Hemagglutinin-specific CD4+ T-cell responses following 2009-pH1N1 inactivated split-vaccine inoculation in humans

Influenza A virus remains a major threat to public health, and the inactivated split-virus vaccine is the most prevalent vaccine used worldwide. However, our knowledge about cellular immune responses to the inactivated influenza virus vaccine and its correlation with humoral responses are yet limited, which has restricted our understanding of the vaccine’s protective mechanisms. Herein, in two clinical trials, T-cell responses specific for both previously identified human leucocyte antigen (HLA)-I-restricted epitopes from influenza virus and hemagglutinin (HA) protein were longitudinally investigated before, during, and after a two-dose vaccination with the inactivated 2009 pandemic H1N1 (2009-pH1N1) vaccine. A robust antibody response in all of the donors after vaccination was observed. Though no CD8⁺ T-cell responses to known epitopes were detected, HA-specific T-cell responses were primed following vaccination, and the responses were found to be mainly CD4⁺ T-cell dependent. However, HA-specific T-cells circulating in peripheral blood dropped to baseline levels 6 weeks after vaccination, but humoral immune responses maintained a high level for 4 months post-vaccination. Significant correlations between the magnitude of the HA-specific T-cell responses and hemagglutination inhibition antibody titers were demonstrated, indicating a priming role of HA-specific T-cells for humoral immune responses.In conclusion, our study indicates that HA-specific CD4⁺ T-cell responses can be primed by the inactivated 2009-pH1N1 vaccine, which may coordinate with the elicitation of antibody protection. These findings would benefit a better understanding of the immune protective mechanisms of the widely used inactivated 2009-pH1N1 vaccine.     

Influenza vaccination among healthcare personnel after pandemic influenza H1N1

The purpose of this study was to evaluate the coverage rates for influenza vaccination among health-care personnel (HCP), and if the reasons for accepting influenza vaccine by HCP and the frequency of vaccine-related adverse events (AEs) in 2010-2011 were different compared to 2009-2010. The AEs were detected by telephoning the worker one week after the vaccination. The coverage for seasonal vaccination in 2009-2010 was 31.0%, whereas that for 2009 pandemic influenza (H1NI) was 22.2% and 24.4% (p < 0.05) in 2010-2011. The most frequent reason for being vaccinated during the three campaigns was to “protect my health”. Over 80.5% of the HCP reported 2009 pandemic influenza (H1N1) vaccine-related AEs compared to the 25.3% and 25.4% reporting seasonal vaccine-related AEs in 2009-2010 and 2010-2011 respectively (p < 0.05). None of the AEs were severe. Specific measures should be implemented in our country to recover and improve poor vaccination coverage.     

No association between 2008-09 influenza vaccine and influenza A(H1N1)pdm09 virus infection, Manitoba, Canada, 2009

We conducted a population-based study in Manitoba, Canada, to investigate whether use of inactivated trivalent influenza vaccine (TIV) during the 2008-09 influenza season was associated with subsequent infection with influenza A(H1N1)pdm09 virus during the first wave of the 2009 pandemic. Data were obtained from a provincewide population-based immunization registry and laboratory-based influenza surveillance system. The test-negative case-control study included 831 case-patients with confirmed influenza A(H1N1)pdm09 virus infection and 2,479 controls, participants with test results negative for influenza A and B viruses. For the association of TIV receipt with influenza A(H1N1)pdm09 virus infection, the fully adjusted odds ratio was 1.0 (95% CI 0.7-1.4). Among case-patients, receipt of 2008-09 TIV was associated with a statistically nonsignificant 49% reduction in risk for hospitalization. In agreement with study findings outside Canada, our study in Manitoba indicates that the 2008-09 TIV neither increased nor decreased the risk for infection with influenza A(H1N1)pdm09 virus.     

Hospitalized patients with pandemic (H1N1) 2009, Kenya

To describe the epidemiology and clinical course of patients hospitalized with pandemic (H1N1) 2009 in Kenya, we reviewed medical records of 49 such patients hospitalized during July-November 2009. The median age (7 years) was lower than that in industrialized countries. More patients had HIV than the general Kenyan population.     

Pandemic (H1N1) 2009 encephalitis in woman, Taiwan

We report an unusual case of pandemic (H1N1) 2009-related encephalitis in an immunocompetent woman. Although rare cases of pandemic (H1N1) 2009 associated with encephalitis have been reported previously, in this patient, direct viral invasion of the central nervous system was shown by simultaneous detection of viral RNA and pleocytosis.     

Early detection of pandemic (H1N1) 2009, Bangladesh

To explore Bangladesh's ability to detect novel influenza, we examined a series of laboratory-confirmed pandemic (H1N1) 2009 cases. During June-July 2009, event-based surveillance identified 30 case-patients (57% travelers); starting July 29, sentinel sites identified 252 case-patients (1% travelers). Surveillance facilitated response weeks before the spread of pandemic (H1N1) 2009 infection to the general population.     

Improved neutralizing antibody response in the second season after a single dose of pandemic (H1N1) 2009 influenza vaccine in HIV-1-positive adults

Neutralizing antibody titers were determined before and after a single dose of pandemic (H1N1) 2009 influenza vaccine in HIV-1-positive Japanese adults in the first season of the pandemic and in those in the second season who had already received the vaccine in the first season. The antibody response rate at 2-month post-vaccination increased significantly from 49.0% (50/102, 95%CI: 39.0-59.1%) in the 2009/2010 season to 66.7% (42/63, 95%CI: 53.7-78.1%) in the 2010/2011 season. Geometric mean antibody titers (fold dilution) at baseline, at 2 months, and at 4 months also increased significantly from 4.4 (95%CI: 3.3-5.7), 19.0 (95%CI: 13.4-26.8) and 13.7 (95%CI: 9.3-20.2), respectively, in the 2009/2010 season to 8.3 (95%CI: 5.8-11.7), 47.0 (95%CI: 32.2-68.6) and 38.2 (95%CI: 23.8-61.4), respectively, in the 2010/2011 season. Although the vaccine response was low in the first season, it was improved in the second season.     

Central European Vaccination Advisory Group (CEVAG) guidance statement on recommendations for 2009 pandemic influenza A(H1N1) vaccination

The 2009 influenza A(H1N1) pandemic is markedly different from seasonal influenza with the disease affecting the younger population and a larger than expected number of severe or fatal cases has been seen in pregnant women, obese people and in people who were otherwise healthy. In Europe, influenza activity caused by the 2009 influenza A(H1N1) virus has passed the winter peak with nearly all countries now reporting lower influenza activity. However, although the rate of 2009 pandemic influenza A(H1N1) is declining, fatal cases continue to be reported and the future is hard to predict. The most effective protection against influenza is vaccination and increasing vaccine coverage is the only way to eliminate uncertainties regarding possible future waves of 2009 pandemic influenza A(H1N1). Recommendations have been developed for several central European countries but there is no clear or uniform definition with respect to priority groups or age groups who should receive vaccination. This paper contains the Central European Vaccination Advisory Group (CEVAG) guidance statement on recommendations for the vaccination of adults and children against 2009 pandemic influenza A(H1N1). CEVAG recommends vaccination of all health-care workers, pregnant women, children ≥6 months and <2 years of age and people with chronic medical conditions as a first priority.     

广元市甲型H1N1流感抗体水平调查

目的了解广元市人群甲型H1N1流感病毒感染水平,为评估疫情发展趋势提供信息支持。方法采集不同年龄段的城市和农村人口的血清用血凝抑制实验（HI）方法进行抗体检测,用统计学方法对抗体水平进行分析。结果 2010年共采集754份血清标本,其中甲型H1N1抗体阳性140份,阳性率18.6%,GMT1∶11。不同时间点、不同地区调查对象甲型H1N1抗体水平差异有统计学意义（P〈0.05）,不同性别、不同年龄组之间抗体水平差异无统计学意义（P〉0.05）。多因素logistic回归分析显示,甲型H1N1疫苗接种、调查时间和地区差异与HI抗体阳性呈显著性相关。结论广元市人群中18%以上具有甲型H1N1流感保护抗体,但抗体水平仍然较低,应进一步加强甲型H1N1流感疫苗的宣传和接种。     

2009年四川省甲型H1N1流感重症及死亡病例流行病学分析

目的了解2009年四川省甲型H1N1流感重症及死亡病例的流行病学特征,为制定防控和治疗对策提供客观依据。方法采用Excel2010建立数据库,SPSS18.0对数据进行描述性分析和单因素条件Logistic回归分析。结果重症病例主要集中在成都、德阳及绵阳地区,发生率最高地区为德阳、遂宁及自贡;重症病例与死亡病例均在11月达到高峰;男性病例较女性病例更易转变为重症病例（P=0.01）,65岁及以上年龄段病例重症发生率最高,达50%;29.08%（57/196）的重症病例和38.10%（8/21）的死亡病例患有慢性基础性疾病,患有肺部疾病、心血管疾病及代谢性疾病的患者更容易转变成重症病例甚至死亡;84.54%（175/207）的重症病例和90.48%（19/21）的死亡病例出现不同程度的并发症,主要包括肺炎、呼吸衰竭、心力衰竭等。结论甲型H1N1流感患者拖延就诊时间可导致病情恶化。重症病例神经氨酸酶抑制剂的及时使用,将有效减少死亡的发生。     

Does receipt of seasonal influenza vaccine predict intention to receive novel H1N1 vaccine: Evidence from a nationally representative survey of U.S. adults

We analyze data on the intention of U.S. adults to receive novel H1N1 vaccine if available this fall, and studies the relationship between the intention to be vaccinated against novel H1N1 and the uptake of seasonal influenza vaccine last year. We surveyed a nationally representative sample of U.S. adults (n = 2067) via the Internet between May 26th and June 8th, 2009. Our results imply a vaccination rate for novel H1N1 of 49.6%, which corresponds to roughly 115 million adult vaccinations. Moreover, novel H1N1 vaccination intentions are strongly associated with seasonal influenza vaccinations, suggesting common attitudinal barriers to both vaccines.     

社区甲型流感临床特征分析与比较

目的分析和比较社区散发新型甲型H1N1流感和季节性流感临床特征,为临床诊治甲型流感提供参考依据。方法回顾性分析2009年5-10月来医院发热门诊就诊的具有流感样症状的患者,均经实时荧光定量PCR检测。结果在确诊的129例甲型流感患者中,新型甲型H1N1流感65例,占50.4%,季节性甲型流感64例,占49.6%;新型甲型H1N1流感组平均年龄21岁,季节性甲型流感组36岁,两组差异有统计学意义(P<0.01);新型甲型H1N1流感组学生占47例,占72.3%,季节性甲型流感组13例,占20.3%,两组差异有统计学意义(P<0.01);从临床表现比较,除流涕、扁桃体肿大,两组差异有统计学意义(均P<0.01)外;其他差异均无统计学意义。结论医院确诊的甲型流感患者均为轻型;新型甲型H1N1流感以年轻学生为主;两组甲型流感临床特征相似,需经PCR检测确诊分型。     

Pandemic (H1N1) 2009 and Hajj Pilgrims Who Received Predeparture Vaccination, Egypt

In Egypt, vaccination against pandemic (H1N1) 2009 virus was required of pilgrims departing for the 2009 Hajj. A survey of 551 pilgrims as they returned to Egypt found 542 (98.1% [weighted]) reported receiving the vaccine; 6 (1.0% [weighted]) were infected with influenza virus A (H3N2) but none with pandemic (H1N1) 2009 virus.