2019年广州市甲型H1N1流感病毒全基因组序列的遗传特征分析

目的 对甲型H1N1流感病毒进行基因组全序列遗传特征分析,为流感的科学防控提供新数据.方法 选取7株2019年广州市甲型H1N1流感病毒进行全基因组序列测定,分析其遗传特征.结果 7株病毒的核苷酸同源性最高为PB2基因(98.8％～99.9％),最低为NA基因(97.3％～99.2％).总体上,不同月份的H1N1流感分...     

Differential use of antivirals for treatment of patients with influenza A(H1N1)pdm09 in Germany

Background

The World Health Organization recommends early antiviral treatment for patients with severe influenza illness or those at increased risk for severe illness.

Objectives

The aim of this study was to determine the proportion of cases with laboratory‐confirmed A(H1N1)pdm09 infection that have been treated with antivirals in Germany during the pandemic (H1N1) 2009 and to investigate factors associated with the use of antivirals.

Methods

We analyzed cases with laboratory‐confirmed A(H1N1)pdm09 infection notified to national health authorities in Germany between week 29/2009 and week 17/2010 using multivariable logistic regression. Severity of disease was defined by pneumonia or death.

Results and conclusions

Of 160 804 cases with laboratory‐confirmed A(H1N1)pdm09 infection, 22% were treated with antivirals. Cases with severe disease were more likely to be treated with antivirals than cases without severe disease (odds ratio = 1·66; 95% confidence interval: 1·46–1·89). In the group with at least one underlying medical condition, only children aged between 1 and 4 years had significant lower odds for receiving antiviral treatment compared with cases in the age group 15 to 49 years (odds ratio = 0·75; 95% confidence interval: 0·6–0·94). In conclusion, the implementation of international recommendations on use of antivirals differed according to the age of patients in Germany during the pandemic (H1N1) 2009. This indicates that the potential of antivirals to prevent severe influenza might not have been fully exhausted. The reasons leading to the observed differences in patient management need to be investigated.     

Characterization of influenza A(H1N1)pdm09 viruses isolated from Nepalese and Indian outbreak patients in early 2015

We characterized influenza A(H1N1)pdm09 isolates from large‐scale outbreaks that occurred in Nepal and India in early 2015. Although no specific viral features, which may have caused the outbreaks, were identified, an S84N substitution in hemagglutinin was frequently observed. Chronological phylogenetic analysis revealed that these Nepalese and Indian viruses possessing the S84N substitution constitute potential ancestors of the novel genetic subclade 6B.1 virus that spread globally in the following (2015/16) influenza season. Thus, active surveillance of circulating influenza viruses in the Southern Asia region, including Nepal and India, would be beneficial for detecting novel variant viruses prior to their worldwide spread.     

Clinical epidemiology and predictors of outcome in children hospitalised with influenza A(H1N1)pdm09 in 2009: a prospective national study

Background

There are few large-scale, prospective studies of influenza A(H1N1)pdm09 in children that identify predictors of adverse outcomes.

Objectives

We aimed to examine clinical epidemiology and predictors for adverse outcomes in children hospitalised with influenza A(H1N1)pdm09 in Australia.

Methods

Active hospital surveillance in six tertiary paediatric referral centres (June–September, 2009). All children aged <15 years admitted with laboratory-confirmed influenza A(H1N1)pdm09 were studied.

Results

Of 601 children admitted with laboratory-confirmed influenza, 506 (84·2%) had influenza A(H1N1)pdm09. Half (51·0%) of children with influenza A(H1N1)pdm09 were previously healthy. Hospital stay was longer in children with pre-existing condition (mean 6·9 versus 4·9 days; P = 0·02) as was paediatric intensive care unit (PICU) stay (7·0 versus 2·3 days; P = 0·005). Rapid diagnosis decreased both antibiotic use and length of hospital and PICU stay. Fifty (9·9%) children were admitted to a PICU, 30 (5·9%) required mechanical ventilation and 5 (0·9%) died. Laboratory-proven bacterial co-infection and chronic lung disease were significant independent predictors of PICU admission (OR 6·89, 95% CI 3·15–15·06 and OR 3·58, 95% CI 1·41–9·07, respectively) and requirement for ventilation (OR 5·61, 95% CI 2·2–14·28 and OR 5·18, 95% CI 1·8–14·86, respectively). Chronic neurological disease was a predictor of admission to PICU (OR 2·30, 95% CI 1·14–4·61).

Conclusions

During the 2009 pandemic, influenza was a major cause of hospitalisation in tertiary paediatric hospitals. Co-infection and underlying chronic disease increased risk of PICU admission and/or ventilation. Half the children admitted were previously healthy, supporting a role for universal influenza vaccination in children.     

2016-2020年福建省A(H1N1)pdm09流感病毒HA基因特征分析

目的 分析2016-2020年福建省A(H1N1)pdm09亚型流感病毒的血凝素(Hemagglutinin, HA)基因特征,了解与其他省份和全球范围内时间和空间上的分布差异。方法 选取2016-2020年福建省流感监测网络实验室分离A(H1N1)pdm09流感毒株基因序列测定。基因序列用MEGA、Net NGlyc 1.0 Server分析基因特征。结果 2016-2020年福建省A(H1N1)pdm09亚型流感病毒HA基因进化树分析与其他省份及国外大部分一致,但仍有少部分不同。HA分支由6B转化为6B.1并演化至6B.1A5A。HA基因变异主要在抗原性决定簇Sa、Ca、Sb。对于不同地区疫苗株匹配度也会有差异。结论 福建省A(H₁N₁)pdm09病毒流行株具有遗传多样性。     

Whole‐genome analysis of influenza A(H1N1)pdm09 viruses isolated in Uganda from 2009 to 2011

We report a whole‐genome analysis of 19 influenza A(H1N1)pdm09 isolates from four Ugandan hospitals between 2009 and 2011. The isolates differed from the vaccine strain A/California/07/2009 by three amino acid substitutions P100S, S220T, and I338V in the hemagglutinin and by two amino acid substitutions V106I and N248D in the neuraminidase proteins with consistent mutations in all gene segments distinguishing isolates from the 2009/2010 to 2010/2011 seasons. Phylogenetic analysis showed low genetic evolution, with genetic distances of 0%–1.3% and 0.1%–1.6% for HA and NA genes, respectively. The amino acid substitutions did not lead to antigenic differences from the reference strains.     

Relationships between A(H1N1)pdm09 influenza infection and infections with other respiratory viruses

Background

A(H1N1)pdm09, a new influenza pandemic virus emerged in 2009. The A(H1N1)pdm09 infection had several unique characteristics which included rapid transmissibility and high morbidity in obese individuals, pregnant women and individuals suffering from chronic diseases.

Objectives

To study the relationships between A(H1N1)pdm09 influenza infection and infections with other respiratory viruses such as respiratory syncytial virus (RSV), human metapneumo virus (hMPV), adenovirus and seasonal influenza.

Methods

Samples (nasopharyngeal swabs or aspirates) collected between 2007 until 2012 from patients of various ages that were hospitalized due to respiratory virus infections were analyzed for the presence of various respiratory viruses, using qRT-PCR.

Results

In 2009–2010, when the pandemic influenza A(H1N1)pdm09 first appeared, two major infection peaks were noted and individuals of various ages were infected. Following the decline of the A(H1N1)pdm09 virus infection, the percentages of patients infected with adenovirus and hMPV increased, while infection frequency with RSV B and with seasonal influenza virus decreased. Furthermore, RSV infections were delayed and very few percentages of patients were co-infected with more than one virus. Interestingly, the A(H1N1)pdm09 virus lost its dominancy when it reappeared in the winter of 2010–2011, and at this time, only the incidence of RSV infections was affected by the A(H1N1)pdm09 virus.

Conclusions

The A(H1N1)pdm09 virus had distinct effects on other respiratory viruses when it first appeared versus later, when it evolved from being a pandemic to a seasonal virus.     

A(H1N1)pdm09 hemagglutinin D222G and D222N variants are frequently harbored by patients requiring extracorporeal membrane oxygenation and advanced respiratory assistance for severe A(H1N1)pdm09 infection

Background

In patients with A(H1N1)pdm09 infection, severe lung involvement requiring admission to intensive care units (ICU) has been reported. Mutations at the hemagglutinin (HA) receptor binding site (RBS) have been associated with increased virulence and disease severity, representing a potential marker of critical illness.

Objectives

To assess the contribution of HA‐RBS variability in critically ill patients, A(H1N1)pdm09 virus from adult patients with severe infection admitted to ICU for extracorporeal membrane oxygenation support (ECMO) during influenza season 2009–2011 in Piemonte (4·2 million inhabitants), northwestern Italy, was studied.

Patients and methods

We retrospectively analyzed HA‐RBS polymorphisms in ICU patients and compared with those from randomly selected inpatients with mild A(H1N1)pdm09 disease and outpatients with influenza from the local surveillance program.

Results

By HA‐RBS direct sequencing of respiratory specimens, D222G and D222N viral variants were identified in a higher proportion in ICU patients (n = 8/24, 33·3%) than in patients with mild disease (n = 2/34, 6%) or in outpatients (n = 0/44) (Fisher''s exact test P < 0·0001; OR 38·5; CI 95% 4·494–329·9). Eleven ICU patients died (42%), three of them carrying the D222G variant, which was associated with RBS mutation S183P in two. D222G and D222N mutants were identified in upper and lower respiratory samples.

Conclusions

A(H1N1)pdm09 HA substitutions D222G and D222N were harbored in a significantly higher proportion by patients with acute respiratory distress for A(H1N1)pdm09 severe infection requiring ICU admission and ECMO. These data emphasize the importance of monitoring viral evolution for understanding virus–host adaptation aimed at the surveillance of strain circulation and the study of viral correlates of disease severity.     

Immunogenicity of influenza A(H1N1)pdm09 vaccine and the associated factors on lowered immune response in patients with hepatitis C

Background Patients with underlying disease represent a high‐risk group for influenza‐associated complications and hospitalization. However, few studies investigated the immunogenicity of influenza vaccine in patients with liver disease. Objective To examine immunogenicity of influenza A(H1N1)pdm09 vaccine in patients with liver disease and to explore the associated factors on lowered immune response. Patients/Methods A single subcutaneous dose of monovalent inactivated unadjuvanted split‐virus influenza A(H1N1)pdm09 vaccination was performed in 80 patients with chronic hepatitis C virus infection at Osaka City University Hospital in Japan. To measure the hemagglutination inhibition antibody titer, serum samples were collected before and 3 weeks after vaccination. Results No serious adverse events were observed. After vaccination, antibody titers ≥1:40 were observed in 56 patients (71%). The corresponding seroconversion proportion was 72%, and the mean fold rise was 10·3. Immune responses were robust regardless of severity of liver disease or existence of probable cirrhosis. However, patients with older age, lower body mass index, or receiving Stronger Neo‐Minophagen C tended to show lower antibody responses to A(H1N1)pdm09 vaccine. In addition, reduced immune responses were observed in patients who had received the 2009/10 seasonal vaccination prior to A(H1N1)pdm09 vaccination. Conclusions Single dose of A(H1N1)pdm09 vaccine achieved a sufficient level of immunity among patients with chronic hepatitis C. Antibody response may be affected by age, body mass index, Stronger Neo‐Minophagen C administration, and recent seasonal influenza vaccination.     

Counting pandemic deaths: comparing reported numbers of deaths from influenza A(H1N1)pdm09 with estimated excess mortality

Background

During the wave 1 of the influenza A(H1N1)pdm09 virus, Norway appeared to be suffering from high mortality rates. However, by the end of the pandemic, it was widely reported that the number of deaths were much lower than previous years.

Objectives

The mortality burden from influenza is often assessed by two different approaches: counting influenza‐certified deaths and estimating the mortality burden using models. The purpose of this study is to compare the number of reported deaths with results from two different models for estimating excess mortality during the pandemic in Norway. Additionally, mortality estimates for the pandemic season are compared with non‐pandemic influenza seasons.

Methods

Numbers on reported influenza A(N1h1)pdm09 deaths are gived by the Cause of Death Registry at Statistics Norway and an ad hoc registry at the Norwegian Institute of Public Health. Overall and Pnemumonia and Influenza certified mortality is modeled using Poission regression, adjusting for levels of reported influenza‐like illness and seasonal and year‐to‐year variation.

Results and conclusions

Modelling results suggest that the excess mortality in older age groups is considerably lower during the pandemic than non‐pandemic seasons, but there are indications of an excess beyond what was reported during the pandemic. This highlights the benefits of both methods and the importance of explaining where these numbers come from.     

Surveillance of hospitalised severe cases of influenza A(H1N1)pdm09 and related fatalities in nine EU countries in 2010–2011

Please cite this paper as: Snacken et al. (2012) Surveillance of hospitalised severe cases of Influenza A(H1N1)pdm09 and related fatalities in nine EU countries in 2010–2011. Influenza and Other Respiratory Viruses 6(601), e93–e96. A few months into the 2009 influenza pandemic, nine European countries implemented case‐based surveillance of hospitalised severe influenza infections. In the present study, we assess the association between patient characteristics, in particular underlying conditions, and the severity level of influenza A(H1N1)pdm09 infection during the 2010‐2011 season. Patient age, the presence of underlying conditions, pneumonia, acute respiratory distress syndrome (ARDS) and the need for ventilation were significantly associated with the severity of influenza A(H1N1)pdm09 infection. Despite limitations essentially because of the heterogeneity of the data reported, this study provides insight into severe influenza cases.     

2019-2020年海南省A(H1N1)pdm09 流感病毒基因特性分析

目的 分析海南省A(H1N1) pdm09亚型流感病毒的抗原性和基因特性,了解病毒的变异情况,为海南省A(H1N1)pdm09亚型流感病毒的防控提供依据.方法 选取14株2019-2020年海南省流感监测网络实验室分离到的A(H1N1)pdm09亚型流感病毒进行基因序列测定,测序结果用MEGA 10.1.8和DNAST...     

Epidemiology of influenza A (H1N1)pdm09‐associated deaths in the United States,September–October 2009

Please cite this paper as: Regan et al. (2012) Epidemiology of influenza A (H1N1)pdm09‐associated deaths in the United States, September–October 2009. Influenza and Other Respiratory Viruses 6(601), e169–e177. Background From April to July 2009, the United States experienced a wave of influenza A (H1N1)pdm09 virus (H1N1pdm09) infection. The majority of the deaths during that period occurred in persons <65 years of age with underlying medical conditions. Objective To describe the epidemiology of H1N1pdm09‐associated deaths in the US during the fall of 2009. Methods We collected demographic, medical history, and cause of death information on a nationally representative, stratified random sample of 323 H1N1pdm09‐associated deaths that occurred during September 1–October 31, 2009. Results Data were available for 302/323 (93%) deaths. Most cases (74%) were 18–64 years of age and had ≥1 underlying medical condition (72%). Among cases aged <18 years, 16/43 (37%) had a chronic lung disease, and 15/43 (35%) a neurological disorder; among cases aged ≥18 years, 94/254 (37%) had a chronic lung disease and 84/254 (33%) had a metabolic disorder. The median number of days between symptom onset and death was six among children (range, 1–48) and 12 among adults (range, 0–109). Influenza antiviral agents were prescribed for 187/268 (70%) of cases, but only 48/153 (31%) received treatment within 2 days of illness onset. Conclusions The characteristics of H1N1pdm09 deaths identified during the fall of 2009 were similar to those occurring April–July 2009. While most cases had conditions that were known to increase the risk for severe outcomes and were recommended to receive antiviral therapy, a minority of cases received antivirals early in the course of illness.     

Excess mortality impact of two epidemics of pandemic influenza A(H1N1pdm09) virus in Hong Kong

Hong Kong experienced two large epidemics of pandemic influenza A(H1N1pdm09). We used regression methods to estimate the excess mortality associated with each epidemic. The first epidemic of H1N1pdm09 peaked in September 2009 and was associated with 2·13 [95% confidence interval (CI): −8·08, 11·82] excess all-cause deaths per 100 000 population. The second epidemic of H1N1pdm09 in early 2011 was associated with 4·72 [95% CI: −0·70, 10·50] excess deaths per 100 000 population. More than half of the estimated excess all-cause deaths were attributable to respiratory causes in each epidemic. The reasons for substantial impact in the second wave remain to be clarified.     

福建省1例不明原因肺炎病例中甲型H1N1流感病毒的全基因组特征分析

目的了解1例不明原因肺炎病例中甲型H1N1流感病毒的生物学特性和变异情况,为临床治疗与疫情防控提供依据。方法利用MDCK细胞分离不明原因肺炎病例中的甲型H1N1流感病毒,分离的毒株经全基因组测序后分析其抗原性、致病性和耐药性等特征。结果从该病例的咽拭子标本中分离得到1株甲型H1N1流感病毒并命名为A/FujianGulou/SWL64/2016(H1N1),其8个节段的核苷酸和氨基酸序列与A/California/07/2009(H1N1)疫苗株的相似性分别为96.9%~98.9%和96.7%~99.5%。氨基酸序列分析显示HA蛋白共有18个位点发生突变,其中K163Q、S185T、S203T和D222N变异涉及到3个不同的抗原位点,提示病毒发生抗原漂移;与受体结合位点相关的D222N突变还提示病毒感染下呼吸道的能力增强。耐药性分析显示该病毒对金刚烷胺耐药,对达菲仍然敏感。结论本次研究的甲型H1N1流感病毒具有抗原漂移现象,且具备引发重症肺炎的分子特征,应进一步加强监测,为疫情防控奠定基础。