Regional variation in mortality impact of the 2009 A(H1N1) influenza pandemic in China

Background

Laboratory‐confirmed deaths grossly underestimate influenza mortality burden, so that reliable burden estimates are derived from indirect statistical studies, which are scarce in low‐ and middle‐income settings.

Objectives

Here, we used statistical excess mortality models to estimate the burden of seasonal and pandemic influenza in China.

Methods

We modeled data from a nationally representative population‐based death registration system, combined with influenza virological surveillance data, to estimate influenza‐associated excess mortality for the 2004–2005 through 2009–2010 seasons, by age and region.

Results

The A(H1N1) pandemic was associated with 11·4–12·1 excess respiratory and circulatory (R&C) deaths per 100 000 population in rural sites of northern and southern China during 2009–2010; these rates were 2·2–2·8 times higher than those of urban sites (P < 0·01). Influenza B accounted for a larger proportion of deaths than pandemic A(H1N1) in 2009–2010 in some regions. Nationally, we attribute 126 200 (95% CI, 61 000–248 400) excess R&C deaths (rate of 9·4/100 000) and 2 323 000 (1 166 000–4 533 000) years of life lost (YLL) to the first year of A(H1N1)pdm circulation.

Conclusions

The A(H1N1) pandemic posed a mortality and YLL burden comparable to that of interpandemic influenza in China. Our high burden estimates in rural areas highlight the need to enhance epidemiological surveillance and healthcare services, in underdeveloped and remote areas.     

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.     

2009年北京市老年人甲型H1N1流感流行病学分析

目的 分析2009年北京市老年人感染甲型H1N1流感(甲流)分布特征.方法 采用描述性流行病学研究方法对2009年北京市老年人甲流进行流行特征分析.结果北京市老年人确诊甲流病例321例,确诊发病率为13.2/10万;11、12月份发病最多,占84.7%;地区分布中以近郊区分布最多,占53.0%;通过年龄分布分析发现,85岁以上年龄组发病率最高,为19.2/10万,并随着年龄增长病情有加重趋势(x2=7.24,P＜0.01);病例分型中轻症比例最高,占63.6%,重症和危重症病例占36.4%;轻、重、危重病例之间的体质指数(BMI)差异无统计学意义(x2=8.14,P=0.52);甲流病情有随着基础性疾病加重的趋势,病情程度与基础性疾病的数量有关(x2=123.0,P＜0.01).结论 北京市老年人甲流发病率较高,危重症比例较大,应是重点防控的人群之一.     

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.     

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.     

Factors associated with the transmission of pandemic (H1N1) 2009 among hospital healthcare workers in Beijing,China

Background With the increase in patient activity during the 2009 H1N1 pandemic, came an associated increase in occupational infections of healthcare workers (HCWs). Objectives The aim of this study was to examine factors associated with the transmission of pandemic (H1N1) 2009 among HCWs. Methods A 1:4 matched case–control study by hospital, ward, age, and gender was conducted in HCWs from hospitals in Beijing during February 2010. Cases were diagnosed with pandemic (H1N1) 2009, and controls had neither influenza‐like illness nor diagnosis with pandemic (H1N1) 2009 during August 2009 to January 2010. Information during 7 days before symptom onset of case was collected, and controls were queried about the same period. Results A total of 51 cases identified via National Notifiable Infectious Disease Surveillance System participated in this study. Controls were matched to cases for a total of 255 individuals. About 19·6% (10/51) of cases and 26·0% (53/204) of controls recalled they had conducted a high‐risk procedure on a patient with pandemic (H1N1) 2009. 72·5% (37/51) of cases and 71·6% (146/204) of controls stated they wore medical masks in ≥80% of working time. Only 5·9% (3/51) and 36·3% (74/204) of cases and controls, respectively, reported receiving pandemic vaccination. Participants receiving pandemic vaccination had a significantly lower risk of infection during the pandemic (OR = 0·150, 95% CI: 0·047–0·479, P = 0·001). The estimated vaccine effectiveness was 85·0%. Conclusions We showed a high vaccine effectiveness of the pandemic vaccine and that vaccination was the only factor significantly associated with risk of infection in HCWs.     

2009中国新型甲型H1N1流感临床科研亮点

自2009年3月以来,首先发生在美国和墨西哥的新型甲型H1N1流感疫情迅速波及全球。中国科学家,包括流行病学家、病毒学家和临床医生深入研究疾病规律,并取得了可喜成绩。中国卫生部新型甲型H1N1流感专家组组长王辰教授领导课题组克服各种困难,及时总结了中国新型甲型H1N1流感早期病例的临床特征。他们发现,中国应对新发传染病的措施是及时有效的,病情早期的病例症状多数较轻,大约33%的患者没有发热症状,实时逆转录聚合酶链反应(PT-PCR)方法病毒核酸阳性持续中位时间约为6d。年龄小于14岁、男性、症状发生48h后才接受奥司他韦治疗均为病毒核酸持续检测阳性的独立危险因素。     

甲型H1N1流感患者免疫学指标分析

目的分析甲型H1N1流感患者免疫学指标的特点。方法以明确诊断的87例甲型H1N1流感患者为研究对象,比较疾病急性期、恢复期部分免疫学指标变化情况,并进行统计学分析。结果在病程急性期,淋巴细胞总数、GIN＋T淋巴细胞、CD8＋T淋巴细胞及B淋巴细胞计数明显下降。随着病情的恢复,以上指标均明显上升;总补体溶血活性CH50在整个病程中均处于较高水平。结论在甲型H1N1流感病程中,机体细胞免疫起着重要作用。     

Oseltamivir-resistant influenza A 2009 H1N1 virus in immunocompromised patients

Please cite this paper as: Couturier et al. (2010). Oseltamivir-resistant influenza A 2009 H1N1 virus in immunocompromised patients. Influenza and Other Respiratory Viruses 4(4), 199–204. Background First-line treatment of influenza A 2009 H1N1 relies on neuraminidase inhibitors such as oseltamivir. Resistance conferred by the H275Y neuraminidase gene mutation is concerning and likely to increase. Objectives To characterize oseltamivir resistance in a hospital-based patient population. Patients and Methods All available respiratory specimens positive for influenza A by direct fluorescent antibody, RT-PCR, or culture from patients at the University of Utah 5/09-12/09 were collected. Specimens were confirmed as 2009 H1N1 by the Utah Department of Health. RT-PCR and pyrosequencing were used to test for the H275Y mutation (CDC protocol). Pyro Mark Q24 AQ software (Qiagen, Valencia, CA, USA) was used to allow for quantitative H275Y mutation analysis. Medical records of patients with resistant virus were reviewed. Results We tested 191 influenza A virus-positive samples from 187 unique patients. Fifty (27%) patients were hospitalized. Four patient specimens (2·1%) were found to carry the H275Y mutation. Three patients were hospitalized, representing 6% of inpatient samples tested. Three patients had undergone hematopoietic stem cell transplant in the past year. Two patients died. Their influenza viruses were confirmed to be oseltamivir-resistant at an independent reference laboratory and through the Center for Disease Control and Prevention (CDC). One patient reported no history of prior oseltamivir exposure. Conclusions Widespread oseltamivir resistance among 2009 H1N1 remains a potential threat. Rapid techniques, such as pyrosequencing, which has the additional benefit of identifying mixed mutant populations of virus, may play a key role in identifying at-risk individuals and potentially unsuspected cases. Targeted surveillance of immunocompromised patients will be critical toward improving future influenza planning and therapy.     

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.     

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.