Coverage rates of influenza vaccine in Italy during the 2002/3 and 2003/04 seasons: a cross-sectional study

The objective of this survey was to assess the level of influenza vaccination coverage in the season 2002/ 2003 compared with the season 2003/2004 in Italy, to understand the drivers and barriers to vaccination and to determine the intention for vaccination for the following winter. We conducted a random-sampling, telephone-based household survey among non-institutionalised individuals representative of the population aged 14 years and above. The surveys for 2002/2003 and 2003/2004 used the same questionnaire and were subsequently pooled. Four target groups were determined for analysis: (1) persons aged 65 years and above; (2) people working in the medical field; (3) persons suffering from a chronic illness and (4) all other groups. The overall sample consisted of 4010 people. The influenza vaccination coverage rate in Italy increased from 19.6% in season 2002/2003 to 22.2% in season 2003/2004. The most frequent reasons mentioned by vaccinees to get vaccinated were advice received from the family doctor or nurse (48.9%), influenza being considered a serious illness which people did not want to contract (38.5%) and not wanting to pass the influenza bug to family and friends (29.2%). Reasons mentioned by never vaccinated people for not getting vaccinated were the fact that people did not consider it before (34.9%), the opinion that one was not very likely to catch influenza (32.2%) and influenza not being a serious illness (23.4%). Options encouraging an influenza vaccination are a recommendation by the family doctor or nurse (58.4%), more available information on the vaccine regarding efficacy and tolerance (34.4%) and more available information on the disease (24.3%). We therefore suggest that family doctors be better informed on influenza vaccine and the disease itself in order to enable them to actively inform their patients on these topics accordingly.     

Influenza vaccination coverage rates in five European countries-a population-based cross-sectional analysis of two consecutive influenza seasons

INTRODUCTION: Influenza continues to be a considerable health problem in Europe. Vaccination is the only preventive measure, reducing mortality and morbidity of influenza in all age groups. OBJECTIVES: The objective of this survey was to assess the level of influenza vaccination coverage during two consecutive influenza seasons (2002/2003 and 2003/2004) in six European countries, to understand the driving forces and barriers to vaccination and to determine vaccination intentions for the following winter. METHODS: We conducted a random-sampling, telephone-based household survey among non-institutionalised individuals representative of the population aged 14 and over. The surveys used the same questionnaire for two consecutive winters: 2002/2003 and 2003/2004 data were used for Germany, Italy, Spain and the United Kingdom. 2001/2002 and 2002/2003 data were used for France. The data were subsequently pooled. Four target groups were determined for analysis: (1) persons aged 65 and over; (2) people working in the medical field; (3) persons suffering from chronic illness and (4) a group composed of persons aged 65 and over or working in the medical field or suffering from a chronic illness. RESULTS: The overall sample consisted of 20,118 individuals. The influenza vaccination coverage rate increased from 21.3% in the first season to 23.2% in the second season. The increase in coverage is statistically significant (p=0.01). The most frequent reasons for being vaccinated given by vaccines were: influenza, considered to be a serious illness which people wanted to avoid (55.8%), having received advice from the family doctor or nurse to be vaccinated (55.2%) and not wanting to infect family and friends (36.1%). Reasons for not being vaccinated mentioned by people who have never been vaccinated were: not expecting to catch influenza (40.4%), not having considered vaccination before (33.3%) and not having received a recommendation from the family doctor to be vaccinated (27.3%). Options encouraging influenza vaccination are: recommendation by the family doctor or nurse (53.1%), more available information on the vaccine regarding efficacy and tolerance (32.1%) and more information available about the disease (26.7%). Adjusted odds ratios for target group vaccination were between 3.6 (Germany) and 13.7 (UK). Vaccination rates among healthcare workers were generally very low. Adjusted odds ratios were between 0.7 (Germany) and 1.5 (Spain). CONCLUSION: The vaccination coverage during the second season increased in comparison to the first season. The family doctor is the most important source of encouragement for people to be vaccinated against influenza. It seems that the public would be more likely to be vaccinated if they had more information on the efficacy and tolerance of the vaccine, as well as the disease. We, therefore, suggest that family doctors be better informed on influenza vaccine and the disease itself, so that they can actively inform their patients on these topics.     

Surveillance of influenza in Apulia, Italy, 1999-2000, 2000-2001, 2001-2002, and 2002-2003 seasons

BACKGROUND: The objective of this study was to evaluate, within the Italian National Influenza Epidemiological and Virological Surveillance, the rate of vaccination coverage, the incidence of Influenza Like-Illness (ILI), the incidence of Acute Respiratory Illness (ARI), and to identify the virus strains circulating in Apulia from 1999 to 2003. METHODS: Vaccination coverage rates were calculated based on the number of doses administered to individuals > 65 years of age. Every week, sentinel physicians reported ILI and ARI cases having occurred among their patients. Voluntary general practitioners (GPs) and paediatricians (Ps) collected oropharyngeal swab samples from patients suspected with ILI. Influenza viruses were isolated and identified by cell culture (MDCK cells) and RT-PCR. Virological surveillance was carried out by the ISS, in collaboration with a network of peripheral laboratories. RESULTS: In Apulia, vaccination coverage progressively increased to 68.6% during the 2002-2003 season. The analysis of ILI cases showed higher incidence rates during the 1999-2000 and 2002-2003 seasons. ARI rates appeared to have a more constant trend. ILI and ARI incidence rates were higher in the 0-14 year age group. CONCLUSION: The increase in vaccination coverage rates and implementation of the network of clinical, and epidemiological and virological surveillance are fundamental for the control and prevention of influenza.     

Influenza vaccination coverage rates in the UK: a comparison of two monitoring methods during the 2002-2003 and 2003-2004 seasons

OBJECTIVES: To assess the feasibility of measuring influenza vaccination coverage during 2002-2003 and 2003-2004 seasons using a telephone survey; to compare these findings with routine vaccine uptake monitoring based on data provided by general practitioners. STUDY DESIGN: Telephone-based survey. METHODS: We interviewed a random sample of non-institutionalized individuals representative of the population aged 16 years and over. Four target groups were determined for analysis: (1) people aged 65 years and over; (2) healthcare workers; (3) people under 65 years with chronic illnesses, which placed them at risk for influenza; and (4) a group composed of all three previous groups combined. RESULTS: The overall sample consisted of 4054 people (about 2000 per season). Population influenza vaccine coverage in the UK increased from 22.3% in 2002-2003 to 24.2% in 2003-2004. Vaccine uptake was strongly age dependent, even in people aged 65 years and over (the ages at which all people are routinely targeted). In both seasons, the estimates of vaccine uptake in people aged 65 years and over were remarkably consistent with those obtained through routine monitoring. Vaccine uptake in healthcare workers was markedly suboptimal. CONCLUSIONS: In the UK, a telephone-based system of monitoring influenza vaccine uptake seems robust enough to generate data that are comparable with routine vaccine monitoring undertaken using data provided by general practitioners. Although such a system cannot easily contribute towards monitoring of vaccination at local and regional levels, it offers a validated method of estimating vaccine uptake that is independent of healthcare workers' time. This may be especially important for a pandemic vaccination programme, especially in countries in which healthcare resources are scarce, or where the configuration of healthcare services is less conducive to internal monitoring than is the case in the UK.     

Rapid assessment of influenza vaccination coverage among HMO members--northern California influenza seasons, 2001-02 through 2004-05

The Vaccine Safety Datalink (VSD) is a collaborative project involving CDC and eight health maintenance organizations (HMOs) in the United States. Computerized data on vaccination, medical outcomes, and patient demographics are collected and linked under a standard protocol at multiple HMOs. Beginning with the 2003-04 influenza season, the VSD team and one of the HMOs, Kaiser Permanente Northern California (KPNC), established an automated system for rapid detection of potentially adverse events after vaccinations among its members. During the 2004-05 influenza season, in response to the influenza vaccine shortfall and resulting prioritization of vaccine distribution, this rapid analysis system also was used to assess influenza vaccination coverage weekly among KPNC members. The results indicated that KPNC followed Advisory Committee on Immunization Practices (ACIP) prioritization guidelines by targeting influenza vaccination to children aged 6-23 months and adults aged >/=65 years. For the 2005-06 influenza season, the rapid analysis system should be expanded to include data from additional HMOs and more detailed information on vaccinees (e.g., high risk for influenza complications) to better characterize influenza vaccination coverage during the 2005-06 influenza season on a weekly basis.     

Evolution of influenza vaccination coverage in France from 2001 to 2006

INTRODUCTION: The increased risk of a new influenza pandemic has raised awareness of the need for high influenza vaccination rates. OBJECTIVES: This study aims at assessing trends in influenza vaccination coverage from 2001 to 2006 in France, at understanding the drivers and barriers, and to identify vaccination intentions for 2006/2007. METHODS: We conducted a mail-based household survey on 9,835 persons representative of the population from age 15. Essentially, the same questionnaire was used in all seasons. RESULTS: The influenza vaccination coverage rate slightly increased, reaching 24.2% in 2005/2006 (70.1% in patients over 65). In the last two seasons the fact that the vaccination was provided for free was the most frequent reason for getting vaccinated. Older age, considering influenza as a serious disease and recommendations from the family doctor or nurse were also important drivers for vaccination. Only 2% of those vaccinated in 2005/2006 indicated the threat of avian influenza as a reason. The reasons for non-vaccination among persons never vaccinated before were feeling too young for vaccination, never having considered vaccination before and absence of recommendation by the family doctor. Among those who were previously vaccinated but not in the current season, the reasons for not being vaccinated were not finding vaccination necessary, forgetfulness and having influenza-like illness despite vaccination. CONCLUSION: Stable vaccination rates were observed from 2001 to 2006. France is well on its way to reach the international vaccination goal set by the WHO (75% in the elderly population), but continuously effort is needed for others.     

Measuring maternal Tdap and influenza vaccination rates: Comparison of two population-based methods

Pregnant women are routinely recommended to receive Tdap and influenza vaccines to prevent disease and complications among mothers and newborns. Monitoring population trends in maternal vaccination is important in order to evaluate the implementation of these recommendations and to identify pockets of need. We present two methods for measuring maternal vaccination among a state population and discuss the strengths and drawbacks of each method. First, we matched maternal information from records of Wisconsin births during 2013–2015 with maternal vaccination records in the Wisconsin Immunization Registry. Second, we used an all-payer health insurance claims database to identify Wisconsin women with deliveries during 2013–2015 and vaccinations received during pregnancy. Both methods produced similar trends and indicated a substantial increase in the percentage of women receiving Tdap during pregnancy, and lower vaccination rates among women who were Medicaid-insured. When available and timely, both methods are useful for monitoring maternal vaccination.     

Influenza vaccination coverage against seasonal and pandemic influenza and their determinants in France: a cross-sectional survey

Background  

Following the emergence of the influenza A(H1N1)2009 virus, the French ministry of health decided to offer free vaccination against pandemic influenza to the entire French population. Groups of people were defined and prioritised for vaccination.     

A prospective, Internet-based study of the effectiveness and safety of influenza vaccination in the 2001-2002 influenza season

The effectiveness of the influenza vaccine used in the 2001-2002 influenza season in Japan was investigated in a large-scale, geographically widely distributed, Internet-based study. Data were collected from 8841 of 9902 subjects registered by 38 clinics prior to the start of influenza season. Subjects were categorized into three groups by vaccination regimen: unvaccinated, vaccinated once, and vaccinated twice. Efficacy was also analyzed for three age groups: 0-15, 16-64, and 65-104 years. Influenza-like illness (ILI) was diagnosed according to Ministry of Health (MWH, Labor and Welfare in Japan) criteria. Laboratory-confirmed influenza cases were analyzed separately. The respective vaccine efficacy in the 0-15 years group for the one- and two-dose regimens was 67.6 and 84.5% for ILI and 54.0 and 79.8% for laboratory-confirmed influenza. Influenza vaccination was also shown to be effective in subjects 16-64 years. Vaccine effectiveness was not able to be determined for the over 65 years group, probably due to an insufficient number of infected patients. These results suggest that influenza vaccination is effective for children and adults and that a two-dose regimen is superior to a single dose in children 0-15 years.     

Influenza vaccination coverage among hospital personnel over three consecutive vaccination campaigns (2001-2002 to 2003-2004)

This study was carried out to assess influenza vaccination coverage among hospital personnel and the impact of health promotion campaigns, within the hospital, designed to increase vaccination coverage over three consecutive vaccination campaigns (2001-2002 to 2003-2004). The health promotion tool used in the 2001-2002 and 2002-2003 were informative posters distributed throughout the hospital. In the 2003-2004 season, the recommendation was also published in the internal bulletin and Web site of the hospital. In addition, a physician and a nurse from the Department of Preventive Medicine visited all departments offering vaccination in the work place. The overall vaccination coverage in the 2001-2002 campaign was 16% with coverage of 11.5% in nurses and 15% in physicians. In the 2002-2003 and 2003-2004 campaigns the overall vaccination coverage was 21% and 40%, respectively (p<0.01). Staff physicians and resident physicians reached 60 and 42% coverage rates in the 2003-2004 campaign, but coverage in nurses and nursing assistant remained around 30% (p<0.01). In summary, influenza vaccination coverage among hospital based healthcare personnel increased significantly during the last three seasons, however, it still remains low despite active attempts at promoting influenza vaccination.     

State-specific influenza vaccination coverage among adults aged > or =18 years--United States, 2003-04 and 2005-06 influenza seasons

Influenza epidemics occur seasonally and result in substantial morbidity and mortality among adults in the United States. Adult groups included in the 2007 Advisory Committee on Immunization Practices (ACIP) recommendation for annual influenza vaccination are persons aged 18-49 years with high-risk conditions (i.e., conditions associated with an increased risk for complications from influenza), persons aged > or =50 years, health-care personnel, and others who are household contacts or caregivers of persons at high risk (e.g., persons with high-risk conditions or children aged < or =59 months). In addition, adults who want to reduce the risk for becoming ill with influenza or of transmitting influenza to others should be vaccinated. Healthy People 2010 (HP2010) objectives include increasing vaccination levels to 90% for adults aged > or =65 years (objective 14-29a) and 60% for persons aged 18-64 years who have one or more high-risk conditions (objective 14-29c). From the 1992-93 through 2003-04 influenza seasons, seasonal influenza vaccination coverage estimates (based on Behavioral Risk Factor Surveillance System [BRFSS] data) among adults aged > or =65 years trended upward, except for three seasons (1997-98, 1999-00, and 2000-01) when no increases occurred (Figure). To evaluate recent state-specific progress toward the HP2010 objectives, CDC compared data from the 2004 and 2006 BRFSS surveys, which reflected vaccinations received during the 2003-04 and 2005-06 influenza seasons; data from the 2004-05 influenza season, which have been published previously, were not included in this comparison because that season was marked by a substantial shortage of influenza vaccine. This report describes the results of the analysis, which indicated that influenza vaccination coverage for the 2005-06 season did not return to levels observed before the vaccine shortage of 2004-05 and remained substantially below HP2010 targets. Comprehensive measures are needed to improve influenza vaccination coverage among adult populations in the United States, including increasing adoption of recommended adult immunization practices by health-care providers, raising public awareness about influenza vaccination, vaccinating throughout the influenza season, and ensuring stable supplies of readily available vaccine.     

The 2001/2002 influenza season and the vaccine composition for the 2002/2003 season

The epidemic in the influenza season 2001/2002 was of moderate activity just like in 2000/2001. The influenza epidemic started in week 2 of 2002 when the clinical influenza activity reported by the general practitioner network of the Netherlands Institute of Primary Health Care (NIVEL) increased. This was caused by influenza A viruses of the H3N2 subtype in particular. All influenza A viruses of this subtype were closely related to the vaccine strain for this subtype, A/Moscow/10/99. Influenza B viruses and influenza A/H1 viruses isolated this season had surprising features. The influenza B viruses originated from two lineages. Viruses of the B/Yamagata/16/88 lineage have been circulating for more than twelve years. The vaccine reference strain B/Sichuan/379/99 belongs to this lineage. The B/Victoria/2/87 lineage reappeared again after an absence in Europe of more than ten years and accounted for 50% of the influenza B viruses that were isolated in the Netherlands. Therefore the vaccine will have provided only partial protection against influenza B. The only influenza A/H1 virus that was isolated appeared to be of a new subtype H1N2. The H1 hemagglutinin of this virus was closely related to that of the vaccine strain A/New Caledonia/20/99. The N2 neuraminidase originated from recent human influenza A/H3N2 viruses. Therefore the vaccine probably provided good protection against the new H1N2 subtype. Based in part on these data, the World Health Organization has advised that the vaccines for the season 2002/2003 should contain the following or comparable influenza-virus strains: A/Moscow/10/99 (H3N2), A/New Caledonia/20/99 (H1N1) and B/Hong Kong/330/01, the latter being an influenza B virus of the B/Victoria/2/87 lineage.     

Epidemiology of vertebral osteomyelitis (VO) in France: analysis of hospital-discharge data 2002-2003

Vertebral osteomyelitis (VO) is a rare event. To estimate the incidence of VO in France for 2002-2003, national hospital-discharge data were used. Hospital stays were categorized as definite, probable or possible VO. Unique patient identification numbers allowed the investigators to link patients with multiple hospital stays and to analyse data for individual patients. A sample of medical records was reviewed to assess the specificity of the VO case definition. In 2002-2003, 1977 and 2036 hospital stays corresponding to 1422 and 1425 patients (median age 59 years, male:female ratio 1.5) were classified as definite (64%), probable (24%) and possible (12%) VO. The overall incidence of VO was 2.4/100,000. Incidence increased with age: 0.3/100,000 (70 years). The main infectious agents reported were Staphylococcus spp. (38%) and Mycobacterium tuberculosis (31%). The most frequent comorbidities were septicaemia (27%) and endocarditis (9%). Three percent of patients died. A review of 90 medical records confirmed the diagnosis of VO in 94% of cases. Using a hospital database and a specific case definition, nationwide surveillance of VO is possible.     

Reproduction rates for 1990-2002 and intrinsic rates for 2000-2001: United States.

OBJECTIVE: This report presents revised rates of reproduction for 1990-93, reproduction rates for 1994-2002, and intrinsic rates for 2000-2001. The revised rates for 1991-93 are based on populations consistent with the April 1, 2000, census, as are the rates for 1994-2002. METHODS: Tabular and graphic data on the reproduction and intrinsic rates by race and Hispanic origin of mother are presented and described. RESULTS: Rates of reproduction (total fertility, gross reproduction, and net reproduction rates), the intrinsic rate of natural increase, and the intrinsic birth rate were lower in 2001 (and 2002) than 1990. Among the race and Hispanic subgroups, the reproduction rates were lower for all groups except Cubans and whites (total). The overall intrinsic death rate increased between 1990 and 2001 with the rate declining for whites (total) but increasing for blacks (total).     

Chemosusceptibility analysis of Plasmodium falciparum imported from Comoros to Marseilles, France in 2001-2003

OBJECTIVES: The aim of this work was to study the chemosensitivity of Plasmodium falciparum strains isolated from patients presenting with malaria after having returned from Comoros Islands in 2002-2003, and hospitalized at the North University Hospital, in Marseilles, France. MATERIALS AND METHODS: In vitro drug susceptibility (for strains maintained in culture) and mutation-specific polymerase chain reaction (PCR) assays (for all strains) were performed. RESULTS: Out of 23 strains kept in culture, 50% were shown to be resistant in vitro to chloroquine, 50% were resistant to pyrimethamine, 40% to cycloguanil, 25% to atovaquone, and 7% to mefloquine. However all these strains were susceptible to quinine, halofantrine, and artemether. Moreover, 48 strains were tested by molecular methods. As a result, 69% were shown to have the Asp108 mutation in the dihydrofolate reductase gene (Pfdhfr), the basic mutation associated with antifolate resistance, and 54% had additional mutations Ile51 plus Arg59, associated with a high level of resistance. Furthermore, 90% of the 20 strains tested in 2003 were shown to have the point mutation Pfcrt76 in the P. falciparum chloroquine resistance transporter (Pfcrt) gene recently proposed as a molecular marker of chloroquine-resistance. CONCLUSION: Obtaining plasmodium strains from Comoros to be tested in Marseilles, where all laboratory facilities are available, is a unique opportunity to establish a surveillance of falciparum drug resistance in the Comoros islands.     

Four years of lessons learned: The 2001-2004 Maryland influenza prevention seasons.

More than 36,000 Americans die and 200,000 more are hospitalized because of influenza every\year. Despite the wide availability of a vaccine to prevent influenza, the vast majority of Americans go unimmunized. The Maryland Department of Health and Mental Hygiene (DHMH) and the Maryland Partnership for Prevention (MPP) collect data about the state's local health departments' influenza season practices and experiences and compile them into the annual Maryland Influenza Season Final Report. The report becomes a tool for DHMH, MPP, and the state's 24 local health departments to plan improvements in influenza vaccination services. This article chronicles four influenza seasons. Influenza season challenges experienced in three of the last four influenza seasons underscore the importance of coordination and communication efforts to ensure that vaccine is efficiently delivered to the most vulnerable populations. The partnership between DHMH and MPP has facilitated access to information on ordering and administration practices, communication systems, community partnerships, and lessons learned, thus enabling the state of Maryland to continually optimize its influenza vaccination promotion efforts.     

Economic evaluation of vaccination against influenza in the elderly: an experience from a population-based influenza vaccination program in Taiwan

Due to viral strains, influenza season, and consultations and admission rates varying from country to country, the continued economic evaluation of influenza vaccination for the elderly people aged 65 years and above is paramount, particularly in areas with dense population. Efficacy and cost-effective analysis of influenza vaccination in reducing all-cause mortality and hospitalization was therefore elucidated based on a prospective and population-based study targeted to 226,997 elderly people aged 65 years and above residing in Taipei county, Taiwan between 1 October 2000 and 31 March 2001. Vaccination against influenza for the elderly persons can lead to a 29% (95% CI: 23-35%) significant reduction of all-cause deaths. Approximately, 20% (95% CI: 9-30%) significant reduction in hospitalization was observed for average-risk group but 4% (95% CI: -4-11%) non-significant reduction for high-risk group. Community-based influenza vaccination program for elderly people aged 65 years and above was demonstrated to be effective in reducing mortality in all elderly people but not significantly in reducing hospitalization. Universal vaccination program for the elderly people seems cost-effective in averting death or gaining life years.     

Influenza vaccination coverage among persons aged 50-64 years enrolled in commercial managed health-care plans--United States, 2003-04 and 2004-05 influenza seasons

To combat an unexpected shortage of influenza vaccine in the fall of 2004, CDC issued guidance to direct available vaccine supplies to persons in designated priority groups (e.g., persons aged >/=65 years, persons with certain health conditions, health-care workers, and close contacts of persons at high risk for complications from influenza). Analyses of influenza vaccination coverage for the 2004-05 influenza season indicated that coverage levels for adults in priority groups nearly reached the levels of previous years, whereas coverage levels among adults not in priority groups were approximately half the levels of the 2003-04 season. These findings suggested that national public health actions to direct available vaccine supply to persons at high risk for complications from influenza during the supply disruption were successful. To assess influenza vaccination coverage among persons aged 50-64 years for the 2004-05 influenza season relative to the 2003-04 season and to estimate the effect of shortages on selected subgroups, the National Committee for Quality Assurance (NCQA) analyzed data from a survey of persons enrolled in commercial managed care health plans. This report summarizes the findings of that analysis, which indicated that, although vaccination coverage declined substantially from 2003-04 to 2004-05 among all subgroups in this age range, respondents who were older or who reported poorer health status exhibited smaller relative declines in vaccination coverage between the two seasons.     

无锡市2001年～2002年度流感监测分析

目的：监测分析我市流行性感冒的流行和流感病毒变异情况．为流感防治对策提供理论依据。方法：①疫情监测,设立哨点医院．在内科、儿科门诊监测流感样病例和肺炎病例;②病原学监测,用鸡胚双腔对监测标本做病毒分离,用微量血凝抑制试验(HI)进行型别鉴定;③血清学监测,采集不同年龄组的自然人群血清．检测甲1型、甲3型和乙型流感病毒抗体水平。以血凝抑制抗体滴度≥1：10判为阳性,滴度≥1：40判为有保护性作标准。结果：监测期间疫情基本平稳,2001年冬曾出现一个流感样病例发病高峰,同时伴随肺炎发病增高。发病构成≤14岁占90．71％．≥60岁较低。2001年10月～2002年3月分离出2株甲1型流感病毒．型别为A1／沪防／7／99;2002年10月～2003年3月分离出流感病毒7株。型别均为B型,其中6株为B／Yamanashi／166／98,1株为B／Victoria。毒株分离出时间与流感样病例发病高峰相一致,标本源于13岁以下患者。人群抗体监测,甲3型流感抗体水平较高,抗体阳性率≥87．05％;甲1型抗体阳性率偏低≤27．38％;乙型抗体阳性率2002年为21．13％。明显低于2001年的74．85％。结论：本地人群对甲1和乙型流感缺乏免疫力,下一流行季节存在甲1和乙型流感流行的可能。