Global burden of influenza as a cause of cardiopulmonary morbidity and mortality

Pseudovirus nanoparticles targeting the receptor binding HA1 domains of influenza viruses elicited high HA1-specific antibody responses and protected mice against mortality caused by influenza virus challenges

The continually high disease burden of influenza and the relatively low effectiveness of current influenza vaccines call for enhanced vaccine strategies. We previously generated unique S-HA1 pseudovirus nanoparticles (PVNPs) displaying the receptor binding HA1 antigens of the H7N9 subtype as an influenza vaccine candidate and characterized their features in biochemistry, biophysics, structure, and immune response. In this follow up study, we created new S-HA1 PVNPs displaying the HA1 antigens of other common influenza viruses, including two H1N1 strains, one H3N2 strain, and an influenza B virus, respectively. The recombinant PVNPs react well with antibodies against hemagglutinins (HAs) or mouse sera obtained after influenza virus challenge. 3D structural models were constructed to comprehend the structural features and size variations of the S-HA1 PVNPs. The PVNPs are immunogenic, eliciting high titers of HA1-specific serum antibodies that recognized commercial HA1 proteins. Importantly, the S-HA1 PVNP representing the H1N1 PR8 strain provided mice with 100 % protection against mortality caused by challenge with the mouse-adapted influenza virus of the same PR8 strain. The S-HA1 PVNP representing the H1N1 2009 pandemic strain conferred mice with 50 % protection against mortality caused by challenge with the 1934 PR8 strain, despite the two strains circulating 75 years apart. Our data demonstrated the feasibility of generating S-HA1 PVNPs to display HA1 antigens of diverse influenza A and B viruses. The readily available S-HA1 PVNPs hold promise as influenza vaccines, presenting a novel approach to combat the deadly influenza disease.

A comparative study of influenza surveillance systems and administrative data in England during the 2022-2023 season

Accurate and representative surveillance is essential for understanding the impact of influenza on healthcare systems. During the 2022-2023 influenza season, the Northern Hemisphere experienced its most significant epidemic wave since the onset of the COVID-19 pandemic in 2020. Concurrently, new surveillance systems, developed in response to the pandemic, became available within health services. In this study, we analysed per capita admission rates from National Health Service hospital Trusts across four surveillance systems in England during the winter of 2022-2023. We examined differences in reporting timeliness, data completeness, and regional coverage, modelling key epidemic metrics including the maximum admission rates, cumulative seasonal admissions, and growth rates by fitting generalised additive models at national and regional levels. From modelling the admission rates per capita, we find that different surveillance systems yield varying estimates of key epidemiological metrics, both spatially and temporally. While national data from these systems generally align on the maximum admission rate and growth trends, discrepancies emerge at the subnational level, particularly in the cumulative admission rate estimates, with notable issues observed in London and the East of England. The rapid growth and decay phases of the epidemic contributed to higher uncertainty in these estimates, especially in regions with variable data quality. The study highlights that the choice of surveillance system can significantly influence the interpretation of influenza trends, especially at the subnational level, where regional disparities may mask true epidemic dynamics. Comparing multiple data sources enhances our understanding of the impact of seasonal influenza epidemics and highlights the limitations of relying on a single system.

Cost-effectiveness of seasonal influenza vaccination in WHO-defined high-risk populations in Bangladesh

Background

Bangladesh carries a substantial health and economic burden of seasonal influenza, particularly among the World Health Organization (WHO)-defined high-risk populations. We implemented a modelling study to determine the cost-effectiveness of influenza vaccination in each of five high-risk groups (pregnant women, children under five years of age, adults with underlying health conditions, older adults (≥60 years), and healthcare personnel) to inform policy decisions on risk group prioritisation for influenza vaccination in Bangladesh.

Methods

We implemented a Markov decision-analytic model to estimate the impact of influenza vaccination for each target risk group. We obtained model inputs from hospital-based influenza surveillance data, unpublished surveys, and published literature (preferentially from studies in Bangladesh, followed by regional and global ones). We used quality-adjusted life years (QALY) as the health outcome of interest. We also estimated incremental cost-effectiveness ratios (ICERs) for each risk group by comparing the costs and QALY of vaccinating compared to not vaccinating each group, where the ICER represents the additional cost needed to achieve one year of additional QALY from a given intervention. We considered a willingness-to-pay threshold (ICER) of less than one gross domestic product (GDP) per capita as highly cost-effective and of one to three times GDP per capita as cost-effective (per WHO standard). For Bangladesh, this threshold ranges between USD 2462 and USD 7386.

Results

The estimated ICERs were USD -99, USD -87, USD -4, USD 792, and USD 229 per QALY gained for healthcare personnel, older adults (≥60), children aged less than five years, adults with comorbid conditions, and pregnant women, respectively. For all risk groups, ICERs were below the WHO willingness-to-pay threshold for Bangladesh. Vaccinating pregnant women and adults with comorbid conditions was highly cost-effective per additional life year gained, while vaccinating healthcare personnel, older adults (≥60), and children under five years were cost-saving per additional life year gained.

Conclusions

Influenza vaccination to all target risk groups in Bangladesh would be either cost-saving or cost-effective, per WHO guidelines of GDP-based thresholds.

Accurate detection of influenza A virus by use of a novel cross-priming isothermal amplification-based point-of-care assay

Influenza virus is known to cause respiratory tract infections of varying severity in individuals of all ages. The EasyNAT Rapid Flu assay is a newly developed in vitro diagnostic test that employs cross-priming isothermal amplification (CPA) to detect and differentiate influenza A and B viruses in human nasopharyngeal (NP) swabs. The aim of this study is to determine the performance characteristics of the EasyNAT Rapid Flu assay for rapid detection of influenza virus. The limit of detection (LOD) and cross-reactivity of the EasyNAT Rapid Flu assay were assessed. The clinical performance of the assay was evaluated using NP swab samples that were tested with real-time reverse-transcription polymerase chain reaction (RT-PCR) and Xpert Xpress Flu/RSV assay. The LOD for the detection of influenza A and B using the EasyNAT Rapid Flu assay was found to be 500 copies/mL. Furthermore, the assay exhibited no cross-reactivity with other common respiratory viruses tested. For the 114 NP swab samples tested for influenza A using both the EasyNAT Rapid Flu assay and real-time RT-PCR, the two assays demonstrated a high level of agreement (κ = 0.963, P < 0.001), with a positive percentage agreement (PPA) of 97.7% and a negative percentage agreement (NPA) of 98.6%. Similarly, for the 43 NP swab samples tested for influenza A and B using both the EasyNAT Rapid Flu assay and Xpert Xpress Flu/RSV assay, the two assays showed a high level of agreement (κ = 0.933, P < 0.001), with the overall rate of agreement (ORA) of 97.7% for influenza A and 100% for influenza B. The EasyNAT Rapid Flu assay demonstrates excellent performance in the detection of influenza A, highlighted by its strong agreement with RT-PCR-based assays.IMPORTANCEThe newly developed EasyNAT Rapid Flu assay is an innovative cross-priming isothermal amplification-based method designed for detecting influenza A and B viruses at point-of-care settings. This study aims to thoroughly assess the analytical and clinical performance of the assay, offering valuable insights into its potential advantages and limitations. The findings of this research hold significant implications for clinical practice.

Influvac Tetra: clinical experience on safety, efficacy, and immunogenicity

INTRODUCTION

This paper summarizes the safety and immunogenicity data of Influvac Tetra across all age groups starting from 6 months of age, obtained during its clinical development program.

AREAS COVERED

The article covers the clinical development program of Influvac Tetra based on five registration studies that included different age groups, different comparators, and participants from Europe and Asia. Safety and immunogenicity were assessed in all studies and in one study, the efficacy of Influvac Tetra was assessed.

EXPERT OPINION

Seasonal influenza is a vaccine-preventable disease that can cause serious complications. Several types of influenza vaccines are available, including egg-based (standard dose, high dose, and adjuvanted), cell-based, and recombinant. The COVID-19 pandemic has stimulated innovation in the development such as mRNA vaccines. However, these vaccines are still in development and the true value still has to be proven. Regardless of the type of vaccine, it is also important to increase overall vaccination coverage. ECDC recommends that EU Member States implement action plans and policies aimed at reaching 75% coverage in at-risk groups and healthcare workers. Even so, vaccine coverage is still far from recommended.

Natural History of Influenza B Virus-Current Knowledge on Treatment, Resistance and Therapeutic Options

Influenza B virus (IBV) significantly impacts the health and the economy of the global population. WHO global health estimates project 1 billion flu cases annually, with 3 to 5 million resulting in severe disease and 0.3 to 0.5 million influenza-related deaths worldwide. Influenza B virus epidemics result in significant economic losses due to healthcare expenses, reduced workforce productivity, and strain on healthcare systems. Influenza B virus epidemics, such as the 1987-1988 Yamagata lineage outbreak and the 2001-2002 Victoria lineage outbreak, had a significant global impact. IBV's fast mutation and replication rates facilitate rapid adaptation to the environment, enabling the evasion of existing immunity and the development of resistance to virus-targeting treatments. This leads to annual outbreaks and necessitates the development of new vaccination formulations. This review aims to elucidate IBV's evolutionary genomic organization and life cycle and provide an overview of anti-IBV drugs, resistance, treatment options, and prospects for IBV biology, emphasizing challenges in preventing and treating IBV infection.

Association of recent respiratory illness and influenza with acute myocardial infarction among the Bangladeshi population: A case-control study

Current evidence suggests that recent acute respiratory infections and seasonal influenza may precipitate acute myocardial infarction (AMI). This study examined the potential link between recent clinical respiratory illness (CRI) and influenza, and AMI in Bangladesh. Conducted during the 2018 influenza season at a Dhaka tertiary-level cardiovascular (CV) hospital, it included 150 AMI cases and two control groups: 44 hospitalized cardiac patients without AMI and 90 healthy individuals. Participants were matched by gender and age groups. The study focused on self-reported CRI and laboratory-confirmed influenza ascertained via quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) within the preceding week, analyzed using multivariable logistic regression. Results showed that cases reported CRI, significantly more frequently than healthy controls (27.3% vs. 13.3%, adjusted odds ratio (aOR): 2.21; 95% confidence interval (CI): 1.05-4.06), although this was not significantly different from all controls (27.3% vs. 22.4%; aOR: 1.19; 95% CI: 0.65-2.18). Influenza rates were insignificantly higher among cases than controls. The study suggests that recent respiratory illnesses may precede AMI onset among Bangladeshi patients. Infection prevention and control practices, as well as the uptake of the influenza vaccine, may be advocated for patients at high risk of acute CV events.

Systemic perturbations in amino acids/amino acid derivatives and tryptophan pathway metabolites associated with murine influenza A virus infection

BACKGROUND

Influenza A virus (IAV) is the only influenza virus causing flu pandemics (i.e., global epidemics of flu disease). Influenza (the flu) is a highly contagious disease that can be deadly, especially in high-risk groups. Worldwide, these annual epidemics are estimated to result in about 3 to 5 million cases of severe illness and in about 290,000 to 650,000 respiratory deaths. We intend to reveal the effect of IAV infection on the host's metabolism, immune response, and neurotoxicity by using a mouse IAV infection model.

METHODS

51 metabolites of murine blood plasma (33 amino acids/amino acid derivatives (AADs) and 18 metabolites of the tryptophan pathway) were analyzed by using Ultra-High-Performance Liquid Chromatography-Mass Spectrometry with Electrospray Ionization at the acute (7 days post-infection (dpi)), resolution (14 dpi), and recovery (21 dpi) stages of the virus infection in comparison with controls.

RESULTS

Among the 33 biogenic amino acids/AADs, the levels of five amino acids/AADs (1-methylhistidine, 5-oxoproline, α-aminobutyric acid, glutamine, and taurine) increased by 7 dpi, whereas the levels of ten amino acids/AADs (4-hydroxyproline, alanine, arginine, asparagine, cysteine, citrulline, glycine, methionine, proline, and tyrosine) decreased. By 14 dpi, the levels of one AAD (3-methylhistidine) increased, whereas the levels of five amino acids/AADs (α-aminobutyric acid, aminoadipic acid, methionine, threonine, valine) decreased. Among the 18 metabolites from the tryptophan pathway, the levels of kynurenine, quinolinic acid, hydroxykynurenine increased by 7 dpi, whereas the levels of indole-3-acetic acid and nicotinamide riboside decreased.

CONCLUSIONS

Our data may facilitate understanding the molecular mechanisms of host responses to IAV infection and provide a basis for discovering potential new mechanistic, diagnostic, and prognostic biomarkers and therapeutic targets for IAV infection.

Transcriptomic Profiling of Influenza A Virus-Infected Mouse Lung at Recovery Stage Using RNA Sequencing

Influenza A virus (IAV) is known to cause mild to severe respiratory illness. Under some conditions, the infection can lead to pneumonia (viral or bacterial), acute respiratory distress syndrome, and other complications that can be fatal, especially in vulnerable populations such as the elderly, young children, and individuals with underlying health conditions. Despite previous studies, little is known about the host immune response and neuroimmune interactions in IAV infection. Using RNA sequencing, we performed transcriptomic analysis of murine lung tissue 21 days post infection (dpi) with IAV (H1N1) in order to find the differentially expression genes (DEGs) related to the host immune response and neuroimmune interactions inside the lung during recovery. Among 792 DEGs, 434 genes were up-regulated, whereas 358 genes were down-regulated. The most prominent molecular functions of the up-regulated genes were related to the immune response and tissue repair, whereas a large proportion of the down-regulated genes were associated with neural functions. Although further molecular/functional studies need to be performed for these DEGs, our results facilitate the understanding of the host response (from innate immunity to adaptive immunity) and neuroimmune interactions in infected lungs at the recovery stage of IAV infection. These genes might have potential uses as mechanistic/diagnostic biomarkers and represent possible targets for anti-IAV therapies.

A Rare Association: Non-ST Elevation Myocardial Infarction (NSTEMI) Secondary to Respiratory Syncytial Virus (RSV) Infection

We present a case report on a rare association between non-ST elevation myocardial infarction (NSTEMI) and respiratory syncytial virus (RSV) infection in a patient with no traditional risk factors for cardiovascular disease (CVD) including a family history of premature coronary artery disease (CAD). While RSV is commonly known for its respiratory manifestations, it has been increasingly recognized as a cause of significant morbidity and mortality in adults, particularly those with underlying comorbidities. However, the association between RSV infection and NSTEMI, especially in patients without traditional risk factors, remains relatively unexplored. Our case involves a 31-year-old healthy adult who presented with progressive exertional chest pain and flu-like symptoms. Electrocardiogram (EKG) changes and elevated troponin levels indicated NSTEMI. Laboratory tests confirmed RSV infection. Angiography revealed significant coronary artery disease requiring percutaneous coronary intervention. This case highlights the need for healthcare professionals to be aware of the potential cardiovascular (CV) complications associated with RSV infection, even in patients without traditional risk factors. It expands our understanding of viral respiratory infections as potential triggers for acute coronary syndromes (ACS) and emphasizes the importance of considering RSV infection in the differential diagnosis of NSTEMI, especially in young otherwise healthy individuals. Further research is warranted to explore the underlying mechanisms and develop preventive strategies for RSV-related cardiovascular complications.

The role of vaccination in COPD: influenza, SARS-CoV-2, pneumococcus, pertussis, RSV and varicella zoster virus

Exacerbations of COPD are associated with worsening of the airflow obstruction, hospitalisation, reduced quality of life, disease progression and death. At least 70% of COPD exacerbations are infectious in origin, with respiratory viruses identified in approximately 30% of cases. Despite long-standing recommendations to vaccinate patients with COPD, vaccination rates remain suboptimal in this population.Streptococcus pneumoniae is one of the leading morbidity and mortality causes of lower respiratory tract infections. The Food and Drug Administration recently approved pneumococcal conjugate vaccines that showed strong immunogenicity against all 20 included serotypes. Influenza is the second most common virus linked to severe acute exacerbations of COPD. The variable vaccine efficacy across virus subtypes and the impaired immune response are significant drawbacks in the influenza vaccination strategy. High-dose and adjuvant vaccines are new approaches to tackle these problems. Respiratory syncytial virus is another virus known to cause acute exacerbations of COPD. The vaccine candidate RSVPreF3 is the first authorised for the prevention of RSV in adults ≥60 years and might help to reduce acute exacerbations of COPD. The 2023 Global Initiative for Chronic Lung Disease report recommends zoster vaccination to protect against shingles for people with COPD over 50 years.

The evolution, characterization and phylogeography of avian influenza H9N2 viruses from India

The low pathogenic avian influenza H9N2 virus is a significant zoonotic agent and contributes genes to highly pathogenic avian influenza (HPAI) viruses. H9N2 viruses are prevalent in India with a reported human case. We elucidate the spatio-temporal origins of the H9N2 viruses from India. A total of 30H9N2 viruses were isolated from poultry and environmental specimens (years 2015-2020). Genome sequences of H9N2 viruses (2003-2020) from India were analyzed, revealing several substitutions. We found five reassortant genotypes. The HA, NA and PB2 genes belonged to the Middle-Eastern B sublineage; NP and M to the classical G1 lineage; PB1, PA and NS showed resemblance to genes from either HPAI-H7N3/H5N1 viruses. Molecular clock and phylogeography revealed that the introduction of all the genes to India took place around the year 2000. This is the first report of the genesis and evolution of the H9N2 viruses from India, and highlights the need for surveillance.

The burden of lower respiratory infections and their underlying etiologies in the Middle East and North Africa region, 1990-2019: results from the Global Burden of Disease Study 2019

BACKGROUND

Lower respiratory infections (LRIs) cause substantial mortality and morbidity. The present study reported and analysed the burden of LRIs in the Middle East and North Africa (MENA) region between 1990 and 2019, by age, sex, etiology, and socio-demographic index (SDI).

METHODS

The data used in this study were sourced from the Global Burden of Disease (GBD) study 2019. The annual incidence, deaths, and disability-adjusted life-years (DALYs) due to LRIs were presented as counts and age-standardised rates per 100,000 population, along with their 95% uncertainty intervals (UIs). The average annual percent changes (AAPC) in the age-standardised incidence, death and DALYs rates were calculated using Joinpoint software and correlations (Pearson's correlation coefficient) between the AAPCs and SDIs were calculated using Stata software.

RESULTS

In 2019, there were 34.1 million (95% UI 31.7-36.8) incident cases of LRIs in MENA, with an age-standardised rate of 6510.2 (95% UI 6063.6-6997.8) per 100,000 population. The number of regional DALYs was 4.7 million (95% UI 3.9-5.4), with an age-standardised rate of 888.5 (95% UI 761.1-1019.9) per 100,000 population, which has decreased since 1990. Furthermore, Egypt [8150.8 (95% UI 7535.8-8783.5)] and Afghanistan [61.9 (95% UI 52.1-72.6)] had the highest age-standardised incidence and death rates, respectively. In 2019, the regional incidence and DALY rates were highest in the 1-4 age group, in both females and males. In terms of deaths, pneumococcus and H. influenza type B were the most and least common types of LRIs, respectively. From 1990 to 2019, the burden of LRIs generally decreased with increasing SDI. There were significant positive correlations between SDI and the AAPCs for the age-standardised incidence, death and DALY rates (p < 0.05). Over the 1990-2019 period, the regional incidence, deaths and DALYs attributable to LRIs decreased with AAPCs of - 1.19% (- 1.25 to - 1.13), - 2.47% (- 2.65 to - 2.28) and - 4.21% (- 4.43 to - 3.99), respectively.

CONCLUSIONS

The LRI-associated burden in the MENA region decreased between 1990 and 2019. SDI had a significant positive correlation with the AAPC and pneumococcus was the most common underlying cause of LRIs. Afghanistan, Yemen and Egypt had the largest burdens in 2019. Further studies are needed to investigate the effectiveness of healthcare interventions and programs to control LRIs and their risk factors.

Dung biomass smoke exposure impairs resolution of inflammatory responses to influenza infection

Epidemiological studies associate biomass smoke with an increased risk for respiratory infections in children and adults in the developing world, with 500,000 premature deaths each year attributed to biomass smoke-related acute respiratory infections including infections caused by respiratory viruses. Animal dung is a biomass fuel of particular concern because it generates more toxic compounds per amount burned than wood, and is a fuel of last resort for the poorest households. Currently, there is little biological evidence on the effects of dung biomass smoke exposure on immune responses to respiratory viral infections. Here, we investigated the impact of dung biomass exposure on respiratory infection using a mouse model of dung biomass smoke and cultured primary human small airway epithelial cells (SAECs). Mice infected with influenza A virus (IAV) after dung biomass smoke exposure had increased mortality, lung inflammation and virus mRNA levels, and suppressed expression of innate anti-viral mediators compared to air exposed mice. Importantly, there was still significant tissue inflammation 14 days after infection in dung biomass smoke-exposed mice even after inflammation had resolved in air-exposed mice. Dung biomass smoke exposure also suppressed the production of anti-viral cytokines and interferons in cultured SAECs treated with poly(I:C) or IAV. This study shows that dung biomass smoke exposure impairs the immune response to respiratory viruses and contributes to biomass smoke-related susceptibility to respiratory viral infections, likely due to a failure to resolve the inflammatory effects of biomass smoke exposure.

Airborne Transmission and Control of Influenza and Other Respiratory Pathogens

Despite uncertainty about the specific transmission risk posed by airborne, spray-borne, and contact modes for influenza, SARS-CoV-2, and other respiratory viruses, there is evidence that airborne transmission via inhalation is important and often predominates. An early study of influenza transmission via airborne challenge quantified infectious doses as low as one influenza virion leading to illness characterized by cough and sore throat. Other studies that challenged via intranasal mucosal exposure observed high doses required for similarly symptomatic respiratory illnesses. Analysis of the Evaluating Modes of Influenza Transmission (EMIT) influenza human-challenge transmission trial—of 52 H3N2 inoculated viral donors and 75 sero-susceptible exposed individuals—quantifies airborne transmission and provides context and insight into methodology related to airborne transmission. Advances in aerosol sampling and epidemiologic studies examining the role of masking, and engineering-based air hygiene strategies provide a foundation for understanding risk and directions for new work.

A Case-Crossover Analysis of the Association between Exposure to Total PM2.5 and Its Chemical Components and Emergency Ambulance Dispatches in Tokyo

A limited number of studies have investigated the association between short-term exposure to PM_2.5 components and morbidity. The present case-crossover study explored the association between exposure to total PM_2.5 and its components and emergency ambulance dispatches, which is one of the indicators of morbidity, in the 23 Tokyo wards. Between 2016 and 2018 (mean mass concentrations of total PM_2.5 13.5 μg/m³), we obtained data, from the Tokyo Fire Department, on the daily cases of ambulance dispatches. Fine particles were collected at a fixed monitoring site and were analyzed to estimate the daily mean concentrations of carbons and ions. We analyzed 1038301 cases of health-based all-cause ambulance dispatches by using a conditional logistic regression model. The average concentrations of total PM_2.5 over one and the previous day were positively associated with the number of ambulance dispatches. In terms of PM_2.5 components, the percentage increase per interquartile range (IQR) increase was 0.8% for elemental carbon (IQR = 0.8 μg/m³; 95% CI = 0.3-1.3%), 0.9% for sulfate (2.1 μg/m³; 0.5-1.4%), and 1.1% for ammonium (1.3 μg/m³; 0.4-1.8%) in the PM_2.5-adjusted models. This is the first study to find an association between some specific components in PM_2.5 and ambulance dispatches.

The balancing role of distribution speed against varying efficacy levels of COVID-19 vaccines under variants

During a pandemic, vaccination plays an important role in reducing the infection spread or adverse outcomes such as hospitalizations and deaths. However, a vaccine's overall public health impact depends not only on its initial efficacy, but also its efficacy against emerging variants and ease and speed of distribution. For example, mutations in SARS-CoV-2 raised concerns about diminishing vaccine effectiveness against COVID-19 caused by particular variants. Furthermore, due to supply-chain challenges, the accessibility and distribution of the vaccines have been hindered in many regions, especially in low-income countries, while the second or third wave of the COVID-19 pandemic has occurred due to the variants. Hence, we evaluated the interactions between the speed of distribution and efficacy against infection of multiple vaccines when variants emerge by utilizing a Susceptible-Infected-Recovered-Deceased model and assessing the level of infection attack rate. Our results show that speed is a key factor to a successful immunization strategy to control the pandemic even when the emerging variants may reduce the efficacy of a vaccine. Understanding the interactions between speed and efficacy and distributing vaccines that are available as quickly as possible are crucial to eradicate the pandemic before new variants spread.

Clinical validation of a multiplex PCR-based detection assay using saliva or nasopharyngeal samples for SARS-Cov-2, influenza A and B

The COVID-19 pandemic has resulted in significant diversion of human and material resources to COVID-19 diagnostics, to the extent that influenza viruses and co-infection in COVID-19 patients remains undocumented and pose serious public-health consequences. We optimized and validated a highly sensitive RT-PCR based multiplex-assay for the detection of SARS-CoV-2, influenza A and B viruses in a single-test. This study evaluated clinical specimens (n = 1411), 1019 saliva and 392 nasopharyngeal swab (NPS), tested using two-assays: FDA-EUA approved SARS-CoV-2 assay that targets N and ORF1ab gene, and the PKamp-RT-PCR based assay that targets SARS-CoV-2, influenza viruses A and B. Of the 1019 saliva samples, 17.0% (174/1019) tested positive for SARS-CoV-2 using either assay. The detection rate for SARS-CoV-2 was higher with the multiplex assay compared to SARS-specific assay [91.9% (160/174) vs. 87.9% (153/174)], respectively. Of the 392 NPS samples, 10.4% (41/392) tested positive for SARS-CoV-2 using either assay. The detection rate for SARS-CoV-2 was higher with the multiplex assay compared to SARS-specific assay [97.5% (40/41) vs. 92.1% (39/41)], respectively. This study presents clinical validation of a multiplex-PCR assay for testing SARS-CoV-2, influenza A and B viruses, using NPS and saliva samples, and demonstrates the feasibility of implementing the assay without disrupting the existing laboratory workflow.

Bioengineered pseudovirus nanoparticles displaying the HA1 antigens of influenza viruses for enhanced immunogenicity

Even with implementation of current influenza vaccines, influenza still claims up to 500,000 lives worldwide annually, indicating a need for a better vaccine strategy. We have developed a technology to generate unique S60-HA1 pseudovirus nanoparticles (PVNPs) that display the receptor-binding HA1 domains of influenza viruses. Each self-assembled S60-HA1 PVNP consists of a T = 1 icosahedral S60 nanoparticle that resembles the inner shell of norovirus capsid and 60 surface-displayed HA1 antigens that are excellent vaccine targets. Soluble S60-HA1 PVNPs presenting HA1 antigens of H7N9 influenza virus subtypes have been produced efficiently in large amount. Their three-dimensional (3D) structures have been solved by cryogenic electron microscopy. The PVNP-displayed HA1 antigens react with HA-specific antibody, and retain authentic sialic acid binding specificity and hemagglutinate human erythrocytes. The PVNPs are highly immunogenic, eliciting high titers of HA1-specific antibodies in mice and the mouse sera strongly inhibited hemagglutinations of homologous and heterologous influenza virus HA proteins. Therefore, the S60-HA1 PVNPs may provide useful reagents to study influenza viruses and offer a potential new vaccine tactic to fight the deadly influenza disease.

Forecasting influenza-like illness trends in Cameroon using Google Search Data

Although acute respiratory infections are a leading cause of mortality in sub-Saharan Africa, surveillance of diseases such as influenza is mostly neglected. Evaluating the usefulness of influenza-like illness (ILI) surveillance systems and developing approaches for forecasting future trends is important for pandemic preparedness. We applied and compared a range of robust statistical and machine learning models including random forest (RF) regression, support vector machines (SVM) regression, multivariable linear regression and ARIMA models to forecast 2012 to 2018 trends of reported ILI cases in Cameroon, using Google searches for influenza symptoms, treatments, natural or traditional remedies as well as, infectious diseases with a high burden (i.e., AIDS, malaria, tuberculosis). The R2 and RMSE (Root Mean Squared Error) were statistically similar across most of the methods, however, RF and SVM had the highest average R2 (0.78 and 0.88, respectively) for predicting ILI per 100,000 persons at the country level. This study demonstrates the need for developing contextualized approaches when using digital data for disease surveillance and the usefulness of search data for monitoring ILI in sub-Saharan African countries.

Ancillary benefits of seasonal influenza vaccination in middle-income countries

While seasonal influenza vaccines (SIV) remain the best method to prevent influenza-associated illnesses, implementing SIV programs may benefit countries beyond disease reduction, strengthening health systems and national immunization programs, or conversely, introduce new challenges. Few studies have examined perceived impacts of SIV introduction beyond disease reduction on health systems; understanding such impacts will be particularly salient in the context of COVID-19 vaccine introduction. We collected qualitative data from key informants-Partnership for Influenza Vaccine Introduction (PIVI) contacts in six middle-income PIVI vaccine recipient countries-to understand perceptions of ancillary benefits and challenges from SIV implementation. Respondents reported benefits associated with SIV introduction, including improved attitudes to SIV among risk groups (characterized by increased demand) and perceptions that SIV introduction improved relationships with other ministries and collaboration with mass media. Challenges included sustaining investment in SIV programs, as vaccine supply did not always meet coverage goals, and managing SIV campaigns.

Prevalence and healthcare utilization of acute respiratory infections among cancer survivors in the United States: a population-based study

Objective: To examine the prevalence and healthcare use of acute respiratory tract infections (RTIs) among cancer survivors in the United States in a population-based cohort.Methods: Medical Expenditure Panel Survey for 2013, 2015, and 2017 was accessed and adults (>20 years) with known status of cancer diagnosis were reviewed. Multivariable logistic regression analysis was then used to examine factors associated with the likelihood of influenza and pneumonia as well as the likelihood of hospitalization secondary to acute RTIs.Results: A total of 75,665 participants were included (including 6397 cancer survivors and 68,733 participants without a cancer history). Within the cohort of cancer survivors, upper RTIs were recorded in 10.6% and influenza and pneumonia were recorded in 7.8%. Within the cohort of cancer survivors, individuals with influenza and pneumonia have a higher total healthcare expenditure (mean: 19,387.59 $ versus 12,714.57 $; P < 0.001) and total out-of-pocket expenditure (mean: 1494.61 $ versus 1159.27 $; P < 0.001). Multivariable logistic regression analysis showed that a history of cancer was associated with a higher likelihood of influenza and pneumonia (OR: 1.119; 95% CI: 1.005-1.247; P = 0.041) as well as hospitalization following acute RTIs (1.586; 95% CI: 1.197-2.103; P = 0.001).Conclusions: Within the studied cohort, cancer Survivors were more likely to be diagnosed with influenza and pneumonia and they were more likely to be hospitalized because of acute RTIs.

Influenza and pneumonia-attributed deaths among cancer patients in the United States; a population-based study

Objective: To assess the patterns and trends of influenza and pneumonia-attributed deaths among cancer patients in the United States.Methods: Surveillance, Epidemiology and End Results (SEER) database was accessed and cancer patients diagnosed 1975-2016 who have been included in the SEER-9 registries were included. The primary endpoint of the study is standardized mortality rate (SMR; calculated as observed/ Expected (O/E) ratio for death from influenza and pneumonia among cancer patients).Results: The current study evaluates a total of 3,579,199 cancer patients (diagnosed 1975-2016) within the SEER-9 registries; and influenza and pneumonia-attributed deaths represent 1.5% of the recorded deaths for this cohort. SMR for influenza/ pneumonia-attributed death within the first year following cancer diagnosis was 1.88 (1.83-1.94);while SMR for influenza/pneumonia-attributed death following the first year was 1.11 (1.10-1.12). Within the first year following cancer diagnosis, SMR from influenza/pneumonia was higher among individuals with black race (SMR for white race: 1.75 (95% CI: 1.69-1.81) while SMR for black race: 2.90 (95% CI: 2.65-3.16), lung cancer (SMR for lung cancer: 4.39 (95% CI: 4.11-4.69)), head and neck cancer (SMR for oral cavity/ pharynx cancer: 4.02 (95% CI: 3.50-4.59)), lymphomas (SMR for lymphoma: 3.28 (95% CI: 2.92-3.68)), leukemias (SMR for leukemia: 3.32 (95% CI: 2.89-3.80)) and myeloma (SMR for myeloma: 3.91 (95% CI: 3.28-4.63)).Conclusions: Cancer patients are more likely to have influenza/ pneumonia-attributed death compared to the general US population. This risk is higher among patients with lung cancer, head and neck cancer, and hematological malignancies.

The disease burden of influenza beyond respiratory illness

Although influenza is primarily considered a respiratory infection and causes significant respiratory mortality, evidence suggests that influenza has an additional burden due to broader consequences of the illness. Some of these broader consequences include cardiovascular events, exacerbations of chronic underlying conditions, increased susceptibility to secondary bacterial infections, functional decline, and poor pregnancy outcomes, all of which may lead to an increased risk for hospitalization and death. Although it is methodologically difficult to measure these impacts, epidemiological and interventional study designs have evolved over recent decades to better take them into account. Recognizing these broader consequences of influenza virus infection is essential to determine the full burden of influenza among different subpopulations and the value of preventive approaches. In this review, we outline the main influenza complications and societal impacts beyond the classical respiratory symptoms of the disease.

Characterization of humoral and cellular immune features of gamma-irradiated influenza vaccine

The most widely used influenza vaccines are prepared by chemical inactivation. However, chemical, especially formalin, treatment-induced modifications of the antigenic structure of the virus are frequently associated with adverse effects including low efficacy of protection, unexpected immune responses, or exacerbation of disease. Gamma-irradiation was suggested as an alternative influenza virus inactivation method due to its great features of completely inactivating virus while not damaging the structures of protein antigens, and cross-protective ability against heterologous strains. However, immunological features of gamma radiation-inactivated influenza vaccine have not been fully understood. In this study, we aimed to investigate the humoral and cellular immune responses of gamma radiation-inactivated influenza vaccine. The gamma irradiation-inactivated influenza vaccine (RADVAX_FluA) showed complete viral inactivation but retained normal viral structure with functional activities of viral protein antigens. Intranasal immunization of RADVAX_FluA provided better protection against influenza virus infection than formalin-inactivated influenza virus (FIV) in mice. RADVAX_FluA greatly enhanced the production of virus-specific serum IgG and alveolar mucosal IgA, which effectively neutralized HA (hemagglutinin) and NA (neuraminidase) activities, and blocked viral binding to the cells, respectively. Further analysis of IgG subclasses showed RADVAX_FluA-immunized sera had higher levels of IgG1 and IgG2a than those of FIV-immunized sera. In addition, analysis of cellular immunity found RADVAX_FluA induced strong dendritic cells (DC) activation resulting in higher DC-mediated activation of CD8⁺ T cells than FIV. The results support improved immunogenicity by RADVAX_FluA.

Chronic exposure to arsenite enhances influenza virus infection in cultured cells

Arsenic is a ubiquitous environmental toxicant that has been associated with human respiratory diseases. In humans, arsenic exposure has been associated with increased risk of respiratory infection. Considering the existing epidemiological evidence and the well-established impact of arsenic on epithelial cell biology, we posited that the effect of arsenic exposure in epithelial cells could enhance viral infection. In this study, we characterized influenza virus A/WSN/33 (H1N1) infection in Madin-Darby Canine Kidney (MDCK) cells chronically exposed to low levels of sodium arsenite (75 ppb). We observed a 27.3-fold increase in viral matrix (M2) protein (24 hours postinfection [p.i.]), a 1.35-fold increase in viral mRNA levels, and a 126% increase in plaque area in arsenite-exposed MDCK cells (48 hours p.i.). Arsenite exposure resulted in 114% increase in virus attachment-positive cells (2 hours p.i.) and 224% increase in α-2,3 sialic acid-positive cells. Interestingly, chronic exposure to arsenite reduced the effect of the antiviral drug, oseltamivir in MDCK cells. We also found that exposure to sodium arsenite resulted in a 4.4-fold increase in viral mRNA levels and significantly increased cytotoxicity in influenza A/Udorn/72 (H3N2) infected BEAS-2B cells. This study suggests that chronic arsenite exposure could result in enhanced influenza infection in epithelial cells, and that this may be mediated through increased sialic acid binding. Finally, the decreased effectiveness of the anti-influenza drug, oseltamivir, in arsenite-exposed cells raises substantial public health concerns if this effect translates to arsenic-exposed, influenza-infected people.

The Importance of Vaccinating Children and Pregnant Women against Influenza Virus Infection

Influenza virus infection is responsible for significant morbidity and mortality in the pediatric and pregnant women populations, with deaths frequently caused by severe influenza-associated lower respiratory tract infection and acute respiratory distress syndrome (ARDS). An appropriate immune response requires controlling the viral infection through activation of antiviral defenses, which involves cells of the lung and immune system. High levels of viral infection or high levels of inflammation in the lower airways can contribute to ARDS. Pregnant women and young children, especially those born prematurely, may develop serious complications if infected with influenza virus. Vaccination against influenza will lead to lower infection rates and fewer complications, even if the vaccine is poorly matched to circulating viral strains, with maternal vaccination offering infants protection via antibody transmission through the placenta and breast milk. Despite the health benefits of the influenza vaccine, vaccination rates around the world remain well below targets. Trust in the use of vaccines among the public must be restored in order to increase vaccination rates and decrease the public health burden of influenza.

Maternal Influenza Vaccination and the Risk of Laboratory-Confirmed Influenza Among Household Contacts Under the Age of Five in Mali

Influenza transmission is increased among household contacts. Vaccination decreases transmission; however it is unclear how vaccinating a single individual alters disease risk among household contacts, particularly in regions with low vaccination coverage. Pregnant women were randomized to influenza or control vaccination. Households were visited weekly until infants born to enrolled women reached 6 months. Household contacts younger than 5 years were tested for laboratory-confirmed influenza (LCI). Incidence of LCI and rate ratios (RtR) comparing incidence between vaccine groups were calculated. The secondary infection rate (SIR) was calculated for households where LCI was detected. The H1N1 strain in the vaccine was a match for circulating H1N1 during the study, thus, all analyses were performed for H1N1-LCI and any LCI. A total of 5,345 household contacts younger than 5 years followed for a mean of 228 days (standard deviation [SD] = 45 days) experienced 2,957 influenza-like illness episodes. Incidence of any LCI and H1N1-LCI was 23 (N = 276) and 7.3 per 100,000 days (N = 89), respectively. Household contacts of women who received influenza vaccine had fewer LCI (RtR = 0.90; 95% CI: 0.71, 1.14) and fewer H1N1-LCI (RtR = 0.73; 95% CI: 0.48, 1.11) episodes than contacts in control households. Incidence of LCI and household SIR were low in households of women enrolled in an influenza vaccine trial in Mali. Although low incidence made statistical significance difficult to detect, there was a trend for decreased rates of H1N1-LCI in households where a pregnant mother received influenza vaccination.

Burden of influenza-associated respiratory hospitalizations in the Americas, 2010-2015

BACKGROUND

Despite having influenza vaccination policies and programs, countries in the Americas underutilize seasonal influenza vaccine, in part because of insufficient evidence about severe influenza burden. We aimed to estimate the annual burden of influenza-associated respiratory hospitalizations in the Americas.

METHODS

Thirty-five countries in the Americas with national influenza surveillance were invited to provide monthly laboratory data and hospital discharges for respiratory illness (International Classification of Diseases 10th edition J codes 0-99) during 2010-2015. In three age-strata (<5, 5-64, and ≥65 years), we estimated the influenza-associated hospitalizations rate by multiplying the monthly number of respiratory hospitalizations by the monthly proportion of influenza-positive samples and dividing by the census population. We used random effects meta-analyses to pool age-group specific rates and extrapolated to countries that did not contribute data, using pooled rates stratified by age group and country characteristics found to be associated with rates.

RESULTS

Sixteen of 35 countries (46%) contributed primary data to the analyses, representing 79% of the America's population. The average pooled rate of influenza-associated respiratory hospitalization was 90/100,000 population (95% confidence interval 61-132) among children aged <5 years, 21/100,000 population (13-32) among persons aged 5-64 years, and 141/100,000 population (95-211) among persons aged ≥65 years. We estimated the average annual number of influenza-associated respiratory hospitalizations in the Americas to be 772,000 (95% credible interval 716,000-829,000).

CONCLUSIONS

Influenza-associated respiratory hospitalizations impose a heavy burden on health systems in the Americas. Countries in the Americas should use this information to justify investments in seasonal influenza vaccination-especially among young children and the elderly.

Physicians' awareness and practice toward influenza and pneumococcal vaccines for high-risk patients

Objectives:

The aim of the study is to assess the awareness of family medicine residents about influenza and pneumococcal vaccination for high-risk patients and to verify the most significant variables that might affect residents’ knowledge and the tools needed to enhance their practice.

Materials and Methods:

This cross-sectional study was conducted at four major hospitals in Riyadh, Saudi Arabia, during the period, October through December 2017. A pretested self-administered questionnaire was handed to 180 family residents. Descriptive statistics were used to analyze the study data. The Chi-square test was used to compare categorical variables data. The One-way ANOVA test was used to detect the significant difference.

Results:

The overall knowledge of physicians about influenza and pneumococcal vaccines was inadequate and was more toward pneumococcal vaccine, in spite their respectable knowledge about the target population. The main reasons for non- prescribing of vaccines were forgetfulness (59.4%), the availability of vaccines (33.9%), and the patients’ refusal (23.3%). The tools that might help for prescribing were the need for the presence of electronic reminder (69.4%) and the patients should follow a regular family physician (47.2%).

Conclusion:

Knowledge and practice of influenza and pneumococcal vaccination are inadequate. This is mainly because of forgetfulness owing to minimal guideline awareness, lack of vaccine availability, and patients’ refusal. The important recommendations to enhance vaccination practice among physicians are the implementation of electronic reminders, regular follow-up with the same physician in addition to educational programs during residency, and patient education about the importance of vaccinations as a means of disease prevention.

Respiratory Syncytial Virus and Associations With Cardiovascular Disease in Adults

Respiratory syncytial virus (RSV) is historically known for causing respiratory illness in young children, but the appreciation of its impact on older adults is growing. Studies have shown that hospitalization for respiratory illness due to RSV is complicated by cardiovascular events in 14% to 22% of adult patients, including worsening congestive heart failure, acute coronary syndrome, and arrhythmias. Additionally, underlying cardiovascular disease is associated with hospitalization in 45% to 63% of adults with confirmed RSV. In summary, patients with cardiopulmonary disease have higher rates of health care utilization for RSV-related illness and worse outcomes. Patients with cardiovascular disease likely represent an important target population for the rapidly developing field of RSV vaccines.

Hospitalization and death among patients with influenza, Guatemala, 2008-2012

Background

Influenza is a major cause of respiratory illness resulting in 3–5 million severe cases and 291,243-645,832 deaths annually. Substantial health and financial burden may be averted by annual influenza vaccine application, especially for high risk groups.

Methods

We used an active facility-based surveillance platform for acute respiratory diseases in three hospitals in Guatemala, Central America, to estimate the incidence of laboratory-confirmed hospitalized influenza cases and identify risk factors associated with severe disease (defined as admission to the intensive care unit (ICU) or death). We enrolled patients presenting with signs and symptoms of acute respiratory infection (ARI) and obtained naso- and oropharyngeal samples for real-time reverse transcriptase polymerase chain reaction (RT-PCR). We used multivariable logistic regression to identify risk factors for ICU admission or death, adjusted for age and sex.

Results

From May 2008 to July 2012, among 6326 hospitalized ARI cases, 446 (7%) were positive for influenza: of those, 362 (81%) had influenza A and 84 (18%) had influenza B. Fifty nine percent of patients were aged ≤ 5 years, and 10% were aged ≥ 65 years. The median length of hospitalization was 5 days (interquartile range: 5). Eighty of 446 (18%) were admitted to the ICU and 28 (6%) died. Among the 28 deaths, 7% were aged ≤ 6 months, 39% 7–60 months, 21% 5–50 years, and 32% ≥ 50 years. Children aged ≤ 6 months comprised 19% of cases and 22% of ICU admissions. Women of child-bearing age comprised 6% of cases (2 admitted to ICU; 1 death). In multivariable analyses, Santa Rosa site (adjusted odds ratio [aOR] = 10, 95% confidence interval [CI] = 2–50), indigenous ethnicity (aOR = 4, 95% CI = 2–13, and radiologically-confirmed pneumonia (aOR = 5, 95% CI = 3–11) were independently associated with severe disease. Adjusted for hospital utilization rate, annual incidence of hospitalized laboratory-confirmed influenza was 24/100,000 overall, 93/100,000 for children aged < 5 years and 50/100,000 for those ≥ 65 years.

Conclusions

Influenza is a major contributor of hospitalization and death due to respiratory diseases in Guatemala. Further application of proven influenza prevention and treatment strategies is warranted.

Influenza surveillance during the 2009-2010, 2010-2011, 2011-2012, and 2012-2013 seasons in Algeria

We report the activity and circulation of influenza viruses in Algeria during four influenza seasons, from a national surveillance study carried out from 2009-2010 to 2012-2013. A total of 2766 samples from in- and outpatients, with no age restriction, were collected. The overall proportion of specimens that tested influenza positive was 46.0%. Overall, 96.6% of influenza A viruses were subtyped, and A/H1 subtypes accounted for 57.3% of influenza A viruses. Influenza A/H1 and A/H3 virus subtypes cocirculated in 2009-2010. In 2010-2011, a high proportion of type B viruses (66.2%) was observed. The subtype H3N2 was identified in 99% of cases typed in 2011-2012. Influenza A/H3N2 and B virus cocirculated in 2012-2013. A remarkably low influenza vaccination rate of 2.4% was observed among all age groups. Antibiotics were prescribed for 926 (41.3%) patients, and no difference was observed between patients with confirmed influenza and patients with influenza-like illness not related to influenza. The burden of influenza is largely undocumented in Algeria and strategies to expand this surveillance across the country are needed. Strategies to increase vaccination coverage are warranted to control and prevent influenza in individuals at risk of complications as well as in the general population.

CD4 T cells in protection from influenza virus: Viral antigen specificity and functional potential

CD4 T cells convey a number of discrete functions to protective immunity to influenza, a complexity that distinguishes this arm of adaptive immunity from B cells and CD8 T cells. Although the most well recognized function of CD4 T cells is provision of help for antibody production, CD4 T cells are important in many aspects of protective immunity. Our studies have revealed that viral antigen specificity is a key determinant of CD4 T cell function, as illustrated both by mouse models of infection and human vaccine responses, a factor whose importance is due at least in part to events in viral antigen handling. We discuss research that has provided insight into the diverse viral epitope specificity of CD4 T cells elicited after infection, how this primary response is modified as CD4 T cells home to the lung, establish memory, and after challenge with a secondary and distinct influenza virus strain. Our studies in human subjects point out the challenges facing vaccine efforts to facilitate responses to novel and avian strains of influenza, as well as strategies that enhance the ability of CD4 T cells to promote protective antibody responses to both seasonal and potentially pandemic strains of influenza.

Baloxavir marboxil: the new influenza drug on the market

For the first time in nearly 20 years there is a new class of antiviral drug for influenza. The latest approved antiviral is baloxavir marboxil (trade name, Xofluza) which targets the endonuclease function of the viral PA polymerase subunit and prevents the transcription of viral mRNA. The most promising aspect of this new drug is its pharmacology which allows for effective treatment of influenza A or B virus infection with just a single dose. A clinical trial showed greater reductions in viral loads with baloxavir marboxil treatment compared with oseltamivir, although no difference in the time to alleviation of symptoms between these two drugs. With this new class of influenza drug comes exciting prospects for combination therapy with the neuraminidase inhibitors which may help to abate concerns about the development of resistance.

Design of Nanoparticulate Group 2 Influenza Virus Hemagglutinin Stem Antigens That Activate Unmutated Ancestor B Cell Receptors of Broadly Neutralizing Antibody Lineages

Influenza vaccines targeting the highly conserved stem of the hemagglutinin (HA) surface glycoprotein have the potential to protect against pandemic and drifted seasonal influenza viruses not covered by current vaccines. While HA stem-based immunogens derived from group 1 influenza A viruses have been shown to induce intragroup heterosubtypic protection, HA stem-specific antibody lineages originating from group 2 may be more likely to possess broad cross-group reactivity. We report the structure-guided development of mammalian-cell-expressed candidate vaccine immunogens based on influenza A virus group 2 H3 and H7 HA stem trimers displayed on self-assembling ferritin nanoparticles using an iterative, multipronged approach involving helix stabilization, loop optimization, disulfide bond addition, and side-chain repacking. These immunogens were thermostable, formed uniform and symmetric nanoparticles, were recognized by cross-group-reactive broadly neutralizing antibodies (bNAbs) with nanomolar affinity, and elicited protective, homosubtypic antibodies in mice. Importantly, several immunogens were able to activate B cells expressing inferred unmutated common ancestor (UCA) versions of cross-group-reactive human bNAbs from two multidonor classes, suggesting they could initiate elicitation of these bNAbs in humans.IMPORTANCE Current influenza vaccines are primarily strain specific, requiring annual updates, and offer minimal protection against drifted seasonal or pandemic strains. The highly conserved stem region of hemagglutinin (HA) of group 2 influenza A virus subtypes is a promising target for vaccine elicitation of broad cross-group protection against divergent strains. We used structure-guided protein engineering employing multiple protein stabilization methods simultaneously to develop group 2 HA stem-based candidate influenza A virus immunogens displayed as trimers on self-assembling nanoparticles. Characterization of antigenicity, thermostability, and particle formation confirmed structural integrity. Group 2 HA stem antigen designs were identified that, when displayed on ferritin nanoparticles, activated B cells expressing inferred unmutated common ancestor (UCA) versions of human antibody lineages associated with cross-group-reactive, broadly neutralizing antibodies (bNAbs). Immunization of mice led to protection against a lethal homosubtypic influenza virus challenge. These candidate vaccines are now being manufactured for clinical evaluation.

Severe acute respiratory infections (SARI) from influenza in adult patients in Chile: the experience of a sentinel hospital

Objective

To 1) describe clinical characteristics of adult patients in Chile with severe acute respiratory infections (SARI) associated with influenza viruses, and 2) analyze virus subtypes identified in specimens collected from those patients, hospital resources used in clinical management, clinical evolution, and risk factors associated with a fatal outcome, using observational data from the SARI surveillance network (SARInet).

Methods

Adults hospitalized from 1 July 2011 to 31 December 2015 with influenza-associated SARI at a SARI sentinel surveillance hospital in Santiago were identified and the presence of influenza in all cases confirmed by reverse transcription polymerase chain reaction (RT-PCR), using respiratory samples.

Results

A total of 221 patients (mean age: 74.1 years) were hospitalized with influenza-associated SARI during the study period. Of this study cohort, 91.4% had risk factors for complications and 34.3% had been vaccinated during the most recent campaign. Pneumonia was the most frequent clinical manifestation, occurring in 57.0% of the cohort; other manifestations included influenza-like illness, exacerbated chronic bronchitis, decompensated heart failure, and asthmatic crisis. Cases occurred year-round, with an epidemic peak during autumn–winter. Both influenza A (H1N1pdm09 and H3N2) and B virus co-circulated. Critical care beds were required for 26.7% of the cohort, and 19.5% needed ventilatory assistance. Multivariate analysis identified four significant factors associated with in-hospital mortality: 1) being bedridden (adjusted odds ratio (aOR): 22.3; 95% confidence interval (CI): 3.0–164); 2) admission to critical care unit (aOR: 8.9; CI: 1.44–55); 3) Pa0₂/Fi0₂ ratio < 250 (aOR: 5.8; CI: 1.02–33); and 4) increased serum creatinine concentration (> 1 mg/dL) (aOR: 5.47; CI: 1.20–24). Seasonal influenza vaccine was identified as a significant protective factor (aOR: 0.14; CI: 0.021–0.90).

Conclusions

Influenza-associated SARI affected mainly elderly patients with underlying conditions. Most patients evolved to respiratory failure and more than one-quarter required critical care beds. Clinical presentation was variable. Death was associated with host characteristics and disease-associated conditions, and vaccine was protective. Virus type did not influence outcome.

Prioritization of risk groups for influenza vaccination in resource limited settings - A case study from South Africa

BACKGROUND

Due to competing health priorities, low- and middle-income countries (LMIC) may need to prioritize between different influenza vaccine risk groups. Risk group prioritization may differ in LMIC based upon programmatic feasibility, country-specific prevalence of risk conditions and influenza-associated morbidity and mortality.

METHODS

In South Africa, we collected local disease burden data (both published and unpublished) and published vaccine efficacy data in risk groups and healthy adults. We used these data to aid policy makers with risk group prioritization for influenza vaccination. We used the following formula to assess potential vaccine averted disease in each risk group: rate of influenza-associated hospitalization (or death) per 100,000 population * influenza vaccine efficacy (VE). We further estimated the cost per hospital day averted and the cost per year of life saved by influenza vaccination.

RESULTS

Pregnant women, HIV-infected adults, and adults and children with tuberculosis disease had among the highest estimates of hospitalizations averted per 100,000 vaccinated and adults aged 65 years and older had the highest estimated deaths averted per 100,000 vaccinated. However, when assessing both the cost per hospital day averted (range: USD148-1,344) and the cost per year of life saved (range: USD112-1,230); adults and children with TB disease, HIV-infected adults and pregnant women had the lowest cost per outcome averted.

DISCUSSION

An assessment of the potential disease outcomes averted and associated costs may aid policymakers in risk group prioritization for influenza vaccination.

Influenza vaccination coverage among US-Mexico land border crossers: 2009 H1N1 pandemic and 2011-2012 influenza season

BACKGROUND

The high volume of US-Mexico land border crossings can facilitate international dissemination of influenza viruses.

METHODS

We surveyed adult pedestrians crossing into the United States at two international land ports of entry to assess vaccination coverage during the 2009H1N1 influenza pandemic and 2011-2012 influenza season.

RESULTS

Of 559 participants in 2010, 23.4% reported receipt of the 2009H1N1 vaccine. Of 1423 participants in 2012, 33.7% received the 2011-2012 influenza vaccine. Both years, those crossing the border ≥8 times per month had lower vaccination coverage than those crossing less frequently. US-border residents had lower H1N1 coverage than those in other locations. Vaccination coverage was higher for persons age ≥65 years and, in 2010 only, those with less than high school education. Although most participants believed it is important to get vaccinated, only half believed the influenza vaccine was safe and effective. The main reasons for not receiving the influenza vaccine were beliefs of low risk of disease, time constraints, and concerns about vaccine safety (in 2010) or efficacy (in 2012).

CONCLUSIONS

International land border crossers are a large and unique category of travelers that require targeted binational strategies for influenza vaccination and education.

Review of seasonal influenza vaccination in the Eastern Mediterranean Region: Policies, use and barriers

Vaccination is the main control measure for influenza and its severe complications. To better understand the influenza vaccination situation in the Eastern Mediterranean Region, we conducted an extensive review of literature published between 2006 and 2016 in the region on influenza vaccine policies, use, recommendations and coverage. Forty-eight articles met the inclusion criteria. These originated from 11 of the 22 countries of the region, with most being from Saudi Arabia and Iran. The review revealed knowledge gaps and misconceptions about influenza and its vaccines even among healthcare workers. Most of the papers reviewed reported low coverage in the target populations. Limited literature on the number of countries with concrete national influenza vaccination policies was available, which may not accurately represent the situation in the Region. In conclusion, lack of awareness and knowledge are the main barriers to influenza vaccination, which remains very low in the Eastern Mediterranean Region. Countries of the region need to promote and invest in research on influenza vaccination, which is critical to inform evidence-based programmes and policies to improve vaccination rates and control influenza.

Seasonal Influenza Infections and Cardiovascular Disease Mortality

IMPORTANCE

Cardiovascular deaths and influenza epidemics peak during winter in temperate regions.

OBJECTIVES

To quantify the temporal association between population increases in seasonal influenza infections and mortality due to cardiovascular causes and to test if influenza incidence indicators are predictive of cardiovascular mortality during the influenza season.

DESIGN, SETTING, AND PARTICIPANTS

Time-series analysis of vital statistics records and emergency department visits in New York City, among cardiovascular deaths that occurred during influenza seasons between January 1, 2006, and December 31, 2012. The 2009 novel influenza A(H1N1) pandemic period was excluded from temporal analyses.

EXPOSURES

Emergency department visits for influenza-like illness, grouped by age (≥0 years and ≥65 years) and scaled by laboratory surveillance data for viral types and subtypes, in the previous 28 days.

MAIN OUTCOMES AND MEASURES

Mortality due to cardiovascular disease, ischemic heart disease, and myocardial infarction.

RESULTS

Among adults 65 years and older, who accounted for 83.0% (73 363 deaths) of nonpandemic cardiovascular mortality during influenza seasons, seasonal average influenza incidence was correlated year to year with excess cardiovascular mortality (Pearson correlation coefficients ≥0.75, P ≤ .05 for 4 different influenza indicators). In daily time-series analyses using 4 different influenza metrics, interquartile range increases in influenza incidence during the previous 21 days were associated with an increase between 2.3% (95% CI, 0.7%-3.9%) and 6.3% (95% CI, 3.7%-8.9%) for cardiovascular disease mortality and between 2.4% (95% CI, 1.1%-3.6%) and 6.9% (95% CI, 4.0%-9.9%) for ischemic heart disease mortality among adults 65 years and older. The associations were most acute and strongest for myocardial infarction mortality, with each interquartile range increase in influenza incidence during the previous 14 days associated with mortality increases between 5.8% (95% CI, 2.5%-9.1%) and 13.1% (95% CI, 5.3%-20.9%). Out-of-sample prediction of cardiovascular mortality among adults 65 years and older during the 2009-2010 influenza season yielded average estimates with 94.0% accuracy using 4 different influenza metrics.

CONCLUSIONS AND RELEVANCE

Emergency department visits for influenza-like illness were associated with and predictive of cardiovascular disease mortality. Retrospective estimation of influenza-attributable cardiovascular mortality burden combined with accurate and reliable influenza forecasts could predict the timing and burden of seasonal increases in cardiovascular mortality.

Laboratory-Confirmed Respiratory Infections as Predictors of Hospital Admission for Myocardial Infarction and Stroke: Time-Series Analysis of English Data for 2004-2015

Background

Acute respiratory infections are associated with increased risk of myocardial infarction (MI) and stroke; however, the role of different organisms is poorly characterized.

Methods

Time-series analysis of English hospital admissions for MI and stroke (age-stratified: 45-64, 65-74, ≥75 years), laboratory-confirmed viral respiratory infections, and environmental data for 2004-2015. Weekly counts of admissions were modeled using multivariable Poisson regression with weekly counts of respiratory viruses (influenza, parainfluenza, rhinovirus, respiratory syncytial virus [RSV], adenovirus, or human metapneumovirus [HMPV]) investigated as predictors. We controlled for seasonality, long-term trends, and environmental factors.

Results

Weekly hospital admissions in adults aged ≥45 years averaged 1347 (interquartile range [IQR], 1217-1541) for MI and 1175 (IQR, 1023-1395) for stroke. Respiratory infections ranged from 11 cases per week (IQR, 5-53) for influenza to 55 (IQR, 7-127) for rhinovirus. In the adjusted models, all viruses except parainfluenza were significantly associated with MI and ischemic stroke admissions in those aged ≥75. Among 65- to 74-year-olds, adenovirus, rhinovirus, and RSV were associated with MI but not ischemic stroke admissions. Respiratory infections were not associated with MI or ischemic stroke in people aged 45-64 years, nor with hemorrhagic stroke in any age group. An estimated 0.4%-5.7% of MI and ischemic stroke admissions may be attributable to respiratory infection.

Conclusions

We identified small but strongly significant associations in the timing of respiratory infection (with HMPV, RSV, influenza, rhinovirus, and adenovirus) and MI or ischemic stroke hospitalizations in the elderly.

Clinical Trials Registration

NCT02984280.

Maternal viral mimetic administration at the beginning of fetal hypothalamic nuclei development accelerates puberty in female rat offspring

This study aimed to investigate the effects of maternal viral infection during a critical time window of fetal hypothalamic development on timing of puberty in the female offspring. For that purpose, a viral mimetic (i.e., synthetic double-strand RNA, namely, polyinosinic–polycytidylic acid, poly (I:C)) or saline was injected (i.p.) to the pregnant rats during the beginning (day 12 of pregnancy, n = 5 for each group) or at the end of this time window (day 14 of pregnancy, n = 5 for each group). Four study groups were formed from the female pups (n = 9–10 pups/group). Following weaning of pups, vaginal opening and vaginal smearing was studied daily until 2 sequential estrous cycles were observed. During the second diestrus phase, blood samples were taken for progesterone, leptin, corticosterone, follicle-stimulating hormone, and luteinizing hormone. Maternal poly (I:C) injection on day 12 of pregnancy increased body mass and reduced the time to puberty in the female offspring. Neither poly (I:C) nor timing of injection affected other parameters studied (p > 0.05). It has been shown for the first time that maternal viral infection during the beginning of fetal hypothalamic development might hasten puberty by increasing body mass in rat offspring.

Burden of Influenza in Less Than 5-Year-Old Children Admitted to Hospital with Pneumonia in Developing and Emerging Countries: A Descriptive, Multicenter Study

This descriptive 4-year study reports the proportion of detection of influenza viruses in less than 5-year-old children hospitalized for pneumonia in eight developing and emerging countries and describes clinical and microbiological characteristics of influenza-related pneumonia cases. Hospitalized children presenting radiologically confirmed pneumonia aged 2-60 months were prospectively enrolled in this observational standardized study. Mean proportion of isolated influenza virus was 9.7% (95% confidence interval: 7.9-11.8%) among 888 pneumonia children analyzed, with moderate heterogeneity between countries-ranging from 6.2% in Cambodia to 18.8% in Haiti. The clinical characteristics of children with influenza-related pneumonia were not substantially different from those of other pneumonia cases. Influenza A H1N1-related pneumonia cases appeared as more severe than pneumonia cases related to other strains of influenza. Streptococcus pneumoniae was detected more often in blood samples from influenza-related cases than in those without detected influenza viruses (19.7% versus 9.5%, P = 0.018). Influenza-related pneumonia is frequent among children less than 5 years old with pneumonia, living in developing and emerging countries. Influenza might be a frequent etiologic agent responsible for pneumonia or a predisposing status factor for pneumococcal-related pneumonia in this population.

Trends of influenza B during the 2010-2016 seasons in 2 regions of north and south Italy: The impact of the vaccine mismatch on influenza immunisation strategy

Influenza A and B viruses are responsible for respiratory infections, representing globally seasonal threats to human health. The 2 viral types often co-circulate and influenza B plays an important role in the spread of infection. A 6-year retrospective surveillance study was conducted between 2010 and 2016 in 2 large administrative regions of Italy, located in the north (Liguria) and in the south (Sicily) of the country, to describe the burden and epidemiology of both B/Victoria and B/Yamagata lineages in different healthcare settings. Influenza B viruses were detected in 5 of 6 seasonal outbreaks, exceeding influenza A during the season 2012-2013. Most of influenza B infections were found in children aged ≤ 14 y and significant differences were observed in the age-groups infected by the different lineages. B/Victoria strains prevailed in younger population than B/Yamagata, but also were more frequently found in the community setting. Conversely, B/Yamagata viruses were prevalent among hospitalized cases suggesting their potential role in the development of more severe disease. The relative proportions of viral lineages varied from year to year, resulting in different lineage-level mismatch for the B component of trivalent influenza vaccine. Our findings confirmed the need for continuous virological surveillance of seasonal epidemics and bring attention to the adoption of universal influenza immunization program in the childhood. The use of tetravalent vaccine formulations may be useful to improve the prevention and control of the influenza burden in general population.

Epidemiologic and Spatiotemporal Characterization of Influenza and Severe Acute Respiratory Infection in Uganda, 2010-2015

RATIONALE

Little is known about the epidemiology of severe acute respiratory infection (SARI) or influenza in sub-Saharan Africa. Characterization of influenza transmission dynamics and risk factors for severe disease and mortality is critical to inform prevention and mitigation strategies.

OBJECTIVES

To characterize the epidemiology and transmission dynamics of influenza and risk factors for influenza-associated severe respiratory infection in Uganda.

METHODS

Clinicians at 12 sentinel surveillance sites prospectively collected clinical data and upper respiratory tract samples from consecutive patients who met criteria for SARI and influenza-like illness (ILI). Samples were tested for influenza A and B viruses using real-time reverse transcription-polymerase chain reaction. Spatial and spatiotemporal cluster modeling was performed to identify loci of increased influenza transmission. Morbidity and mortality were assessed through chart review in a defined subset of patients. Univariable and multivariable analyses were used to identify risk factors for severe respiratory infection, prolonged hospitalization, and in-hospital mortality.

MEASUREMENTS AND MAIN RESULTS

From October 2010 to June 2015, 9,978 patients met case definitions for SARI and ILI and had samples tested for influenza A and B. Of the 9,978 patient samples tested, 1,113 (11.2%) were positive for influenza. Among 6,057 patients with ILI, 778 samples (12.8%) were positive, and among 3,921 patients with SARI, 335 samples (8.5%) were positive. Significant clustering of influenza cases was observed in urban and periurban areas and during rainy seasons. Among 1,405 cases of SARI with available outcome data, in-hospital mortality was 1.6%. Infection with the 2009 pandemic A/H1N1 subtype and prolonged time to presentation were independently associated with SARI among influenza cases.

CONCLUSIONS

Influenza is associated with a substantial proportion of acute respiratory infection in Uganda. As influenza vaccination programs are developed in East Africa, timing campaigns to confer protection during rainy seasons should be considered, particularly among high-risk urban populations.

Influenza-associated thrombotic microangiopathies

Thrombotic microangiopathy (TMA) refers to phenotypically similar disorders, including hemolytic uremic syndromes (HUS) and thrombotic thrombocytopenic purpura (TTP). This review explores the role of the influenza virus as trigger of HUS or TTP. We conducted a literature survey in PubMed and Google Scholar using HUS, TTP, TMA, and influenza as keywords, and extracted and analyzed reported epidemiological and clinical data. We identified 25 cases of influenza-associated TMA. Five additional cases were linked to influenza vaccination and analyzed separately. Influenza A was found in 83%, 10 out of 25 during the 2009 A(H1N1) pandemic. Two patients had bona fide TTP with ADAMTS13 activity <10%. Median age was 15 years (range 0.5-68 years), two thirds were male. Oligoanuria was documented in 81% and neurological involvement in 40% of patients. Serum C3 was reduced in 5 out of 14 patients (36%); Coombs test was negative in 7 out of 7 and elevated fibrin/fibrinogen degradation products were documented in 6 out of 8 patients. Pathogenic complement gene mutations were found in 7 out of 8 patients tested (C3, MCP, or MCP combined with CFB or clusterin). Twenty out of 24 patients recovered completely, but 3 died (12%). Ten of the surviving patients underwent plasma exchange (PLEX) therapy, 5 plasma infusions. Influenza-mediated HUS or TTP is rare. A sizable proportion of tested patients demonstrated mutations associated with alternative pathway of complement dysregulation that was uncovered by this infection. Further research is warranted targeting the roles of viral neuraminidase, enhanced virus-induced complement activation and/or ADAMTS13 antibodies, and rational treatment approaches.

Associations between meteorological parameters and influenza activity in a subtropical country: Case of five sentinel sites in Yaoundé-Cameroon

Influenza is associated with highly contagious respiratory infections. Previous research has found that influenza transmission is often associated with climate variables especially in temperate regions. This study was performed in order to fill the gap of knowledge regarding the relationship between incidence of influenza and three meteorological parameters (temperature, rainfall and humidity) in a tropical setting. This was a retrospective study performed in Yaoundé-Cameroon from January 2009 to November 2015. Weekly proportions of confirmed influenza cases from five sentinel sites were considered as dependent variables, whereas weekly values of mean temperature, average relative humidity and accumulated rainfall were considered as independent variables. A univariate linear regression model was used in determining associations between influenza activity and weather covariates. A time-series method was used to predict on future values of influenza activity. The data was divided into 2 parts; the first 71 months were used to calibrate the model, and the last 12 months to test for prediction. Overall, there were 1173 confirmed infections with influenza virus. Linear regression analysis showed that there was no statistically significant association observed between influenza activity and weather variables. Very weak relationships (-0.1 < r < 0.1) were observed. Three prediction models were obtained for the different viral types (overall positive, Influenza A and Influenza B). Model 1 (overall influenza) and model 2 (influenza A) fitted well during the estimation period; however, they did not succeed to make good forecasts for predictions. Accumulated rainfall was the only external covariate that enabled good fit of both models. Based on the stationary R², 29.5% and 41.1% of the variation in the series can be explained by model 1 and 2, respectively. This study laid more emphasis on the fact that influenza in Cameroon is characterized by year-round activity. The meteorological variables selected in this study did not enable good forecast of future influenza activity and certainly acted as proxies to other factors not considered, such as, UV radiation, absolute humidity, air quality and wind.