2009年甲型H1N1流感大流行期间上海市人群甲型H1N1流感疫苗接种前流感感染率调查

目的了解2009年甲型H1N1流感大流行期间,上海市健康人群甲型H1N1流感、甲型季节性流感H1和乙型季节性流感BY、BV抗体水平,以掌握流感流行或大流行的规律。方法采用分层抽样的方法随机选取不同职业重点人群作为研究对象,应用血凝抑制试验对其血清进行流感病毒抗体检测。结果 2009年下半年,共检测上海市531名不同职业人群的各型流感抗体水平,其中甲型H1N1流感和季节性流感H1、BY、BV抗体阳性率分别为53.7%、83.6%、71.6%、13.9%。不同人群各型流感抗体水平阳性率有所不同。甲型H1N1流感抗体水平以小学生最高,几何平均滴度(GMT)=77.9;其次是医务人员,GMT=69.3;最低为公安系统工作人员,GMT=10.1。结论在2009年甲型H1N1流感大流行期间,上海市健康人群甲型H1N1流感抗体阳性率较高,且不同年龄、不同职业人群之间抗体阳性率存在差异。甲型季节性流感抗体的阳性率高于乙型季节性流感抗体的阳性率。     

湘西自治州甲型H1N1流感血清流行病学调查

目的 了解湘西自治州人群甲型H1N1流感病毒感染状况和免疫水平,分析流感流行趋势,为制定针对性的防治措施提供依据.方法 采用多阶段分层随机抽样方法,于2010年1月4月8月共选取675人进行问卷调查,并采集血液标本进行甲型H1N1流感病毒血凝抗体检测.结果 在不同季节,不同职业人群中H1抗体阳性率不同(P＜0.05),同时在出现过急性呼吸道症以及接种过甲型H1N1流感疫苗的人群中H1抗体阳性率相对较高(P＜0.05).H1抗体GMT呈现季节性变化(P＜0.05),在不同年龄,不同职业人群中抗体水平大小差异有统计学意义(P＜ 0.05,P＜ 0.01).调查还发现发现出现过急性呼吸道症人群中抗体GMT和中位数高于未出现呼吸道症状者(P＜ 0.001);接种过甲型H1N1流感疫苗者抗体GMT和中位数也同样高于未接种者(P＜ 0.001).在不同性别和民族人群中,抗体的阳性率和水平大小无统计学差异.结论 目前湘西地区甲型H1N1流感已经得到有效控制,但鉴于人群中保护性抗体水平季节性变化,下一阶段重点是定期开展快速的血清学监测,并且继续对高危人群实施甲型H1N1流感疫苗接种.     

上海市卢湾区甲型H1N1流感与季节性流感流行特征比较分析

目的 比较甲型H1N1流感与季节性流感流行特征,为制定干预措施提供科学依据.方法 对卢湾区2009年7月～2011年11月流感监测病例进行分析,并于2011年10月对卢湾区200名居民进行流感HI抗体检测.结果 2009年,AH1N1阳性率最高,为30％;2010年,AH3、BV阳性率较高,分别为13％和12％;2011年,AH1N1、BV阳性率较高,分别为12％和11％.AH1N1流行季节主要为冬季,AH3主要为夏季,BV主要为春季.全人群BY和AH1抗体滴度较高,分别为1∶918和1∶897,BV、AH3和AH1N1抗体滴度较低,分别为1∶625,1∶599和1∶120.AH1N1全人群抗体水平低于季节性流感.结论 应继续加强流感疫苗接种工作,建议流感疫苗组分应继续包括AH3、AH1N1、BV毒株组分.     

江苏省2009年3岁以上自然人群新甲型H1N1流感血清流行病学调查

目的 了解江苏省2009年3岁以上自然人群新甲型H1N1流感抗体水平及流行趋势.方法 利用微量半加敏血凝抑制(HI)方法检测江苏省不同时间(2008年11月和2009年7、8、11月)人群新甲型H1N1流感抗体,比较不同时间、人群及地区的新甲型H1N1流感保护性抗体阳性率和抗体几何平均滴度(GMTs).结果 在新甲型H1N1流感输入江苏地区后第一个流行季节内,2009年7、8、11月人群HI保护性抗体阳性率依次为3.46%、7.59%和16.94%,表现出随时间推移而呈总体增长趋势(P=0.000),不同时间点的性别间保护性抗体阳性率的差异无统计学意义(P＞0.05);除2009年11月外,不同性别间的抗体GMT差异均无统计学意义.同一时间点不同年龄组间、同一年龄组的不同时间点间,HI保护性抗体阳性率、抗体GMT水平比较的差异均有统计学意义(P＜0.05).HI保护性抗体阳性率和抗体GMT存在地区差异(P＜0.05).结论 在2009年8月后江苏地区12～17岁人群成为新甲型H1N1流感暴发的主要人群,至2009年11月该人群总体新甲型H1N1流感保护性抗体阳性率仍较低,该病在全省的流行仍将持续一段时间.     

淄博市甲型H1N1流感感染状况的调查

目的了解淄博市不同人群甲型H1N1流感实际感染水平和动态变化趋势,为应对流感大流行,完善防控措施提供可靠依据。方法 2010年1月～9月期间,采取多阶段随机抽样方法抽取4500名调查对象,进行问卷调查,并采集血清利用血凝抑制方法检测甲型H1N1流感抗体水平。结果该市甲型H1N1流感病毒抗体阳性率为25.60%,自然感染率为21.09%,显性感染和隐性感染比例为1.97︰1;抗体阳性率以16～24和6～15岁年龄组最高,60岁以上年龄组最低;教师和学生阳性率最高,医务人员阳性率相对较低;第1次调查抗体阳性率最高,第3次调查最低,接种甲型H1N1流感疫苗半年后抗体阳性率为11.36%。结论甲型H1N1流感大流行期间,该市实际感染人数远远超过确诊病例数,学龄人群和年轻人是最大的感染群体,人群中存在无症状感染者,自然感染或接种疫苗后抗体水平随时间推移逐步下降。     

职业暴露人群A(H5N1)和甲型H1N1流感血清抗体分析

目的:了解人禽流感A(H5N1)和甲型H1N1流感职业暴露人群中的感染状况。方法:对职业暴露人群进行个案调查,采用血凝抑制法(HI)检测职业暴露人群血清中人禽流感A(H5N1)和甲型H1N1流感抗体。结果:2009年-2010年采集的624份职业暴露人群血清中未检测出人禽流感A(H5N1)抗体,而在2009年采集的血清中有5份检测出甲型H1N1流感抗体,抗体阳性率为1.55%,2010年采集的血清中抗体阳性率为11.96%,其中<29岁阳性率为17.19%,30岁～59岁阳性率为10.87%。结论:职业暴露人群中未检测出A(H5N1)流感抗体,但仍需加强职业暴露人群监测。同时甲型H1N1流感抗体水平较低,缺乏相应的抗体水平保护。     

2010年兵团甲型H1N1流感血清学检测结果分析

目的:了解兵团2010年自然人群新甲型H1N1流感抗体水平及流行趋势。方法:利用血凝抑制(HI)试验方法检测兵团不同时间、人群新甲型H1N1流感抗体,比较不同时间、人群的新甲型H1N1流感抗体阳性率。结果:从1月-3月不同时间的检测,甲型H1N1流感抗体阳性率随着时间推移总体呈现下降趋势,依次为16.7%、15.6%、5.0和4.6%,差别有统计学意义。不同年龄组人群的甲型H1N1抗体阳性率差别较大,7岁～17岁年龄组最高(35.0%),不同年龄组抗体阳性率(P)差别有统计学意义。不同年龄组人群接种甲型H1N1疫苗后抗体阳性率差别无统计学意义。结论:兵团有10.2%的人群具有甲型H1N1流感保护性抗体,普通人群中已经建立一定的免疫屏障。7岁～17岁人群是新甲型H1N1流感暴发的主要人群,应重点防控。     

长沙市甲型H1N1流感血清流行病学调查

目的了解长沙市人群甲型H1N1流感病毒感染状况和免疫水平。方法采用多阶段随机抽样方法,从长沙五个城区选取1 500人进行问卷调查,并采集血液标本进行甲型H1N1流感病毒血凝抗体检测。结果调查人群中共有559人甲型H1N1流感抗体呈阳性,阳性率37.27%;经标化后,估计长沙市城区人群抗体阳性率为30.47%。按年龄组分,6~15岁(55.97%)和16~24岁(50.51%)组抗体阳性率较高;按职业分,学生(56.35%)和医务人员(57.14%)抗体阳性率较高。已接种甲型H1N1流感疫苗的人群抗体阳性率(77.08%)明显高于未接种组(27.81%)。长沙市普通人群甲型H1N1流感的感染率27.81%,隐性感染者比例为41.54%。2009年5月-2010年1月流感样病例的抗体阳性率(36.04%)较非流感样病例(26.21%)高;2007-2010年1月接种过季节性流感疫苗人群的抗体阳性率(40.00%)高于未接种组(26.88%)。结论长沙市人群尚未建立应对甲型H1N1流感有效的免疫屏障,仍需加强防控;接种甲型H1N1流感疫苗是获得保护性抗体最有效的途径。     

贵阳市人群甲型H1N1流感血清流行病学调查

目的:了解贵州省2009年甲型H1N1流感大流行高峰后期人群感染水平及流行趋势。方法:于2010年1月4日-2010年3月29日共4次在贵阳市随机抽取医院门诊患者、血液中心志愿者,利用血凝抑制(HI)方法进行血清标本甲型H1N1流感抗体检测。结果:4次调查的人群抗体阳性率依次为27.17%、14.99%、23.65%、12.59%。不同时间段之间抗体阳性率的差别有统计学意义(P<0.05)。男女性别之间抗体水平差别无统计学意义(P>0.05)。4个年龄组中6岁～17岁组抗体阳性率除第2次调查时略低于0岁～5岁组,其余3次均为最高。接种甲型H1N1流感疫苗的人群抗体阳性率为48%,高于非接种者的18.75%。结论:贵阳市人群甲型H1N1流感抗体水平较低,仍需加强防控,及时接种流感疫苗是获得保护性抗体最有效的途径。     

2010年云南省部分人群甲型H1N1流感抗体监测分析

目的 了解云南省普通人群甲型H1N1流感抗体水平,分析和预测其流行趋势,为预防和控制疫情提供依据.方法 2010年1-3月,对云南省不同年龄组部分人群开展了4次调查,用血凝抑制试验进行抗体检测.结果 云南省普通人群甲型H1N1流感抗体阳性率为28.300(452/1 600),3月的抗体阳性率和GMT高于1,2月.结论...     

Protective efficacy of an inactivated Eurasian avian-like H1N1 swine influenza vaccine against homologous H1N1 and heterologous H1N1 and H1N2 viruses in mice

Eurasian avian-like H1N1 (EA H1N1) swine influenza viruses are prevalent in pigs in Europe and Asia, but occasionally cause human infection, which raises concern about their pandemic potential. Here, we produced a whole-virus inactivated vaccine with an EA H1N1 strain (A/swine/Guangxi/18/2011, SW/GX/18/11) and evaluated its efficacy against homologous H1N1 and heterologous H1N1 and H1N2 influenza viruses in mice. A strong humoral immune response, which we measured by hemagglutination inhibition (HI) and virus neutralization (VN), was induced in the vaccine-inoculated mice upon challenge. The inactivated SW/GX/18/11 vaccine provided complete protection against challenge with homologous SW/GX/18/11 virus in mice and provided effective protection against challenge with heterologous H1N1 and H1N2 viruses with distinctive genomic combinations. Our findings suggest that this EA H1N1 vaccine can provide protection against both homologous H1N1 and heterologous H1N1 or H1N2 virus infection. As such, it is an excellent vaccine candidate to prevent H1N1 swine influenza.     

H1N1 vaccination

Early results (January to April) from the 2010 Canadian Community Health Survey show that an estimated 41% of Canadians (excluding those in the territories) aged 12 or older had been vaccinated for H1N1 by April 2010. The percentages were higher in the Atlantic provinces, Quebec and Saskatchewan than in Canada overall. Relatively high percentages of females and people aged 45 or older were vaccinated; the percentage of immigrants who had done so was relatively low. Being in a priority group (health-care worker, having children younger than 5 in the household, or having a chronic condition that could increase the risk for complications from H1N1) increased the likelihood of vaccination. A history of seasonal flu vaccination and having a regular doctor were also associated with H1N1 vaccination. Nearly three-quarters of those who had not been vaccinated reported that they did not think it was necessary.     

Co-circulation of pandemic 2009 H1N1, classical swine H1N1 and avian-like swine H1N1 influenza viruses in pigs in China

The pandemic A/H1N1 influenza viruses emerged in both Mexico and the United States in March 2009, and were transmitted efficiently in the human population. They were transmitted occasionally from humans to other mammals including pigs, dogs and cats. In this study, we report the isolation and genetic analysis of novel viruses in pigs in China. These viruses were related phylogenetically to the pandemic 2009 H1N1 influenza viruses isolated from humans and pigs, which indicates that the pandemic virus is currently circulating in swine populations, and this hypothesis was further supported by serological surveillance of pig sera collected within the same period. Furthermore, we isolated another two H1N1 viruses belonging to the lineages of classical swine H1N1 virus and avian-like swine H1N1 virus, respectively. Multiple genetic lineages of H1N1 viruses are co-circulating in the swine population, which highlights the importance of intensive surveillance for swine influenza in China.     

接种甲型H1N1流感疫苗后患甲型H1N1流感分析

目的 分析接种甲型H1N1流感疫苗后发生甲型H1N1流感感染的病例,探讨发病原因,为进一步提高疫苗预防效果提供参考依据.方法 对接种甲型H1N1流感疫苗后发生甲型H1N1流感感染148例,进行回顾性调查分析.结果 接种甲型H1N1流感疫苗11176例.发生甲型H1N1感染148例,感染率1.32%,其中1～14 d感染81例,感染率0.72%,＞15 d感染67例,感染率0.60%.结论 甲型H1N1流感病毒裂解疫苗是一种安全高效的疫苗,不足之处尚待进一步探讨、完善.     

Influenza A Strain-Dependent Pathogenesis in Fatal H1N1 and H5N1 Subtype Infections of Mice

To determine if fatal infections caused by different highly virulent influenza A viruses share the same pathogenesis, we compared 2 different influenza A virus subtypes, H1N1 and H5N1. The subtypes, which had shown no pathogenicity in laboratory mice, were forced to evolve by serial passaging. Although both adapted viruses evoked diffuse alveolar damage and showed a similar 50% mouse lethal dose and the same peak lung concentration, each had a distinct pathologic signature and caused a different course of acute respiratory distress syndrome. In the absence of any virus labeling, a histologist could readily distinguish infections caused by these 2 viruses. The different histologic features described in this study here refute the hypothesis of a single, universal cytokine storm underlying all fatal influenza diseases. Research is thus crucially needed to identify sets of virulence markers and to examine whether treatment should be tailored to the influenza virus pathotype.     

H1N1 influenza is here

On 11 June WHO announced that the spread of H1N1 had reached pandemic phase 6. Since then countries around the world have increased their planning and preparedness for the continuing pandemic. Guidelines have been issued and circulated but confusion continues over their interpretation. We need to remind ourselves of the principles behind control measures and educate and reinforce standard infection control procedures in the acute hospital setting.     

Protection against a European H1N2 swine influenza virus in pigs previously infected with H1N1 and/or H3N2 subtypes

A novel swine influenza virus, H1N2, circulates in European swine populations together with H1N1 and H3N2 viruses. This study examines whether post-infection immunity to H1N1 and/or H3N2 viruses provides cross-protection against H1N2 infection. Pigs (n=51) were inoculated intranasally with either Sw/Belgium/1/98 (H1N1) or Sw/Flanders/1/98 (H3N2), or with both viruses at a 5-week interval. Control groups were left uninoculated or inoculated with Sw/Gent/7625/99 (H1N2). Four weeks later, all the pigs were challenged intranasally and intratracheally with a high H1N2 virus dose. The challenge control pigs showed typical influenza symptoms, and all had high H1N2 virus titres in the lungs and nasal virus excretion during 6 or 7 days. The H1N2-immune pigs showed total clinical and virological protection. Pigs immune against H1N1 or H3N2 only were not protected against disease and virus replication in the lungs, but virus excretion was 2 days shorter. By contrast, pigs immune against both H1N1 and H3N2 did not show disease and H1N2 virus replication was either undetectable or markedly reduced. Haemagglutination inhibition (HI) and virus neutralisation (VN) tests indicated that cross-protection against H1N2 was probably not mediated by antibodies against the haemagglutinin (HA). Antibodies inhibiting the neuraminidase (NA) of H1N2 were at minimal levels in H3N2 only-immune pigs, but they were consistently found in (H1N1+H3N2)-immune pigs. The immune response against the internal proteins, which are relatively conserved in H1N1, H3N2 and H1N2 viruses, may play a significant role in protection against H1N2. Given the severe challenge model used here, cross-protection against H1N2 could be more pronounced under natural conditions of infection.