Divergent seasonal patterns of influenza types A and B across latitude gradient in Tropical Asia

Introduction

Influenza circulation in tropics and subtropics reveals a complex seasonal pattern with year‐round circulation in some areas and biannual peaks in others.

Methods

We analyzed influenza surveillance data from nine countries around southern and southeastern Asia spanning latitudinal gradient from equatorial to temperate zones to further characterize influenza type‐specific seasonality in the region. We calculated proportion of positives by month out of positives during that year and adjust for variation in samples tested and positivity in these countries.

Results

Influenza A epidemics were identified between November and March during winters in areas lying above 30°N latitude, during monsoon months of June–November in areas between 10° and 30°N latitude, and no specific seasonality for influenza A virus circulation in areas lying closer to the equator. Influenza B circulation coincided with influenza A circulation in areas lying above 30°N latitude; however, in areas south of 30°N Asia, influenza B circulated year round at 3–8% of annual influenza B positives during most months with less pronounced peaks during post‐monsoon period.

Conclusion

Even though influenza B circulates round the year in most areas of the tropical regions of southern and southeastern Asia, the most appropriate time for influenza vaccination using the most recent WHO recommended vaccine would be prior to the monsoon season conferring protection against influenza A and B peaks.     

Rapid influenza molecular testing in secondary care and influenza surveillance in England: Any impact?

IntroductionThe use of rapid molecular testing for influenza diagnosis is becoming increasingly popular. Used at the point of care or in a clinical laboratory, these tests detect influenza A and B viruses, though many do not distinguish between influenza A subtypes. The UK Severe Influenza Surveillance System (USISS) collects surveillance data on laboratory‐confirmed influenza admissions to secondary care in England.This study set out to understand how rapid influenza molecular testing was being used and how it might influence the availability of subtyping data collected on influenza cases admitted to secondary care in England.MethodsAt the end of the 2017/2018 and 2018/2019 influenza seasons, a questionnaire was sent to all National Health Service Hospital Trusts in England to evaluate the use of rapid influenza testing. Surveillance data collected through USISS was analysed from 2011/2012 to 2020/2021.ResultsOf responding trusts, 42% (13/31) in 2017/2018 and 55% (9/17) in 2018/2019 used rapid influenza molecular tests, either alone or in combination with other testing. The majority of rapid tests used did not subtype the influenza A result, and limited follow‐up testing occurred.Surveillance data showed significant proportions of influenza A hospital and intensive care unit/high dependency unit admissions without subtyping information, increasing by approximately 35% between 2012/2013 and 2020/2021.ConclusionsThe use of rapid influenza molecular tests is a likely contributing factor to the large proportion of influenza A hospitalisations in England that were unsubtyped. Given their clear clinical advantages, further work must be done to reinforce these data for public health through integrated genomic surveillance.     

An avian outbreak associated with panzootic equine influenza in 1872: an early example of highly pathogenic avian influenza?

Please cite this paper as: Morens and Taubenberger (2010) An avian outbreak associated with panzootic equine influenza in 1872: an early example of highly pathogenic avian influenza? Influenza and Other Respiratory Viruses 4(6), 373–377. Background An explosive fatal epizootic in poultry, prairie chickens, turkeys, ducks and geese, occurred over much of the populated United States between 15 November and 15 December 1872. To our knowledge the scientific literature contains no mention of the nationwide 1872 poultry outbreak. Objective To understand avian influenza in a historical context. Results The epizootic progressed in temporal-geographic association with a well-reported panzootic of equine influenza that had begun in Canada during the last few days of September 1872. The 1872 avian epizootic was universally attributed at the time to equine influenza, a disease then of unknown etiology but widely believed to be caused by the same transmissible respiratory agent that caused human influenza. Conclusions Another microbial agent could have caused the avian outbreak; however, its strong temporal and geographic association with the equine panzootic, and its clinical and epidemiologic features, are most consistent with highly pathogenic avian influenza. The avian epizootic could thus have been an early instance of highly pathogenic avian influenza.     

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2011年2月卫生部组织我国流感防治研究领域的专家制定并发布了《流行性感冒诊断与治疗指南(2011年版)》(以下简称《2011版指南》)。《2011版指南》从病原学、临床表现、诊断、治疗、预防等方面集中反映了流感的最新进展,强调了诊断和治疗。总体上说,《2011版指南》与先前卫生部发布的各类流感指南的基本原则一致,但是内容更加细化和全面,具有较强的临床指导性。本文就《2011版指南》的背景、定义、要点和特色作一解读。     

2011—2015年北京市儿童流行性感冒流行特征分析

目的 了解北京市儿童2011—2015年流行性感冒(流感)的流行特征和流感病毒优势株的变化,为儿童流感的防控提供参考.方法 利用北京市儿童医院2011—2015年监测到的流感样病例(influenza like illness,ILI)及流感病原学监测数据,分析流感流行趋势和流感病毒的构成情况.结果 在7331597例门、急诊病例中监测到ILI 638623例,ILI占门、急诊就诊病例的8.71％,0～岁组所占比例最高,为69.56％;采集门诊ILI咽拭子标本5351例,其中流感病毒核酸阳性515例.各年份优势毒株构成不同,夏季也出现了ILI就诊的高峰.结论 2011—2015年各年份流感流行高峰出现在冬春季,小于5岁儿童是主要易感人群,建议夏季就诊高峰对儿童ILI开展多病原检测,从而可采取有针对性的预防及治疗措施.     

Parental perceptions and predictors of consent for school‐located influenza vaccination in urban elementary school children in the United States

Background

School-located influenza vaccination (SLV) programs have the potential to mass-vaccinate all enrolled children, but parental consent is required.

Objective

To examine parental attitudes and determine predictors of parental consent for vaccination of schoolchildren through SLV programs.

Patients/Methods

Surveys were distributed to parents of 4517 children during 2009–2010 (year 1) and 4414 children during 2010–2011 (year 2) in eight elementary schools in conjunction with a SLV program.

Results

Participants included 1259 (27·9%) parents in year 1 and 1496 (33·9%) in year 2. Parental consent for 2009 H1N1, 2009 seasonal, and 2010 seasonal influenza vaccines was obtained from 738 (70·8%), 673 (64·5%), and 1151 (77·2%) respondents, respectively. During the 2009 pandemic, respondents concerned about influenza severity were twice as likely to consent for the 2009 H1N1 vaccination compared to unconcerned respondents (OR 2·04, 95% CI:1·19–3·51). During year 2, factors that predicted parental consent were the perception of high susceptibility to influenza infection (OR 2·19, 95% CI:1·50–3·19) and high benefit of vaccine (OR 2·23, 95% CI:1·47–3·40). In both years, college-educated parents were more likely to perceive vaccine risks (year 1: 83·6 versus 61·5%, P < 0·001 and year 2: 81·1% versus 60·6%, P < 0·001) and less likely to consent for seasonal influenza vaccine (year 1: OR 0·69, 95% CI:0·53–0·89 and year 2: OR 0·61, 95% CI:0·47–0·78) compared to non-college-educated parents.

Conclusions

Parents who appreciate the risks of influenza and benefits of vaccination are more likely to consent for SLV. More research is needed to determine how to address heightened safety concerns among college-educated parents.     

Universal Influenza Vaccines,a Dream to Be Realized Soon

Due to frequent viral antigenic change, current influenza vaccines need to be re-formulated annually to match the circulating strains for battling seasonal influenza epidemics. These vaccines are also ineffective in preventing occasional outbreaks of new influenza pandemic viruses. All these challenges call for the development of universal influenza vaccines capable of conferring broad cross-protection against multiple subtypes of influenza A viruses. Facilitated by the advancement in modern molecular biology, delicate antigen design becomes one of the most effective factors for fulfilling such goals. Conserved epitopes residing in virus surface proteins including influenza matrix protein 2 and the stalk domain of the hemagglutinin draw general interest for improved antigen design. The present review summarizes the recent progress in such endeavors and also covers the encouraging progress in integrated antigen/adjuvant delivery and controlled release technology that facilitate the development of an affordable universal influenza vaccine.     

The relative efficacy of trivalent live attenuated and inactivated influenza vaccines in children and adults

In the United States, two types of vaccines are recommended for the prevention of influenza: an intranasal live attenuated influenza vaccine (LAIV) for eligible individuals aged 2-49 years and unadjuvanted injectable trivalent inactivated vaccines (TIV) for eligible individuals aged ≥ 6 months. Several recent studies have compared the efficacy of the 2 vaccines in children and adults. In children 6 months to 18 years of age, each of the four comparative studies of LAIV and TIV demonstrated that LAIV was more protective. In individuals 17-49 years of age, most comparative studies have demonstrated that LAIV and TIV were similarly efficacious or that TIV was more efficacious. However, LAIV was shown to be more protective than TIV in new military recruits of all ages, and placebo-controlled studies in adults in 1997-1998 suggested that LAIV was more protective against the mismatched A/H3N2 strain. The relative efficacy of LAIV and TIV among young adults may vary depending on the specific population and the antigenic match between the vaccines and circulating strains. In adults 60 years of age and older, limited data suggest that the two vaccines are similarly effective. In children and adults, studies also suggest that the relative efficacy of LAIV versus TIV may increase when measured against more severe illness. Additional research comparing LAIV and TIV is needed in adults and would also be valuable in older children and adolescents. Studies should examine the role of pre-existing immunity as well as vaccine impact on influenza illness of varying severity.     

2015-2019年池州市流感监测结果分析

目的通过研究2015-2019年池州市流感病原学监测结果,对病原学型别及流行病学特征进行分析,为流感的防控提供科学依据。方法采集哨点监测医院流感样病例(ILI)鼻咽拭子标本,并收集医院报表的数据(流感样病人年龄、性别、年龄分组依据均来自报表数据),采用实时荧光定量PCR方法对标本进行核酸检测,并对结果进行描述性统计和分析,率的比较采用χ2检验。结果2015-2019年池州市共监测标本5075例,阳性1279例,阳性率为25.20%。检出的流感型别中甲型为765例,占阳性标本数的59.81%(765/1279),病原学类型以新甲H1和季节性H3型为主,乙型为514例,占阳性标本数的40.19%(514/1279),病原学分型以Victoria和Yamagata为主。5个年龄组中,6~15岁组阳性率最高(34.45%)。不同性别组的流感检测阳性率差异无统计学意义(P>0.05)。流感的暴发流行也多集中在青少年,聚集性高的地方,且甲乙型均有暴发。结论2015-2019年池州市5年来流感病毒流行以冬季、春季高发,夏季多为散在流行,偶伴有小高峰。主要以乙型、新型H1N1型、季节性H3型交替流行为主;流感监测和预防控制取得一定成果;但流感疫情仍然严峻,为有效防控流感疫情,需对辖区实施流感防控举措。重点应加强学龄前儿童和中小学生的流感防治工作。     

Single‐dose inhaled laninamivir: registered in Japan and its potential role in control of influenza epidemics

Please cite this paper as: Sunagawa et al. (2012) Single‐dose inhaled laninamivir: registered in Japan and its potential role in control of influenza epidemics. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2012.00351.x.     

Cell-Adapted Mutations and Antigenic Diversity of Influenza B Viruses in Missouri, 2019–2020 Season

Influenza B viruses (IBVs) are causing an increasing burden of morbidity and mortality, yet the prevalence of culture-adapted mutations in human seasonal IBVs are unclear. We collected 368 clinical samples from patients with influenza-like illness in Missouri during the 2019–2020 influenza season and recovered 146 influenza isolates including 38 IBV isolates. Of MDCK-CCL34, MDCK-Siat1, and humanized MDCK (hCK), hCK showed the highest virus recovery efficiency. All Missourian IBVs belonged to the Victoria V1A.3 lineage, all of which contained a three-amino acid deletion on the HA protein and were antigenically distant from the Victoria lineage IBV vaccine strain used during that season. By comparing genomic sequences of these IBVs in 31 paired samples, eight cell-adapted nonsynonymous mutations were identified, with the majority in the RNA polymerase. Analyses of IBV clinical sample–isolate pairs from public databases further showed that cell- and egg-adapted mutations occurred more widely in viral proteins, including the receptor and antibody binding sites on HA. Our study suggests that hCK is an effective platform for IBV isolation and that culture-adapted mutations may occur during IBV isolation. As culture-adapted mutations may affect subsequent virus studies and vaccine development, the knowledge from this study may help optimize strategies for influenza surveillance, vaccine strain selection, and vaccine development.     

Immunization with live influenza viruses in an experimental model of allergic bronchial asthma: infection and vaccination

Background Asthmatics in particular have a need for influenza vaccines because influenza infection is a frequent cause of hospitalization of patients with bronchial asthma. Currently, only inactivated influenza vaccines are recommended for influenza prevention in asthma sufferers. Objective The aim of our study was to analyze and compare the effects of influenza infection and vaccination with live attenuated influenza vaccine (LAIV) on different phases of experimental murine allergic bronchial asthma (acute asthma and remission phase) and on subsequent exposure to allergen in sensitized animals. Methods Ovalbumin (OVA)‐specific serum IgE levels, IL‐4 production by spleen and lung lymphocytes, and histological changes in the lungs of mice infected with pathogenic virus or LAIV were studied at two phases of OVA‐induced bronchial asthma (acute asthma and remission). Results Infection with pathogenic virus both in acute asthma and remission led to asthma exacerbation associated with the production of OVA‐specific IgE, IL‐4 and significant inflammatory infiltration in airways. Infection, even after complete virus clearance, induced the aggravation of lung inflammation and IgE production in asthmatic mice additionally exposed to OVA. Immunization with LAIV at remission did not enhance allergic inflammatory changes in the lung, OVA‐specific IgE or IL‐4 production. Then after additional OVA exposure, histological and immunological changes in these mice were the same as in the control group. Conclusions Influenza infection provokes asthma exacerbation regardless of the disease phase. Immunization with LAIV during the remission phase of bronchial asthma is safe and does not interfere upon subsequent contact of asthma sufferers with allergen.     

Influenza A and D Viruses in Non-Human Mammalian Hosts in Africa: A Systematic Review and Meta-Analysis

We conducted a systematic review and meta-analysis to investigate the prevalence and current knowledge of influenza A virus (IAV) and influenza D virus (IDV) in non-human mammalian hosts in Africa. PubMed, Google Scholar, Wiley Online Library and World Organisation for Animal Health (OIE-WAHIS) were searched for studies on IAV and IDV from 2000 to 2020. Pooled prevalence and seroprevalences were estimated using the quality effects meta-analysis model. The estimated pooled prevalence and seroprevalence of IAV in pigs in Africa was 1.6% (95% CI: 0–5%) and 14.9% (95% CI: 5–28%), respectively. The seroprevalence of IDV was 87.2% (95% CI: 24–100%) in camels, 9.3% (95% CI: 0–24%) in cattle, 2.2% (95% CI: 0–4%) in small ruminants and 0.0% (95% CI: 0–2%) in pigs. In pigs, H1N1 and H1N1pdm09 IAVs were commonly detected. Notably, the highly pathogenic H5N1 virus was also detected in pigs. Other subtypes detected serologically and/or virologically included H3N8 and H7N7 in equids, H1N1, and H3N8 and H5N1 in dogs and cats. Furthermore, various wildlife animals were exposed to different IAV subtypes. For prudent mitigation of influenza epizootics and possible human infections, influenza surveillance efforts in Africa should not neglect non-human mammalian hosts. The impact of IAV and IDV in non-human mammalian hosts in Africa deserves further investigation.     

Using capture‐recapture methods to estimate influenza hospitalization incidence rates

BackgroundAccurate population estimates of disease incidence and burden are needed to set appropriate public health policy. The capture–recapture (C‐R) method combines data from multiple sources to provide better estimates than is possible using single sources.MethodsData were derived from clinical virology test results and from an influenza vaccine effectiveness study from seasons 2016–2017 to 2018–2019. The Petersen C‐R method was used to estimate the population size of influenza cases; these estimates were then used to calculate adult influenza hospitalization burden using a Centers for Disease Control and Prevention (CDC) multiplier method.ResultsOver all seasons, 343 influenza cases were reported in the clinical database, and 313 in the research database. Fifty‐nine cases (17%) reported in the clinical database were not captured in the research database, and 29 (9%) cases in the research database were not captured in the clinical database. Influenza hospitalizations were higher among vaccinated (58%) than the unvaccinated (35%) in the current season and were similar among unvaccinated (51%) and vaccinated (49%) in the previous year. Completeness of the influenza hospitalization capture was estimated to be 76%. The incidence rates for influenza hospitalizations varied by age and season and averaged 307–309 cases/100,000 adult population annually.ConclusionUsing C‐R methods with more than one database, along with a multiplier method with adjustments improves the population estimates of influenza disease burden compared with relying on a single‐data source.     

流行性感冒

流行性感冒(简称“流感”)可引起全球大流行。引起流感的病原体是分节段的RNA流感病毒,流感病毒每年在人群中循环,可引起季节性流感的发生。而流感病毒在流行过程中常引发抗原的“漂移”变异,是老年人等高危人群发病死亡的主要原因之一。因此需要WHO组织全球的流感监测,经过检测分析,推测次年流行的季节性流感病毒,以应疫苗的制备。