Global mortality associated with seasonal influenza epidemics: New burden estimates and predictors from the GLaMOR Project

Analysis of spatial and temporal aggregation of influenza cases in Quzhou before and after COVID-19 pandemic

BACKGROUND

The global seasonal influenza activity has decreased during the coronavirus disease 2019 (COVID-19) pandemic. Non-pharmaceutical interventions (NPIs), such as reducing gatherings and wearing masks, can have varying impacts on the spread of influenza. We aim to analyse the basic characteristics, epidemiology and space-time clustering of influenza in Quzhou city before and after the COVID-19 pandemic based on five years of surveillance data.

METHODS

Influenza case incidence data from 2018-2023 were collected and organized in Quzhou City to analyse the space-time aggregation of influenza incidence before and after COVID-19 pandemic through global spatial autocorrelation analysis and space-time scan analysis methods.

RESULTS

The annual average fluctuation of influenza in Quzhou City from 2018-2023 was large, with gradual decreases in 2019-2020, 2020-2021 and 2021-2022, all of which showed obvious winter and spring peaks; The highest incidence rate in 2022-2023, with a bimodal distribution. The majority of the population is under 15 years of age, accounting for more than 70% of the population. The population classification is dominated by students, nursery children and children in the diaspora. In 2020-2021, the cases in the student group of the 5-14 years old population declined. Global spatial autocorrelation analysis of influenza incidence rate in Quzhou City in each year of 2019-2023Moran's I > 0 and p < 0.05. Space-time scan analysis of the aggregation area is located in Longyou County and the township streets on the border of urban counties, and the number of aggregation areas decreased significantly in 2020-2021 and 2021-2022.

CONCLUSION

The COVID-19 pandemic has an important impact on changes in influenza incidence levels and spatial and temporal epidemiologic aggregation patterns. Influenza incidence in Quzhou City fluctuates widely, with large changes in the age and occupational composition ratios of the incidence population, and influenza incidence presents a more pronounced spatial correlation and aggregation.

Interactive effects of air pollutants and viral exposure on daily influenza hospital visits in Mongolia

BACKGROUND

Air pollution is a well-documented public health hazard linked to various adverse health outcomes. While studies have shown associations between elevated levels of air pollutants and increased influenza incidence, there is a notable knowledge gap concerning the interactive effects of air pollution and viral exposure on respiratory viral infections.

OBJECTIVES

This study sought to examine the interactive effects of air pollution and viral exposure on influenza hospital visits in Ulaanbaatar, Mongolia.

METHODS

We conducted a time-series analysis linking daily hospital visits for influenza disease (defined as ICD10 diagnosis codes J11) with ambient concentrations of air pollutants (PM1, PM2.5, PM10, NO2, SO2, and O3) over a period of 7 years. Viral exposure for a specific geographical region was estimated based on influenza hospital visits within acute (previous day) and sub-acute (preceding 7 days) exposure windows. Covariates included long-term time trend, temperature, temperature variation, relative humidity, holiday, and raw coal ban policy. An over-dispersed generalized linear model (GLM) with a quasi-Poisson distribution was used to assess associations, exploring interactions and lag effects up to 3 days. Season-specific models and stratified analyses by sex and age were performed, with sensitivity analyses using multi-pollutant models.

RESULTS

A total of 16,364 influenza hospital visits were recorded, with significantly higher rates of visits during the winter season. All six pollutants amplified the effects of viral exposure on hospital visits in cold months, while only PM1, PM2.5, and O3 showed synergistic effects in warm months. Stronger synergistic effects were observed among children under 5 years old, particularly for O3.

CONCLUSIONS

Air pollution significantly amplified the adverse effects of viral exposure on influenza-hospital visits, particularly among young children and during high viral exposure periods. These findings underscore the need for employing protective measures against both air pollution and viral infections.

AI-assisted diagnostic approach for the influenza-like illness in children: decision support system for patients and clinicians

Influenza-like illnesses (ILI), such as influenza and RSV, pose significant global health burdens, especially in febrile children under 6 years old. Differentiating these from bacterial infections based solely on clinical symptoms is challenging. While PCR tests are reliable, they are costly and time-consuming. An effective predictive tool would help doctors prioritize tests and guide parents on seeking emergency care for their febrile children. We collected data from 2,559 children who visited the hospital for ILI inspections. We developed XGBoost models, comparing nine different machine learning algorithms. Our AI-assisted diagnostic pipeline consists of two stages: Decision Support System for patients (DSS-P): An in-house model using sex, age, symptoms, and medical history to decide on hospital visits. Decision Support System for clinicians (DSS-C): An in-hospital model incorporating breath sound types and Chest X-ray results to determine the necessity of clinical tests. We tested various experimental settings, including the addition of RAT-tested samples and the combined consideration of influenza and RSV. The performance for influenza achieved an Area Under the Curve of 0.749 and 0.776, while RSV achieved 0.907 and 0.924 in DSS-P and DSS-C, respectively. We identified biomarkers, noting that most biomarkers had opposite effects for influenza and RSV. This study developed predictive models for influenza and RSV and explored their underlying mechanisms. An expectation tool to guide doctors in prioritizing tests or assisting parents in deciding on emergency care for their febrile child would be invaluable. Biomarker analysis performed can provide insight on clinical fields.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13534-024-00450-8.

Retrospective study on the epidemiological characteristics of multi-pathogen infections of hospitalized severe acute respiratory tract infection and influenza-like illness in Xinjiang from January to May 2024

BACKGROUND

Acute respiratory tract infections are very common and can be caused by many pathogens. The aim of this study was to understand the characteristics of multi-pathogen infections of respiratory tract infections during the seasonal changes in winter and spring in Xinjiang.

METHODS

Throat swab samples were collected from 2791 patients with influenza-like illness (ILI) and hospitalized severe acute respiratory tract infection (SARI) in Xinjiang from January 2024 to May 2024 for multi-pathogen detection. Then, the infection frequency of pathogens and their distribution characteristics in different months, genders, regions and case classifications were analyzed.

RESULTS

The positive infection rate of pathogens in 2791 patients was 48.30% (1348/2791). The proportion of patients infected with respiratory pathogens in the 0-9 age group was the highest. Of all pathogens detected, MP was most common in positive patients (22.03%). The highest frequency of multiple infections was SPn. RSV, FluA and FluB were the main infectious pathogens in January and February. The number of RV, HPIV and MP infections showed an increasing trend from January to May. Compared to female patients, male patients are more likely to be infected with ADV and SPn. Compared with hospitalized SARI patients, outpatient and emergency ILI patients were more susceptible to infection with ADV and FluB. However, hospitalized SARI patients were more susceptible to infection with RSV and MP. The positive infected patients mainly came from northern Xinjiang (60.83%). Compared with other regions, the proportion of ADV positive patients in northern Xinjiang was higher.

CONCLUSION

This study revealed the distribution characteristics of pathogen infection in patients with respiratory tract infections in different months, genders, regions and case classifications during the seasonal changes of winter and spring in Xinjiang for the first time, which is helpful to formulate more effective treatment strategies and preventive measures.

CLINICAL TRIAL NUMBER

not applicable.

Antiviral activity of silver nanoparticles against H1N1 influenza virus

BACKGROUND

Influenza virus is a significant cause of annual global respiratory disease and death. According to the limited availability of effective drugs and vaccines, innovative antivirals are currently being investigated as possible strategies to contain the spread of infectious agents. Among the various types of nanoparticles, silver nanoparticles (Ag-NPs) have attracted great interest due to their exceptional physicochemical properties. This study aims to investigate the antiviral activity of Ag-NPs against the influenza A virus (IAV)/H1N1.

METHODS

The MTT assay was used to determine the possible cytotoxicity of the Ag-NPs. Madin-Darby canine kidney (MDCK) cells were exposed to Ag-NPs extract in conjunction with 100 cell culture infectious dose 50% (CCID50) of virus administered at time intervals during the infection process. The antiviral activity of the extract was evaluated under pre-treatment, post-treatment, and simultaneous assay. Viral titer reduction was assayed using hemagglutination (HA) and CCID50 assays. Viral RNA relative quantification by real-time Polymerase Chain Reaction approach was performed in each experimental condition.

RESULTS

The study yielded significant findings regarding the inhibitory effects of Ag-NPs on the IAV/H1N1. Silver nanoparticles showed dose-dependent inhibition of the virus, with the strongest effect observed when administered simultaneously with the virus which the virus titer exhibited a substantial decrease from 5 Log10 in the control group to 1 Log10 in the initial samples, further reducing to 2 Log10 per milliliter at lower concentrations. Notably, Ag-NPs demonstrated a greater reduction in virus titer during the simultaneous stage, showing a statistically significant difference (P < 0.05) between the control and experimental groups). The reduction in viral titer was also evident in both pre- and post-inoculation stages, although the effects were different.

CONCLUSION

Silver nanoparticles possess inhibitory effects on the growth of the IAV/H1N1, with a significant reduction in virus titer. These findings suggest the potential of Ag-NPs as effective antiviral agents and highlight opportunities for further research and potential clinical applications in combating IAV (H1N1) infections.

Comparing physician and large language model responses to influenza patient questions in the online health community

INTRODUCTION

During influenza season, some patients tend to seek medical advice through online platforms. However, due to time constraints, the informational and emotional support provided by physicians is limited. Large language models (LLMs) can rapidly provide medical knowledge and empathy, but their capacity for providing informational support to patients with influenza and assisting physicians in providing emotional support is unclear. Therefore, this study evaluated the quality of LLM-generated influenza advice and its emotional support performance in comparison with physician advice.

METHODS

This study utilized 200 influenza question-answer pairs from the online health community. Data collection consisted of two parts: (1) A panel of board-certified physicians evaluated the quality of LLM advice vs physician advice. (2) Physician advice was polished using an LLM, and the LLM-rewritten advice was compared to the original physician advice using the LLM module.

RESULTS

For informational support, there was no significant difference between LLM and physician advice in terms of the presence of incorrect information, omission of information, extent of harm or empathy. Nevertheless, compared to physician advice, LLM advice was more likely to cause harm and to be in line with medical consensus. LLM was also able to assist physicians in providing emotional support, since the LLM-rewritten advice was significantly more respectful, friendly and empathetic, when compared with physician advice. Also, the LLM-rewritten advice was logically smooth. In most cases, LLM did not add or omit the original medical information.

CONCLUSION

This study suggests that LLMs can provide informational and emotional support for influenza patients. This may help to alleviate the pressure on physicians and promote physician-patient communication.

Ultrasensitive Specific Detection of Anti-influenza A H1N1 Hemagglutinin Monoclonal Antibody Using Silicon Nanowire Field Effect Biosensors

Rapid and sensitive detection of virus-related antigens and antibodies is crucial for controlling sudden seasonal epidemics and monitoring neutralizing antibody levels after vaccination. However, conventional detection methods still face challenges related to compatibility with rapid, highly sensitive, and compact detection apparatus. In this work, we developed a Si nanowire (SiNW)-based field-effect biosensor by precisely controlling the process conditions to achieve the required electrical properties via complementary metal-oxide-semiconductor (CMOS)-compatible nanofabrication processes. The SiNW surface was chemically modified with 2-aminoethylphosphonic acid, followed by a dehydration condensation reaction with influenza A H1N1 hemagglutinin (HA1), to enable specific detection of anti-HA1 immunoglobulin G (IgG). We successfully detected the anti-influenza IgG with concentrations ranging from 1 aM to 100 nM, achieving a remarkable detection limit of 6.0 aM. To demonstrate specificity, a control experiment was conducted using normal mouse IgG with concentrations of 6 aM to 600 nM. The results showed a high specificity, with the signal being 6-fold greater for the target IgG compared to the control IgG. This work demonstrates the capability of SiNW biosensors to detect anti-influenza A H1N1 hemagglutinin monoclonal antibody with enhanced detection sensitivity and specificity. This work lays the groundwork for future applications in detecting antibodies after vaccination or immunotherapy, contributing to the effective management of infectious pandemics.

Hospitalisation from seasonal influenza among persons with type 1 diabetes: a cohort study from the Swedish National Diabetes Register

OBJECTIVES

The aim of this study was to investigate the risk of severe influenza resulting in hospitalisation among adults with type 1 diabetes (T1D).

DESIGN

Nationwide cohort study using register data.

SETTINGS

Data from the National Diabetes Register (NDR) linked to the Swedish Patient Register, Statistics Sweden and the Swedish Population Register.

PARTICIPANTS

Persons with T1D in the Swedish NDR n=35 596 and control persons from the Swedish Population Register matched on age, sex and county of residence, n=155 590.

PRIMARY AND SECONDARY OUTCOMES

Hospitalisation from seasonal influenza from October 2013 to December 2019. Season-wise incidence and HRs were analysed in the T1D group compared with controls. Secondary outcomes were associations between clinical variables and hospitalisation due to seasonal influenza for persons with T1D.

RESULTS

There were 347 (1.0%) influenza admissions in persons with T1D and 332 (0.2%) in the control group. The overall incidence rate was 16.9/10 000 person-years in the T1D group and 3.6/10 000 person-years for the control group. Persons with T1D had an unadjusted HR 4.7 (95% CI 4.0 to 5.5) for risk of hospitalisation from influenza during the study period and HR 3.4 (95% CI 2.9 to 4.0) when adjusted for age, sex, socioeconomic factors and chronic medical conditions at baseline. Within the T1D cohort, individuals hospitalised due to influenza were older, were more often smokers, had lower glomerular filtration rate and more often had a previous history of ischaemic heart disease and stroke.

CONCLUSIONS

To our knowledge, this is the first large study to highlight that persons with T1D have a threefold higher risk of hospitalisation due to seasonal influenza compared with matched controls from the general population. It is important for healthcare professionals to acknowledge this excess risk, particularly in older persons with T1D, who have cardiovascular risk factors and reduced kidney function.

Are we serologically prepared against an avian influenza pandemic and could seasonal flu vaccines help us?

The current situation with H5N1 highly pathogenic avian influenza virus (HPAI) is causing a worldwide concern due to multiple outbreaks in wild birds, poultry, and mammals. Moreover, multiple zoonotic infections in humans have been reported. Importantly, HPAI H5N1 viruses with genetic markers of adaptation to mammals have been detected. Together with HPAI H5N1, avian influenza viruses H7N9 (high and low pathogenic) stand out due to their high mortality rates in humans. This raises the question of how prepared we are serologically and whether seasonal vaccines are capable of inducing protective immunity against these influenza subtypes. An observational study was conducted in which sera from people born between years 1925-1967, 1968-1977, and 1978-1997 were collected before or after 28 days or 6 months post-vaccination with an inactivated seasonal influenza vaccine. Then, hemagglutination inhibition, viral neutralization, and immunoassays were performed to assess the basal protective immunity of the population as well as the ability of seasonal influenza vaccines to induce protective responses. Our results indicate that subtype-specific serological protection against H5N1 and H7N9 in the representative Spanish population evaluated was limited or nonexistent. However, seasonal vaccination was able to increase the antibody titers to protective levels in a moderate percentage of people, probably due to cross-reactive responses. These findings demonstrate the importance of vaccination and suggest that seasonal influenza vaccines could be used as a first line of defense against an eventual pandemic caused by avian influenza viruses, to be followed immediately by the use of more specific pandemic vaccines.IMPORTANCEInfluenza A viruses (IAV) can infect and replicate in multiple mammalian and avian species. Avian influenza virus (AIV) is a highly contagious viral disease that occurs primarily in poultry and wild water birds. Due to the lack of population immunity in humans and ongoing evolution of AIV, there is a continuing risk that new IAV could emerge and rapidly spread worldwide, causing a pandemic, if the ability to transmit efficiently among humans was gained. The aim of this study is to analyze the basal protection and presence of antibodies against IAV H5N1 and H7N9 subtypes in the population from different ages. Moreover, we have evaluated the humoral response after immunization with a seasonal influenza vaccine. This study is strategically important to evaluate the level of population immunity that is a major factor when assessing the impact that an emerging IAV strain would have, and the role of seasonal vaccines to mitigate the effects of a pandemic.

Safety and Immunogenicity of mRNA-1010, an Investigational Seasonal Influenza Vaccine, in Healthy Adults: Final Results From a Phase 1/2 Randomized Trial

BACKGROUND

Seasonal influenza remains a global public health concern. A messenger RNA (mRNA)-based quadrivalent seasonal influenza vaccine, mRNA-1010, was investigated in a first-in-human, phase 1/2 clinical trial conducted in 3 parts.

METHODS

In parts 1 to 3 of this stratified observer-blind study, adults aged ≥18 years were randomly assigned to receive a single dose (6.25-200 µg) of mRNA-1010 or placebo (part 1) or an active comparator (Afluria; parts 2 and 3). Primary study objectives were assessment of safety, reactogenicity, and humoral immunogenicity of mRNA-1010, placebo (part 1), or active comparator (parts 2 and 3). Exploratory end points included assessment of cellular immunogenicity (part 1) and antigenic breadth against vaccine heterologous strains (A/H3N2; parts 1 and 2).

RESULTS

In all study parts, solicited adverse reactions were reported more frequently for mRNA-1010 than placebo or Afluria, and most were grade 1 or 2 in severity. No vaccine-related serious adverse events or deaths were reported. In parts 1 and 2, a single dose of mRNA-1010 (25-200 µg) elicited robust day 29 hemagglutination inhibition titers that persisted through 6 months. In part 3, lower doses of mRNA-1010 (6.25-25 µg) elicited day 29 hemagglutination inhibition titers that were higher or comparable to those of Afluria for influenza A strains. When compared with Afluria, mRNA-1010 (50 µg) elicited broader A/H3N2 antibody responses (part 2). mRNA-1010 induced greater T-cell responses than placebo at day 8 that were sustained or stronger at day 29 (part 1).

CONCLUSIONS

Data support the continued development of mRNA-1010 as a seasonal influenza vaccine.

CLINICAL TRIALS REGISTRATION

NCT04956575 (https://clinicaltrials.gov/study/NCT04956575).

Insights into the ecological and climate crisis: Emerging infections threatening human health

The Anthropocene era is marked by unprecedented human-induced alterations to the environment, resulting in a climate emergency and widespread ecological deterioration. A staggering number of up to one million species of plants and animals are in danger of becoming extinct, which includes over 10 % of insect species and 40 % of plant species. Unrestrained release of greenhouse gases, widespread deforestation, intense agricultural practices, excessive fishing, and alterations in land use have exceeded the ecological boundaries that were once responsible for humanity's wellbeing. As per the Intergovernmental Panel on Climate Change (IPCC), existing policies are expected to result in a minimum rise in global temperature of +2 °C, with more recent assessments indicating a potential increase of up to +2.9 °C. The effects of climate change and ecological degradation on the formation of diseases are complex and have multiple aspects. Deforestation diminishes biodiversity and compels wildlife to come into greater proximity with humans, hence promoting the transmission of zoonotic diseases. Climate change intensifies these impacts by modifying the habitats of disease carrying organisms, resulting in the expansion of vector-borne diseases such as malaria, dengue, and Zika virus into previously unaffected areas. Furthermore, climate change amplifies the occurrence and severity of extreme weather phenomena, which undermines water, sanitation, and hygiene (WASH) practices. This creates an environment conducive to the transmission of waterborne diseases such as cholera in densely populated resettlement camps. Climate-induced disasters contribute to the complexity of epidemiological landscapes, exacerbating antimicrobial resistance and posing a threat to modern medical advancements. This narrative review investigates the complex connections between the ecological-climatic crises and emerging illnesses, offering an overview on how environmental changes contribute to outbreaks that pose a substantial threat to public health.

Damage sensing through TLR9 regulates inflammatory and antiviral responses during influenza infection

Host response aimed at eliminating the infecting pathogen, as well as the pathogen itself, can cause tissue injury. Tissue injury leads to the release of a myriad of cellular components including mitochondrial DNA (mtDNA), which the host senses through pattern recognition receptors. How the sensing of tissue injury by the host shapes the anti-pathogen response remains poorly understood. In this study, we utilized mice that are deficient in toll-like receptor-9 (TLR9), which binds to unmethylated CpG DNA sequences such as those present in bacterial and mtDNA. To avoid direct pathogen sensing by TLR9, we utilized the influenza virus, which lacks ligands for TLR9, to determine how damage sensing by TLR9 contributes to anti-influenza immunity. Our data showed that TLR9-mediated sensing of tissue damage promoted an inflammatory response during early infection, driven by epithelial and myeloid cells. Along with the diminished inflammatory response, the absence of TLR9 led to impaired viral clearance manifested as higher and prolonged influenza components in myeloid cells, including monocytes and macrophages, rendering them highly inflammatory. The persistent inflammation driven by infected myeloid cells led to persistent lung injury and impaired recovery in influenza-infected TLR9-/- mice. Further, we found elevated TLR9 ligands in the plasma samples of patients with influenza infection and its association with the disease severity in hospitalized patients, demonstrating its clinical relevance. Overall, we demonstrated an essential role of damage sensing through TLR9 in promoting anti-influenza immunity and inflammatory response. AUTHOR SUMMARY: Tissue damage is an inevitable outcome of clinically relevant lung infections, but the host mechanisms for detecting such damage during infection are not well understood. We investigated the role of Toll-like receptor 9 (TLR9) in sensing tissue damage caused by influenza. Since influenza lacks TLR9 ligands, we hypothesized that TLR9 signaling is driven by tissue damage molecules like mitochondrial DNA (mtDNA). Our data revealed that TLR9 deficiency reduces early inflammatory lung injury but impairs viral clearance, resulting in extensive infection of immune cells, persistent inflammation, and delayed recovery. Myeloid-specific TLR9 deletion ameliorated late-stage inflammatory responses. In humans, influenza-infected individuals exhibited elevated TLR9 activity and mtDNA levels in plasma compared to healthy controls, with higher TLR9 activation potential correlating with severe disease requiring ICU admission. These findings suggest that TLR9-mediated damage sensing triggers both inflammatory tissue injury and viral clearance. These data indicate that TLR9 activity can serve as a crucial biomarker and therapeutic target to limit influenza-induced tissue injury.

Respiratory virus detections in children presenting to an Australian paediatric referral hospital pre-COVID-19 pandemic, January 2014 to December 2019

Acute respiratory infections cause significant paediatric morbidity, but for pathogens other than influenza, respiratory syncytial virus (RSV), and SARS-CoV-2, systematic monitoring is not commonly performed. This retrospective analysis of six years of routinely collected respiratory pathogen multiplex PCR testing at a major paediatric hospital in New South Wales Australia, describes the epidemiology, year-round seasonality, and co-detection patterns of 15 viral respiratory pathogens. 32,599 respiratory samples from children aged under 16 years were analysed. Most samples were associated with a hospital admission (24,149, 74.1%) and the median age of sampling was 16 months (IQR 5-53). Viruses were detected in 62.9% (20,510) of samples, with single virus detections occurring in 73.5% (15,082) of positive samples. In instances of single virus detection, rhinovirus was most frequent (5125, 40.6%), followed by RSV-B (1394, 9.2%) and RSV-A (1290, 8.6%). Moderate to strong seasonal strength was observed for most viruses with some notable exceptions. Rhinovirus and enterovirus were detected year-round and low seasonal strength was observed for adenovirus and bocavirus. Biennial seasonal patterns were observed for influenza B and parainfluenza virus 2. Co-detections occurred in 5,428 samples, predominantly with two (4284, 79.0%) or three viruses (904, 16.7%). The most common co-detections were rhinovirus-adenovirus (566, 10.4%), rhinovirus-enterovirus (357, 8.3%), and rhinovirus-RSV-B (337, 7.9%). Ongoing pan-pathogen surveillance, integrating both laboratory and clinical data, is necessary to assist in identification of key pathogens and combination of pathogens to support effective preventative public health strategies and reduce the burden of paediatric respiratory infections.

Obesity Is a Risk Factor for Severe Influenza Virus Infection and COVID-19 in Children

During influenza A virus or severe acute respiratory syndrome coronavirus 2 infection in adults, obesity is an independent risk factor for severe disease. In children, evidence is less clear. Research is needed to elucidate the mechanisms underpinning any association between obesity and severe respiratory viral infections in children.

Effects of fine particulate matter and its chemical constituents on influenza-like illness in Guangzhou, China

BACKGROUND

Although the link between fine particulate matter (PM2.5) and influenza-like illness (ILI) is well established, the effect of the chemical constituents of PM2.5 on ILI remains unclear. This study aims to explore this effect in Guangzhou, China.

METHODS

Daily data on ILI cases, PM2.5 levels, and specific PM2.5 constituents (black carbon [BC], chlorine [Cl-], ammonia [NH4+], nitrate [NO3-], and sulfate [SO42-]) in Guangzhou, China, were collected for the period of 2014-2019. Additionally, data on gaseous pollutants and meteorological conditions were obtained. By using quasi-Poisson regression models, the association between exposure to PM2.5 and its constituents and ILI risk was estimated. Stratified subgroup analyses were performed by gender, age, and season to explore in depth the effects of these factors on disease risk.

RESULTS

Single-pollutant modeling results showed that an increase of one interquartile range (IQR) in Cl-, SO42-, PM2.5, NH4+, BC, and NO3- corresponded to relative risks of ILI of 1.046 (95 % CI: 1.004, 1.090) (lag03), 1.098 (95 % CI: 1.058, 1.139) (lag01), 1.091 (95 % CI: 1.054, 1.130) (lag02), 1.093 (95 % CI: 1.049, 1.138) (lag02), 1.111 (95 % CI: 1.074, 1.150) (lag03), and 1.103 (95 % CI: 1.061, 1.146) (lag03), respectively. Notably, the association between ILI and BC remained significant even after adjusting for PM2.5 mass. Subgroup analyses indicated that individuals aged 5-14 and 15-24 years may exhibit higher sensitivity to BC and Cl- exposure than other individuals. Furthermore, stronger associations were observed during the cold season than during the warm season.

CONCLUSIONS

Results showed that the mass and constituents of PM2.5 were significantly correlated with ILI. Specifically, the carbonaceous fractions of PM2.5 were found to have a pronounced effect on ILI. These findings underscore the importance of implementing effective measures to reduce the emission of specific sources of PM2.5 constituents to mitigate the risk of ILI. Nevertheless, limitations such as potential exposure misclassification and regional constraints should be considered.

Galectin-3 disrupts tight junctions of airway epithelial cell monolayers by inducing expression and release of matrix metalloproteinases upon influenza A infection

Galectins are β-galactosyl-binding lectins with key roles in early development, immune regulation, and infectious disease. Influenza A virus (IAV) infects the airway epithelia, and in severe cases may lead to bacterial superinfections and hypercytokinemia, and eventually, to acute respiratory distress syndrome (ARDS) through the breakdown of airway barriers. The detailed mechanisms involved, however, remain poorly understood. Our prior in vivo studies in a murine model system revealed that upon experimental IAV and pneumococcal primary and secondary challenges, respectively, galectin-1 and galectin-3 (Gal-3) are released into the airway and bind to the epithelium that has been desialylated by the viral neuraminidase, contributing to secondary bacterial infection and hypercytokinemia leading to the clinical decline and death of the animals. Here we report the results of in vitro studies that reveal the role of the extracellular Gal-3 in additional detrimental effects on the host by disrupting the integrity of the airway epithelial barrier. IAV infection of the human airway epithelia cell line A549 increased release of Gal-3 and its binding to the A549 desialylated cell surface, notably to the transmembrane signaling receptors CD147 and integrin-β1. Addition of recombinant Gal-3 to A549 monolayers resulted in enhanced expression and release of matrix metalloproteinases, leading to disruption of cell-cell tight junctions, and a significant increase in paracellular permeability. This study reveals a critical mechanism involving Gal-3 that may significantly contribute to the severity of IAV infections by promoting disruption of tight junctions and enhanced permeability of the airway epithelia, potentially leading to lung edema and ARDS.

Safety and immunogenicity of mRNA-based seasonal influenza vaccines formulated to include multiple A/H3N2 strains with or without the B/Yamagata strain in US adults aged 50-75 years: a phase 1/2, open-label, randomised trial

BACKGROUND

Inclusion of additional influenza A/H3N2 strains in seasonal influenza vaccines could expand coverage against multiple, antigenically distinct, cocirculating A/H3N2 clades and potentially replace the no longer circulating B/Yamagata strain. We aimed to evaluate the safety and immunogenicity of three next-generation seasonal influenza mRNA vaccines with different compositions that encode for haemagglutinins of multiple A/H3N2 strains, with or without the B/Yamagata strain, in adults.

METHODS

This randomised, open-label, phase 1/2 trial enrolled healthy adults aged 50-75 years across 22 sites in the USA. Participants were randomly assigned (1:1:1:1:1:1:1) via interactive response technology to receive a single dose of mRNA-1011.1 (pentavalent; containing one additional A/H3N2 strain [Newcastle]), mRNA-1011.2 (quadrivalent; B/Yamagata replaced with one additional A/H3N2 strain [Newcastle]), mRNA-1012 at one of two dose levels (pentavalent; B/Yamagata replaced with two additional A/H3N2 strains [Newcastle and Hong Kong]), or one of three quadrivalent mRNA-1010 controls each encoding one of the A/H3N2 study strains. The primary outcomes were safety, evaluated in all randomly assigned participants who received a study vaccination (safety population), and reactogenicity, evaluated in all participants from the safety population who contributed any solicited adverse reaction data (solicited safety population). The secondary outcome was humoral immunogenicity of investigational mRNA vaccines at day 29 versus mRNA-1010 control vaccines based on haemagglutination inhibition antibody (HAI) assay in the per-protocol population. Here, we summarise findings from the planned interim analysis after participants had completed day 29. The study is registered with ClinicalTrials.gov, NCT05827068, and is ongoing.

FINDINGS

Between March 27 and May 9, 2023, 1183 participants were screened for eligibility, 699 (59·1%) were randomly assigned, and 696 (58·8%) received vaccination (safety population, n=696; solicited safety population, n=694; per-protocol population, n=646). 382 (55%) of the 696 participants in the safety population self-reported as female and 314 (45%) as male. Frequencies of solicited adverse reactions were similar across vaccine groups; 551 (79%) of 694 participants reported at least one solicited adverse reaction within 7 days after vaccination and 83 (12%) of 696 participants reported at least one unsolicited adverse event within 28 days after vaccination. No vaccine-related serious adverse events or deaths were reported. All three next-generation influenza vaccines elicited robust antibody responses against vaccine-matched influenza A and B strains at day 29 that were generally similar to mRNA-1010 controls, and higher responses against additional A/H3N2 strains that were not included within respective mRNA-1010 controls. Day 29 geometric mean fold rises in HAI titres from day 1 against vaccine-matched A/H3N2 strains were 3·0 (95% CI 2·6-3·6; Darwin) and 3·1 (2·6-3·8; Newcastle) for mRNA-1011.1; 3·3 (2·7-4·1; Darwin) and 4·2 (3·4-5·2; Newcastle) for mRNA-1011.2; 3·4 (2·9-4·0; Darwin), 4·5 (3·6-5·5; Newcastle), and 5·1 (4·2-6·2; Hong Kong) for mRNA-1012 50·0 μg; and 2·6 (2·2-3·1; Darwin), 3·7 (3·0-4·6; Newcastle), and 4·1 (3·3-5·1; Hong Kong) for mRNA-1012 62·5 μg. Inclusion of additional A/H3N2 strains did not reduce responses against influenza A/H1N1 or influenza B strains, and removal of B/Yamagata did not affect responses to B/Victoria.

INTERPRETATION

These data support the continued clinical development of mRNA-based next-generation seasonal influenza vaccines with broadened influenza A/H3N2 strain coverage.

FUNDING

Moderna.

Evaluation of the Seegene Allplex™ RV master assay for one-step simultaneous detection of eight respiratory viruses in nasopharyngeal specimens

BACKGROUND

The Seegene Allplex™ RV Master (RVM) assay is a one-step multiplex real-time reverse transcription polymerase chain reaction (RT-PCR) system for detecting eight viral respiratory pathogens from nasopharyngeal swab, aspirate, and bronchoalveolar lavage specimens. The eight RVM targets are: severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), Influenza A (Flu A), Influenza B (Flu B), Human respiratory syncytial virus (RSV), adenovirus (AdV), rhinovirus (HRV), parainfluenza virus (PIV), and metapneumovirus (MPV). The assay is based on Seegene's multiple detection temperature (MuDT) technology and provides cycle threshold (Ct) values for each of its viral targets upon PCR completion.

OBJECTIVE

We aimed to evaluate the diagnostic performance of the RVM assay by calculating sensitivity, specificity, accuracy, Positive Predictive Value (PPV), Negative Predictive Value (NPV), Positive Percent Agreement (PPA), Negative Percent Agreement (NPA), and Overall Percent Agreement (OPA) compared to definite diagnosis and analogous reference assays.

STUDY DESIGN

Diagnostic sensitivity, specificity, accuracy, PPV, and NPV were calculated by comparing the results of the RVM assay to that of definite diagnosis assays; while PPA, NPA, and OPA were calculated by comparing results of the RVM assay to that of analogous reference products. Definite diagnosis and reference methods comprised whole genome sequencing and PCR genotyping, the Allplex™ SARS-CoV-2/FluA/FluB/RSV and Respiratory Panels 1, 2, and 3 assays (Seegene), and the Xpert® Xpress SARS-CoV-2/FluA/FluB/RSV Plus assay (Cepheid). Reproducibility of the RVM assay using fully-automated and semi-automated nucleic acid (NA) extraction workflows and as performed by independent operators was also assessed. In total, 249 positive respiratory specimens and at least 50 negative specimens for each target tested were used for this evaluation study.

RESULTS

Sensitivity, specificity, accuracy, PPV, NPV, PPA, NPA, and OPA ranged from 95.7 % to 100 % for detecting all eight targets tested on the RVM assay. Reproducibility PPA, NPA, and OPA between automated and semi-automated NA extraction workflows were all >97.9 %, while the reproducibility PPA, NPA and OPA between independent operators were all 100 %.

CONCLUSION

These results demonstrate a high level of sensitivity, specificity, accuracy and diagnostic predictive value of the RVM assay and high agreement with comparable reference assays in identifying all eight of its targets. Taken together, our study underscores the diagnostic utility of the RVM assay in detecting eight viral respiratory pathogens.

Administration of antigenically distinct influenza viral particle combinations as an influenza vaccine strategy

One approach for developing a more universal influenza vaccine is to elicit strong immune responses against canonically immunosubdominant epitopes in the surface exposed viral glycoproteins. While standard vaccines typically induce responses directed primarily against mutable epitopes in the hemagglutinin (HA) head domain, there are generally limited or variable responses directed against epitopes in the relatively more conserved HA stalk domain and neuraminidase (NA) proteins. Here we describe a vaccine approach that utilizes a combination of wildtype (WT) influenza virus particles along with virus particles engineered to display a trimerized HA stalk in place of the full-length HA protein to elicit both responses simultaneously. After initially generating the "headless" HA-containing viral particles in the A/Hawaii/70/2019 (HI/19) genetic background and demonstrating the ability to elicit protective immune responses directed against the HA-stalk and NA, we co-formulated those virions with unmodified WT viral particles. The combination vaccine elicited "hybrid" and protective responses directed against the HA-head, HA-stalk, and NA proteins in both naïve and pre-immune mice and ferrets. Collectively, our results highlight a potentially generalizable method combining viral particles with differential antigenic compositions to elicit broader immune responses that may lead to more durable protection from influenza disease post-vaccination.

Burden of Acute Respiratory Infections Caused by Influenza Virus, Respiratory Syncytial Virus, and SARS-CoV-2 with Consideration of Older Adults: A Narrative Review

Influenza virus, respiratory syncytial virus (RSV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are acute respiratory infections (ARIs) that can cause substantial morbidity and mortality among at-risk individuals, including older adults. In this narrative review, we summarize themes identified in the literature regarding the epidemiology, seasonality, immunity after infection, clinical presentation, and transmission for these ARIs, along with the impact of the COVID-19 pandemic on seasonal patterns of influenza and RSV infections, with consideration of data specific to older adults when available. As the older adult population increases globally, it is of paramount importance to fully characterize the true disease burden of ARIs in order to develop appropriate mitigation strategies to minimize their impact in vulnerable populations. Challenges associated with characterizing the burden of these diseases include the shared symptomology and clinical presentation of influenza virus, RSV, and SARS-CoV-2, which complicate accurate diagnosis and highlight the need for improved testing and surveillance practices. To this end, multiple regional, national, and global virologic and disease surveillance systems have been established to provide accurate knowledge of viral epidemiology, support appropriate preparedness and response to potential outbreaks, and help inform prevention strategies to reduce disease severity and transmission. Beyond the burden of acute illness, long-term health consequences can also result from influenza virus, RSV, and SARS-CoV-2 infection. These include cardiovascular and pulmonary complications, worsening of existing chronic conditions, increased frailty, and reduced life expectancy. ARIs among older adults can also place a substantial financial burden on society and healthcare systems. Collectively, the existing data indicate that influenza virus, RSV, and SARS-CoV-2 infections in older adults present a substantial global health challenge, underscoring the need for interventions to improve health outcomes and reduce the disease burden of respiratory illnesses.Graphical abstract and video abstract available for this article.

A cross-sectional study on the understanding and attitudes toward influenza and influenza vaccines among different occupational groups in China

This study aimed to assess the level of knowledge regarding influenza viruses and vaccines among different professional groups to investigate the reasons for vaccine hesitancy. We collected 2190 questionnaires regarding influenza vaccines in China in 2022. The respondents were categorized into the general population (GP), foreign affairs workforce population (FAWP), and veterinary workforce population (VWP) according to their job positions. Linear regression was used to assess the association between multiple factors and influenza vaccination rates. The association between work and influenza vaccination rates was also assessed by grouping different workforce populations. The vaccination rate of the GP was higher than that of the VWP (odds ratio: 1.342, 95% confidence interval: 1.025-1.853), surpassing the rates reported in previous studies. This may be attributed to heightened concerns about infectious diseases influenced by the ongoing coronavirus disease 2019 pandemic. Despite the VWP's more in-depth knowledge of the VWP on zoonotic diseases and their recognition of their importance, there was no significant difference in influenza knowledge among the three populations. This discrepancy contrasts with the observed differences in vaccination rates. Further investigation revealed that, compared with FAWP, the price of vaccines emerged as a primary influencing factor for vaccination rates (odds ratio:0.398, 95%CI; 0.280-0.564). General concerns regarding the protective effects and side effects of vaccines were also noted.

Neutralization potency of the 2023-24 seasonal influenza vaccine against circulating influenza H3N2 strains

Seasonal influenza is a severe disease that significantly impacts public health, causing millions of infections and hundreds of thousands of deaths each year. Seasonal influenza viruses, particularly the H3N2 subtype, exhibit high antigenic variability, often leading to mismatch between vaccine strains and circulating strains. Therefore, rapidly assessing the alignment between existing seasonal influenza vaccine and circulating strains is crucial for enhancing vaccine efficacy. This study, based on a pseudovirus platform, evaluated the match between current influenza H3N2 vaccine strains and circulating strains through cross-neutralization assays using clinical human immune sera against globally circulating influenza virus strains. The research results show that although mutations are present in the circulating strains, the current H3N2 vaccine strain still imparting effective protection, providing a scientific basis for encouraging influenza vaccination. This research methodology can be sustainably applied for the neutralization potency assessment of subsequent circulating strains, establishing a persistent methodological framework.

COBRA N2 NA vaccines induce protective immune responses against influenza viral infection

Influenza neuraminidase (NA) is a promising target for a broadly protective vaccine. In this study, the Computationally Optimized Broadly Reactive Antigen (COBRA) methodology was used to develop N2 NA vaccine candidates. The unique wild type (WT) N2 sequences of human and swine influenza strains isolated between 1957 and 2019 were used to design the COBRA N2-A NA vaccine, while the unique WT N2 sequences of human influenza strains isolated between 2000 and 2019 were used to design the COBRA N2-B NA vaccine. Sera collected from COBRA N2 NA vaccinated mice showed more broadly reactive antibody responses against a broad panel of H×N2 influenza virus strains than sera collected from mice vaccinated with WT N2 NA vaccines. Antibodies elicited by COBRA or WT N2 NA antigens cross react with recent human H3N2 influenza viruses from different clades, while the antibodies elicited by A/Switzerland/9715293/2013 hemagglutinin (HA) reacted with viruses from the same clade. Furthermore, mice vaccinated with COBRA N2-B NA vaccine had lower viral lung titers compared to mock vaccinated mice when challenged with human H3N2 influenza viruses. Thus, the COBRA N2 NA vaccines elicit broadly protective murine anti-NA antibodies against multiple strains across subtypes and the viral loads were significantly decreased in the lungs of the mice in the COBRA N2 NA vaccine groups, compared to the mice in the mock vaccinated group, indicating that the COBRA-based N2 subtype NA vaccines have a potential to be a component in a universal influenza vaccine.

Impact of COVID-19 pandemic on influenza vaccination rate among health care workers

Vaccinations against influenza are critical in mitigating the severity of the disease, preventing its transmission, and restricting its dissemination. Concerns about vaccination hesitancy among healthcare workers (HCWs) have been duly recognized during and following the COVID-19 pandemic. To examine the extent to which the COVID-19 pandemic has influenced the adoption of vaccinations among HCWs. A cross-sectional online survey was conducted four years after the COVID-19 pandemic among HCWs in Saudi Arabia. We performed a logistic regression analysis using influenza vaccination uptake as the dependent variable and perceived COVID-19 pandemic's impact, age, gender, marital status, employment status, education level, monthly income, respondent's overall health, doctor visits, tobacco use, number of adults in the household, and number of children in the household as independent variables. The study included 574 participants, an 86% response rate. Of the sample, 47% reported they had the influenza vaccination. HCWs who reported a greater negative impact due to the COVID-19 pandemic were 40% more likely to acquire the influenza vaccine (OR = 1.4, 95% CI [1.24, 1.58]). Compared to HCWs without children, HCWs with a child had a 44% lower likelihood of taking the influenza vaccination (OR = 0.34, 95% CI [0.16, 0.69]). The odds of HCWs obtaining the influenza vaccine were 4.5 times higher for those who reported one yearly medical visit, 2.6 times higher for two, and 1.4 times higher for three or more. HCWs who experienced more severe COVID-19 outcomes were more likely to get vaccinated against the virus. However, long-term monitoring of this inclination is necessary.

The conserved protein DopA is required for growth, drug tolerance and virulence in Aspergillus fumigatus

The majority of Aspergillus fumigatus reproduction occurs asexually, with large numbers of conidiophores producing small hydrophobic conidia dispersed aerially. When healthy hosts inhale conidia, the mucosal cilia and phagocytosis by the innate immune system can remove them. However, in immunocompromised hosts, the conidia are not removed, which allows them to germinate, forming mycelium that invades host tissues and causes disease. Previously we isolated a white A. fumigatus A1j strain incapable of producing conidia and screened several genes (including dopA) with significant expression differences and mutant loci in A1j. DopA homologous proteins in other species have been partially studied and are known to participate in various membrane transport-related cellular functions. Defects in these proteins in Saccharomyces cerevisiae, Caenorhabditis elegans, and Aspergillus nidulans result in defective cell morphology and abnormal growth. In this study, we observed reduced conidia production and abnormal development of spore-producing structures in the A. fumigatus dopA null strain, compared to parental strain, and demonstrated that dopA also modulates stress response and virulence of A. fumigatus.

Intranasal influenza-vectored vaccine expressing pneumococcal surface protein A protects against Influenza and Streptococcus pneumoniae infections

Streptococcus pneumoniae and influenza A virus (IAV) are significant agents of pneumonia cases and severe respiratory infections globally. Secondary bacterial infections, particularly by Streptococcus pneumoniae, are common in IAV-infected individuals, leading to critical outcomes. Despite reducing mortality, pneumococcal vaccines have high production costs and are serotype specific. The emergence of new circulating serotypes has led to the search for new prevention strategies that provide a broad spectrum of protection. In this context, vaccination using antigens present in all serotypes, such as Pneumococcal Surface Protein A (PspA), can offer broad coverage regardless of serotype. Employing the reverse genetics technique, our research group developed a recombinant influenza A H1N1 virus that expresses PspA (Flu-PspA), through the replacement of neuraminidase by PspA. This virus was evaluated as a bivalent vaccine against infections caused by influenza A and S. pneumoniae in mice. Initially, we evaluated the Flu-PspA virus's ability to infect cells and express PspA in vitro, its capacity to multiply in embryonated chicken eggs, and its safety when inoculated in mice. Subsequently, the protective effect against influenza A and Streptococcus pneumoniae lethal challenge infections in mice was assessed using different immunization protocols. Analysis of the production of antibodies against PspA4 protein and influenza, and the binding capacity of anti-PspA4 antibodies/complement deposition to different strains of S. pneumoniae were also evaluated. Our results demonstrate that the Flu-PspA virus vaccine efficiently induces PspA protein expression in vitro, and that it was able to multiply in embryonated chicken eggs even without exogenous neuraminidase. The Flu-PspA-based bivalent vaccine was demonstrated to be safe, stimulated high titers of anti-PspA and anti-influenza antibodies, and protected mice against homosubtypic and heterosubtypic influenza A and S. pneumoniae challenge. Moreover, an efficient binding of antibodies and complement deposition on the surface of pneumococcal strains ascribes the broad-spectrum vaccine response in vivo. In summary, this innovative approach holds promise for developing a dual-protective vaccine against two major respiratory pathogens.

An evaluation of the National Influenza Vaccination Program in the Republic of Moldova, 2023-2024

During the 2023-2024 influenza season, the Republic of Moldova, a lower-middle income country seeking accession into the European Union, independently financed their influenza vaccine supply transitioning from external support from the Partnership for International Vaccine Initiatives, a collaboration conceived in 2015. As part of this transition, a mixed-methods evaluation was conducted from May 2023 - January 2024 to identify current strengths and weaknesses of the influenza vaccination program. A total of 157 interviews were conducted: one with the National Immunization Program (NIP), six with district health officers, 18 at health facilities, 18 with caregivers/parents, 34 with healthcare workers, 43 with adults with chronic diseases, 19 with pregnant women, and 13 vaccine observation sessions; further five expert interviews with an international organization, the insurance company, senior government officials in public health and within the ministry of health, and those involved with COVID-19 were conducted. The Republic of Moldova's NIP has benefited from decades of experience, internal commitments to progress, and contributions from external partners. Despite this progress, the evaluation recognized four areas for improvement. Recommendations from the evaluation assessment included: 1) develop a national strategy for immunization, including the establishment of national goals in consultation with the national immunization technical advisory group (NITAG); 2) expand immunization communications and advocacy initiatives, particularly to adults and pregnant individuals; 3) leverage trusted patient-doctor relationships and encourage vaccination as a healthcare norm with physician specialists; and 4) conduct operations research to better understand vaccine hesitancy in populations such as pregnant individuals. Additional thematic findings emphasized the importance of ensuring timely receipt of vaccine doses into the country no later than September, as medical providers reported difficulty administering doses when vaccines were delivered after September. Our findings outline ways to further strengthen the Republic of Moldova's self-sustained annual influenza vaccination program.

Unraveling influenza sentinel surveillance in Pakistan 2008-2024: Epidemiological insights during the pre and post pandemic period of COVID-19

BACKGROUND

The coronavirus pandemic has substantially influenced the transmission pattern of other respiratory viruses. However, screening and detecting other respiratory pathogens was unheeded during this time to combat the COVID-19 pandemic. High virulence and re assortment factors intensify the importance of influenza virus surveillance for effective disease management. Therefore, the present surveillance study was designed to determine the influenza positivity rate from 2008-24. This study will provide integral support in depicting a panoramic representation of two respiratory-pandemic periods, 2010-11 and 2019-2021, for influenza and COVID-19 pandemics, respectively.

METHODS

An inferential cross-sectional study was conducted from 2008 to 2024 by collecting influenza surveillance data from twelve sentinel sites in Pakistan. Clinical and demographic data was recorded at sample collection time. Specimens were collected through nasopharyngeal/throat swabs and stored in viral transport medium (VTM) at the sentinel site laboratory at 2-4 °C. Viral RNA was isolated from the samples using KingFisher TM Flex Purification System and MagMAX™ Viral/Pathogen Nucleic Acid Extraction Kit.

RESULTS

Within 16 years, 78118 samples were tested for influenza, of which 7999 (10.2 %) appeared positive. The positivity rate appeared very low in recent years, with only a 3.5 % positivity rate observed in 2020. Influenza A strain H1N1pdm09 seemed to be the prominent strain (n = 3407, 42.6 %), followed by influenza B (n = 2125, 26.6 %).

CONCLUSION

The positivity of influenza samples was 10.2 % and recorded in patients where typical clinical representation of influenza was absent. Fewer samples were reported during the coronavirus pandemic, which might be because influenza screening was hindered and overlooked to combat the SARS-CoV-2 virus, and the patient threshold was very high for COVID-19 virus screening.

Comprehensive molecular epidemiology of influenza viruses in Brazil: insights from a nationwide analysis

Influenza A and B viruses represent significant global health threats, contributing substantially to morbidity and mortality rates. However, a comprehensive understanding of the molecular epidemiology of these viruses in Brazil, a continental-size country and a crucial hub for the entry, circulation, and dissemination of influenza viruses within South America, still needs to be improved. This study addresses this gap by consolidating data and samples across all Brazilian macroregions, as part of the Center for Viral Surveillance and Serological Assessment project, together with an extensive number of other Brazilian sequences provided by a public database during the epidemic seasons spanning 2021-23. Phylogenetic analysis of the hemagglutinin segment of influenza A/H1N1pdm09, A/H3N2, and influenza B/Victoria-lineage viruses revealed that in 2021 and in the first semester of 2022, the A/H3N2 2a.3 strain was the predominant circulating strain. Subsequently, the A/H3N2 2b became the prevalent strain until October, when it was substituted by A/H1N1pdm09 5a.2a and 5a.2a.1 lineages. This scenario was maintained during the year of 2023. B/Victoria emerged and circulated at low levels between December 2021 and September 2022 and then became coprevalent with A/H1N1pdm09 5a.2a and 5a.2a.1 lineages. The comparison between the vaccine strain A/Darwin/9/2021 and circulating viruses revealed shared mutations to aspartic acid at residues 186 and 225 across all A/H3N2 lineages from 2021 to 2023, altering the charge in the receptor-binding domain. For A/H1N1pdm09, the 2022 consensus of 5a.2a.1 and the vaccine strain A/Victoria/2570/2019 showed 14 amino acid substitutions. Key residues H180, D187, K219, R223, E224, and T133 are involved in hydrogen interactions with sialic acids, while N130, K142, and D222 may contribute to distance interactions based on docking analyses. Importantly, distinct influenza A lineage frequency patterns were observed across Brazil's macroregions, underscoring the regional variations in virus circulation. This study characterizes influenza A and B viruses circulating in Brazil, providing insights into their circulation patterns and dynamics across Brazilian macroregions. These findings hold significant implications for public health interventions, informing strategies to mitigate transmission risks, optimize vaccination efforts, and enhance outbreak control measures.

Profiling Bacteria in the Lungs of Patients with Severe Influenza Versus COVID-19 with or without Aspergillosis

Rationale: The influence of the lung bacterial microbiome, including potential pathogens, in patients with influenza-associated pulmonary aspergillosis (IAPA) or coronavirus disease (COVID-19)-associated pulmonary aspergillosis (CAPA) has yet to be explored. Objectives: To explore the composition of the lung bacterial microbiome and its association with viral and fungal infection, immunity, and outcome in severe influenza versus COVID-19 with or without aspergillosis. Methods: We performed a retrospective study in mechanically ventilated patients with influenza and COVID-19 with or without invasive aspergillosis in whom BAL for bacterial culture (with or without PCR) was obtained within 2 weeks after ICU admission. In addition, 16S rRNA gene sequencing data and viral and bacterial load of BAL samples from a subset of these patients, and of patients requiring noninvasive ventilation, were analyzed. We integrated 16S rRNA gene sequencing data with existing immune parameter datasets. Measurements and Main Results: Potential bacterial pathogens were detected in 20% (28/142) of patients with influenza and 37% (104/281) of patients with COVID-19, whereas aspergillosis was detected in 38% (54/142) of patients with influenza and 31% (86/281) of patients with COVID-19. A significant association between bacterial pathogens in BAL fluid and 90-day mortality was found only in patients with influenza, particularly patients with IAPA. Patients with COVID-19, but not patients with influenza, showed increased proinflammatory pulmonary cytokine responses to bacterial pathogens. Conclusions: Aspergillosis is more frequently detected in the lungs of patients with severe influenza than bacterial pathogens. Detection of bacterial pathogens associates with worse outcome in patients with influenza, particularly in those with IAPA, but not in patients with COVID-19. The immunological dynamics of tripartite viral-fungal-bacterial interactions deserve further investigation.

Age-related STING suppression in macrophages contributes to increased viral load during influenza a virus infection

Ageing is a major risk factor that contributes to increased mortality and morbidity rates during influenza A virus (IAV) infections. Macrophages are crucial players in the defense against viral infections and display impaired function during ageing. However, the impact of ageing on macrophage function in response to an IAV infection remains unclear and offers potential insight for underlying mechanisms. In this study, we investigated the immune response of young and aged human monocyte-derived macrophages to two different H1N1 IAV strains. Interestingly, macrophages of aged individuals showed a lower interferon response to IAV infection, resulting in increased viral load. Transcriptomic data revealed a reduced expression of stimulator of interferon genes (STING) in aged macrophages albeit the cGAS-STING pathway was upregulated. Our data clearly indicate the importance of STING signaling for interferon production by applying a THP-1 STING knockout model. Evaluation of mitochondrial function during IAV infection revealed the release of mitochondrial DNA to be the activator of cGAS-STING pathway. The subsequent induction of apoptosis was attenuated in aged macrophages due to decreased STING signaling. Our study provides new insights into molecular mechanisms underlying age-related immune impairment. To our best knowledge, we are the first to discover an age-dependent difference in gene expression of STING on a transcriptional level in human monocyte-derived macrophages possibly leading to a diminished interferon production.

Computational screening of phytocompounds from C. amboinicus identifies potential inhibitors of influenza A (H3N2) virus by targeting hemagglutinin

The H3N2 subtype of the influenza A virus continues to be a notable public health issue due to its association with seasonal epidemics and severe human morbidity. The constrained effectiveness of current antiviral medications, combined with the inevitable emergence of drug-resistant variants, mandates the exploration of innovative therapeutic approaches. This study focuses on the identification of phytocompounds from Coleus amboinicus with the potential to target hemagglutinin, viral protein involved in viral entry by binding to sialyl glycoconjugates receptors on the surface of host cells. Molecular docking studies were carried out to assess the efficacy of C. amboinicus phytocompounds with hemagglutinin receptor-binding site. The study revealed that among the 84 signature phytocompounds, isosalvianolic acid and salvianolic acid C showed the highest docking scores and favourable intermolecular interactions. Pharmacokinetic analysis and Pan-assay interference compounds (PAINS) filtering confirmed that isosalvianolic acid meets the criteria outlined in Lipinski's rule of five, exhibits favourable ADMET profiles and passes PAINS filters. Furthermore, the molecular dynamics simulations followed by radius of gyration (Rg), solvent accessible surface area (SASA), and MM-PBSA calculations for binding free energy, verified the stability of the docked complexes. Together, the study identifies isosalvianolic acid as a promising inhibitor of the H3N2 virus by binding to hemagglutinin, indicating its potential as a strategy for therapeutic intervention.

A Clinical and Economic Comparison of Cell-Based Versus Recombinant Influenza Vaccines in Adults 18-64 Years in the United States

BACKGROUND

This analysis compares the cost-effectiveness of a cell-based influenza vaccine to a recombinant influenza vaccine, and each to no vaccination. The analysis is based on United States (US) commercial and societal perspectives.

METHODS

A Susceptible-Exposed-Infectious-Recovered (SEIR) transmission model of the total US population followed with a cost-effectiveness model for 18-64-year-olds was used to estimate the clinical and economic impact of vaccination over one influenza season (2018-2019). Deterministic and probabilistic sensitivity analyses were conducted.

RESULTS

Both enhanced vaccines prevented a substantial number of influenza cases and influenza-related deaths compared to no vaccination. The cell-based vaccine was associated with higher quality-adjusted life years (QALYs) gained compared to the recombinant vaccine or no vaccination. The cell-based vaccine had a 36% lower vaccination cost, amounting to $2.8 billion in cost savings, compared to the recombinant vaccine. The incremental cost-effectiveness ratios (ICERs) for the cell-based vaccine, compared to the recombinant vaccine or no vaccination, were dominant from all payer perspectives, regardless of risk groups.

CONCLUSIONS

Overall, the cell-based vaccine was cost-saving compared to the recombinant vaccine for subjects aged 18-64 years in the US, achieving comparable health outcomes with a significant reduction in associated costs.

Contribution of immunoglobulin products in influencing seasonal influenza infection and severity in antibody immune deficiency patients receiving immunoglobulin replacement therapy

Seasonal and pandemic influenza infection present a potential threat to patients with antibody deficiency. The acceptance and effect of the current recommendation for annual vaccination against influenza for patients with antibody deficiency is not well investigated and due to antigenic drift or shift the protective capacity of regular IgG replacement therapy (IgRT) is considered low. This narrative review considers the effect of influenza vaccination in immunodeficient patients and discusses available information on the effect of immunoglobulin products on seasonal influenza infectivity and severity in antibody deficiency patients receiving IgRT. The humoral immune response to seasonal influenza vaccination is reduced in patients with antibody immune deficiency. However, there is no evidence that the proportion of patients with primary antibody deficiency who develop influenza illness, and the severity of such illness, is increased when compared with the general population. The IgRT that patients receive has been shown to contain neutralizing antibodies as a consequence of past flu infections against both the hemagglutinin and neuraminidase surface proteins and other viral internal proteins of different influenza A virus strains. Studies have demonstrated not only significant levels of specific but also cross-reactive antibodies against seasonal influenza virus strains. Thus, despite the yearly changes in influenza viral antigenicity that occur, IgRT could potentially contribute to the protection of patients against seasonal influenza. Currently, only limited clinical data are available confirming a preventative effect of IgRT with respect to seasonal influenza infection. In conclusion, there is some evidence that IgRT could contribute to protection against seasonal influenza in patients with antibody-related immunodeficiency. However, additional clinical data are needed to confirm the extent and relevance of this protection and identify the main responsible virus targets of that protection.

Seasonal Influenza Vaccine Literacy and Hesitancy of Elderly Czechs: An Analysis Using the 5C Model of Psychological Antecedents

Objectives

Seasonal influenza vaccination rates among the elderly in the Czech Republic are alarmingly low, making it one of the least vaccinated countries in Europe. This study explored the role of vaccine literacy and insurance coverage on vaccination status.

Methods

An analytical cross-sectional study was conducted in Summer 2023 using a self-administered questionnaire covering vaccine literacy (functional, interactive, and critical skills), negative perceptions towards influenza vaccination, and the 5C model (confidence, complacency, constraints, calculation, and collective responsibility). Individuals aged 55 and older were included in the study. Mediation analyses assessed the indirect effects of insurance coverage on vaccination status.

Results

Significant differences were noted in vaccination rates based on insurance coverage, chronic diseases, regular medication use, and previous COVID-19 and pneumococcal vaccinations. Vaccine literacy, especially interactive and critical skills, was higher among vaccinated individuals. Confidence and collective responsibility were significant promoters, while complacency and constraints were barriers to vaccination. Mediation analyses indicated that negative perceptions, confidence, and collective responsibility significantly mediated the relationship between insurance coverage and vaccination status.

Conclusion

Enhancing vaccine literacy and addressing psychological antecedents are crucial for improving influenza vaccination rates among the elderly. Policy measures should include improving vaccine literacy, building public confidence, and addressing negative perceptions.

Analyzing Changes in Attitudes and Behaviors towards Seasonal Influenza Vaccination in Spain's Adult Population over Three Seasons

Background/Objectives: The experience of the COVID-19 pandemic has turned the spotlight on the importance of public health measures and disease prevention. Despite this, the acceptance of influenza vaccination has remained low in most countries (and far from the 75% target set by the World Health Organization). The objective of this study has been to investigate how attitudes and behaviors regarding influenza vaccination in the Spanish adult population have changed over the last three years (from 2021 to 2024) in order to analyze trends in influenza vaccination. Methods: To this end, a cross-sectional study was conducted through 2206 telephone interviews, and the results were compared with those obtained in previous campaigns. Results: The findings indicate a significant decline in overall vaccination intent. Healthcare professionals remain the most influential factor in encouraging vaccination, yet there is a notable increase in the lack of vaccine recommendations, contributing to the decision not to vaccinate. This study also reveals low awareness of the influenza vaccine campaign, emphasizing the need for improved public health communication. Conclusions: To counteract these trends, this study recommends intensifying awareness campaigns, strengthening the role of healthcare providers in vaccine advocacy, and tailoring communication strategies. These efforts are crucial to enhancing vaccination coverage and protecting vulnerable populations against influenza.

Fighting the flu: a brief review on anti-influenza agents

The influenza virus causes one of the most prevalent and lethal infectious viral diseases of the respiratory system; the disease progression varies from acute self-limiting mild fever to disease chronicity and death. Although both the preventive and treatment measures have been vital in protecting humans against seasonal epidemics or sporadic pandemics, there are several challenges to curb the influenza virus such as limited or poor cross-protection against circulating virus strains, moderate protection in immune-compromised patients, and rapid emergence of resistance. Currently, there are four US-FDA-approved anti-influenza drugs to treat flu infection, viz. Rapivab, Relenza, Tamiflu, and Xofluza. These drugs are classified based on their mode of action against the viral replication cycle with the first three being Neuraminidase inhibitors, and the fourth one targeting the viral polymerase. The emergence of the drug-resistant strains of influenza, however, underscores the need for continuous innovation towards development and discovery of new anti-influenza agents with enhanced antiviral effects, greater safety, and improved tolerability. Here in this review, we highlighted commercially available antiviral agents besides those that are at different stages of development including under clinical trials, with a brief account of their antiviral mechanisms.

Different effects of air pollutant concentrations on influenza A and B in Sichuan, China

BACKGROUND

The detrimental effects of air pollution on the respiratory system are well documented. Previous research has established a correlation between air pollutant concentration and the frequency of outpatient visits for influenza-like illness. However, studies investigating the variations in infection among different influenza subtypes remain sparse. We aimed to determine the correlation between air pollutant levels and different influenza subtypes in Sichuan Province, China.

METHODS

A generalized additive model and distributed lag nonlinear model were employed to assess the association between air pollutants and influenza subtypes, utilizing daily influenza data obtained from 30 hospitals across 21 cities in Sichuan Province. The analysis considered the temporal effects and meteorological factors. The study spanned from January 1, 2017, to December 31, 2019. To provide a more precise evaluation of the actual impact of air pollution on different subtypes of influenza, we also performed subgroup analyses based on factors such as gender, age, and geography within the population.

RESULTS

During the investigation, 17,462 specimens from Sichuan Province tested positive for influenza. Among these, 12,607 and 4855 were diagnosed with Flu A and B, respectively. The related risk of influenza A infection significantly increased following exposure to PM2.5 on Lag2 days (RR=1.008, 95 % confidence interval [CI]: 1.000-1.016), SO2 and CO on Lag1 days (RR=1.121, 95 % CI: 1.032-1.219; RR=1.151, 95 % CI: 1.030-1.289), and NO2 on Lag0 day (RR=1.089, 95 % CI: 1.035-1.145). PM10 and SO2 levels on Lag0 day, PM2.5 levels on Lag1 day, and CO levels on Lag6 day, with a reduced risk of influenza B (RR=0.987, 95 % CI: 0.976-0.997; RR=0.817, 95 % CI: 0.676-0.987; RR=0.979, 95 % CI: 0.970-0.989; RR=0.814, 95 % CI: 0.561-0.921).

CONCLUSION

The findings from the overall population and subgroup analyses indicated that the impact of air pollutant concentrations on influenza A and B is inconsistent, with influenza A demonstrating greater susceptibility to these pollutants. Minimizing the levels of SO2, CO, NO2, and PM2.5 can significantly decrease the likelihood of contracting influenza A. Analyzing the influence of environmental contaminants on different influenza subtypes can provide insights into seasonal influenza trends and guide the development of preventive and control strategies.

Highly-Efficient Selection of Aptamers for Quantitative Fluorescence Detecting Multiple IAV Subtypes

Influenza A virus (IAV) can cause infectious respiratory diseases in humans and animals. IAVs mutate rapidly through antigenic drift and shift, resulting in the emergence of numerous IAV subtypes and significant challenges for IAV detection. Therefore, achieving the simultaneous detection of multiple IAVs is crucial. In this work, three specific aptamers targeting the hemagglutination (HA) protein of the influenza A H5N1, H7N9, and H9N2 viruses were screened using a multichannel magnetic microfluidic chip. The aptamers exhibit nanomolar affinity and excellent specificity for the HA protein of H5N1, H7N9, and H9N2 viruses. Furthermore, three specific aptamers were truncated and labeled with different fluorescence markers to realize fluorescence quantitative detection of influenza A H5N1, H7N9, and H9N2 viruses through an aptamer sandwich assay in 1 h. The limit of detection (LOD) of the developed method is 0.38 TCID50/mL for the H5N1 virus, 0.75 TCID50/mL for the H7N9 virus, and 1.14 TCID50/mL for the H9N2 virus. The detection method has excellent specificity, strong anti-interference ability, and good reproducibility. This work provides a sensitive quantitative detection method for the H5N1, H7N9, and H9N2 viruses, enabling quantitative fluorescence detection for multiple IAV subtypes.

Antigenic analysis of the influenza B virus hemagglutinin protein

Influenza B viruses (IBVs) primarily infect humans and are a common cause of respiratory infections in humans. Here, to systematically analyze the antigenicity of the IBVs Hemagglutinin (HA) protein, 31 ​B/Victoria and 19 ​B/Yamagata representative circulating strains were selected from Global Initiative of Sharing All Influenza Data (GISAID), and pseudotyped viruses were constructed with the vesicular stomatitis virus system. Guinea pigs were immunized with three doses of vaccines (one dose of DNA vaccines following two doses of pseudotyped virus vaccines) of the seven IBV vaccine strains, and neutralizing antibodies against the pseudotyped viruses were tested. By comparing differences between various vaccine strains, we constructed several pseudotyped viruses that contained various mutations based on vaccine strain BV-21. The vaccine strains showed good neutralization levels against the epidemic virus strains of the same year, with neutralization titers ranging from 370 to 840, while the level of neutralization against viruses prevalent in previous years decreased 1-10-fold. Each of the high-frequency epidemic strains of B/Victoria and B/Yamagata not only induced high neutralizing titers, but also had broadly neutralizing effects against virus strains of different years, with neutralizing titers ranging from 1000 to 7200. R141G, D197 ​N, and R203K were identified as affecting the antigenicity of IBV. These mutation sites provide valuable references for the selection and design of a universal IBV vaccine strain in the future.

Influenza-associated and COVID-19-associated pulmonary aspergillosis in critically ill patients

Influenza-associated pulmonary aspergillosis (IAPA) and COVID-19-associated pulmonary aspergillosis (CAPA) are increasingly recognised as important complications in patients requiring intensive care for severe viral pneumonia. The diagnosis can typically be made in 10-20% of patients with severe influenza or COVID-19, but only when appropriate diagnostic tools are used. Bronchoalveolar lavage sampling for culture, galactomannan testing, and PCR forms the cornerstone of diagnosis, whereas visual examination of the tracheobronchial tract during bronchoscopy is required to detect invasive Aspergillus tracheobronchitis. Azoles are the first-choice antifungal drugs, with liposomal amphotericin B as an alternative in settings where azole resistance is prevalent. Despite antifungal therapy, IAPA and CAPA are associated with poor outcomes, with fatality rates often exceeding 50%. In this Review, we discuss the mechanistic and clinical aspects of IAPA and CAPA. Moreover, we identify crucial knowledge gaps and formulate directions for future research.

Development and validation of nomogram for predicting the risk of transferring to the ICU for children with influenza

OBJECTIVE

Development of a nomogram model for predicting the magnitude of risk of transferring hospitalized children with influenza to the ICU.

METHODS

In a single-center retrospective study, 318 children with influenza who were hospitalized in our hospital from January 2018 to August 2023 were collected as study subjects. Children with influenza were randomly assigned to the training set and validation set in a ratio of 4:1. In the training set, risk factors were identified using univariate and multivariate logistic regression analyses, and a nomogram model was created on this basis. The validation set was used to evaluate the predictive power of the model.

RESULTS

Multifactorial logistic regression analysis revealed six independent risk factors for transfer to the ICU in hospitalized children with influenza, including elevated peripheral white blood cell counts, elevated large platelet ratios, reduced mean platelet width, reduced complement C3, elevated serum globulin levels, and reduced total immunoglobulin M levels. Using these six metrics as predictors to construct a nomogram graphical model, the C-index was 0.970 (95% Cl: 0.953-0.988). The areas under the curve for the training and validation sets were 0.966 (95%Cl 0.947-0.985) and 0.919 (95%Cl 0.851-0.986), respectively.

CONCLUSION

A nomogram for predicting the risk of transferring to the ICU for children with influenza was developed and validated, which demonstrates good calibration and clinical benefits.

Development and validation of a nomogram to predict severe influenza

BACKGROUND

Influenza is an acute respiratory disease posing significant harm to human health. Early prediction and intervention in patients at risk of developing severe influenza can significantly decrease mortality.

METHOD

A comprehensive analysis of 146 patients with influenza was conducted using the Gene Expression Omnibus (GEO) database. We assessed the relationship between severe influenza and patients' clinical information and molecular characteristics. First, the variables of differentially expressed genes were selected using R software. Least absolute shrinkage and selection operator (LASSO) and multivariate logistic regression analysis were performed to investigate the association between clinical information and molecular characteristics and severe influenza. A nomogram was developed to predict the presence of severe influenza. At the same time, the concordance index (C-index) is adopted area under the receiver operating characteristic (ROC), area under the curve (AUC), decision curve analysis (DCA), and calibration curve to evaluate the predictive ability of the model and its clinical application.

RESULTS

Severe influenza was identified in 47 of 146 patients (32.20%) and was significantly related to age and duration of illness. Multivariate logistic regression demonstrated significant correlations between severe influenza and myloperoxidase (MPO) level, haptoglobin (HP) level, and duration of illness. A nomogram was formulated based on MPO level, HP level, and duration of illness. This model produced a C-index of 0.904 and AUC of 0.904.

CONCLUSIONS

A nomogram based on the expression levels of MPO, HP, and duration of illness is an efficient model for the early identification of patients with severe influenza. These results will be useful in guiding prevention and treatment for severe influenza disease.

Protection against the H1N1 influenza virus using self-assembled nanoparticles formed by lumazine synthase and bearing the M2e peptide

There is an urgent need for influenza vaccines that offer broad cross-protection. The highly conserved ectodomain of the influenza matrix protein 2 (M2e) is a promising candidate; however, its low immunogenicity can be addressed. In this study, we developed influenza vaccines using the Lumazine synthase (LS) platform. The primary objective of this study was to determine the protective potential of M2e proteins expressed on Lumazine synthase (LS) nanoparticles. M2e-LS proteins, produced through the E. coli system, spontaneously assemble into nanoparticles. The study investigated the efficacy of the M2e-LS nanoparticle vaccine in mice. Mice immunized with M2e-LS nanoparticles exhibited significantly higher levels of intracellular cytokines than those receiving soluble M2e proteins. The M2e-LS protein exhibited robust immunogenicity and provided 100% protection against cross-clade influenza.

Towards a Comprehensive Definition of Pandemics and Strategies for Prevention: A Historical Review and Future Perspectives

The lack of a universally accepted definition of a pandemic hinders a comprehensive understanding of and effective response to these global health crises. Current definitions often lack quantitative criteria, rendering them vague and limiting their utility. Here, we propose a refined definition that considers the likelihood of susceptible individuals contracting an infectious disease that culminates in widespread global transmission, increased morbidity and mortality, and profound societal, economic, and political consequences. Applying this definition retrospectively, we identify 22 pandemics that occurred between 165 and 2024 AD and were caused by a variety of diseases, including smallpox (Antonine and American), plague (Justinian, Black Death, and Third Plague), cholera (seven pandemics), influenza (two Russian, Spanish, Asian, Hong Kong, and swine), AIDS, and coronaviruses (SARS, MERS, and COVID-19). This work presents a comprehensive analysis of past pandemics caused by both emerging and re-emerging pathogens, along with their epidemiological characteristics, societal impact, and evolution of public health responses. We also highlight the need for proactive measures to reduce the risk of future pandemics. These strategies include prioritizing surveillance of emerging zoonotic pathogens, conserving biodiversity to counter wildlife trafficking, and minimizing the potential for zoonotic spillover events. In addition, interventions such as promoting alternative protein sources, enforcing the closure of live animal markets in biodiversity-rich regions, and fostering global collaboration among diverse stakeholders are critical to preventing future pandemics. Crucially, improving wildlife surveillance systems will require the concerted efforts of local, national and international entities, including laboratories, field researchers, wildlife conservationists, government agencies and other stakeholders. By fostering collaborative networks and establishing robust biorepositories, we can strengthen our collective capacity to detect, monitor, and mitigate the emergence and transmission of zoonotic pathogens.

Risk of COVID-19 in Children throughout the Pandemic and the Role of Vaccination: A Narrative Review

At the beginning of the coronavirus disease 2019 (COVID-19) pandemic, persons ≥65 years of age and healthcare personnel represented the most vulnerable groups with respect to risk of infection, severe illness, and death. However, as the pandemic progressed, there was an increasingly detrimental effect on young children and adolescents. Severe disease and hospitalization increased over time in pediatric populations, and containment measures created substantial psychosocial, educational, and economic challenges for young people. Vaccination of children against COVID-19 has been shown to reduce severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and severe outcomes in pediatric populations and may also help to prevent the spread of variants of concern and improve community immunity. This review discusses the burden of COVID-19 on children throughout the pandemic, the role of children in disease transmission, and the impact of COVID-19 vaccination.

Study on the impact of meteorological factors on influenza in different periods and prediction based on artificial intelligence RF-Bi-LSTM algorithm: to compare the COVID-19 period with the non-COVID-19 period

OBJECTIVE

At different times, public health faces various challenges and the degree of intervention measures varies. The research on the impact and prediction of meteorology factors on influenza is increasing gradually, however, there is currently no evidence on whether its research results are affected by different periods. This study aims to provide limited evidence to reveal this issue.

METHODS

Daily data on influencing factors and influenza in Xiamen were divided into three parts: overall period (phase AB), non-COVID-19 epidemic period (phase A), and COVID-19 epidemic period (phase B). The association between influencing factors and influenza was analysed using generalized additive models (GAMs). The excess risk (ER) was used to represent the percentage change in influenza as the interquartile interval (IQR) of meteorology factors increases. The 7-day average daily influenza cases were predicted using the combination of bi-directional long short memory (Bi-LSTM) and random forest (RF) through multi-step rolling input of the daily multifactor values of the previous 7-day.

RESULTS

In periods A and AB, air temperature below 22 °C was a risk factor for influenza. However, in phase B, temperature showed a U-shaped effect on it. Relative humidity had a more significant cumulative effect on influenza in phase AB than in phase A (peak: accumulate 14d, AB: ER = 281.54, 95% CI = 245.47 ~ 321.37; A: ER = 120.48, 95% CI = 100.37 ~ 142.60). Compared to other age groups, children aged 4-12 were more affected by pressure, precipitation, sunshine, and day light, while those aged ≥ 13 were more affected by the accumulation of humidity over multiple days. The accuracy of predicting influenza was highest in phase A and lowest in phase B.

CONCLUSIONS

The varying degrees of intervention measures adopted during different phases led to significant differences in the impact of meteorology factors on influenza and in the influenza prediction. In association studies of respiratory infectious diseases, especially influenza, and environmental factors, it is advisable to exclude periods with more external interventions to reduce interference with environmental factors and influenza related research, or to refine the model to accommodate the alterations brought about by intervention measures. In addition, the RF-Bi-LSTM model has good predictive performance for influenza.

An SIS sex-structured influenza A model with positive case fatality in an open population with varying size

This work aims to study the role of sex disparities on the overall outcome of influenza A disease. Therefore, the classical Susceptible-Infected-Susceptible (SIS) endemic model was extended to include the impact of sex disparities on the overall dynamics of influenza A infection which spreads in an open population with a varying size, and took the potential lethality of the infection. The model was mathematically analyzed, where the equilibrium and bifurcation analyses were established. The model was shown to undergo a backward bifurcation at $ \mathcal{R}_0 = 1 $, for certain range of the model parameters, where $ \mathcal{R}_0 $ is the basic reproduction number of the model. The asymptotic stability of the equilibria was numerically investigated, and the effective threshold was determined. The differences in susceptibility, transmissibility and case fatality (of females with respect to males) are shown to remarkably affect the disease outcomes. Simulations were performed to illustrate the theoretical results.

Antivirals for treatment of severe influenza: a systematic review and network meta-analysis of randomised controlled trials

BACKGROUND

The optimal antiviral drug for treatment of severe influenza remains unclear. To support updated WHO influenza clinical guidelines, this systematic review and network meta-analysis evaluated antivirals for treatment of patients with severe influenza.

METHODS

We systematically searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Cumulative Index to Nursing and Allied Health Literature, Global Health, Epistemonikos, and ClinicalTrials.gov for randomised controlled trials published up to Sept 20, 2023, that enrolled hospitalised patients with suspected or laboratory-confirmed influenza and compared direct-acting influenza antivirals against placebo, standard care, or another antiviral. Pairs of coauthors independently extracted data on study characteristics, patient characteristics, antiviral characteristics, and outcomes, with discrepancies resolved by discussion or by a third coauthor. Key outcomes of interest were time to alleviation of symptoms, duration of hospitalisation, admission to intensive care unit, progression to invasive mechanical ventilation, duration of mechanical ventilation, mortality, hospital discharge destination, emergence of antiviral resistance, adverse events, adverse events related to treatments, and serious adverse events. We conducted frequentist network meta-analyses to summarise the evidence and evaluated the certainty of evidence using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. This study is registered with PROSPERO, CRD42023456650.

FINDINGS

Of 11 878 records identified by our search, eight trials with 1424 participants (mean age 36-60 years for trials that reported mean or median age; 43-78% male patients) were included in this systematic review, of which six were included in the network meta-analysis. The effects of oseltamivir, peramivir, or zanamivir on mortality compared with placebo or standard care without placebo for seasonal and zoonotic influenza were of very low certainty. Compared with placebo or standard care, we found low certainty evidence that duration of hospitalisation for seasonal influenza was reduced with oseltamivir (mean difference -1·63 days, 95% CI -2·81 to -0·45) and peramivir (-1·73 days, -3·33 to -0·13). Compared with standard care, there was little or no difference in time to alleviation of symptoms with oseltamivir (0·34 days, -0·86 to 1·54; low certainty evidence) or peramivir (-0·05 days, -0·69 to 0·59; low certainty evidence). There were no differences in adverse events or serious adverse events with oseltamivir, peramivir, and zanamivir (very low certainty evidence). Uncertainty remains about the effects of antivirals on other outcomes for patients with severe influenza. Due to the small number of eligible trials, we could not test for publication bias.

INTERPRETATION

In hospitalised patients with severe influenza, oseltamivir and peramivir might reduce duration of hospitalisation compared with standard care or placebo, although the certainty of evidence is low. The effects of all antivirals on mortality and other important patient outcomes are very uncertain due to scarce data from randomised controlled trials.

FUNDING

World Health Organization.

Development and characterization of monoclonal antibodies recognizing nucleocapsid protein of multiple SARS-CoV-2 variants

Rapid antigen test (RAT) is widely used for SARS-CoV-2 infection diagnostics. However, test sensitivity has decreased recently due to the emergence of the Omicron variant and its sublineages. Here we developed a panel of SARS-CoV-2 nucleocapsid protein (NP) specific mouse monoclonal antibodies (mAbs) and assessed their sensitivity and specificity to important SARS-CoV-2 variants. We identified seven mAbs that exhibited strong reactivity to SARS-CoV-2 variants and recombinant NP (rNP) by Western immunoblot or ELISA. Their specificity to SARS-CoV-2 was confirmed by negative or low reactivity to rNPs from SARS-CoV-1, MERS, and common human coronaviruses (HCoV-HKU1, HCoV-CO43, HCoV-NL63, and HCoV-229E). These seven mAbs were further tested by immunoplaque assay against selected variants of concern (VOCs), including two Omicron sublineages, and five mAbs (F461G13, F461G7, F459G7, F457G3, and F461G6), showed strong reactions, warranting further suitability testing for the development of diagnostic assay.