H1N1 influenza: critical care aspects

During the Northern Hemisphere spring of 2009, a novel H1N1 influenza A virus emerged in Mexico, causing widespread human infection and acute critical respiratory illness. The 2009 H1N1 virus spread initially to the United States and Canada, with subsequent rapid global dissemination, leading the World Health Organization (WHO) to declare "a public health emergency of international concern" in April 2009, and upgrading the viral threat to pandemic status in June 2009. Despite initial fears, the severity of the 2009 H1N1 pandemic overall did not differ significantly from that of seasonal influenza. However, the demographics of those at risk of severe illness did differ (affecting children and young adults, rather than the very young and the very old). The 2009 H1N1 pandemic led to rapid implementation of health care initiatives, including the provision of critical care services, to limit the effect of the influenza outbreak on the community. This review focuses on the critical care response to the H1N1 pandemic and examines whether the implementation of critical care services as planned a priori matched the reality of the clinical workload and the patient burden that transpired during the 2009 H1N1 influenza pandemic.     

Clinical features of the hospitalized patients with 2009 pandemic influenza A (H1N1) in Santa Fe,Argentina

Background During 2009 occurred the emergence and global spread of a novel influenza A (H1N1) virus. We describe the clinical and epidemiologic features of hospitalized patients who survived and patients who died because of pandemic 2009 influenza A (H1N1) infection reported in Santa Fe, Argentina, from May to July 2009. Methods Using medical charts, we collected data on 242 patients who were hospitalized with confirmed laboratory results (defined as positive by specific PCR for pandemic 2009 influenza A H1N1). Results During the study period, there were 242 cases of hospitalization or death. Of the 242, 46% were admitted to an intensive care unit (ICU) and 33·5% died. The mean age was 27·8 years for surviving and 39·6 for those who died. Twenty‐eight percent of hospitalizations involved persons under the age of 15 years; 33% of the patients were between the age of 15 and 44 years; and only 3·3% were 65 years of age or older. Sixty‐seven percent had an underlying medical conditions, including diabetes, obesity, heart and lung diseases, and pregnancy. Of the 242 patients, 68% had findings consistent with pneumonia. Treatment with oseltamivir was administered to 227 (93 · 8%) patients from which 38 received oseltamivir within 48 hours after the onset of symptoms. Conclusions The pandemic strain caused severe illness, including pneumonia and acute respiratory distress syndrome, and resulted in ICU admissions in 46% of patients and death in 33·5%. The mean age of hospitalized infected cases was lower than is common with seasonal influenza. Underlying medical conditions were common in the 67% the evaluated patients. Patients who died had a higher prevalence of comorbidities (86·4%) than those who survived (57%), suggesting that the presence of chronic illness may increase the likelihood of death. However, the severe illness was also identified among young, healthy persons.     

Pandemic novel 2009 H1N1 influenza: what have we learned?

In March 2009, cases of influenza-like illness in Mexico caused by a novel H1N1 virus containing genes from swine, avian, and human influenza strains were reported. Within several weeks, 2009 H1N1 disseminated rapidly and was the predominant influenza strain globally. On June 11, 2009, the World Health Organization declared that criteria for an influenza pandemic had been met. Concern that this pandemic would rival the 1918 pandemic was high. Fortunately, that was not the case. Influenza-related disease activity peaked in late October to November 2009. By August 2010, the H1N1 influenza virus had moved into the postpandemic period. During the 2010-2011 season, influenza A H3N2 has been the predominant serotype, but the 2009 H1N1 continues to co-circulate with H3N2 and B strains. In contrast to previous seasonal influenza strains, the novel 2009 H1N1 strain preferentially affected young adults, with a clustering of severe and fatal cases in adults between the ages of 30 and 50 years. Additionally, H1N1 displayed a heightened potential for severe lung injury as well as gastrointestinal symptoms. Risk factors for severe disease included obesity, morbid obesity, pregnancy, immunosuppression, asthma (in children), chronic obstructive pulmonary disease, neurological disorders, other comorbidities, HIV-infection, poverty, and lack of access to care. However, >25% of deaths were in previously healthy individuals. Molecular tools for identifying 2009 H1N1 were rapidly developed, but the volume of samples quickly overwhelmed available laboratory services. Further, in the early phases of the pandemic, the volume of patients presenting to emergency rooms, acute care clinics, and physician's offices overwhelmed health care resources. Fortunately, most cases were mild; in the United States, only one in 400 required intensive care unit care, and one in 2000 died. Because most infected individuals have mild, self-limited disease, the risk/benefit assessment for early access to antiviral agents must balance the potential benefit for reducing transmission, disease severity, and burden on health care providers against the potential for dissemination of viral resistance and drug-related adverse events. Monovalent vaccines against 2009 H1N1 were developed and ready for distribution by September 2009, but initial supplies were inadequate to impact the bulk of cases that occurred in the Northern Hemisphere between April and September 2009. Continued efforts to develop universal vaccines and improve access to effective vaccines are critical.     

Factors associated with severe illness in pandemic 2009 influenza a (H1N1) infection: implications for triage in primary and secondary care

Pandemic (H1N1) 2009 influenza virus (pH1N1/09) infection spread rapidly around the globe, leading to a phase 6 pandemic level of alert declared in June 2009. The WHO declared the end of the pandemic in August 2010. Although for the majority of infected patients, it manifest as a mild, self-limiting illness, a proportion appeared to follow an adverse clinical course, requiring higher level care and aggressive management strategies. Experience with previous pandemics suggests that H1N1 will continue to circulate for many years. The aim of this review is to evaluate data from published case series reporting patients with pH1N1/09 influenza to identify clinical markers of severe disease. Comorbid illnesses including chronic lung disease, obesity and pregnancy have been shown to confer increased risk of severe infection. Admission vital signs, laboratory investigations and chest radiographic features can guide admitting clinicians to stratify patients’ risk of severe disease, however, the currently available severity scoring tools have only a limited role in risk assessment. Knowledge of high risk parameters remains important for clinicians triaging patients with suspected pH1N1/09 influenza and to inform strategies for future pandemics.     

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...     

甲型H1NI流感研究进展

目前南半球大部分国家已经历了甲型H1N1流感流行高峰期,而北半球温带地区逐渐进入活跃期,部分国家和地区出现地区性暴发。尽管当前甲型H1N1的流行总体上比较温和,但随着发病人数的增加,重症及危重症病例数逐渐增多,死亡病例也在明显增加。本文复习近期文献,就目前甲型H1N1流感流行态势、临床特点、病毒变异和耐药以及疫苗等热点问题作一综述,为临床医师掌握最新研究动态、及时发现和救治重症及危重症病例、降低病死率提供帮助。     

Pandemic influenza A (2009 H1N1) in children with acute lymphoblastic leukaemia

Pandemic influenza A (2009‐H1N1) usually results in mild clinical illness, but in some individuals it can be life‐threatening. There are no reports of this disease among paediatric patients with acute lymphoblastic leukaemia (ALL). We report ten consecutive patients with ALL and pandemic influenza treated in a single institution. Median age was 7 years (range: 3–12). All were treated with oseltamivir. There were no deaths. Two patients under intensive chemotherapy developed pneumonia and one required ventilatory support. ALL patients under maintenance treatment had mild disease. In conclusion, in our series only patients under intensive treatment developed a moderate to severe disease.     

Clinical features, complications and mortality in critically ill patients with 2009 influenza A(H1N1) in Sfax,Tunisia

Please cite this paper as: Damak et al.(2011) Clinical features, complications and mortality in critically ill patients with 2009 influenza A(H1N1) in Sfax,Tunisia. Influenza and Other Respiratory Viruses 5(4), 230–240 Purpose Africa, as the rest of the world, was touched by the 2009 pandemic influenza A(H1N1). In the literature, a few publications covering this subject emerged from this continent. We prospectively describe baseline characteristics, treatment and outcomes of consecutive critically ill patients with confirmed 2009 influenza A(H1N1) in the intensive care unit (ICU) of Sfax hospital. Methods From 29 November 2009 through 21 January 2010, 32 patients with confirmed 2009 influenza A(H1N1) were admitted to our ICU. We prospectively analysed data and outcomes of these patients and compared survivors and dead patients to identify any predictors of death. Results Patients were young (mean, 36·1 [SD], 20·7 years) and 21 (65·6%) of whom had co‐morbidities. During ICU care, 29 (90·6%) patients had respiratory failure; among these, 15 (46·9%) patients required invasive ventilation with a median duration of 9 (IQR 3–12) days. In our experience, respiratory dysfunction can remain isolated but may also be associated with other dysfunctions or complications, such as, septic shock, seizures, myasthenia gravis exacerbation, Guillan–Barre syndrome, acute renal failure, nosocomial infections and biological disturbances. The nine patients (28·1%) who died had greater initial severity of illness (SAPS II and sequential organ failure assessment (SOFA) scores) but also a higher SOFA score and increasing severity of organ dysfunction during their ICU evolution. Conclusion Critical illness from the 2009 influenza A(H1N1) in Sfax occurred in young individuals and was associated with severe acute respiratory and additional organ system failure. SAPS II and SOFA scores at ICU admission, and also during evolution, constitute a good predictor of death.     

Complications of the 2009 influenza A/H1N1 pandemic in pregnant women in The Netherlands: a national cohort study

The 2009 influenza A/H1N1 pandemic caused an increase in complications in pregnant women. To be well prepared for a next pandemic, we investigated the obstetric and maternal complications of this pandemic. In our national cohort of 59 pregnant women who were admitted to the hospital, no major complications apart from preterm birth and admission to the neonatal intensive care unit were observed. Although the small size of this study precludes us drawing any definitive conclusions, comparing our results with those in other countries suggests that the influenza A/H1N1 pandemic had a relatively benign course in pregnant women in The Netherlands.     

Identification and epidemiology of severe respiratory disease due to novel swine-origin influenza A (H1N1) virus infection in Alberta

BACKGROUND:

In March 2009, global surveillance started detecting cases of influenza-like illness in Mexico. By mid-April 2009, two pediatric patients were identified in the United States who were confirmed to be infected by a novel influenza A (H1N1) strain. The present article describes the first identified severe respiratory infection and the first death associated with pandemic H1N1 (pH1N1) in Canada.

METHODS:

Enhanced public health and laboratory surveillance for pH1N1 was implemented throughout Alberta on April 24, 2009. Respiratory specimens from all patients with a respiratory illness and travel history or those presenting with a severe respiratory infection requiring hospitalization underwent screening for respiratory viruses using molecular methods. For the first severe case identified and the first death due to pH1N1, histocompatibility leukocyte antigens were compared by molecular methods.

RESULTS:

The first death (a 39-year-old woman) occurred on April 28, 2009, and on May 1, 2009, a 10-year-old child presented with severe respiratory distress due to pH1N1. Both patients had no travel or contact with anyone who had travelled to Mexico; the cases were not linked. Histocompatibility antigen comparison of both patients did not identify any notable similarity. pH1N1 strains identified in Alberta did not differ from the Mexican strain.

CONCLUSION:

Rapid transmission of pH1N1 continued to occur in Alberta following the first death and the first severe respiratory infection in Canada, which were identified without any apparent connection to Mexico or the United States. Contact tracing follow-up suggested that oseltamivir may have prevented ongoing transmission of pH1N1.     

The relative clinical impact of 2009 pandemic influenza A (H1N1) in the community compared to seasonal influenza in the Netherlands was most marked among 5-14 year olds

Please cite this paper as: van Gageldonk‐Lafeber et al. (2011) The relative clinical impact of 2009 pandemic influenza A (H1N1) in the community compared to seasonal influenza in the Netherlands was most marked among 5–14 year olds. Influenza and Other Respiratory Viruses 5(6), e513–e520. Background So far, most pandemic influenza reports were based on case studies focusing on severe disease. For public health policy, it is essential to consider the overall impact of the pandemic, including mild diseases. Objectives The aim of our study is to gain insight into the epidemiology of 2009 pandemic influenza in the community and to estimate the relative impact of pandemic compared to seasonal influenza. Methods The relative impact of pandemic influenza in the general population was assessed as the influenza‐like illness (ILI) incidence during the pandemic season compared with that during regular seasons. Influenza‐like illness incidences and virus diagnostics were derived from continuous sentinel surveillance systems. The incidence of hospital admissions, based on the mandatory notification of pandemic influenza, was used to relate the impact of severe disease to that in the community. Results The overall incidence of general practitioners‐attended ILI was 96 consultations per 10 000 persons. Highest incidences were reported in children and lowest in persons aged ≥65 years. For 5–14 year olds, the incidence during the pandemic was higher than during all preceding seasons. Samples originating from 5 to 19 year olds were statistically significant more often positive for pandemic influenza A (H1N1) 2009 virus as compared with samples from 0 to 4 year olds. Moreover, the incidence of hospital admission owing to pandemic influenza was highest in the youngest children. Conclusions Our study showed that while the absolute incidences of 2009 pandemic influenza were highest in children aged 0–4 years, the relative clinical impact in the community compared to seasonal influenza in previous years was most noticeable in healthy children 5–14 years of age.     

Clinical factors predictive of PCR positive in pandemic H1N1 2009 influenza virus infection

Please cite this paper as: Phungoen et al. (2011) Clinical factors predictive of PCR positive in pandemic H1N1 2009 influenza virus infection. Influenza and Other Respiratory Viruses 5(6), e558–e562. Objective Pandemic H1N1 2009 influenza virus (H1N1) has been spreading globally. Clinical features might be predictive and may be different among countries. Even though the PCR test is a confirmatory test for this viral infection, it is expensive and limited in most Thai health care facilities. We studied predictive factors of PCR positive in H1N1 suspected patients. Methods Consecutive patients who had influenza‐like illness less than seven days and had been tested for H1N1 by the real‐time PCR method between May and July 2009 were enrolled. Clinical data was collected and compared between those who had positive and negative PCR tests. Results There were 6494 patients had flu‐like symptoms. Of those, 166 patients were done PCR test and 75 patients (45·18%) had positive PCR test. There were four predictors for positive PCR test including history of contact with confirmed H1N1 patients, headache, body temperature, and coryza with the adjusted odds ratio (95% confidence interval) of 2·84 (1·09–7·40), 6·25 (1·42–27·49), 1·69 (1·08–2·66), and 0·31 (0·12–0·79), respectively. Conclusions Clinical factors can be both suggestive and protective factors for H1N1 infection. These factors may be helpful in clinical practice to assess the possibility of the H1N1 infection in people who are at risk; particularly in resource‐limited health care facilities.     

Lack of evidence for pre-symptomatic transmission of pandemic influenza virus A(H1N1) 2009 in an outbreak among teenagers; Germany, 2009

Please cite this paper as: Hermes et al. (2011) Lack of evidence for pre‐symptomatic transmission of pandemic influenza virus A(H1N1) 2009 in an outbreak among teenagers; Germany, 2009. Influenza and Other Respiratory Viruses 5(6), e499–e503. Background Observations on the role of pre‐symptomatic transmission in the spread of influenza virus are scanty. In June 2009, an outbreak of pandemic A(H1N1) 2009 infection occurred at a teenager’s party in Germany. The objective of this study was to identify risk factors for pandemic A(H1N1) 2009 infection. Methods We performed a retrospective cohort study among party guests. A case was defined as pandemic A(H1N1) 2009 infection confirmed by rRT‐PCR who developed influenza‐like illness between 1 and 5 June 2009. Contact patterns among party guests were evaluated. Results In eight (36%) of 27 party guests, the outcome was ascertained. A travel returnee from a country with endemic pandemic A(H1N1) 2009 who fell ill toward the end of the party was identified as the source case. Party guests with pandemic A(H1N1) 2009 infection had talked significantly longer to the source case than non‐infected persons (P‐value: 0·001). Importantly, none (0/9) of those who had left the party prior to the source case’s symptom onset became infected compared to 7 (41%) of 17 who stayed overnight (P = 0·06), and these persons all had transmission‐prone contacts to the source case. Conclusions In this outbreak with one index case, there was no evidence to support pre‐symptomatic transmission of pandemic A(H1N1) 2009. Further evidence is required, ideally from larger studies with multiple index cases, to more accurately characterize the potential for pre‐symptomatic transmission of influenza virus.     

Acute Respiratory Distress Syndrome as a presenting manifestation in young patients infected with H1N1 influenza virus

Introduction

The new strain of influenza A (H1N1) 2009, often referred to colloquially as “swine flu”, which was first detected in April 2009, raised to a pandemic of which the impact was not completely predictable. As reported, numerous cases with severe respiratory failure were also seen among young previously healthy people.

Patients

In the present study, we report eight cases of influenza A (H1N1) 2009 admitted to our medical intensive care with severe respiratory failure between November and December 2009 and in January 2011. All patients were older than 30 but younger than 50 years, had clinical and radiological evidence of an Acute Respiratory Distress Syndrome (ARDS) and needed invasive ventilatory support.

Results

Six of the eight patients had no relevant underlying disease; one had a pre-existing idiopathic lung fibrosis and another had a chronic obstructive pulmonary disease (COPD), an abuse of alcohol and an adiposities grade 3. Four patients needed an extracorporeal membrane oxygenation (ECMO) due to severe respiratory failure with global respiratory insufficiency that could not be treated by conservative ventilatory support. The one patient with a pre-existing lung fibrosis died shortly after lung transplantation despite use of an extracorporeal membrane oxygenation. One other patient died due to a subarachnoidal bleeding under the anticoagulatory regime during ECMO therapy. The adipose COPD-patient died due to septic shock with multiple organ failure without possibility for ECMO support.

Conclusions

The clinical course of severe cases of influenza A (H1N1) 2009-infection is markedly different from the disease pattern seen during epidemics of seasonal influenza. Most of the patients admitted to our intensive care unit due to influenza A (H1N1) 2009 associated ARDS were previously healthy young people.     

Original Article: A primary school outbreak of pandemic 2009 influenza A (H1N1) in China

Please cite this paper as: Huai et al. (2010) A primary school outbreak of pandemic 2009 influenza A (H1N1) in China. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2010.00150.x. Background  We investigated the first known outbreak of pandemic 2009 influenza A (H1N1) at a primary school in China. Objectives  To describe epidemiologic findings, identify risk factors associated with 2009 H1N1 illness, and inform national policy including school outbreak control and surveillance strategies. Methods  We conducted retrospective case finding by reviewing the school’s absentee log and retrieving medical records. Enhanced surveillance was implemented by requiring physicians to report any influenza‐like illness (ILI) cases to public health authorities. A case–control study was conducted to detect potential risk factors for 2009 H1N1 illness. A questionnaire was administered to 50 confirmed cases and 197 age‐, gender‐, and location‐matched controls randomly selected from student and population registries. Results  The attack rate was 4% (50/1314), and children from all grades were affected. When compared with controls, confirmed cases were more likely to have been exposed to persons with respiratory illness either in the home or classroom within 7 days of symptom onset (OR, 4·5, 95% CI: 1·9–10·7). No cases reported travel or contact with persons who had traveled outside of the country. Conclusions  Findings in this outbreak investigation, including risk of illness associated with contacting persons with respiratory illness, are consistent with those reported by others for seasonal influenza and 2009 H1N1 outbreaks in school. The outbreak confirmed that community‐level transmission of 2009 H1N1 virus was occurring in China and helped lead to changes in the national pandemic policy from containment to mitigation.     

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.     

Influenza A/H1N1 2009 pneumonia in kidney transplant recipients: characteristics and outcomes following high‐dose oseltamivir exposure

S.P. Watcharananan, T. Suwatanapongched, P. Wacharawanichkul, W. Chantratitaya, V. Mavichak, S.B. Mossad. Influenza A/H1N1 2009 pneumonia in kidney transplant recipients: characteristics and outcomes following high‐dose oseltamivir exposure.
Transpl Infect Dis 2010: 12: 127–131. All rights reserved Abstract: We report 2 cases of severe pneumonia due to the novel pandemic influenza A/H1N1 2009 in kidney transplant recipients. Our patients initially experienced influenza‐like illness that rapidly progressed to severe pneumonia within 48 h. The patients became hypoxic and required non‐invasive ventilation. The novel influenza A/H1N1 2009 was identified from their nasal swabs. These cases were treated successfully with a relatively high dose of oseltamivir, adjusted for their renal function. Clinical improvement was documented only after a week of antiviral therapy. Despite early antiviral treatment, we showed that morbidity following novel pandemic influenza A/H1N1 2009 infection is high among kidney transplant recipients.     

Systematic review of clinical and epidemiological features of the pandemic influenza A (H1N1) 2009

The aim of this systematic review was to summarise the clinical and epidemiological features of the pandemic influenza A (H1N1) 2009. We did a systematic search of published literature reporting clinical features of laboratory-confirmed pandemic influenza A (H1N1) 2009 from 1 April 2009 to 31 January 2010. Forty-four articles met our inclusion criteria for the review. The calculated weighted mean age of confirmed cases was 18·1 years, with the median ranging from 12 to 44 years. Cough (84·9%), fever (84·7%), headache (66·5%), runny nose (60·1%) and muscle pain (58·1%) were the most common symptoms of confirmed cases. One or more pre-existing chronic medical conditions were found in 18·4% of cases. Almost two-thirds (64%) of cases were aged between 10 and 29 years, 5·1% were aged over 50 years and only 1·1% were aged over 60 years. The confirmed case fatality ratio was 2·9% (95% CI 0·0-6·7%), an extracted average from 12 of 42 studies reporting fatal cases (937 fatal cases among 31,980 confirmed cases), which gives an overall estimated infected case fatality ratio of 0·02%. Early in the pandemic, disease occurred overwhelmingly in children and younger adults, with cough and fever as the most prevalent clinical symptoms of the confirmed cases. A high infection rate in children and young adults, with sparing of the elderly population, has implications for pandemic influenza management and control policies.     

北京市2009年甲型H1N1流行性感冒危重症与死亡病例流行病学特征及其影响因素分析

目的 了解北京市2009年甲型H1N1流行性感冒(流感)危重症与死亡病例的流行病学特征,探讨影响甲型H1N1流感病情严重程度的主要因素.方法 利用北京市2009年甲型H1N1流感病例个案信息进行描述性分析和多因素Logistic回归分析.结果 北京市2009年甲型H1N1流感感染率为66.1/10万,25～60岁组人群感染率最高,为86.8/10万.0～5岁组和60岁以上年龄组危重症感染率(12.5/10万,3.9/10万)、死亡率(0.9/10万,0.7/10万)和病死率(2.4%,3.3%)较高.549例危重症病例中学龄前儿童110例,比例最高,占20.0%,69例死亡病例中离、退休人员17例,比例最高,占24.6%.超过70.0%的危重症和死亡病例均在发病后2 d内到医院就诊.危重症病例和死亡病例中,均以有心血管疾病的病例比例最高,其次为慢性肺部疾病.多因素Logistic回归分析显示,甲型H1N1流感病例中,60岁以上、慢性肺部疾病及心血管疾病可能导致其病情较重,OR值分别为3.586(95%CI 1.586～8.117)、2.126(95%CI 1.178～3.835)和1.954(95%CI 1.126～3.391).结论 60岁以上、伴心血管疾病及慢性肺部疾病等因素可能加重甲型H1N1流感病例病情.     

Risk factors for pandemic H1N1 2009 infection in healthcare personnel of four general hospitals

To characterize an outbreak of pandemic H1N1 2009 among healthcare personnel (HCP), we conducted a cross-sectional survey of HCP who had worked in four general hospitals during the outbreak. More than one-quarter of responding HCP (27.6%) had influenza-like illness (ILI) during the outbreak. The estimated infection rate of pandemic H1N1 2009 was 9.1% in the study of HCP. Independent risk factors for ILI were female gender, <40 years of age, the presence of chronic diseases associated with influenza complications, having family members with ILI or pandemic H1N1 2009, and working in influenza outpatient, influenza inpatient, non-influenza outpatient or emergency departments. During the outbreak of pandemic H1N1 2009, HCP frequently had ILI or the influenza infection. The development of the influenza infection in HCP was associated with some of their baseline characteristics, occupational risk factors, and non-occupational ones during the outbreak.