scholarly journals Developing a system to estimate the severity of influenza infection in England: findings from a hospital-based surveillance system between 2010/2011 and 2014/2015

2017 ◽  
Vol 145 (7) ◽  
pp. 1461-1470 ◽  
Author(s):  
N. L. BODDINGTON ◽  
N. Q. VERLANDER ◽  
R. G. PEBODY
Keyword(s):  
Surveillance System ◽  
Influenza A ◽  
Influenza Pandemic ◽  
Influenza Infection ◽  
Rapid Assessment ◽  
Age Groups ◽  
Influenza Viruses ◽  
Influenza Surveillance ◽  
High Dependency ◽  
The Impact

SUMMARYThe UK Severe Influenza Surveillance System (USISS) was established following the 2009 influenza pandemic to monitor severe seasonal influenza. This article describes the severity of influenza observed in five post-2009 pandemic seasons in England. Two key measures were used to assess severity: impact measured through the cumulative incidence of laboratory-confirmed hospitalised influenza and case severity through the proportion of confirmed hospitalised cases admitted into intensive care units (ICU)/high dependency units (HDU). The impact of influenza varied by subtype and age group across the five seasons with the highest crude cumulative hospitalisation incidence for influenza A/H1N1pdm09 cases in 2010/2011 and in 0–4 year olds each season for all-subtypes. Case severity also varied by subtype and season with a higher hospitalisation: ICU ratio for A/H1N1pdm09 and older age groups (older than 45 years). The USISS system provides a tool for measuring severity of influenza each year. Such seasonal surveillance can provide robust baseline estimates to allow for rapid assessment of the severity of seasonal and emerging influenza viruses.

scholarly journals Real-time estimation of the hospitalization fatality risk of influenza A(H1N1)pdm09 in Hong Kong

2015 ◽  
Vol 144 (8) ◽  
pp. 1579-1583
Author(s):  
J. Y. WONG ◽  
P. WU ◽  
E. H. Y. LAU ◽  
T. K. TSANG ◽  
V. J. FANG ◽  
...  
Keyword(s):  
Hong Kong ◽  
Real Time ◽  
Influenza A ◽  
Early Stage ◽  
Influenza Pandemic ◽  
Influenza Viruses ◽  
Right Censoring ◽  
Fatality Risk ◽  
Influenza A H1n1 ◽  
The Impact

SUMMARYDuring the early stage of an epidemic, timely and reliable estimation of the severity of infections are important for predicting the impact that the influenza viruses will have in the population. We obtained age-specific deaths and hospitalizations for patients with laboratory-confirmed H1N1pdm09 infections from June 2009 to December 2009 in Hong Kong. We retrospectively obtained the real-time estimates of the hospitalization fatality risk (HFR), using crude estimation or allowing for right-censoring for final status in some patients. Models accounting for right-censoring performed better than models without adjustments. The risk of deaths in hospitalized patients with confirmed H1N1pdm09 increased with age. Reliable estimates of the HFR could be obtained before the peak of the first wave of H1N1pdm09 in young and middle-aged adults but after the peak in the elderly. In the next influenza pandemic, timely estimation of the HFR will contribute to risk assessment and disease control.

scholarly journals Natural Variation Can Significantly Alter the Sensitivity of Influenza A (H5N1) Viruses to Oseltamivir

2006 ◽  
Vol 50 (11) ◽  
pp. 3809-3815 ◽  
Author(s):  
M. A. Rameix-Welti ◽  
F. Agou ◽  
P. Buchy ◽  
S. Mardy ◽  
J. T. Aubin ◽  
...  
Keyword(s):  
Influenza A ◽  
Influenza Pandemic ◽  
Fold Increase ◽  
Influenza Viruses ◽  
Control Measures ◽  
Inhibition Assay ◽  
Highly Pathogenic ◽  
H5n1 Influenza ◽  
The Impact

ABSTRACT Geographic spread of highly pathogenic avian H5N1 influenza viruses may give rise to an influenza pandemic. During the first months of a pandemic, control measures would rely mainly on antiviral drugs, such as the neuraminidase (NA) inhibitors oseltamivir and zanamivir. In this study, we compare the sensitivities to oseltamivir of the NAs of several highly pathogenic H5N1 viruses isolated in Asia from 1997 to 2005. The corresponding 50% inhibitory concentrations were determined using a standard in vitro NA inhibition assay. The Km for the substrate and the affinity for the inhibitor (Ki ) of NA were determined for a 1997 and a 2005 virus, using an NA inhibition assay on cells transiently expressing the viral enzyme. Our data show that the sensitivities of the NAs of H5N1 viruses isolated in 2004 and 2005 to oseltamivir are about 10-fold higher than those of earlier H5N1 viruses or currently circulating H1N1 viruses. Three-dimensional modeling of the N1 protein predicted that Glu248Gly and Tyr252His changes could account for increased sensitivity. Our data indicate that genetic variation in the absence of any drug-selective pressure may result in significant variations in sensitivity to anti-NA drugs. Although the clinical relevance of a 10-fold increase in the sensitivity of NA to oseltamivir needs to be investigated further, the possibility that sensitivity to anti-NA drugs could increase (or possibly decrease) significantly, even in the absence of treatment, underscores the need for continuous evaluation of the impact of genetic drift on this parameter, especially for influenza viruses with pandemic potential.

scholarly journals Viral factors in influenza pandemic risk assessment

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Marc Lipsitch ◽  
Wendy Barclay ◽  
Rahul Raman ◽  
Charles J Russell ◽  
Jessica A Belser ◽  
...  
Keyword(s):  
Influenza A ◽  
Influenza Pandemic ◽  
Influenza Viruses ◽  
Influenza Surveillance ◽  
Human Influenza ◽  
Biological Assays ◽  
Genetic Sequence ◽  
Reservoir Species ◽  
Response Measures ◽  
Receptor Binding Specificity

The threat of an influenza A virus pandemic stems from continual virus spillovers from reservoir species, a tiny fraction of which spark sustained transmission in humans. To date, no pandemic emergence of a new influenza strain has been preceded by detection of a closely related precursor in an animal or human. Nonetheless, influenza surveillance efforts are expanding, prompting a need for tools to assess the pandemic risk posed by a detected virus. The goal would be to use genetic sequence and/or biological assays of viral traits to identify those non-human influenza viruses with the greatest risk of evolving into pandemic threats, and/or to understand drivers of such evolution, to prioritize pandemic prevention or response measures. We describe such efforts, identify progress and ongoing challenges, and discuss three specific traits of influenza viruses (hemagglutinin receptor binding specificity, hemagglutinin pH of activation, and polymerase complex efficiency) that contribute to pandemic risk.

scholarly journals Pandemic influenza A(H1N1) 2009 breakthrough infections and estimates of vaccine effectiveness in Germany 2009-2010

2010 ◽  
Vol 15 (18) ◽  
Author(s):  
O Wichmann ◽  
P Stöcker ◽  
G Poggensee ◽  
D Altmann ◽  
D Walter ◽  
...  
Keyword(s):  
Pandemic Influenza ◽  
Influenza A ◽  
Influenza Pandemic ◽  
Rapid Assessment ◽  
Screening Method ◽  
Age Groups ◽  
Vaccine Effectiveness ◽  
Influenza A H1n1 ◽  
Reported Data ◽  
2009 Influenza Pandemic

During the 2009 influenza pandemic, a monovalent AS03-adjuvanted vaccine was almost exclusively used in Germany for immunisation against the 2009 pandemic influenza A(H1N1) virus. One-dose vaccination was recommended for all age groups. We applied the screening method for the rapid assessment of vaccine effectiveness (VE) based on reported data of vaccinated and unvaccinated pandemic influenza cases and vaccination coverage estimates. Preliminary results demonstrate excellent VE in persons aged 14-59 years (96.8%; 95% confidence interval (CI): 95.2-97.9) and moderately high VE in those 60 years or older (83.3%; 95% CI: 71.0-90.5).

scholarly journals Harmonisation of the acute respiratory infection reporting system in the Czech Republic with the European community networks

2005 ◽  
Vol 10 (3) ◽  
pp. 5-6 ◽  
Author(s):  
J Kyncl ◽  
W J Paget ◽  
M Havlickova ◽  
B Kriz
Keyword(s):  
Czech Republic ◽  
Respiratory Infection ◽  
Acute Respiratory Infection ◽  
Reporting System ◽  
Influenza Infection ◽  
Age Groups ◽  
Influenza Surveillance ◽  
Sources Of Information ◽  
The Czech Republic ◽  
The Impact

Respiratory virus activity is detected in Europe each winter, yet the precise timing and size of this activity is highly unpredictable. The impact of influenza infection and/or acute respiratory infection in European countries is continuously monitored through a variety of surveillance systems. All of these sources of information are used to assess the nature and extent of activity of influenza and other respiratory viruses, and to offer guidance on the prevention and control of morbidity and mortality due to influenza at a local, national and international level. The early warning system for a forthcoming influenza epidemic is mainly based on the use of a set of thresholds. In the Czech Republic, the acute respiratory infection (ARI) reporting system, with automated data processing, uses a statistical model for the early detection of unusual increased rates of the monitored indicators. The collected data consists of the number of ARI, the number of complications due to ARI and the population registered with the reporting general practitioners and paediatricians, all collected separately in five age groups. To improve the reporting system in the Czech Republic, clinical data on the weekly incidence of influenza-like illness (ILI) within the same population and the same age groups was started in January 2004. These data fit the European Commission’s recently adopted ILI case definition and allows a better comparison of data with other countries in Europe, in particular those participating in EISS (European Influenza Surveillance Scheme).

scholarly journals The PB2-E627K Mutation Attenuates Viruses Containing the 2009 H1N1 Influenza Pandemic Polymerase

mBio ◽  
2010 ◽  
Vol 1 (1) ◽  
Author(s):  
Brett W. Jagger ◽  
Matthew J. Memoli ◽  
Zong-Mei Sheng ◽  
Li Qi ◽  
Rachel J. Hrabal ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
H1n1 Virus ◽  
Influenza Pandemic ◽  
Influenza Infection ◽  
H1n1 Influenza ◽  
Influenza Viruses ◽  
Pandemic Virus ◽  
2009 H1n1 ◽  
Animal Reservoirs

ABSTRACTThe swine-origin H1N1 influenza A virus emerged in early 2009 and caused the first influenza pandemic in 41 years. The virus has spread efficiently to both the Northern and the Southern Hemispheres and has been associated with over 16,000 deaths. Given the virus’s recent zoonotic origin, there is concern that the virus could acquire signature mutations associated with the enhanced pathogenicity of previous pandemic viruses or H5N1 viruses with pandemic potential. We tested the hypothesis that mutations in the polymerase PB2 gene at residues 627 and 701 would enhance virulence but found that influenza viruses containing these mutations in the context of the pandemic virus polymerase complex are attenuated in cell culture and mice.IMPORTANCEInfluenza A virus (IAV) evolution is characterized by host-specific lineages, and IAVs derived in whole or in part from animal reservoirs have caused pandemics in humans. Because IAVs are known to acquire host-adaptive genome mutations, and since the PB2 gene of the 2009 H1N1 virus is of recent avian derivation, there exists concern that the pathogenicity of the 2009 H1N1 influenza A pandemic virus could be potentiated by acquisition of the host-adaptive PB2-E627K or -D701N mutations, which have been shown to enhance the virulence of other influenza viruses. We present data from a mouse model of influenza infection showing that such mutations do not increase the virulence of viruses containing the 2009 H1N1 viral polymerase.

Variation in the HA antigenicity of A(H1N1)pdm09-related swine influenza viruses

2021 ◽  
Author(s):  
Ahmed Magdy Khalil ◽  
Reiko Yoshida ◽  
Tatsunori Masatani ◽  
Ayato Takada ◽  
Makoto Ozawa
Keyword(s):  
Genetic Diversity ◽  
Amino Acid ◽  
Influenza A ◽  
Influenza Pandemic ◽  
Gene Segment ◽  
Swine Influenza ◽  
Influenza Viruses ◽  
Single Amino Acid ◽  
Ha Gene ◽  
The Impact

Since the influenza pandemic in 2009, the causative agent ‘A(H1N1)pdm09 virus’, has been circulating in both human and swine populations. Although phylogenetic analyses of the haemagglutinin (HA) gene segment have revealed broader genetic diversity of A(H1N1)pdm09-related swine influenza A viruses (swIAVs) compared with human A(H1N1)pdm09 viruses, it remains unclear whether the genetic diversity reflects the antigenic differences in HA. To assess the impact of the diversity of the HA gene of A(H1N1)pdm09-related swIAVs on HA antigenicity, we characterized 12 swIAVs isolated in Japan from 2013 to 2018. We used a ferret antiserum and a panel of anti-HA mouse monoclonal antibodies (mAbs) raised against an early A(H1N1)pdm09 isolate. The neutralization assay with the ferret antiserum revealed that five of the 12 swIAVs were significantly different in their HA antigenicity from the early A(H1N1)pdm09 isolate. The mAbs also showed differential neutralization patterns depending on the swIAV strains. In addition, the single amino acid substitution at position 190 of HA, which was found in one of the five antigenically different swIAVs but not in human isolates, was shown to be one of the critical determinants for the antigenic difference of swIAV HAs. Two potential N-glycosylation sites at amino acid positions 185 and 276 of the HA molecule were identified in two antigenically different swIAVs. These results indicated that the genetic diversity of HA in the A(H1N1)pdm09-related swIAVs is associated with their HA antigenic variation. Our findings highlighted the need for surveillance to monitor the emergence of swIAV antigenic variants with public health importance.

scholarly journals 2750. Sequential Influenza A H1N1 and Influenza A H3N2 Challenge Infections in Healthy Volunteers

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S969-S969 ◽  
Author(s):  
Alison Han ◽  
Luca Giurgea ◽  
Adriana Cervantes-Medina ◽  
Kristina Edwards ◽  
Luz Angela Rosas ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Influenza A ◽  
Reverse Genetics ◽  
Clinical Symptoms ◽  
Influenza Infection ◽  
Influenza Viruses ◽  
Wild Type ◽  
Viral Shedding ◽  
Influenza A H1n1 ◽  
The Impact

Abstract Background Seasonal influenza causes significant annual morbidity and mortality. The effects of yearly exposures on immunity are not clear and recent observations have demonstrated that long lasting protection against a matched strain may not naturally occur. The 2018–2019 influenza season consisted of an initial peak of H1N1 infections followed by a wave of H3N2 infections. These consecutive waves raise questions about how influenza immunity is affected by sequential exposure to different influenza strains. Challenge studies provide a unique opportunity to study this phenomenon. Here we describe a subset of participants who were sequentially infected in two separate challenge studies with wild-type H1N1 and H3N2 viruses. Methods Healthy volunteers completed two sequential influenza challenge studies at the NIH Clinical Center. Participants were inoculated with reverse genetics, cell-based, GMP wild-type influenza viruses, A(H1N1)pdm09 and A(H3N2) strains. Participants remained isolated in the hospital for a minimum of 9 days and were monitored daily for viral shedding and clinical symptoms. After discharge, participants were followed for 2 months. Results Between 2014 and 2017, 14 healthy volunteers were exposed to Influenza A(H1N1) and Influenza A(H3N2). Time between infections ranged from 2 months to 2 years. Thirteen (93%) participants developed confirmed influenza infection after H1N1 challenge and 9 (64%) after H3N2 challenge. Eight (57%) participants developed confirmed infections after both exposures. Variable degrees of symptoms, shedding, and disease severity were observed. Systemic antibody responses to the HA and NA of both H1N1 and H3N2 varied over time during these sequential infections. Conclusion More than half of all participants who completed 2 sequential H1N1 and H3N2 challenge studies demonstrated confirmed infection to both viruses. These sequential infections had varying effects on the disease experienced and the immunity that developed after infection. These observations are important in understanding the impact of sequential exposures on influenza immunity. Disclosures All authors: No reported disclosures.

scholarly journals Infection of mice with influenza A/WSN/33 (H1N1) virus alters alveolar type II cell phenotype

2015 ◽  
Vol 308 (7) ◽  
pp. L628-L638 ◽  
Author(s):  
Christian C. Hofer ◽  
Parker S. Woods ◽  
Ian C. Davis
Keyword(s):  
Influenza A ◽  
Influenza Infection ◽  
Influenza Viruses ◽  
Normal Lung ◽  
Cell Phenotype ◽  
Alveolar Type ◽  
Type I ◽  
Type Ii ◽  
Atii Cell ◽  
The Impact

Influenza viruses cause acute respiratory disease of great importance to public health. Alveolar type II (ATII) respiratory epithelial cells are central to normal lung function and are a site of influenza A virus replication in the distal lung. However, the consequences of infection for ATII cell function are poorly understood. To determine the impact of influenza infection on ATII cells we used C57BL/6-congenic SP-CGFP mice that express green fluorescent protein (GFP) under the control of the surfactant protein-C (SP-C) promoter, which is only active in ATII cells. Most cells isolated from the lungs of uninfected SP-CGFP mice were GFP+ but did not express the alveolar type I (ATI) antigen podoplanin (PODO). ATII cells were also EpCAM+ and α2,3-linked sialosaccharide+. Infection with influenza A/WSN/33 virus caused severe hypoxemia and pulmonary edema. This was accompanied by loss of whole lung GFP fluorescence, reduced ATII cell yields, increased ATII cell apoptosis, reduced SP-C gene and protein expression in ATII cell lysates, and increased PODO gene and protein levels. Flow cytometry indicated that infection decreased GFP+/PODO− cells and increased GFP−/PODO+ and GFP−/PODO− cells. Very few GFP+/PODO+ cells were detectable. Finally, infection resulted in a significant decline in EpCAM expression by PODO+ cells, but had limited effects on α2,3-linked sialosaccharides. Our findings indicate that influenza infection results in a progressive differentiation of ATII cells into ATI-like cells, possibly via an SP-C−/PODO− intermediate, to replace dying or dead ATI cells. However, impaired SP-C synthesis is likely to contribute significantly to reduced lung compliance in infected mice.

scholarly journals Epidemiology of influenza: findings from surveillance system of 40 hospital in Thailand, 2010-2019

2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
T Eamchotchawalit ◽  
P Piyaraj ◽  
P Narongdej ◽  
S Charoensakulchai ◽  
C Chanthowong
Keyword(s):  
Real Time ◽  
Surveillance System ◽  
Influenza A ◽  
Seasonal Influenza ◽  
Influenza Viruses ◽  
Cold Chain ◽  
Influenza Surveillance ◽  
Influenza B ◽  
Private Hospitals ◽  
Influenza A H1n1

Abstract Background Although recent efforts from some Asian countries to describe burden of influenza disease and seasonality, these data are missing for the vast majority, including the private section of Thailand. A near real-time laboratory-based influenza surveillance system, in a network of 40 hospitals was implemented aiming to determine influenza strains circulating in the private hospitals of Thailand and know characteristics, trend and burden of influenza viruses. Methods We obtained the data by monitoring patients with influenza-like illness (ILI) at a network of 40 private hospitals across Thailand. Throat-swab specimens in viral transport media were collected and transported within 24 h of collection using a cold-chain system. The respiratory samples were tested by rapid influenza diagnostic tests and real-time reverse transcription polymerase chain reaction. Results From January 2010 to November 2019, a total of 1,300,594 subjects were tested and 320,499 cases of influenza were identified. Of those positive cases, 116,317(36.3%) were influenza type B, 185,512(57.9%) were influenza A unspecified subtype, 8,833(2.7%) were influenza A(H1N1)pdm2009 and 6,371(1.9%) were seasonal influenza A(H3N2). Positive rate were 50.5 and 49.5 in female and male. Positivity rate was 41.4% in persons 15-49 years followed by 29.1% in 15-14 years, 17.6% in under five children and 11.7% in > 49 years. In 2018-2019 season, the highest positivity rate observed in February and March (39.3%) followed by April (34.2%) and January (32.3%) while the lowest positivity rate was in May (18.1%). Conclusions In Thailand, seasonal Influenza A(H3N2), Influenza A(H1N1)pdm2009 and Influenza B viruses were circulating during 2010-2019. In last season, positivity rate and number of cases peaked in February and March. Key messages Influenza is one of public health problems in Thailand. The need to introduce influenza vaccine and antivirus is important to prevent and treat the disease in future.

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