Course of pandemic influenza A(H1N1) 2009 virus infection in Dutch patients

The clinical dynamics of influenza A(H1N1) 2009 infections in 61 laboratory-confirmed Dutch cases were examined. An episode lasted a median of 7·5 days of which 2 days included fever. Respiratory symptoms resolved slowly, while systemic symptoms peaked early in the episode and disappeared quickly. Severity of each symptom was rated highest in the first few days. Furthermore, diarrhoea was negatively associated with viral load, but not with faecal excretion of influenza virus. Cases with comorbidities appeared to have higher viral loads than the cases without, suggesting a less effective immune response. These results complement information obtained through traditional surveillance.     

32例无基础疾病者甲型H1N1流感危重症特点分析

目的 了解无基础疾病者感染甲型H1N1流感危重症的临床特点、治疗和转归.方法 观察北京地坛医院2009年10月3日-12月31日收治的32例无基础疾病者感染甲型H1N1流感危重症的临床特点、主要治疗和转归.结果 危重症易发生于65岁以下(96.9％)及肥胖者(71.0％).甲型H1N1流感危重症临床特点为高热(96.9...     

Clinical aspects of 2009 pandemic influenza A (H1N1) virus infection in Austria

Purpose

To describe the clinical features, risk factors for severe disease and effectiveness of oseltamivir in patients with 2009 pandemic influenza A (H1N1) virus infection.

Methods

In a prospective, cross-sectional, multicentre study, data on 540 patients with confirmed 2009 H1N1 infection from seven Austrian hospitals were collected using a standardised online case-history form.

Results

The median age of the patients was 19.3 years (range 26 days–90.8 years); point-of-care testing yielded false-negative results in 60.2% of the 176 cases tested. The most common symptoms were fever, cough, fatigue and headache. Overall, 343 patients (63.5%) were hospitalised, 49 (9.1%) were admitted to an intensive care unit (ICU) and 14 (4.1%) died. Case fatality rates were highest (9.1%) in those aged 65 years or older. Factors significantly associated with a higher risk for ICU admission included age, neurological disease, adipositas, and both interstitial pathology and lobular pathology on chest X-ray. No association with pregnancy, malignancy or immunosuppressive therapy was detected. Antiviral treatment significantly reduced the duration of fever by 0.66 days and lowered the risk of ICU admission, but had no significant benefit on survival.

Conclusions

During the 2009 H1N1 influenza pandemic, elderly or obese patients and those with neurological disease had an increased risk for severe H1N1 infection in Austria. Pregnancy was not associated with a higher risk for severe disease in the later phase of the 2009 H1N1 pandemic. Antiviral treatment provided a minimal effect on the symptoms of influenza but reduced the risk of admission to an ICU.     

Respiratory virus infections among hospitalized patients with suspected influenza A H1N1 2009 virus during the first pandemic wave in Brazil

IntroductionDuring the first pandemic wave of the influenza A H1N1 2009 virus, morbidity was particularly high in Brazil. Hospitalizations resulting from severe respiratory disease due to suspected influenza-like illness created an opportunity to identify other respiratory viruses causing lower respiratory infections.ObjectiveThe purpose of this study was to assess viral etiologies among samples collected during the first pandemic wave of H1N1 2009 from hospitalized patients with suspected cases in a Brazilian Sentinel Hospital. Patients and methods: Viral etiologies were investigated in samples from 98 children and 61 adults with fever, cough and dyspnea who were admitted to São Paulo Sentinel Hospital with suspected H1N1 infection.ResultsFrom August to November 2009, in 19.5% (31/159) of the samples 2009 H1N1 virus was detected with 23% (14/61) in adults (median age 25 years, range: 14-55 years) and 18.4% (17/92) in children (median age 5 years, range: 4 months - 11 years). Among the negative samples, a wide range of causative etiologic agents was identified. Human rhinovirus was the most frequent virus (23.91%) in children and human metapneumovirus (11.48%) was the second most frequent in adults, following 2009 H1N1 virus (22.95%).ConclusionsThese data highlight the need to diagnose other viral infections that can co-circulate with influenza and may have been neglected by physicians as causes of severe respiratory diseases.     

Seroepidemiology of pandemic influenza A (H1N1) 2009 virus infections in Pune,India

Background  

In India, Pune was one of the badly affected cities during the influenza A (H1N1) 2009 pandemic. We undertook serosurveys among the risk groups and general population to determine the extent of pandemic influenza A (H1N1) 2009 virus infections.     

Antibody responses against influenza A(H1N1)pdm09 virus after sequential vaccination with pandemic and seasonal influenza vaccines in Finnish healthcare professionals

Background Influenza A(H1N1)pdm09 virus has been circulating in human population for three epidemic seasons. During this time, monovalent pandemic and trivalent seasonal influenza vaccination against this virus have been offered to Finnish healthcare professionals. It is, however, unclear how well vaccine‐induced antibodies recognize different strains of influenza A(H1N1)pdm09 circulating in the population and whether the booster vaccination with seasonal influenza vaccine would broaden the antibody cross‐reactivity. Objectives Influenza vaccine‐induced humoral immunity against several isolates of influenza A(H1N1)pdm09 virus was analyzed in healthcare professionals. Age‐dependent responses were also analyzed. Methods Influenza viruses were selected to represent viruses that circulated in Finland during two consecutive influenza epidemic seasons 2009–2010 and 2010–2011. Serum samples from vaccinated volunteers, age 20–64 years, were collected before and after vaccination with AS03‐adjuvanted pandemic and non‐adjuvanted trivalent seasonal influenza vaccine that was given 1 year later. Results Single dose of pandemic vaccine induced a good albeit variable antibody response. On day 21 after vaccination, depending on the virus strain, 14–75% of vaccinated had reached antibody titers (≥1:40) considered seroprotective. The booster vaccination 1 year later with a seasonal vaccine elevated the seroprotection rate to 57–98%. After primary immunization, younger individuals (20–48 years) had significantly higher antibody titers against all tested viruses than older persons (49–64 years) but this difference disappeared after the seasonal booster vaccination. Conclusions Even a few amino acid changes in influenza A HA may compromise the vaccine‐induced antibody recognition. Older adults (49 years and older) may benefit more from repeated influenza vaccinations.     

Association between seasonal influenza vaccination in 2008-2009 and pandemic influenza A (H1N1) 2009 infection among school students from Kobe, Japan, April-June 2009

We assessed the effect of seasonal trivalent inactivated influenza vaccination (TIV) on pandemic influenza 2009 (pH1N1)-related illness from April to June 2009 among 2849 students (aged 12-18 years). TIV was associated with an increase in the frequency of pH1N1-related illness among subjects (adjusted odds ratio, 1.47; 95% confidence interval, 1.14-1.89). TIV during the 2008-2009 season increased the risk of pH1N1-related illness from April to June 2009.     

Immunogenicity and safety of pandemic influenza A (H1N1) 2009 vaccine: systematic review and meta-analysis

The emergence of the 2009 H1N1 pandemic has highlighted the need to have immunogenicity and safety data on the new pandemic vaccines. There is already considerable heterogeneity in the types of vaccine available and of study performed around the world. A systematic review and meta-analysis is needed to assess the immunogenicity and safety of pandemic influenza A (H1N1) 2009 vaccines. We searched Medline, EMBASE, the Cochrane Library and other online databases up to 1st October 2010 for studies in any language comparing different pandemic H1N1 vaccines, with or without placebo, in healthy populations aged at least 6 months. The primary outcome was seroprotection according to haemagglutination inhibition (HI). Safety outcomes were adverse events. Meta-analysis was performed for the primary outcome. We identified 18 articles, 1 only on safety and 17 on immunogenicity, although 1 was a duplicate. We included 16 articles in the meta-analysis, covering 17,921 subjects. Adequate seroprotection (≥70%) was almost invariably achieved in all age groups, and even after one dose and at low antigen content (except in children under 3 years receiving one dose of non-adjuvanted vaccine). Non-adjuvanted vaccine from international companies and adjuvanted vaccines containing oil in water emulsion (e.g. AS03, MF59), rather than aluminium, performed better. Two serious vaccination-associated adverse events were reported, both of which resolved fully. No death or case of Guillain-Barré syndrome was reported. The pandemic influenza (H1N1) 2009 vaccine, with or without adjuvant, appears generally to be seroprotective after just one dose and safe among healthy populations aged ≥36 months; very young children (6-35 months) may need to receive two doses of non-adjuvanted vaccine or one dose of AS03(A/B)-adjuvanted product to achieve seroprotection.     

2009年甲型H1N1流感大流行重症病例的治疗

本文就呼吸支持、药物治疗（抗病毒药物、皮质类固醇、抗菌药物、乌司他丁）、血浆疗法与营养支持及抗凝疗法等方面介绍了重症甲型H1N1流感的救治经验。随着病例的增加,这些经验对临床医生有很好的指导意义。     

四川省2009甲型H1N1流感的流行病学特征

目的分析四川地区甲型H1N1流感流行病学特点,为今后新发传染病的防控提供参考。方法回顾性分析我院2009年收治的271例甲型H1N1流感病例的来源、年龄及时间分布。结果 1.271例甲型H1N1流感病例,男∶女为1.09∶1,随着病情加重发病年龄逐渐增加,病程亦逐渐延长;2.轻症患者均无基础疾病,危重症患者基础疾病较重症患者多且重;3.绝大多数患者年龄在10~30岁（211例,77.87%）,轻症及重症中无≤2岁及≥65岁的患者,危重症中≥65岁者2例;4.疫情早期（5~9月）患者均为轻症,以输入病例为主（52例,19.19%）,疫情后期以本土暴发病例为主（9月以后）有危重症出现。结论新发传染病疫情早期以轻症、输入病例为主,后期随着社区聚集性疫情,有重危症患者出现;患者年龄、基础疾病是该疾病严重程度的重要影响因素。     

Transmission parameters of the A/H1N1 (2009) influenza virus pandemic: a review

Please cite this paper as: Boëlle P‐Y et al. (2011) Transmission parameters of the A/H1N1 (2009) influenza virus pandemic: a review. Influenza and Other Respiratory Viruses 5(5), 306–316. Background The new influenza virus A/H1N1 (2009), identified in mid‐2009, rapidly spread over the world. Estimating the transmissibility of this new virus was a public health priority. Methods We reviewed all studies presenting estimates of the serial interval or generation time and the reproduction number of the A/H1N1 (2009) virus infection. Results Thirteen studies documented the serial interval from household or close‐contact studies, with overall mean 3 days (95% CI: 2·4, 3·6); taking into account tertiary transmission reduced this estimate to 2·6 days. Model‐based estimates were more variable, from 1·9 to 6 days. Twenty‐four studies reported reproduction numbers for community‐based epidemics at the town or country level. The range was 1·2–3·1, with larger estimates reported at the beginning of the pandemic. Accounting for under‐reporting in the early period of the pandemic and limiting variation because of the choice of the generation time interval, the reproduction number was between 1·2 and 2·3 with median 1·5. Discussion The serial interval of A/H1N1 (2009) flu was typically short, with mean value similar to the seasonal flu. The estimates of the reproduction number were more variable. Compared with past influenza pandemics, the median reproduction number was similar (1968) or slightly smaller (1889, 1918, 1957).