场所,应重点加强防控。     

Long time trends in influenza-like illness and associated determinants in The Netherlands

We analysed long-term epidemiological trends in influenza-like illness (ILI) in The Netherlands and used an ecological analysis to estimate its relationship with age, influenza vaccination, and virological aspects. This study used data from weekly ILI consultation reports from sentinel general practitioners (1986/1987 to 2006/2007), virological data from sentinel ILI patients (1992/1993 to 2006/2007), and data for influenza vaccine uptake (1991-2005). The incidence of ILI consultations, although varying during the study period, was estimated to decrease in the total population by 12.2/10 000 persons each season (95% CI 8.6-15.9). Uptake of influenza vaccination in people aged > or = 65 years (elderly) increased from 28% in 1991 to >70% since 1997. ILI incidence in the elderly declined by 1.7/10 000 persons (P=0.05) per percentage vaccine uptake per season. The decline in ILI incidence over the last 20 years could be related to the increased vaccine uptake. However, insufficient data were present to assess the impact of other potential contributing factors, such as diminished fitness of influenza viruses and changes in consulting behaviour.     

The Influenza Surveillance Program in Western Australia, 2003.

In the winter of 2003 Western Australia experienced its largest epidemic of influenza for at least five years, with activity peaking in August and September. The season was short resulting in very high numbers of cases during the peak weeks. Activity in country areas followed the peak of Metropolitan activity. Influenza A virus was detected in 28.3 per cent of the sentinel samples, and influenza B in less than one per cent. Both routine and sentinel detections and the overall estimates of influenza-like illnesses (ILI) seen by general practitioners at sentinel practices peaked in August and September 2003. The combination of influenza detections and an increase in ILI seemed to be the most accurate predictor of the beginning of winter influenza activity. There was a shift in age distribution for influenza A compared with 2003. Both the sentinel surveillance and routine samples demonstrated an increase of influenza in children and young adults. The majority of influenza A isolates were identified as A/Fujian/411/2002-like, a variant of the A/Moscow strain included in the vaccine. Despite this mismatch there did not seem to have been any noticeable increase in the risk of influenza infection in the vaccinated populations from the sentinel practices, nor was there a relative increase in disease among the highly vaccinated elderly population. A number of other respiratory viruses were identified as causes of influenza-like illness in the sentinel samples. Rhinoviruses and human metapneumovirus were the most common, the latter occurring mainly in adults.     

Annual report of the National Influenza Surveillance Scheme, 2001.

Surveillance of influenza in Australia in 2001 was based on data from national and state-based sentinel practice consultations for influenza-like illness, laboratory isolations of influenza virus and absenteeism rates from a national employer. In 2001, laboratory-confirmed influenza became a notifiable disease and was reported to the National Notifiable Diseases Surveillance System (NNDSS). Influenza A was the dominant type, 81 per cent of which were subtype H1N1 and 19 per cent were subtype H3N2. The influenza A (H1N1) analysed were all A/New Caledonia/20/99-like strains. The H3N2 isolates were antigenically similar to the reference strain A/Moscow/10/99 and the vaccine strain A/Panama/2007/99. The influenza B isolates, which made up only 10 per cent of all isolates, were mainly B/Sichuan/379/99-like strains but 10 per cent of isolates were more closely related to B/Harbin/7/94-like viruses, which circulated in previous years. The Australian 2001 influenza vaccine represented a good match for the circulating viruses and 77 per cent of persons over 65 years in Australia were vaccinated in 2001.     

Preliminary assessment of the effectiveness of the 2003-04 inactivated influenza vaccine--Colorado, December 2003

Influenza activity started earlier than usual in the United States this season, with widespread influenza activity reported in 10 states by November 22, 2003. The predominant influenza viruses (A/Fujian/411/2002 [H3N2]-like viruses) circulating this season differ antigenically from the 2003-04 influenza A (H3N2) vaccine strain. A retrospective cohort study was conducted among workers at a Colorado hospital to provide preliminary data on the effectiveness of trivalent inactivated influenza vaccine (TIV) against influenza-like illness (ILI). This report summarizes the results of that study, which indicated that TIV had no or low effectiveness against ILI. However, additional studies are needed to evaluate the effectiveness of the 2003-04 vaccine against laboratory-confirmed influenza and influenza-related complications, including hospitalization and death. Influenza vaccine continues to be recommended, particularly for persons at increased risk for influenza-related complications, their household contacts, and health-care personnel.     

Effectiveness of trivalent and pandemic influenza vaccines in England and Wales 2008-2010: results from a cohort study in general practice

Estimation of influenza vaccine effectiveness (VE) is complicated by various degrees of mismatch between circulating and vaccine strains each season. We carried out a cohort study to estimate VE of trivalent (TIV) and pandemic influenza vaccines (PIV) in preventing various respiratory outcomes among general practice (GP) patients in England and Wales between 2008 and 2010. Dates of consultations for influenza-like illness (ILI), acute respiratory tract infection (ARTI), lower respiratory tract infection (LRTI) and nasopharyngeal swabs were obtained from the patient-level electronic records of the 100 practices enrolled in a national GP network. Dates of vaccination with TIV and PIV were also extracted. Confounders including age, time period and consultation frequency were adjusted for through Poisson regression models. In the winter of 2008/9, adjusted VE of TIV in preventing ILI was 22.3% (95% CI 13.5%, 30.2%). During the 2009/10 winter VE for PIV in preventing ILI was 21.0% (5.3%, 34.0%). The VE for PIV in preventing PCR-confirmed influenza A/H1N1 (2009) was 63.7% (-6.1%, 87.6%). TIV during the period of influenza circulation of 2008/9 and PIV in the winter of 2009/10 were effective in preventing GP consultations for ILI. The cohort study design could be used each season to estimate VE; however, residual confounding by indication could still present issues, despite adjustment for propensity to consult.     

Flutracking weekly online community survey of influenza-like illness annual report, 2010

Flutracking is a national weekly online survey of influenza-like illness (ILI) completed by community members. Flutracking integrates participants' ILI symptom information with their influenza vaccination status to monitor influenza activity and field vaccine effectiveness (FVE). This report summarises results from the 2010 Flutracking season compared with previous seasons. Nationally, participation in Flutracking has more than doubled between 2008 and 2010, with 5,346 new participants enrolled or recruited in 2010 and a peak weekly participation of 10,773. By the end of the 2010 season, 5,904 of 9,109 (64.8%) participants had received the monovalent pandemic vaccine and/or the 2010 seasonal vaccine. From 2007 to 2010 FVE calculations demonstrated that the seasonal vaccine was effective except in 2009 during the pandemic. Peak 2010 ILI activity occurred in early June and August, and peak weekly 2010 ILI rates (4.2% among unvaccinated participants) were lower than the peak ILI rates during the 2009 pandemic (6.0% among unvaccinated participants). However, the decrease in laboratory notifications was much larger than the decrease in Flutracking rates. In summary, the number of Flutracking participants continued to steadily increase over the 2010 influenza season. The system has shown value in providing weekly vaccination uptake data during and beyond the 2009 influenza pandemic, as well as rapid FVE estimates that are qualitatively aligned with findings from other analyses of vaccine efficacy. Flutracking has also provided estimates of weekly community ILI activity that were not biased by health seeking behaviour and clinician testing practices.     

Surveillance for influenza--United States, 1994-95, 1995-96, and 1996-97 seasons.

PROBLEM/CONDITION: Influenza epidemics occur nearly every year during the winter months and are responsible for substantial morbidity and mortality in the United States, including an average of approximately 114,000 hospitalizations and 20,000 deaths per year. REPORTING PERIOD: This report summarizes U.S. influenza surveillance data from October 1994 through May 1997, from both active and passive surveillance systems. DESCRIPTION OF SYSTEM: During the period covered, CDC received weekly reports from October through May from a) state and territorial epidemiologists on estimates of local influenza activity, b) approximately 140 sentinel physicians on their total number of patient visits and the number of cases of influenza-like illness (ILI), and c) approximately 70 World Health Organization (WHO) collaborating laboratories in the United States on weekly influenza virus isolations. WHO collaborating laboratories also submitted influenza isolates to CDC for antigenic analysis. Throughout the year, vital statistics offices in 121 cities reported deaths related to pneumonia and influenza (P&I) weekly, providing a measure of the impact of influenza on mortality. RESULTS: During the 1994-95 influenza season, 25 state epidemiologists reported regional or widespread activity at the peak of the season. Cases of ILI reported by sentinel physicians exceeded baseline levels for 4 weeks, peaking at 5%. Influenza A(H3N2) was the most frequently isolated influenza virus type/subtype. The longest period of sustained excess mortality was 5 consecutive weeks, when the percentage of deaths attributed to P&I exceeded the epidemic threshold, peaking at 7.6%. During the 1995-96 season, 33 state epidemiologists reported regional or widespread activity at the peak of the season. ILI cases exceeded baseline levels for 5 weeks, peaking at 7%. Influenza A(H1N1) viruses predominated, although influenza A(H3N2) and influenza B viruses also were identified throughout the United States. P&I mortality exceeded the epidemic threshold for 6 consecutive weeks, peaking at 8.2%. The 1996-97 season was the most severe of the three seasons summarized in this report. Thirty-nine state epidemiologists reported regional or widespread activity at the peak of the season. ILI reports exceeded baseline levels for 5 consecutive weeks, peaking at 7%. The proportion of respiratory specimens positive for influenza peaked at 34%, with influenza A(H3N2) viruses predominating. Influenza B viruses were identified throughout the United States, but only one influenza A(H1N1) virus isolate was reported overall. The proportion of deaths attributed to P&I exceeded the epidemic threshold for 10 consecutive weeks, peaking at 9.1%. INTERPRETATION: Influenza A(H1N1), A(H3N2), and B viruses circulated during 1994-1997. Local surveillance data are important because of geographic and temporal differences in the circulation of influenza types/subtypes. PUBLIC HEALTH ACTIONS: CDC conducts active national surveillance annually from October through May for influenza to detect the emergence and spread of influenza virus variants and monitor the impact of influenza-related morbidity and mortality. Surveillance data are provided weekly throughout the influenza season to public health officials, WHO, and health-care providers and can be used to guide prevention and control activities, vaccine strain selection, and patient care.     

2009-2013年南京市流感流行病学特征分析

目的 描述2009-2013年期间南京市流感的流行病学规律和特点。方法 流感样本来源于流感样病例,利用逆转录聚合酶链反应确定阳性病例以及流感分型。采用Excel 2007整理数据和SPSS 19.0进行统计分析。结果 2009-2013年间,南京地区共有流感样病例17 906例,其中阳性2 990例,流感阳性率为16.7%。流感阳性率随月份、季度和年份而改变,南京阳性率高峰主要出现在秋冬季,也伴有一些夏季的高峰。甲型流感主要在夏季、秋季和冬季流行,乙型流感主要在冬季流行。2009-2013年南京优势毒株为甲型H1N1,H3N2和乙型流感。H3N2通常在秋季和夏季达到流行高峰,甲型H1N1大流行在秋季出现高峰,乙型流感主要在冬季流行。南京地区在秋季和初冬出现流行高峰,但有些年份,在夏季和初秋出现H3N2流行高峰。采用移动流行病学方法建立标准模型,一般流感在南京的流行大约持续11周,流行阈值为25.21%,流感阳性的背景率为5.82%。结论 南京流感高峰通常一年发生一次,但在有些年份中,会出现两个流感高峰时期。     

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.     

Annual report of the National Influenza Surveillance Scheme, 1999

An effective national surveillance system is an essential component of a program for the control of influenza. The National Influenza Surveillance Scheme includes data from sentinel general practice consultations for influenza-like illness, laboratory reports of influenza and absenteeism rates from a national employer. The 1999 season peaked between May and September with maximal activity between July and August. Influenza A was the dominant type in all States and Territories with influenza A H3N2 viruses predominating and influenza A H1N1 occurring sporadically. There was no evidence of significant drift among the H3N2 isolates (A/Sydney-like strains) whereas the H1N1 isolates showed significant antigenic changes from the vaccine strain A/Beijing/262/95 and were closely related to a new variant A/New Caledonia/20/99. A small peak in influenza B activity occurred towards the end of the influenza season and isolates remained closely related to the vaccine reference strain B/Beijing/184/93.     

绵阳市2009～2010年流感样病例哨点监测结果分析

目的了解2009～2010年绵阳市流感流行状况,为制定预防控制策略提供依据。方法收集绵阳市2009～2010年流感样病例(ILI)监测资料、流感病毒病原学监测结果以及暴发疫情信息进行分析。结果 2009～2010年3家哨点医院上报ILI36774例,占门急诊总病例数(ILI%)的7.84%,病例以≤24岁的儿童、青少年为主,占87.36%;2009年9～12月呈现1个发病高峰,2010年1～7月疫情平稳,无明显季节性波动;发热门诊的ILI%最高,为87.84%;共采集818份ILI病例标本,经RealtimeRT-PCR法检测,流感病毒核酸阳性标本共381份,阳性率46.58%。包括甲型H1N1流感病毒271份(33.13%),A型未分型流感病毒95份(11.61%),B型流感病毒15份(1.83%);共发生暴发疫情5起,均发生在中、小学校,由甲型H1N1流感病毒引起。结论哨点医院ILI报告质量有待提高,流感监测网络实验室应积极准备开展流感病毒分离工作,加强对各型流感病毒的监测,以预防、控制流感的流行。     

2016 - 2019年包头市甲型H1N1流感病毒基因分析

目的 了解包头市流感病毒的变异情况,评估流行株在致病性、毒性、耐药性方面的改变,以研究结果为依据,为流感防控、指导抗流感药物的选用及筛选新的疫苗代表株提供依据。方法 按分离比例随机抽取2016 - 2019年甲型H1N1疫苗株进行基因测序分析。结果 包头市2016 - 2019的甲型H1N1分离株主要属于6B.1A分支,与疫苗株A/Brisbane/02/2018同源性较高。各年度病毒株与疫苗株A/Brisbane/02/2018的组间遗传距离分别为0.014,0.016,0.014和0.012。分离株抗原位点集中在 Sa 区的163 - 164位点发生变异。分离株2018 - 1139 - HA.seq发生了H275Y位点变异。结论 包头市2016 - 2018年度内甲型H1N1流感病毒分离株与A/Brisbane/02/2018亚型流感病毒同源性较高。相对A/Brisbane/02/2018疫苗株而言,本次分析的病毒基因并未发生抗原漂移现象,可以初步判定目前推荐的疫苗株对当前流行的甲型H1N1流感具有较好的保护效果。     

北京市2007—2008年流感监测预警分析

目的通过对2007—2008年度北京市流感监测数据分析,阐明北京市流感监测系统对流感高峰预警的有效性。方法2007—2008年度北京市共有153家医院开展了流感样病例监测;6家网络实验室开展了流感病原学监测。结果2007年9月至2008年4月,153家医院的平均流感样病例百分比为2．38％;共在14家医院采集流感样病例咽拭子2057份,分离流感病毒611株,以乙型流感病毒Yamagata系为主。以流感病原学监测结果作为流感高峰来临的金标准,利用美国疾病预防控制中心开发的早期异常报告系统,对流感样病例监测数据进行分析,北京市流感样病例监测可以较好地对流感高峰的来临进行预警。结论北京市流感监测是北京市流感防控综合措施中不可或缺的组成部分,可以高效准确地对流感高峰进行预测和预警,同时也为未来流感大流行的预警做好了准备。     

Annual report of the National Influenza Surveillance Scheme, 2003.

Surveillance of influenza in Australia is based on laboratory isolation of influenza viruses, sentinel general-practitioner practices for influenza-like illness, and absenteeism data from a major national employer. In 2003, the peak in influenza activity was in August which was later than in 2002. In 2003, 3,604 laboratory-confirmed cases of influenza were notified to the National Notifiable Diseases Surveillance System, which was marginally lower than for the previous year. Ninety-four per cent of the circulating viruses were influenza A. This was the highest proportion in the last five years. Nine hundred and thirty-five isolates were antigenically analysed: 928 were A(H3), two were A(H1) strains and five were influenza B viruses. The majority (98%) of the A(H3) subtypes were A/Fujian/411/2002(H3N2)-like and have shown a significant antigenic drift. The 2003 Australian influenza vaccine contained A/Panama/2007/99, which induced 2-4-fold lower antibody response against the drifted strain. An A/Fujian/411/2002(H3N2)-like virus has been incorporated in the Australian influenza vaccine for 2004. In 2003, the influenza vaccine was given to 77 per cent of Australians aged over 65 years; the same up take as in 2002.