Oseltamivir-resistant pandemic A(H1N1) 2009 influenza viruses detected through enhanced surveillance in the Netherlands, 2009–2010

Enhanced surveillance of infections due to the pandemic A(H1N1) influenza virus, which included monitoring for antiviral resistance, was carried out in the Netherlands from late April 2009 through late May 2010. More than 1100 instances of infection with the pandemic A(H1N1) influenza virus from 2009 and 2010 [A(H1N1) 2009] distributed across this period were analyzed. Of these, 19 cases of oseltamivir-resistant virus harboring the H275Y mutation in the neuraminidase (NA) were detected. The mean 50% inhibitory concentration (IC₅₀) levels for oseltamivir- and zanamivir-susceptible A(H1N1) 2009 viruses were 1.4-fold and 2-fold, respectively, lower than for the seasonal A(H1N1) influenza viruses from 2007/2008; for oseltamivir-resistant A(H1N1) 2009 virus the IC₅₀ was 2.9-fold lower. Eighteen of the 19 patients with oseltamivir-resistant virus showed prolonged shedding of the virus and developed resistance while on oseltamivir therapy. Sixteen of these 18 patients had an immunodeficiency, of whom 11 had a hematologic disorder. The two other patients had another underlying disease. Six of the patients who had an underlying disease died; of these, five had received cytostatic or immunosuppressive therapy. No indications for onward transmission of resistant viruses were found. This study showed that the main association for the emergence of cases of oseltamivir-resistant A(H1N1) 2009 virus was receiving antiviral therapy and having drug-induced immunosuppression or an hematologic disorder. Except for a single case of a resistant virus not linked to oseltamivir therapy, the absence of detection of resistant variants in community specimens and in specimens from contacts of cases with resistant virus suggested that the spread of resistant A(H1N1) 2009 virus was limited. Containment may have been the cumulative result of impaired NA function, successful isolation of the patients, and prophylactic measures to limit exposure.     

重型甲型H1N1流感的早期预测指标

目的寻求重型甲型H1N1流感患者的早期预测指标。方法比较2009年6月~2010年1月南京地区经RT-PCR确诊的183例普通型和64例重型甲型H1N1流感患者的临床特点及实验室参数,分析重型患者的特征。结果重型外周血白细胞绝对数(6.13±4.06)×109/L,较普通型的(4.48±1.44)×109/L明显偏高(P<0.01);而同期淋巴细胞数(1.23±0.76)×109/L,较普通型(1.50±0.59)×109/L明显下降(P<0.01)。结论除已知的重型甲型H1N1流感指征外,淋巴细胞比例和绝对计数下降可作为重型甲型H1N1患者的早期预测指标。     

Human monoclonal antibodies in single chain fragment variable format with potent neutralization activity against influenza virus H5N1

Effective diagnostic and therapeutic strategies are needed to control and combat the highly pathogenic avian influenza virus (AIV) subtype H5N1. To this end, we developed human monoclonal antibodies (mAbs) in single chain fragment variable (scFv) format towards the H5N1 avian influenza virus to gain new insights for the development of immunotherapy against human cases of H5N1. Using a biopanning based approach a large array of scFvs against H5N1 virus were isolated from the human semi-synthetic ETH-2 phage antibody library. H5N1 ELISA-positive scFvs with unique variable heavy (VH) and light (VL) chain gene sequences showed different biochemical properties and neutralization activity across H5N1 viral strains. In particular, the scFv clones AV.D1 and AV.C4 exerted a significant inhibition of the H5N1 A/Vietnam/1194/2004 virus infection in a pseudotype-based neutralization assay. Interestingly, these two scFvs displayed a cross-clade neutralizing activity versus A/whooping swan/Mongolia/244/2005 and A/Indonesia/5/2005 strains. These studies provide proof of the concept that human mAbs in scFv format with well-defined H5N1 recognition patterns and in vitro neutralizing activity can be easily and rapidly isolated by biopanning selection of an entirely artificial antibody repertoire using inactivated H5N1 virus as a bait.     

H5N1禽流感肺部影像学表现

目的 探讨高致病性禽流感的肺部床头胸片及CT表现.方法 报告6个病例,6例治愈,均为确诊病例.回顾性分析其肺部影像表现.结果 肺部病变主要的影像学特点为:1.床头胸片为弥漫性肺实变和间质改变以及进展迅速,变化快,吸收缓慢.病变早期以双肺斑片状渗出为主,随后迅速扩大,后期表现为两肺弥漫性实变;病变吸收缓慢,先为渗出病灶,且肺部纤维化病灶的吸收持续时间长.结论 胸部X线检查是发现H5N1高致病性禽流感最基本的影像学检查方法,可显示病变密度、形态和范围以及变化情况,有助于判断病情,指导治疗和估计预后.     

In vitro and in vivo efficacy of fluorodeoxycytidine analogs against highly pathogenic avian influenza H5N1, seasonal, and pandemic H1N1 virus infections

Various fluorodeoxyribonucleosides were evaluated for their antiviral activities against influenza virus infections in vitro and in vivo. Among the most potent inhibitors was 2′-deoxy-2′-fluorocytidine (2′-FdC). It inhibited various strains of low and highly pathogenic avian influenza H5N1 viruses, pandemic H1N1 viruses, an oseltamivir-resistant pandemic H1N1 virus, and seasonal influenza viruses (H3N2, H1N1, influenza B) in MDCK cells, with the 90% inhibitory concentrations ranging from 0.13 to 4.6 μM, as determined by a virus yield reduction assay. 2′-FdC was then tested for efficacy in BALB/c mice infected with a lethal dose of highly pathogenic influenza A/Vietnam/1203/2004 H5N1 virus. 2′FdC (60 mg/kg/d) administered intraperitoneally (i.p.) twice a day beginning 24 h after virus exposure significantly promoted survival (80% survival) of infected mice (p = 0.0001). Equally efficacious were the treatment regimens in which mice were treated with 2′-FdC at 30 or 60 mg/kg/day (bid X 8) beginning 24 h before virus exposure. At these doses, 70-80% of the mice were protected from death due to virus infection (p = 0.0005, p = 0.0001; respectively). The lungs harvested from treated mice at day four of the infection displayed little surface pathology or histopathology, lung weights were lower, and the 60 mg/kg dose reduced lung virus titers, although not significantly compared to the placebo controls. All doses were well tolerated in uninfected mice. 2′-FdC could also be administered as late as 72 h post virus exposure and still significantly protect 60% mice from the lethal effects of the H5N1 virus infection (p = 0.019). Other fluorodeoxyribonucleosides tested in the H5N1 mouse model, 2′-deoxy-5-fluorocytidine and 2′-deoxy-2′,2′-difluorocytidine, were very toxic at higher doses and not inhibitory at lower doses. Finally, 2′-FdC, which was active in the H5N1 mouse model, was also active in a pandemic H1N1 influenza A infection model in mice. When given at 30 mg/kg/d (bid X 5) beginning 24 h before virus exposure), 2′-FdC also significantly enhanced survival of H1N1-infected mice (50%, p = 0.038) similar to the results obtained in the H5N1 infection model using a similar dosing regimen (50%, p < 0.05). Given the demonstrated in vitro and in vivo inhibition of avian influenza virus replication, 2′FdC may qualify as a lead compound for the development of agents treating influenza virus infections.     

热毒宁注射液体外抑制甲型H1N1流感病毒的研究

目的 研究热毒宁注射液体外抑制甲型H1N1流感病毒的作用。方法 以奥司他韦为阳性对照,采用CPE和MTT法观察热毒宁注射液对甲型H1N1流感病毒的抑制作用。结果 CPE法结果表明热毒宁注射液最大无毒浓度（TC₀）为16.2 mg/mL,半数中毒浓度为（TC₅₀）为（24.5±8.1）mg/mL;MTT法测定结果表明热毒宁注射液TC₀为16.2 mg/mL,TC₅₀为（21.7±9.4）mg/mL。热毒宁注射液体外抑制甲型H1N1流感病毒结果显示,CPE法和MTT法热毒宁注射液作用感染细胞1次组半数有效浓度（IC₅₀）为（900.0±173.2）、（933.3±57.7）μg/mL,治疗指数（TI）为27.2、23.2;热毒宁注射液作用感染细胞3次组IC₅₀为（666.7±115.5）、（866.7±208.1）μg/mL,TI为36.7、25.0。结论 热毒宁注射液具有明显体外抗甲型H1N1流感病毒的作用。     

人用H5N1禽流感病毒疫苗生产工艺的优化

目的 建立优化的人用H5N1禽流感病毒疫苗生产的工艺。方法 在不同的稀释倍数、收获时间及灭活剂添加量下,通过测量收获液的病毒滴度和血凝效价,来确定病毒的最佳生产条件,并对离心法和凝胶过滤层析法的纯化效果进行对比。结果 103~104半数鸡胚感染量(50% egg infective dose,EID50)病毒接种鸡胚,收获的鸡胚尿囊液的病毒滴度和血凝效价最高,分别为10-8.3EID50和1∶480;在56~72 h血凝效价最高。甲醛浓度1∶10 000灭活144 h为灭活最佳条件。两种纯化方法得到的样品纯度和卵清蛋白的去除率相近,但离心纯化法和凝胶过滤层析纯化法病毒回收率有较大的差异,分别为19%和70%。结论 成功建立了高产毒的鸡胚基质H5N1禽流感病毒培养、灭活及纯化工艺。     

Antiviral effect of a selective COX-2 inhibitor on H5N1 infection in vitro

A selective cyclooxygenase-2 (COX-2) inhibitor has been previously shown to suppress the hyper-induced pro-inflammatory responses in H5N1 infected primary human cells. Here, we demonstrate that COX-2 inhibitors suppress H5N1 virus replication in human macrophages suggesting that H5N1 virus replication (more so than seasonal H1N1 virus) is dependent on activation of COX-2 dependent signaling pathways in host cells. COX-2 and its downstream signaling pathways deserve detailed investigation as a novel therapeutic target for treatment of H5N1 disease.     

Characterization of a trypsin-dependent avian influenza H5N1-pseudotyped HIV vector system for high throughput screening of inhibitory molecules

In this study, we have generated and characterized an avian influenza H5N1 hemagglutinin (HA), neuraminidase (NA) and M2 ion channel pseudotyped HIV-based vector system (HaNaM-pseudotyped HIV vector). The cleavage site of the HA protein was modified to necessitate trypsin-dependent maturation of the glycoprotein. HA, NA and M2 were efficiently incorporated in HIV vector particles which could transduce different cell lines in a trypsin-dependent manner. Results also showed that the presence of avian influenza M2 and NA proteins maximized both vector production and transduction and that transduction was highly sensitive to the specific NA inhibitor oseltamivir (Tamiflu). H5N1 HaNaM-pseudotyped HIV vector system was also adapted for cell-based high throughput screening of drug candidates against influenza virus infection, and its high sensitivity to the specific oseltamivir validates its potential utility in the identification of new influenza inhibitors. Overall, the trypsin-dependent H5N1-pseudotyped HIV vector can mimic avian influenza virus infection processes with sufficient precision to allow for the identification of new antivirals and to study avian influenza virus biology in a lower biosafety level laboratory environment.     

Inactivation of high and low pathogenic avian influenza virus H5 subtypes by copper ions incorporated in zeolite-textile materials

The effect of cotton textiles containing Cu²⁺ held by zeolites (CuZeo-textile) on the inactivation of H5 subtype viruses was examined. Allantoic fluid (AF) containing a virus (AF virus) (0.1 ml) was applied to the textile (3 × 3-cm), and incubated for a specific period at ambient temperature. After each incubation, 0.9 ml of culture medium was added followed by squeezing to recover the virus into the medium. The recovered virus was titrated using Madin-Darby canine kidney (MDCK) cells or 10-day-old embryonated chicken eggs.The highly pathogenic H5N1 and the low pathogenic H5N3 viruses were inactivated on the CuZeo-textile, even after short incubation. The titer of A/chicken/Yamaguchi/7/04 (H5N1) in MDCK cells and in eggs declined by >5.0 log₁₀ and 5.0 log₁₀, respectively, in 30 s. The titer of A/whooper swan/Hokkaido/1/08 (H5N1) in MDCK cells declined by 2.3 and 3.5 in 1 and 5 min, respectively. When A/whistling swan/Shimane/499/83 (H5N3) was treated on the CuZeo-textile for 10 min, the titer declined by >5.0 log₁₀ in MDCK cells and by >3.5 log₁₀ in eggs. In contrast, no decrease in the titers was observed on cotton textiles containing zeolites alone (Zeo-textile). Neither cytopathic effects nor NP antigens were detected in MDCK cells inoculated with the H5N1 virus treated on the CuZeo-textile. The viral genes (H5, N1, M, and NP) were amplified from the virus treated on the CuZeo-textile by RT-PCR. The hemagglutinating activity of the CuZeo-textile treated virus was unaffected, indicating that virus-receptor interactions were maintained. Electron microscopic analysis revealed a small number of particles with morphological abnormalities in the H5N3 virus samples recovered immediately from the CuZeo-textile, while no particles were detectable in the 10-min treated sample, suggesting the rapid destruction of virions by the Cu²⁺ in the CuZeo-textile. The loss of infectivity of H5 viruses could, therefore, be due to the destruction of virions by Cu²⁺. Interestingly, CuCl₂ treatment (500 and 5000 μM) did not have an antiviral effect on the AF viruses (H5N1 and H5N3) even after 48 h of incubation, although the titer of the purified H5N3 virus treated with CuCl₂ declined greatly. The antiviral effect was inhibited by adding the AF to the purified H5N3 virus prior to the CuCl₂ treatment. The known antibacterial/antifungal activities of copper suggest that the CuZeo-textile can be applied at a high level of hygiene in both animals and humans.     

奥司他韦治疗疑似甲型H1N1流感的疗效分析

目的观察奥司他韦（达菲）治疗疑似甲型H1N1流感的疗效。方法47例疑似甲型H1NI流感的病例,随机分成治疗组22例和对照组25例,治疗组给予奥司他韦75mg,每天2次口服,疗程5d;对照组给予常规流感对症治疗（感冒灵冲剂）,疗程5～7d。结果治疗组发热缓解时间与流感样症状持续时间均短于对照组,差异均有统计学意义（P〈0．01）。治疗组应用抗生素的比例为25．1％低于对照组的48．3％,差异有统计学意义（P〈0．01）。结论奥司他韦作为抗流感病毒药物治疗疑似甲型H1N1流感安全有效。     

甲型H5N1禽流感病毒血凝素在sf9昆虫细胞中的表达及其鉴定

目的  利用杆状病毒-昆虫细胞表达系统表达甲型H5N1禽流感病毒血凝素（hemagglutinin,HA）并对其进行鉴定。方法  根据sf9昆虫细胞密码子偏好性,对A/Goose/Guangdong/1/96（H5N1）禽流感病毒的HA基因进行序列优化并全长合成。构建重组供体质粒pFastHA,经PCR及测序鉴定后,转化DH10Bac感受态细胞,获得重组穿梭质粒BacmidHA,用M13引物进行PCR鉴定。采用脂质体法转染sf9细胞,获得重组杆状病毒rBacHA。用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳法（sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE）、蛋白质印迹法以及间接免疫荧光法对rBacHA表达产物进行分析。结果  供体质粒pFastHA经双酶切后产生了1条与预期大小相符的1 707 bp条带,序列测定证实目的基因无突变。穿梭质粒BacmidHA经PCR扩增,得到1条与预期大小相符的3 180 bp条带。SDS-PAGE结果显示,rBacHA表达产物的相对分子质量约为65 000。蛋白质印迹法分析表明,表达产物能与禽流感病毒阳性血清结合。在荧光显微镜下,感染rBacHA的sf9细胞呈现绿色荧光,提示HA基因得到表达。结论  利用杆状病毒-昆虫细胞表达系统成功制备了具有良好抗原性的重组HA蛋白。     

甲型H1N1流感患者C反应蛋白和血小板的变化及意义探讨

目的探讨C反应蛋白(CRP)和血小板(PLT)的动态变化在甲型H1N1流感患者中的临床意义。方法回顾性分析我院2009年10月至2010年1月收治的40例符合甲型H1N1流感诊断标准的患者,比较第1、2、3、4天的CRP和PLT变化,分析CRP和PLT与病情预后的关系。结果好转组及恶化组第1天CRP水平差异无统计学意义(P>0.05),第2、3、4天恶化组患者CRP明显高于好转组,差异有统计学意义(P<0.01);好转组PLT均在正常范围,恶化组PLT呈持续下降,两组差异有统计学意义(P<0.05)。结论 RP和PLT的动态变化对判断甲型H1N1流感患者病情预后有重要帮助,CRP水平升高越明显,PLT水平呈持续下降趋势,提示患者病情越重。     

痰热清注射液治疗甲型H1N1流感并肺炎36例

目的观察痰热清注射液治疗甲型H1N1流感并肺炎的临床效果及不良反应。方法将72例甲型H1N1流感并肺炎患者随机分为治疗组和对照组,每组36例,两组均给予止咳、祛痰、抗病毒、抗感染等常规治疗。治疗组在此基础上加用痰热清注射液静脉滴注,连用7d。结果治疗组在热退、咳嗽、咳痰和肺部啰音消失所需时间及住院时间均明显短于对照组（P〈0.01）。治疗组的显效率（94.4%）与对照组（72.2%）比较差异有统计学意义（P〈0.05）。未见明显药物不良反应。结论痰热清注射液治疗甲型H1N1流感并肺炎疗效确切,安全性良好。     

对禽流感H5N1灭活疫苗与不同免疫方式诱导的免疫应答及异亚型保护研究

目的  观察禽流感H5N1灭活疫苗以不同方式免疫后诱导的免疫应答及抗异亚型病毒攻击的保护作用.  方法 将H5N1灭活疫苗分别通过腹腔和滴鼻方式免疫BALB/c小鼠,同时以PBS作为对照;免疫后分别以PR8和H9N2病毒攻击,观察小鼠的体重变化和生存情况.采用ELISA对各组小鼠攻毒后不同时间的血清IgG及其亚类水平进行动态检测;流式细胞仪检测脾淋巴细胞亚群情况.采用t检验对各组数据进行比较.   结果 PR8和H9N2病毒攻击后,各组小鼠体重均下降,但疫苗组小鼠于后期体重恢复正常,存活率分别为100%和70%-80%,而PBS组小鼠则全部死亡.无论以何种方式免疫,疫苗组的特异性IgG及其亚类水平均明显升高,其中以IgG2a水平升高更为明显.攻毒后疫苗组小鼠脾CD4+与CD8+T淋巴细胞比值出现下降(t=6.8017,P<0.01);滴鼻免疫组与腹腔免疫组相比降低更明显(t=3.9701,P<0.05).    结论   H5N1疫苗免疫原性良好,可诱导较高水平的特异性抗体产生,诱导的抗体亚类以IgG2a为主.两种免疫方式均可对小鼠提供很好的异亚型保护,而滴鼻免疫能够诱导更强的CD8+T细胞应答.     

上海地区人群甲型H1N1流感抗体水平监测分析

Objective To understand levels of antibody to swine-origin influenza A(H1 N1) virus (A/ H1N1) among different age groups in Shanghai, and to compare the levels between antibodies to A/H1N1 and to 2008-2009 seasonal influenza vaccine virus A/Brisbane/59/2007(H1N1). Methods The anti-A/HlN1 antibody levels were determined among 5 age groups (0-5 months, 6 months-4 years, 5-24 years, 25-59 years, and ≥60 years) with routine micro-hemagglutination inhibition test. The positive rates of the antibodies among different age groups were compared by Pearson's X2 test and Fisher' s exact probability test. Results The positive rate of antibody to A/H1N1 in the whole population in Shanghai was 9.2% (37/404). The highest rate was 25.0% (21/84) in the age group of ≥60 years, the next was 10. 0% (8/80) in the age group of 25-59 years, the positive rates in other groups were lower. The result of Pearson's X2 test showed that there were statistically significant differences in the positive rates of the antibodies among different age groups. Of 329 sera positive for antibody to 2008 -2009 seasonal influenza vaccine virus A/Brisbane/59/ 2007 (H1N1), 31 had anti-A/HlNl antibodies, and of 75 sera negative for antibody to A/Brisbane/59/ 2007(H1N1), 6 had anti-A/HlNl antibodies. The result of Pearson's X2 test showed that there were no significant differences in positive rates of antibody to A/H1N1 between the two types of population. Conclusions The anti-A/HlNl levels in Shanghai population are low, and people are generally susceptible to A/H1N1. The sera positive for antibody to A/Brisbane/59/2007(H1N1) can not provide cross-protection against A/H1N1.     

上海地区人群甲型H1N1流感抗体水平监测分析

Objective To understand levels of antibody to swine-origin influenza A(H1 N1) virus (A/ H1N1) among different age groups in Shanghai, and to compare the levels between antibodies to A/H1N1 and to 2008-2009 seasonal influenza vaccine virus A/Brisbane/59/2007(H1N1). Methods The anti-A/HlN1 antibody levels were determined among 5 age groups (0-5 months, 6 months-4 years, 5-24 years, 25-59 years, and ≥60 years) with routine micro-hemagglutination inhibition test. The positive rates of the antibodies among different age groups were compared by Pearson's X2 test and Fisher' s exact probability test. Results The positive rate of antibody to A/H1N1 in the whole population in Shanghai was 9.2% (37/404). The highest rate was 25.0% (21/84) in the age group of ≥60 years, the next was 10. 0% (8/80) in the age group of 25-59 years, the positive rates in other groups were lower. The result of Pearson's X2 test showed that there were statistically significant differences in the positive rates of the antibodies among different age groups. Of 329 sera positive for antibody to 2008 -2009 seasonal influenza vaccine virus A/Brisbane/59/ 2007 (H1N1), 31 had anti-A/HlNl antibodies, and of 75 sera negative for antibody to A/Brisbane/59/ 2007(H1N1), 6 had anti-A/HlNl antibodies. The result of Pearson's X2 test showed that there were no significant differences in positive rates of antibody to A/H1N1 between the two types of population. Conclusions The anti-A/HlNl levels in Shanghai population are low, and people are generally susceptible to A/H1N1. The sera positive for antibody to A/Brisbane/59/2007(H1N1) can not provide cross-protection against A/H1N1.     

甲型H1N1流感肺炎患儿潮气呼吸肺功能的改变

目的探讨甲型H1N1流感肺炎患儿的肺功能变化及其在临床诊断和治疗评估中的意义。方法测定53例甲型H1N1流感肺炎患儿(A组)潮气呼吸肺功能,并与87例同年龄段健康儿童(B组)对照。结果 A组潮气流速-容量环变窄,呼气曲线升枝陡峭,高峰提前,降枝呈波谷样凹陷。与B组比较,A组通气功能指标反映呼气功能障碍,尤其1个月~3岁年龄组患儿(P<0.05)。结论甲型H1N1流感肺炎患儿其急性期肺功能改变主要表现为气道阻塞性通气功能障碍;潮气呼吸肺功能测定可为甲型H1N1流感肺炎患儿评判病情程度及预后评估提供客观依据。     

甲型H1N1流感暴发流行915例发热病历分析

目的：掌握甲型H1N1流感暴发流行情况,采取有效措施,控制甲型H1N1流感在学校内传播及蔓延。方法：对本校2009年9～12月门诊记录的体温37.5℃以上、以呼吸道症状为主的发热大学生的所有资料进行回顾性调查分析。结果：4个月内本校大学生流感样发热915例,发病率为7.08%;11月为发热高峰期;男生发热人数多与女生,差异有统计学意义;体温多为38.1～39.0℃。结论：要控制甲型H1N1流感在学校流行,必须及时采取隔离传染源、切断传播途径、保护易感人群各项有效可行措施。     

上海地区在校中学生接种甲型H1N1流感疫苗前后抗体水平监测分析

 目的  了解上海地区在校中学生接种甲型H1N1流感疫苗前后的抗体水平;观察甲型H1N1流感疫苗对该人群的免疫保护作用。 方法    应用常规微量血凝抑制试验（micro-hemagglutination inhibition test, HIT）对上海地区在校中学生分3个时间段进行甲型H1N1流感病毒抗体的血清学监测,3个时间段的抗体阳性率比较采用Pearson χ2 检验进行分析。 结果  2009年甲型H1N1流感流行前上海地区在校中学生的血清抗体阳性率仅为1.3%。经过一段时间流行后,血清抗体阳性率升至8.5%。接种甲型H1N1流感疫苗后,血清抗体阳性率升至87.3%。经Pearson χ² 检验分析,3个时间段在校中学生的血清甲型H1N1流感抗体阳性率差异有统计学意义（χ²=243.7,P<0.05）。 结论  在甲型H1N1流感流行前,上海地区在校中学生对其几乎没有免疫力,接种甲型H1N1流感疫苗能为该人群提供较好的免疫保护作用。