The burden of influenza in England by age and clinical risk group: a statistical analysis to inform vaccine policy

Antivirals to prepare for surges in influenza cases: an economic evaluation of baloxavir marboxil for the Netherlands

OBJECTIVES

We perform a cost-effectiveness analysis (CEA) and budget impact analysis (BIA) of baloxavir marboxil compared to current care in the Netherlands for patients at risk of influenza-related complications, including patients with comorbidities and the elderly.

METHODS

In the CEA, a decision tree model was developed to assess the cost-effectiveness of baloxavir marboxil for a cohort of 52-year-olds from a societal perspective. A lifetime horizon was taken by incorporating the quality-adjusted life expectancy. The BIA included different epidemiological scenarios, estimating different plausible epidemiological scenarios for seasonal influenza considering the whole Dutch population with an increased risk of influenza complications.

RESULTS

The base-case ICER was estimated to be €8,300 per QALY. At the willingness-to-pay threshold of €20,000 per QALY, the probability of being cost effective was 58%. The base-case expected budget impact was €5.7 million on average per year, ranging from €1.5 million to €10.5 million based on the severity of the influenza epidemic and vaccine effectiveness.

CONCLUSION

In the Netherlands, baloxavir is a cost-effective treatment option for seasonal influenza, with a base-case ICER of €8,300 per QALY for the population aged 60 years and over and patients at high risk of influenza-related complications. For a large part, this ICER is driven by the reduction of the illness duration of influenza and productivity gains in the working population.

Recent advances in the influenza virus vaccine landscape: a comprehensive overview of technologies and trials

SUMMARYIn the United Kingdom (UK) in 2022/23, influenza virus infections returned to the levels recorded before the COVID-19 pandemic, exerting a substantial burden on an already stretched National Health Service (NHS) through increased primary and emergency care visits and subsequent hospitalizations. Population groups ≤4 years and ≥65 years of age, and those with underlying health conditions, are at the greatest risk of influenza-related hospitalization. Recent advances in influenza virus vaccine technologies may help to mitigate this burden. This review aims to summarize advances in the influenza virus vaccine landscape by describing the different technologies that are currently in use in the UK and more widely. The review also describes vaccine technologies that are under development, including mRNA, and universal influenza virus vaccines which aim to provide broader or increased protection. This is an exciting and important era for influenza virus vaccinations, and advances are critical to protect against a disease that still exerts a substantial burden across all populations and disproportionately impacts the most vulnerable, despite it being over 80 years since the first influenza virus vaccines were deployed.

Incidence of Influenza-related Medical Encounters and the Associated Healthcare Resource Use and Complications Across Adult Age Groups in the United States During the 2015-2020 Influenza Seasons

BACKGROUND

Research on influenza burden in adults has focused on crude subgroups with cut-points at 65 years, limiting insight into how burden varies with increasing age. This study describes the incidence of influenza-related outpatient visits, emergency room visits, and hospitalizations, along with healthcare resource use and complications in the aging adult population.

METHODS

Individuals aged ≥18 years in the United States were evaluated retrospectively in 5 seasonal cohorts (2015-2020 seasons) in strata of age with 5-year increments. Person-level electronic medical records linked to pharmacy and medical claims were used to ascertain patient characteristics and outcomes. Influenza-related medical encounters were identified based on diagnostic codes (International Classification of Diseases, 10th Edition, codes J09*-J11*).

RESULTS

Incidence of influenza-related outpatient visits was highest among people aged 18-34 years and declined with increasing age. For emergency room visits, incidence tended to be elevated for people aged 18-34 years, relatively stable from 35 through 60, and increased rapidly after age 60 years. Hospitalization incidence remained relatively stable until about 50 years of age and then increased with age. One in 3 patients was diagnosed with pneumonia after hospitalization, regardless of age. Across seasons, age groups, and clinical settings, on average, 40.8% of individuals were prescribed antivirals and 17.2% antibiotics.

CONCLUSIONS

Incidence of influenza-related hospitalizations begins to increase around age 50 years rather than the more common cut-point of 65, whereas incidence of outpatient visits was highest among younger adults. Influenza infections frequently led to antiviral and antibiotic prescriptions, underscoring the role influenza vaccination can play in combating antimicrobial resistance.

Respiratory Syncytial Virus Hospital Admission Rates and Patients' Characteristics Before the Age of 2 Years in England, 2015-2019

BACKGROUND

A granular understanding of respiratory syncytial virus (RSV) burden in England is needed to prepare for new RSV prevention strategies. We estimated the rates of RSV hospital admissions before the age of 2 years in England and described baseline characteristics.

METHODS

A birth cohort of all infants born between March 1, 2015, and February 28, 2017 (n = 449,591) was established using Clinical Practice Research Datalink-Hospital Episode Statistics. Case cohorts included infants with admission for (1) RSV, (2) bronchiolitis, (3) any respiratory tract infection (RTI) <24 months and (4) RSV predicted by an algorithm <12 months. Baseline characteristics were described in the case and comparative cohorts (infants without corresponding admission). Cumulative incidence and admission rates were calculated. Multiple linear regression was used to estimate the proportion of RTI healthcare visits attributable to RSV.

RESULTS

The RSV-coded/RSV-predicted case cohorts were composed of 4813/12,694 infants (cumulative incidence: 1.1%/2.8%). Case cohort infants were more likely to have low birth weight, comorbidities and to be born during RSV season than comparative cohort infants, yet >77% were term-healthy infants and >54% were born before the RSV season. During the first year of life, 11.6 RSV-coded and 34.4 RSV-predicted hospitalizations occurred per 1000 person-years. Overall, >25% of unspecified lower RTI admissions were estimated to be due to RSV.

CONCLUSIONS

In England, 1 in 91 infants had an RSV-coded admission, likely underestimated by ~3-fold. Most infants were term-healthy infants born before the RSV season. To decrease the total burden of RSV at the population level, immunization programs need to protect all infants.

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.

Capturing the Value of Vaccination within Health Technology Assessment and Health Economics-Practical Considerations for Expanding Valuation by Including Key Concepts

Following the development of a value of vaccination (VoV) framework for health technology assessment/cost-effectiveness analysis (HTA/CEA), and identification of three vaccination benefits for near-term inclusion in HTA/CEA, this final paper provides decision makers with methods and examples to consider benefits of health systems strengthening (HSS), equity, and macroeconomic gains. Expert working groups, targeted literature reviews, and case studies were used. Opportunity cost methods were applied for HSS benefits of rotavirus vaccination. Vaccination, with HSS benefits included, reduced the incremental cost-effectiveness ratio (ICER) by 1.4-50.5% (to GBP 11,552-GBP 23,016) depending on alternative conditions considered. Distributional CEA was applied for health equity benefits of meningococcal vaccination. Nearly 80% of prevented cases were among the three most deprived groups. Vaccination, with equity benefits included, reduced the ICER by 22-56% (to GBP 7014-GBP 12,460), depending on equity parameters. Macroeconomic models may inform HTA deliberative processes (e.g., disease impact on the labour force and the wider economy), or macroeconomic outcomes may be assessed for individuals in CEAs (e.g., impact on non-health consumption, leisure time, and income). These case studies show how to assess broader vaccination benefits in current HTA/CEA, providing decision makers with more accurate and complete VoV assessments. More work is needed to refine inputs and methods, especially for macroeconomic gains.

Number of Influenza Risk Factors Informs an Adult's Increased Potential of Severe Influenza Outcomes: A Multiseason Cohort Study From 2015 to 2020

Background

While studies have evaluated factors influencing the risk of severe influenza outcomes, there is limited evidence on the additive impact of having multiple influenza risk factors and how this varies by age.

Methods

Patients ≥18 years of age in the United States were evaluated retrospectively in 5 seasonal cohorts during the 2015-2020 influenza seasons. Patient-level electronic medical records linked to pharmacy and medical claims were used to ascertain covariates and outcomes. Multivariable logistic regression models were fitted for the overall population and by age subgroups to evaluate the association of demographic and clinical characteristics with odds of influenza-related medical encounters (ICD-10 codes J09*-J11*). The logistic regression models included sex, race/ethnicity, geographic region, baseline health care resource use, vaccination status, specific high-risk comorbidities, number of influenza risk factors, body mass index, and smoking status. Odds ratios from each of the 5 seasons were summarized via fixed effect meta-analysis.

Results

Season cohort sizes ranged from 887 260 to 3 628 168 adults. Of all patient characteristics evaluated, an individual's cumulative number of high-risk influenza conditions, as defined per the Centers for Disease Control and Prevention, was the most predictive of an increased probability of having an influenza-related medical encounter overall and across age groups. For adults of any age, odds ratios for influenza hospitalization ranged from 1.8 (95% CI, 1.7-2.0) for 1 risk factor to 6.4 (95% CI, 5.8-7.0) for ≥4 risk factors.

Conclusions

These results show that a simple measure such as the number of influenza risk factors can be highly informative of an adult's potential for severe influenza outcomes.

Influenza Hospitalization Burden by Subtype, Age, Comorbidity, and Vaccination Status: 2012-2013 to 2018-2019 Seasons, Quebec, Canada

BACKGROUND

Influenza immunization programs aim to reduce the risk and burden of severe outcomes. To inform optimal program strategies, we monitored influenza hospitalizations over 7 seasons, stratified by age, comorbidity, and vaccination status.

METHODS

We assembled data from 4 hospitals involved in an active surveillance network with systematic collection of nasal samples and polymerase chain reaction testing for influenza virus in all patients admitted through the emergency department with acute respiratory infection during the 2012-2013 to 2018-2019 influenza seasons in Quebec, Canada. We estimated seasonal, population-based incidence of influenza-associated hospitalizations by subtype predominance, age, comorbidity, and vaccine status, and derived the number needed to vaccinate to prevent 1 hospitalization per stratum.

RESULTS

The average seasonal incidence of influenza-associated hospitalization was 89/100 000 (95% confidence interval, 86-93), lower during A(H1N1) (49-82/100 000) than A(H3N2) seasons (73-143/100 000). Overall risk followed a J-shaped age pattern, highest among infants 0-5 months and adults ≥75 years old. Hospitalization risks were highest for children <5 years old during A(H1N1) but for highest adults aged ≥75 years during A(H3N2) seasons. Age-adjusted hospitalization risks were 7-fold higher among individuals with versus without comorbid conditions (214 vs 30/100 000, respectively). The number needed to vaccinate to prevent hospitalization was 82-fold lower for ≥75-years-olds with comorbid conditions (n = 1995), who comprised 39% of all hospitalizations, than for healthy 18-64-year-olds (n = 163 488), who comprised just 6% of all hospitalizations.

CONCLUSIONS

In the context of broad-based influenza immunization programs (targeted or universal), severe outcome risks should be simultaneously examined by subtype, age, comorbidity, and vaccine status. Policymakers require such detail to prioritize promotional efforts and expenditures toward the greatest and most efficient program impact.

Influenza vaccination in pregnant women in Iceland 2010-2020 and the burden of influenza in pregnant women and their infants

INTRODUCTION

Influenza vaccinations are recommended in pregnancy to protect both the pregnant woman and the unborn baby. The aim of this study was to assess the influenza vaccine uptake among pregnant women in Iceland in ten influenza seasons and to estimate the influenza disease burden on pregnant women and their infants.

METHODS

This was a retrospective, descriptive study on influenza vaccine uptake among pregnant women and the burden of influenza and influenza-like illness (ILI) among pregnant women and their infants in ten influenza seasons. All women attending a 20-week ultrasound at Landspitali University Hospital in Reykjavik in August-April each influenza season 2010-2020 were included in the study. Data on influenza vaccinations and influenza/ILI diagnoses was collected from central national databases.

RESULTS

The influenza vaccine uptake increased from 6.2 % in 2011-2012 to 37.5 % in 2019-2020. The incidence rate of influenza/ILI among pregnant women ranged from 5.5 to 22.1/1000 person-years. The estimated vaccine effectiveness in the ten influenza seasons was 34-100 %. The incidence rate of influenza/ILI among infants < 12 months of age was 0-13.4/1000 person-years. Influenza vaccinations in pregnancy are protective against influenza/ILI in pregnant women (IRR 0.36, 95 % CI 0.22-0.58), infants in the season of vaccination (IRR 0.40, 95 % CI 0.17-0.97) and probably for infants < 6 months of age (IRR 0.51, 95 % CI 0.22-1.21).

CONCLUSIONS

Influenza vaccine coverage in pregnancy is suboptimal. Influenza vaccinations in pregnancy provide significant protection against influenza/ILI for pregnant women and infants in the season of vaccination. Initiatives to improve maternal vaccination coverage are needed.

Respiratory Syncytial Virus-Associated Hospitalization in Adults With Comorbidities in 2 European Countries: A Modeling Study

BACKGROUND

Individuals with comorbidities are at increased risk of severe respiratory syncytial virus (RSV) infection. We estimated RSV-associated respiratory hospitalization among adults aged ≥45 years with comorbidities in Denmark and Scotland.

METHODS

By analyzing national hospital and virologic data, we estimated annual RSV-associated hospitalizations by 7 selected comorbidities and ages between 2010 and 2018. We estimated rate ratios of RSV-associated hospitalization for adults with comorbidity than the overall population.

RESULTS

In Denmark, annual RSV-associated hospitalization rates per 1000 adults ranged from 3.1 for asthma to 19.4 for chronic kidney disease (CKD). In Scotland, rates ranged from 2.4 for chronic liver disease to 9.0 for chronic obstructive pulmonary disease (COPD). In both countries, we found a 2- to 4-fold increased risk of RSV hospitalization for adults with COPD, ischemic heart disease, stroke, and diabetes; a 1.5- to 3-fold increased risk for asthma; and a 3- to 7-fold increased risk for CKD. RSV hospitalization rates among adults aged 45 to 64 years with COPD, asthma, ischemic heart disease, or CKD were higher than the overall population.

CONCLUSIONS

This study provides important evidence for identifying risk groups and assisting health authorities in RSV vaccination policy making.

Assessing interventions to encourage primary care health workers to recommend influenza vaccination and the impact on vaccination uptake for persons with Non-Communicable diseases in China

BACKGROUND

Influenza vaccination coverage is low among persons with non-communicable diseases (NCDs) in China. Chinese health workers (HWs) do not routinely recommend influenza vaccination despite evidence that recommendations increase vaccine uptake. This study aims to assess whether interventions increased primary care HWs' recommendation for influenza vaccination and measure their impact on influenza vaccine uptake in persons with NCDs.

METHODS

We conducted a cluster randomized controlled study in public primary healthcare clinics in Hubei from November 2018 through April 2019. In the intervention clinics, primary care HWs received training on the benefits of influenza vaccination and were asked to recommend influenza vaccine in routine primary healthcare for persons with NCDs. In the control clinics, primary care HWs did not receive training and provided standard services. We conducted questionnaire surveys before and after the intervention to collect information about recommendations made and receipt of influenza vaccines.

RESULTS

A total of 896 primary care HWs and 4552 persons with NCDs were included. After intervention, a higher percentage of HWs recommended influenza vaccines in intervention clinics compared to control clinics. Vaccinated primary care HWs were more likely to recommend vaccination. Persons with NCDs reported higher influenza vaccination coverage in intervention than control clinics, and primary care HWs' recommendation increased vaccination uptake among persons with NCDs.

CONCLUSIONS

Vaccinated primary care HWs were more likely to recommend influenza vaccination than unvaccinated HWs. Promoting primary care HWs' vaccination and encouraging them to recommend influenza vaccination during routine primary healthcare could increase influenza vaccine receipt among persons with NCDs. Registration number ChiCTR2200067140.

Uncovering the burden of Influenza in children in Portugal, 2008-2018

BACKGROUND

Despite their higher risk of developing severe disease, little is known about the burden of influenza in Portugal in children aged < 5 years old. This study aims to cover this gap by estimating the clinical and economic burden of severe influenza in children, in Portugal, during ten consecutive influenza seasons (2008/09-2017/18).

METHODS

We reviewed hospitalizations in children aged < 5 years old using anonymized administrative data covering all public hospitals discharges in mainland Portugal. The burden of hospitalization and in-hospital mortality directly coded as due to influenza was supplemented by the indirect burden calculated from excess hospitalization and mortality (influenza-associated), estimated for four groups of diagnoses (pneumonia or influenza, respiratory, respiratory or cardiovascular, and all-cause), through cyclic regression models integrating the incidence of influenza. Means were reported excluding the H1N1pdm09 pandemic (2009/10).

RESULTS

The mean annual number of hospitalizations coded as due to influenza was 189 (41.3 cases per 100,000 children aged < 5 years old). Hospitalization rates decreased with increasing age. Nine-in-ten children were previously healthy, but the presence of comorbidities increased with age. Children stayed, on average, 6.1 days at the hospital. Invasive mechanical ventilation was used in 2.4% of hospitalizations and non-invasive in 3.1%. Influenza-associated excess hospitalizations between 2008 and 2018 were estimated at 1,850 in pneumonia or influenza, 1,760 in respiratory, 1,787 in respiratory or cardiovascular, and 1,879 in all-cause models. A total of 95 influenza-associated excess deaths were estimated in all-cause, 14 in respiratory or cardiovascular, and 9 in respiratory models. Over ten years, influenza hospitalizations were estimated to have cost the National Health Service at least €2.9 million, of which 66.5% from healthy children.

CONCLUSIONS

Influenza viruses led to a high number of hospitalizations in children. Most were previously healthy. Results should lead to a reflection on the adequate preventive measures to protect this age group.

Forecasting influenza hospital admissions within English sub-regions using hierarchical generalised additive models

BACKGROUND

Seasonal influenza places a substantial burden annually on healthcare services. Policies during the COVID-19 pandemic limited the transmission of seasonal influenza, making the timing and magnitude of a potential resurgence difficult to ascertain and its impact important to forecast.

METHODS

We have developed a hierarchical generalised additive model (GAM) for the short-term forecasting of hospital admissions with a positive test for the influenza virus sub-regionally across England. The model incorporates a multi-level structure of spatio-temporal splines, weekly cycles in admissions, and spatial correlation. Using multiple performance metrics including interval score, coverage, bias, and median absolute error, the predictive performance is evaluated for the 2022-2023 seasonal wave. Performance is measured against autoregressive integrated moving average (ARIMA) and Prophet time series models.

RESULTS

Across the epidemic phases the hierarchical GAM shows improved performance, at all geographic scales relative to the ARIMA and Prophet models. Temporally, the hierarchical GAM has overall an improved performance at 7 and 14 day time horizons. The performance of the GAM is most sensitive to the flexibility of the smoothing function that measures the national epidemic trend.

CONCLUSIONS

This study introduces an approach to short-term forecasting of hospital admissions for the influenza virus using hierarchical, spatial, and temporal components. The methodology was designed for the real time forecasting of epidemics. This modelling framework was used across the 2022-2023 winter for healthcare operational planning by the UK Health Security Agency and the National Health Service in England.

Estimating the economic burden of influenza on the older population in Malaysia

BACKGROUND

Influenza is a contagious respiratory illness that can cause life-threatening complications among high-risk groups. Estimating the economic burden of influenza is essential to guide policy-making on influenza vaccination programmes, especially in resource-limited settings. This study aimed to estimate the economic burden of influenza on older adults (those aged ≥60 years) in Malaysia from the provider's perspective.

METHODS

The main data source in this study was the MY-DRG Casemix database of a teaching hospital in Malaysia. Cases with principal and secondary diagnoses coded in the International Classification of Diseases version 10 (ICD-10) as J09, J10.0, J10.1, J10.8, J11.0, J11.1, J11.8, J12.8, and J12.9, which represent influenza and its complications, were included in the study. The direct cost of influenza at all severity levels was calculated from the casemix data and guided by a clinical pathway developed by experts. The effect of the variations in costs and incidence rate of influenza for both the casemix and clinical pathway costing approaches was assessed with sensitivity analysis.

RESULTS

A total of 1,599 inpatient and 407 outpatient influenza cases were identified from the MY-DRG Casemix database. Most hospitalised cases were aged <18 years (90.6%), while 77 cases (4.8%) involved older people. Mild, moderate, and severe cases comprised 56.5%, 35.1%, and 8.4% of cases, respectively. The estimated average annual direct costs for managing mild, moderate, and severe influenza were RM2,435 (USD579), RM6,504 (USD1,549), and RM13,282 (USD3,163), respectively. The estimated total annual economic burden of influenza on older adults in Malaysia was RM3.28 billion (USD782 million), which was equivalent to 10.7% of the Ministry of Health Malaysia budget for 2020. The sensitivity analysis indicated that the influenza incidence rate and cost of managing severe influenza were the most important factors influencing the total economic burden.

CONCLUSIONS

Overall, our results demonstrated that influenza imposes a substantial economic burden on the older Malaysian population. The high cost of influenza suggested that further efforts are required to implement a preventive programme, such as immunisation for older people, to reduce the disease and economic burdens.

Synthesis and pharmacodynamic evaluation of naphthalene derivatives against influenza A virus in vitro and in vivo

Influenza A virus is a highly mutable pathogenic pathogen that could cause a global pandemic. It is necessary to find new anti-influenza drugs to resist influenza epidemics due to the seasonal popularity of a certain area every year. Naphthalene derivatives had potential antiviral activity. A series of naphthalene derivatives were synthesized via the metal-free intramolecular hydroarylation reactions of alkynes. Evaluation of their biological efficacy showed that compound 2-aminonaphthalene 4d had better antiviral activity in vitro than ribavirin. By studying the mechanism of action of 2-aminonaphthalene 4din vivo and in vitro, we found that 4d had antiviral activity to three different subtype influenza viruses of A/Weiss/43 (H1N1), A/Virginia/ATCC2/2009 (H1N1) and A/California/2/2014 (H3N2). Compound 4d had the best effect after viral adsorption, and mainly played in the early stage of virus replication. 2-Aminonaphthalene 4d could reduce the replication of virus by inhibiting the NP and M proteins of virus. Compound 4d cut down ROS accumulation, autophagy and apoptosis induced by influenza virus. Inflammatory response mediated by RIG-1 pathway were suppressed in the cell and mice. In addition, the pathological changes of lung tissue and virus titer in mice were reduced by the administration of 4d. Therefore, naphthalene derivative 4d is a potential drug for the treatment of influenza A virus infection.

Influenza hospitalisations in Spain between the last influenza and COVID-19 pandemic (2009-2019)

Knowing the burden of severe disease caused by influenza is essential for disease risk communication, to understand the true impact of vaccination programmes and to guide public health and disease control measures. We estimated the number of influenza-attributable hospitalisations in Spain during the 2010-2011 to 2019-2020 seasons - based on the hospitalisations due to severe acute respiratory infection (SARI) in Spain using the hospital discharge database and virological influenza information from the Spanish Influenza Sentinel Surveillance System (SISSS). The weekly numbers of influenza-attributable hospitalisations were calculated by multiplying the weekly SARI hospitalisations by the weekly influenza virus positivity, obtained from the SISSS in each season, stratified by age group and sex. The influenza-related hospitalisation burden is age-specific and varies significantly by influenza season. People aged 65 and over yielded the highest average influenza-attributable hospitalisation rates per season (615.6 per 100,000), followed by children aged under 5 (251.2 per 100,000). These results provide an essential contribution to influenza control and to improving existing vaccination programmes, as well as to the optimisation and planning of health resources and policies.

The burden of influenza and the role of influenza vaccination in adults aged 50-64 years: A summary of available evidence

Influenza is a vaccine-preventable disease and a global public health problem. Although most national influenza vaccination recommendations focus on subjects aged ≥65 years, an extensive burden of influenza has also been reported in those aged ≥50 years and is exacerbated by immune system aging. The main purpose of this review is to provide an overview of the burden of influenza and its potential prevention within the 50-64 age-group. These subjects account for a large proportion of the workforce, and play a central economic and social role. Individuals aged 50-64 years had a 3-times higher rate of hospitalization and a 9-fold higher mortality rate attributable to influenza than those aged 18-49-years, generating higher influenza-related hospitalization costs. Available data suggest that including healthy subjects aged 50-64 years in influenza vaccination recommendations would allow a broader population to be reached, reducing the economic and social burden of influenza.

Understanding the age spectrum of respiratory syncytial virus associated hospitalisation and mortality burden based on statistical modelling methods: a systematic analysis

BACKGROUND

Statistical modelling studies based on excess morbidity and mortality are important for understanding RSV disease burden for age groups that are less frequently tested for RSV. We aimed to understand the full age spectrum of RSV morbidity and mortality burden based on statistical modelling studies, as well as the value of modelling studies in RSV disease burden estimation.

METHODS

The databases Medline, Embase and Global Health were searched to identify studies published between January 1, 1995, and December 31, 2021, reporting RSV-associated excess hospitalisation or mortality rates of any case definitions using a modelling approach. All reported rates were summarised using median, IQR (Interquartile range) and range by age group, outcome and country income group; where applicable, a random-effects meta-analysis was conducted to combine the reported rates. We further estimated the proportion of RSV hospitalisations that could be captured in clinical databases.

RESULTS

A total of 32 studies were included, with 26 studies from high-income countries. RSV-associated hospitalisation and mortality rates both showed a U-shape age pattern. Lowest and highest RSV acute respiratory infection (ARI) hospitalisation rates were found in 5-17 years (median: 1.6/100,000 population, IQR: 1.3-18.5) and < 1 year (2235.7/100,000 population, 1779.1-3552.5), respectively. Lowest and highest RSV mortality rates were found in 18-49 years (0.1/100,000 population, 0.06-0.2) and ≥ 75 years (80.0/100,000 population, 70.0-90.0) for high-income countries, respectively, and in 18-49 years (0.3/100,000 population, 0.1-2.4) and < 1 year (143.4/100,000 population, 143.4-143.4) for upper-middle income countries. More than 70% of RSV hospitalisations in children < 5 years could be captured in clinical databases whereas less than 10% of RSV hospitalisations could be captured in adults, especially for adults ≥ 50 years. Using pneumonia and influenza (P&I) mortality could potentially capture half of all RSV mortality in older adults but only 10-30% of RSV mortality in children.

CONCLUSIONS

Our study provides insights into the age spectrum of RSV hospitalisation and mortality. RSV disease burden using laboratory records alone could be substantially severely underreported for age groups ≥ 5 years. Our findings confirm infants and older adults should be prioritised for RSV immunisation programmes.

TRIAL REGISTRATION

PROSPERO CRD42020173430.

High Clinical Burden of Influenza Disease in Adults Aged ≥ 65 Years: Can We Do Better? A Systematic Literature Review

INTRODUCTION

Influenza is a respiratory infection associated with a significant clinical burden globally. Adults aged ≥ 65 years are at increased risk of severe influenza-related symptoms and complications due to chronic comorbidity and immunosenescence. Annual influenza vaccination is recommended; however, current influenza vaccines confer suboptimal protection, in part due to antigen mismatch and poor durability. This systematic literature review characterizes the global clinical burden of seasonal influenza among adults aged ≥ 65 years.

METHODS

An electronic database search was conducted and supplemented with a conference abstract search. Included studies described clinical outcomes in the ≥ 65 years population across several global regions and were published in English between January 1, 2012 and February 9, 2022.

RESULTS

Ninety-nine publications were included (accounting for > 156,198,287 total participants globally). Clinical burden was evident across regions, with most studies conducted in the USA and Europe. Risk of influenza-associated hospitalization increased with age, particularly in those aged ≥ 65 years living in long-term care facilities, with underlying comorbidities, and infected with A(H3N2) strains. Seasons dominated by circulating A(H3N2) strains saw increased risk of influenza-associated hospitalization, intensive care unit admission, and mortality within the ≥ 65 years population. Seasonal differences in clinical burden were linked to differences in circulating strains.

CONCLUSIONS

Influenza exerts a considerable burden on adults aged ≥ 65 years and healthcare systems, with high incidence of hospitalization and mortality. Substantial influenza-associated clinical burden persists despite increasing vaccination coverage among adults aged ≥ 65 years across regions included in this review, which suggests limited effectiveness of currently available seasonal influenza vaccines. To reduce influenza-associated clinical burden, influenza vaccine effectiveness must be improved. Next generation vaccine production using mRNA technology has demonstrated high effectiveness against another respiratory virus-SARS-CoV-2-and may overcome the practical limitations associated with traditional influenza vaccine production.

Cost-effectiveness of monoclonal antibody and maternal immunization against respiratory syncytial virus (RSV) in infants: Evaluation for six European countries

BACKGROUND

Respiratory syncytial virus (RSV) imposes a substantial burden on pediatric hospital capacity in Europe. Promising prophylactic interventions against RSV including monoclonal antibodies (mAb) and maternal immunizations (MI) are close to licensure. Therefore, we aimed to evaluate the cost-effectiveness of potential mAb and MI interventions against RSV in infants, for six European countries.

METHODS

We used a static cohort model to compare costs and health effects of four intervention programs to no program and to each other: year-round MI, year-round mAb, seasonal mAb (October to April), and seasonal mAb plus a catch-up program in October. Input parameters were obtained from national registries and literature. Influential input parameters were identified with the expected value of partial perfect information and extensive scenario analyses (including the impact of interventions on wheezing and asthma).

RESULTS

From the health care payer perspective, and at a price of €50 per dose (mAb and MI), seasonal mAb plus catch-up was cost-saving in Scotland, and cost-effective for willingness-to-pay (WTP) values ≥€20,000 (England, Finland) or €30,000 (Denmark) per quality adjusted life-year (QALY) gained for all scenarios considered, except when using ICD-10 based hospitalization data. For the Netherlands, seasonal mAb was preferred (WTP value: €30,000-€90,000) for most scenarios. For Veneto region (Italy), either seasonal mAb with or without catch-up or MI was preferred, depending on the scenario and WTP value. From a full societal perspective (including leisure time lost), the seasonal mAb plus catch-up program was cost-saving for all countries except the Netherlands.

CONCLUSION

The choice between a MI or mAb program depends on the level and duration of protection, price, availability, and feasibility of such programs, which should be based on the latest available evidence. Future research should focus on measuring accurately age-specific RSV-attributable hospitalizations in very young children.

Monitoring COVID-19 and Influenza: The Added Value of a Severe Acute Respiratory Infection Surveillance System in Portugal

Background

Severe acute respiratory infections (SARI) surveillance is recommended to assess the severity of respiratory infections disease. In 2021, the National Institute of Health Doutor Ricardo Jorge, in collaboration with two general hospitals, implemented a SARI sentinel surveillance system based on electronic health registries. We describe its application in the 2021/2022 season and compare the evolution of SARI cases with the COVID-19 and influenza activity in two regions of Portugal.

Methods

The main outcome of interest was the weekly incidence of patients hospitalized due to SARI, reported within the surveillance system. SARI cases were defined as patients containing ICD-10 codes for influenza-like illness, cardiovascular diagnosis, respiratory diagnosis, and respiratory infection in their primary admission diagnosis. Independent variables included weekly COVID-19 and influenza incidence in the North and Lisbon and Tagus Valley regions. Pearson and cross-correlations between SARI cases, COVID-19 incidence and influenza incidence were estimated.

Results

A high correlation between SARI cases or hospitalizations due to respiratory infection and COVID-19 incidence was obtained (ρ = 0.78 and ρ = 0.82, respectively). SARI cases detected the COVID-19 epidemic peak a week earlier. A weak correlation was observed between SARI and influenza cases (ρ = -0.20). However, if restricted to hospitalizations due to cardiovascular diagnosis, a moderate correlation was observed (ρ = 0.37). Moreover, hospitalizations due to cardiovascular diagnosis detected the increase of influenza epidemic activity a week earlier.

Conclusion

In the 2021/2022 season, the Portuguese SARI sentinel surveillance system pilot was able to early detect the COVID-19 epidemic peak and the increase of influenza activity. Although cardiovascular manifestations associated with influenza infection are known, more seasons of surveillance are needed, to confirm the potential use of cardiovascular hospitalizations as an indicator of influenza activity.

Susceptibility identification for seasonal influenza A/H3N2 based on baseline blood transcriptome

Introduction

Influenza susceptibility difference is a widely existing trait that has great practical significance for the accurate prevention and control of influenza.

Methods

Here, we focused on the human susceptibility to the seasonal influenza A/H3N2 of healthy adults at baseline level. Whole blood expression data for influenza A/H3N2 susceptibility from GEO were collected firstly (30 symptomatic and 19 asymptomatic). Then to explore the differences at baseline, a suite of systems biology approaches - the differential expression analysis, co-expression network analysis, and immune cell frequencies analysis were utilized.

Results

We found the baseline condition, especially immune condition between symptomatic and asymptomatic, was different. Co-expression module that is positively related to asymptomatic is also related to immune cell type of naïve B cell. Function enrichment analysis showed significantly correlation with "B cell receptor signaling pathway", "immune response-activating cell surface receptor signaling pathway" and so on. Also, modules that are positively related to symptomatic are also correlated to immune cell type of neutrophils, with function enrichment analysis showing significantly correlations with "response to bacterium", "inflammatory response", "cAMP-dependent protein kinase complex" and so on. Responses of symptomatic and asymptomatic hosts after virus exposure show differences on resisting the virus, with more effective frontline defense for asymptomatic hosts. A prediction model was also built based on only baseline transcription information to differentiate symptomatic and asymptomatic population with accuracy of 0.79.

Discussion

The results not only improve our understanding of the immune system and influenza susceptibility, but also provide a new direction for precise and targeted prevention and therapy of influenza.

Cost-effectiveness of influenza vaccination with a high dose quadrivalent vaccine of the elderly population in Belgium, Finland, and Portugal

BACKGROUND

Seasonal influenza may result in severe outcomes, resulting in a significant increase of hospitalizations during the winter. To improve the protection provided by the standard dose influenza quadrivalent vaccine (SDQIV), a high-dose vaccine (HDQIV) has been developed specifically for adults aged 60 and older who are at higher risk of life-threatening complications.

OBJECTIVES

The aim of this study was to determine the cost-effectiveness of HD QIV vs. SD-QIV in the recommended population of three European countries: Belgium, Finland and Portugal.

METHODS

A cost-utility analysis comparing HDQIV vs. SDQIV was conducted using a decision tree estimating health outcomes conditional on influenza: cases, general practitioner and emergency department visits, hospitalizations and deaths. To account for the full benefit of the vaccine, an additional outcome-hospitalizations attributable to influenza-was also evaluated. Demographic, epidemiological and economic inputs were based on the respective local data. HDQIV relative vaccine efficacy vs. SDQIV was obtained from a phase IV efficacy randomized clinical trial. The incremental cost-effectiveness ratios (ICER) were computed for each country, and a probabilistic sensitivity analysis (1,000 simulations per country) was performed to assess the robustness of the results.

RESULTS

In the base case analysis, HDQIV resulted in improved health outcomes (visits, hospitalizations, and deaths) compared to SDQIV. The ICERs computed were 1,397, 9,581, and 15,267 €/QALY, whereas the PSA yielded 100, 100, and 84% of simulations being cost-effective at their respective willingness-to-pay thresholds, for Belgium, Finland, and Portugal, respectively.

CONCLUSION

In three European countries with different healthcare systems, HD-QIV would contribute to a significant improvement in the prevention of influenza health outcomes while being cost-effective.

Burden of Severe Illness Associated With Laboratory-Confirmed Influenza in Adults Aged 50-64 Years, 2010-2011 to 2016-2017

Background

Understanding the burden of influenza is necessary to optimize recommendations for influenza vaccination. We describe the epidemiology of severe influenza in 50- to 64-year-old residents of metropolitan Toronto and Peel region, Canada, over 7 influenza seasons.

Methods

Prospective population-based surveillance for hospitalization associated with laboratory-confirmed influenza was conducted from September 2010 to August 2017. Conditions increasing risk of influenza complications were as defined by Canada's National Advisory Committee on Immunization. Age-specific prevalence of medical conditions was estimated using Ontario health administrative data. Population rates were estimated using Statistics Canada data.

Results

Over 7 seasons, 1228 hospitalizations occurred in patients aged 50-64 years: 40% due to A(H3N2), 30% A(H1N1), and 22% influenza B. The average annual hospitalization rate was 15.6, 20.9, and 33.2 per 100 000 in patients aged 50-54, 55-59, and 60-64 years, respectively; average annual mortality was 0.9/100 000. Overall, 33% of patients had received current season influenza vaccine; 963 (86%) had ≥1 underlying condition increasing influenza complication risk. The most common underlying medical conditions were chronic lung disease (38%) and diabetes mellitus (31%); 25% of patients were immunocompromised. The average annual hospitalization rate was 6.1/100 000 in those without and 41/100 000 in those with any underlying condition, and highest in those with renal disease or immunocompromise (138 and 281 per 100 000, respectively). The case fatality rate in hospitalized patients was 4.4%; median length of stay was 4 days (interquartile range, 2-8 days).

Conclusions

The burden of severe influenza in 50- to 64-year-olds remains significant despite our universal publicly funded vaccination program. These data may assist in improving estimates of the cost-effectiveness of new strategies to reduce this burden.

Influenza incidence and air pollution: Findings from a four-year surveillance study of prefecture-level cities in China

Background

Influenza is a serious public health problem, and its prevalence and spread show significant spatiotemporal characteristics. Previous studies have found that air pollutants are linked to an increased risk of influenza. However, the mechanism of influence and the degree of their association have not been determined. This study aimed to determine the influence of the air environment on the spatiotemporal distribution of influenza.

Methods

The kernel density estimation and Getis-Ord Gi * statistic were used to analyze the spatial distribution of the influenza incidence and air pollutants in China. A simple analysis of the correlation between influenza and air pollutants was performed using Spearman's correlation coefficients. A linear regression analysis was performed to examine changes in the influenza incidence in response to air pollutants. The sensitivity of the influenza incidence to changes in air pollutants was evaluated by performing a gray correlation analysis. Lastly, the entropy weight method was used to calculate the weight coefficient of each method and thus the comprehensive sensitivity of influenza incidence to six pollution elements.

Results

The results of the sensitivity analysis using Spearman's correlation coefficients showed the following ranking of the contributions of the air pollutants to the influenza incidence in descending order: SO2 >NO2 >CO> PM2.5 >O3 >PM10. The sensitivity results obtained from the linear regression analysis revealed the following ranking: CO>NO2 >SO2 >O3 >PM2.5 >PM10. Lastly, the sensitivity results obtained from the gray correlation analysis showed the following ranking: NO2 >CO>PM10 >PM2.5 >SO2 >O3. According to the sensitivity score, the study area can be divided into hypersensitive, medium-sensitive, and low-sensitive areas.

Conclusion

The influenza incidence showed a strong spatial correlation and associated sensitivity to changes in concentrations of air pollutants. Hypersensitive areas were mainly located in the southeastern part of northeastern China, the coastal areas of the Yellow River Basin, the Beijing-Tianjin-Hebei region and surrounding areas, and the Yangtze River Delta. The influenza incidence was most sensitive to CO, NO2, and SO2, with the occurrence of influenza being most likely in areas with elevated concentrations of these three pollutants. Therefore, the formulation of targeted influenza prevention and control strategies tailored for hypersensitive, medium-sensitive, low-sensitive, and insensitive areas are urgently needed.

Hospital admissions with influenza and impact of age and comorbidities on severe clinical outcomes in Brazil and Mexico

Background

The risk of hospitalization or death after influenza infection is higher at the extremes of age and in individuals with comorbidities. We estimated the number of hospitalizations with influenza and characterized the cumulative risk of comorbidities and age on severe outcomes in Mexico and Brazil.

Methods

We used national hospital discharge data from Brazil (SIH/SUS) from 2010–2018 and Mexico (SAEH) from 2010–2017 to estimate the number of influenza admissions using ICD-10 discharge codes, stratified by age (0–4, 5–17, 18–49, 50–64, and ≥65 years). Duration of hospital stay, admission to the intensive care unit (ICU), and in-hospital case fatality rates (CFRs) defined the severe outcomes. Rates were compared between patients with or without pre-specified comorbidities and by age.

Results

A total of 327,572 admissions with influenza were recorded in Brazil and 20,613 in Mexico, with peaks period most years. In Brazil, the median hospital stay duration was 3.0 days (interquartile range, 2.0–5.0), ICU admission rate was 3.3% (95% CI, 3.2–3.3%), and in-hospital CFR was 4.6% (95% CI, 4.5–4.7). In Mexico, the median duration of stay was 5.0 days (interquartile range, 3.0–7.0), ICU admission rate was 1.8% (95% CI, 1.6–2.0%), and in-hospital CFR was 6.9% (95% CI, 6.5–7.2). In Brazil, ICU admission and in-hospital CFR were higher in adults aged ≥50 years and increased in the presence of comorbidities, especially cardiovascular disease. In Mexico, comorbidities increased the risk of ICU admission by 1.9 (95% CI, 1.0–3.5) and in-hospital CFR by 13.9 (95% CI, 8.4–22.9) in children 0–4 years.

Conclusion

The SIH/SUS and SAEH databases can be used to estimate hospital admissions with influenza, and the disease severity. Age and comorbidities, especially cardiovascular disease, are cumulatively associated with more severe outcomes, with differences between countries. This association should be further analyzed in prospective surveillance studies designed to support influenza vaccination strategy decisions.

Autoantibodies against type I IFNs in patients with critical influenza pneumonia

Autoantibodies neutralizing type I interferons (IFNs) can underlie critical COVID-19 pneumonia and yellow fever vaccine disease. We report here on 13 patients harboring autoantibodies neutralizing IFN-α2 alone (five patients) or with IFN-ω (eight patients) from a cohort of 279 patients (4.7%) aged 6-73 yr with critical influenza pneumonia. Nine and four patients had antibodies neutralizing high and low concentrations, respectively, of IFN-α2, and six and two patients had antibodies neutralizing high and low concentrations, respectively, of IFN-ω. The patients' autoantibodies increased influenza A virus replication in both A549 cells and reconstituted human airway epithelia. The prevalence of these antibodies was significantly higher than that in the general population for patients <70 yr of age (5.7 vs. 1.1%, P = 2.2 × 10-5), but not >70 yr of age (3.1 vs. 4.4%, P = 0.68). The risk of critical influenza was highest in patients with antibodies neutralizing high concentrations of both IFN-α2 and IFN-ω (OR = 11.7, P = 1.3 × 10-5), especially those <70 yr old (OR = 139.9, P = 3.1 × 10-10). We also identified 10 patients in additional influenza patient cohorts. Autoantibodies neutralizing type I IFNs account for ∼5% of cases of life-threatening influenza pneumonia in patients <70 yr old.

Cost-Effectiveness Analysis of Cell Versus Egg-Based Seasonal Influenza Vaccination in Children and Adults in Argentina

Background: Quadrivalent cell-based influenza vaccines (QIVc) avoid egg-adaptive mutations and can be more effective than traditional quadrivalent egg-based influenza vaccines (QIVe). This analysis compared the cost-effectiveness of QIVc and QIVe in Argentinian populations < 65 years old from the payer and societal perspectives. Methods: A static decision tree model compared the costs and health benefits of vaccination with QIVc vs. QIVe using a one-year time horizon. The relative vaccine effectiveness of QIVc vs. QIVe was assumed to be 8.1% for children and 11.4% for adults. An alternative high egg-adaptation scenario was also assessed. Model inputs were sourced from Argentina or the international literature. Deterministic and probabilistic sensitivity analyses were performed. Results: Compared to QIVe, QIVc would prevent 17,857 general practitioner visits, 2418 complications, 816 hospitalizations, and 12 deaths per year. From the payers’ perspective, the incremental cost-effectiveness ratio per quality-adjusted life years gained was USD12,214 in the base case and USD2311 in the high egg-adaptation scenario. QIVc was cost-saving from the societal perspective in both scenarios. Conclusions: QIVc in Argentina would be cost-effective relative to QIVe. The potential health benefits and savings would be even higher in high egg-adaptation seasons.

Urolithin M5 from the Leaves of Canarium album (Lour.) DC. Inhibits Influenza Virus by Targeting Neuraminidase

Ganlanye (GLY), the leaf of Canarium album (Lour.) DC., is a traditional Chinese medicinal herb for warm disease treatment. We found that its aqueous extract could inhibit the influenza A virus. To find and characterize anti-influenza virus phytochemicals from GLY, we performed (1) bioassay-guided isolation, (2) a cell and animal assay, and (3) a mechanism study. Bioassay-guided isolation was used to identify the effective components. Influenza virus-infected MDCK cell and BALB/c mouse models were employed to evaluate the anti-influenza virus activities. A MUNANA assay was performed to find the NA inhibitory effect. As a result, urolithin M5 was obtained from the crude extract of GLY. It inhibited influenza virus activities in vitro and in vivo by suppressing the viral NA activity. In the MDCK cell model, urolithin M5 could inhibit an oseltamivir-resistant strain. In a PR8-infected mouse model, 200 mg/kg/d urolithin M5 protected 50% of mice from death and improved lung edema conditions. GLY was recorded as a major traditional herb for warm disease treatment. Our study identified GLY as a potent anti-influenza herb and showed urolithin M5 as the active component. We first report the in vivo activity of urolithin M5 and support the anti-influenza application of GLY.

Live-attenuated influenza vaccine effectiveness against hospitalization in children aged 2-6 years, the first three seasons of the childhood influenza vaccination program in England, 2013/14-2015/16

INTRODUCTION

In 2013, the United Kingdom began to roll-out a universal annual influenza vaccination program for children. An important component of any new vaccination program is measuring its effectiveness. Live-attenuated influenza vaccines (LAIVs) have since shown mixed results with vaccine effectiveness (VE) varying across seasons and countries elsewhere. This study aims to assess the effectiveness of influenza vaccination in children against severe disease during the first three seasons of the LAIV program in England.

METHODS

Using the screening method, LAIV vaccination coverage in children hospitalized with laboratory-confirmed influenza infection was compared with vaccination coverage in 2-6-year-olds in the general population to estimate VE in 2013/14-2015/16.

RESULTS

The overall LAIV VE, adjusted for age group, week/month and geographical area, for all influenza types pooled over the three influenza seasons was 50.1% (95% confidence interval [CI] 31.2, 63.8). By age, there was evidence of protection against hospitalization from influenza vaccination in both the pre-school (2-4-year-olds) (48.1%, 95% CI 27.2, 63.1) and school-aged children (5-6-year-olds) (62.6%, 95% CI 2.6, 85.6) over the three seasons.

CONCLUSION

LAIV vaccination in children provided moderate annual protection against laboratory-confirmed influenza-related hospitalization in England over the three influenza seasons. This study contributes further to the limited literature to date on influenza VE against severe disease in children.

Trends in COVID-19 hospital outcomes in England before and after vaccine introduction, a cohort study

Widespread vaccination campaigns have changed the landscape for COVID-19, vastly altering symptoms and reducing morbidity and mortality. We estimate trends in mortality by month of admission and vaccination status among those hospitalised with COVID-19 in England between March 2020 to September 2021, controlling for demographic factors and hospital load. Among 259,727 hospitalised COVID-19 cases, 51,948 (20.0%) experienced mortality in hospital. Hospitalised fatality risk ranged from 40.3% (95% confidence interval 39.4-41.3%) in March 2020 to 8.1% (7.2-9.0%) in June 2021. Older individuals and those with multiple co-morbidities were more likely to die or else experienced longer stays prior to discharge. Compared to unvaccinated people, the hazard of hospitalised mortality was 0.71 (0.67-0.77) with a first vaccine dose, and 0.56 (0.52-0.61) with a second vaccine dose. Compared to hospital load at 0-20% of the busiest week, the hazard of hospitalised mortality during periods of peak load (90-100%), was 1.23 (1.12-1.34). The prognosis for people hospitalised with COVID-19 in England has varied substantially throughout the pandemic and according to case-mix, vaccination, and hospital load. Our estimates provide an indication for demands on hospital resources, and the relationship between hospital burden and outcomes.

Exploratory Analysis of the Economically Justifiable Price of a Hypothetical RSV Vaccine for Older Adults in the Netherlands and the United Kingdom

BACKGROUND

In older adults, the burden of respiratory syncytial virus (RSV) resembles that of influenza and may even be considered worse due to the lack of preventive interventions. This study was performed to identify the available literature on RSV infection in older adults, and to provide updated exploratory results of the cost-effectiveness of a hypothetical RSV vaccine in the Netherlands and the United Kingdom.

METHODS

A literature search was performed in Medline and EMBASE on 11 November 2019, which served as input for a static decision-tree model that was used to estimate the EJP, for an RSV vaccine applying different willingness-to-pay (WTP) thresholds. WTP thresholds applied were €20 000 and €50 000 per quality-adjusted life-year for the Netherlands, and £20 000 and £30 000 per quality-adjusted life-year for the United Kingdom. Analyses were-in line with country-specific guidelines-conducted from a societal perspective for the Netherlands and a third-party payer perspective for the United Kingdom. The robustness of the cost-effectiveness results was tested in sensitivity analysis.

RESULTS

After screening the literature, 3 studies for the Netherlands and 6 for the United Kingdom remained to populate the country-specific models. In the base case analysis for the Netherlands (mean RSV incidence, 3.32%), justifiable vaccine prices of €16.38 and €50.03 were found, based on applying the lower and higher WTP thresholds, respectively. Similarly, for the United Kingdom (mean incidence, 7.13%), vaccine prices of £72.29 and £109.74 were found, respectively.

CONCLUSION

RSV vaccination may well be cost-effective in both the Netherlands and the United Kingdom, depending on the exact RSV incidence, vaccine effectiveness and price. However, sensitivity analysis showed that the results were robust based on varying the different parameter estimates and assumptions. With RSV vaccines reaching the final stages of development, a strong need exists for cost-effectiveness studies to understand economically justifiable pricing of the vaccine.

Traditional Chinese Medicine Injections Combined With Oseltamivir for Influenza: Systematic Review and Network Meta-Analysis

Background: As a cause of respiratory tract infections in humans, influenza remains with high morbidity and mortality, with associated significant healthcare burden and increased financial burden. Traditional Chinese medicine injections (TCMIs) combined with oseltamivir (TCMIs + oseltamivir) are the representative therapeutic strategies for influenza, which is a compliant with clinical applications in China. The aim of this study was to describe the comparative efficacy and safety of TCMIs + oseltamivir in patients with influenza, based on the current evidence.

Methods: PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure, Wanfang Data Knowledge Service Platform, VIP information resource integration service platform databases, and the Chinese biomedical literature service system were searched to find randomized controlled trials where TCMIs + oseltamivir are the representative therapeutic strategies for influenza, from inception until October 2021, without language restriction. Two investigators independently screened eligibility criteria, extracted data, and appraised the risk of bias with the same criteria. We conducted a network meta-analysis using the Bayesian random method for each outcome and performed the sensitivity analysis, meta-regression, and Egger’s and Begg’s tests for the reliability and robustness of our results.

Results: Thirty-one trials including 2,893 participants proved eligible and reported on four TCMIs + oseltamivir versus oseltamivir. Network meta-analysis showed Yanhuning (YHN) +oseltamivir (MD = −1.7, 95% CrI: −2.5 to −0.88; SUCRA = 0.89; low certainty of evidence) in fever disappearance time, Tanreqing (TRQ) +oseltamivir (MD = −1.9, 95% CrI: −2.8 to −1; SUCRA = 0.97; low certainty of evidence) in cough disappearance time, and Xiyanping (XYP) +oseltamivir (OR = 5.9, 95% CrI: 3.1 to 11; SUCRA = 0.82; very low certainty of evidence) in the response rate to be more efficacious than oseltamivir alone with the best SUCRA. Based on the combined SUCRA value for primary outcomes, TRQ + oseltamivir is probably better in cough disappearance time, and XYP + oseltamivir and YHN + oseltamivir may be better in fever disappearance time than others. No significant difference in safety between the treatments.

Conclusion: In patients with influenza, TCMIs + oseltamivir only partially improve flu symptoms. Overall therapeutic efficacy and safety are inconclusive, based on low to very low certainty of evidence. However, the safety remains uncertain, and TCMI treatments for influenza should be considered with caution. More high-quality studies examining the efficacy and safety of TCMIs are needed.

Systematic Review Registration:https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42021286994

Association Between Baloxavir Marboxil Prescription for Children with Influenza B Infections and Short-Term Healthcare Consumption in Japan During the 2018-2019 Influenza Season

BACKGROUND

Baloxavir marboxil is an anti-influenza medication that was newly introduced into clinical practice in 2018. Baloxavir might be more beneficial than neuraminidase inhibitors (NAIs), as suggested by a subgroup analysis of a clinical trial. Although the association between baloxavir prescription and healthcare use pertains mainly to influenza A, few studies have investigated the association in influenza B.

METHODS

We evaluated the healthcare utilization of children (0-15 years old) treated with either baloxavir or NAIs between December 2018 and May 2019 using claims records in Japan. The primary endpoint was the composite of medical resource utilization, including hospitalization, antibiotic use, laboratory tests, radiological images, and fluid replacement therapy, over 1-9 days after antiviral prescription. Secondary outcomes representing each single outcome in the composite were examined. Subgroup analyses comparing baloxavir with each NAI were also performed.

RESULTS

Of 4490 patients with influenza B who received antiviral treatment, 51.6% were male, and the median age was 8 years old. Baloxavir was prescribed for 29.4% of the population, and NAIs were prescribed for 70.6%. In the total cohort, 49.3% of patients had any comorbidity related to complicated influenza infection. Concerning the composite endpoint, baloxavir prescription was not associated with a risk of subsequent medical resource use (adjusted odds ratio 1.11; 95% confidence interval 0.90-1.38; P = 0.34). Secondary outcomes and subgroup analyses showed similar results to the primary outcome.

CONCLUSIONS

In a single-year comparative study in Japan, baloxavir prescription for influenza B was not associated with less healthcare consumption than NAIs within 9 days of treatment.

Early life infection and proinflammatory, atherogenic metabolomic and lipidomic profiles in infancy: a population-based cohort study

Background:

The risk of adult onset cardiovascular and metabolic (cardiometabolic) disease accrues from early life. Infection is ubiquitous in infancy and induces inflammation, a key cardiometabolic risk factor, but the relationship between infection, inflammation, and metabolic profiles in early childhood remains unexplored. We investigated relationships between infection and plasma metabolomic and lipidomic profiles at age 6 and 12 months, and mediation of these associations by inflammation.

Methods:

Matched infection, metabolomics, and lipidomics data were generated from 555 infants in a pre-birth longitudinal cohort. Infection data from birth to 12 months were parent-reported (total infections at age 1, 3, 6, 9, and 12 months), inflammation markers (high-sensitivity C-reactive protein [hsCRP]; glycoprotein acetyls [GlycA]) were quantified at 12 months. Metabolic profiles were 12-month plasma nuclear magnetic resonance metabolomics (228 metabolites) and liquid chromatography/mass spectrometry lipidomics (776 lipids). Associations were evaluated with multivariable linear regression models. In secondary analyses, corresponding inflammation and metabolic data from birth (serum) and 6-month (plasma) time points were used.

Results:

At 12 months, more frequent infant infections were associated with adverse metabolomic (elevated inflammation markers, triglycerides and phenylalanine, and lower high-density lipoprotein [HDL] cholesterol and apolipoprotein A1) and lipidomic profiles (elevated phosphatidylethanolamines and lower trihexosylceramides, dehydrocholesteryl esters, and plasmalogens). Similar, more marked, profiles were observed with higher GlycA, but not hsCRP. GlycA mediated a substantial proportion of the relationship between infection and metabolome/lipidome, with hsCRP generally mediating a lower proportion. Analogous relationships were observed between infection and 6-month inflammation, HDL cholesterol, and apolipoprotein A1.

Conclusions:

Infants with a greater infection burden in the first year of life had proinflammatory and proatherogenic plasma metabolomic/lipidomic profiles at 12 months of age that in adults are indicative of heightened risk of cardiovascular disease, obesity, and type 2 diabetes. These findings suggest potentially modifiable pathways linking early life infection and inflammation with subsequent cardiometabolic risk.

Funding:

The establishment work and infrastructure for the BIS was provided by the Murdoch Children’s Research Institute (MCRI), Deakin University, and Barwon Health. Subsequent funding was secured from National Health and Medical Research Council of Australia (NHMRC), The Shepherd Foundation, The Jack Brockhoff Foundation, the Scobie & Claire McKinnon Trust, the Shane O’Brien Memorial Asthma Foundation, the Our Women’s Our Children’s Fund Raising Committee Barwon Health, the Rotary Club of Geelong, the Minderoo Foundation, the Ilhan Food Allergy Foundation, GMHBA, Vanguard Investments Australia Ltd, and the Percy Baxter Charitable Trust, Perpetual Trustees. In-kind support was provided by the Cotton On Foundation and CreativeForce. The study sponsors were not involved in the collection, analysis, and interpretation of data; writing of the report; or the decision to submit the report for publication. Research at MCRI is supported by the Victorian Government’s Operational Infrastructure Support Program. This work was also supported by NHMRC Senior Research Fellowships to ALP (1008396); DB (1064629); and RS (1045161) , NHMRC Investigator Grants to ALP (1110200) and DB (1175744), NHMRC-A*STAR project grant (1149047). TM is supported by an MCRI ECR Fellowship. SB is supported by the Dutch Research Council (452173113).

The impact of clinical risk conditions on influenza and pneumonia diagnoses in England: a nationally representative retrospective cohort study, 2010-2019

The impact of influenza and pneumonia on individuals in clinical risk groups in England has not previously been well characterized. Using nationally representative linked databases (Clinical Practice Research Database (CPRD), Hospital Episode Statistics (HES) and Office for National Statistics (ONS)), we conducted a retrospective cohort study among adults (≥ 18 years) during the 2010/2011-2019/2020 influenza seasons to estimate the incidence of influenza- and pneumonia-diagnosed medical events (general practitioner (GP) diagnoses, hospitalisations and deaths), stratified by age and risk conditions. The study population included a seasonal average of 7.2 million individuals; approximately 32% had ≥1 risk condition, 42% of whom received seasonal influenza vaccines. Medical event incidence rates increased with age, with ~1% of adults aged ≥75 years hospitalized for influenza/pneumonia annually. Among individuals with vs. without risk conditions, GP diagnoses occurred 2-5-fold more frequently and hospitalisations were 7-10-fold more common. Among those with obesity, respiratory, kidney or cardiovascular disorders, hospitalisation were 5-40-fold more common than in individuals with no risk conditions. Though these findings likely underestimate the full burden of influenza, they emphasize the concentration of disease burden in specific age and risk groups and support existing recommendations for influenza vaccination.

Mathematical Modeling Finds Disparate Interferon Production Rates Drive Strain-Specific Immunodynamics during Deadly Influenza Infection

The timing and magnitude of the immune response (i.e., the immunodynamics) associated with the early innate immune response to viral infection display distinct trends across influenza A virus subtypes in vivo. Evidence shows that the timing of the type-I interferon response and the overall magnitude of immune cell infiltration are both correlated with more severe outcomes. However, the mechanisms driving the distinct immunodynamics between infections of different virus strains (strain-specific immunodynamics) remain unclear. Here, computational modeling and strain-specific immunologic data are used to identify the immune interactions that differ in mice infected with low-pathogenic H1N1 or high-pathogenic H5N1 influenza viruses. Computational exploration of free parameters between strains suggests that the production rate of interferon is the major driver of strain-specific immune responses observed in vivo, and points towards the relationship between the viral load and lung epithelial interferon production as the main source of variance between infection outcomes. A greater understanding of the contributors to strain-specific immunodynamics can be utilized in future efforts aimed at treatment development to improve clinical outcomes of high-pathogenic viral strains.

An Economic Comparison of Influenza Vaccines Recommended for Use in Eligible Adults under 65 Years in the United Kingdom

Background: In the United Kingdom (UK), a cell-based quadrivalent influenza vaccine (QIVc) and a recombinant vaccine (QIVr) are recommended for eligible adults under 65 years. The objective of this analysis was to determine the potential cost-effectiveness of QIVc compared to QIVr for this age group using a range of assumptions about relative vaccine effectiveness (rVE). Methods: A dynamic transmission model, calibrated to match infection data from the UK, was used to estimate the clinical and economic impact of vaccination across 10 influenza seasons. The list price was £12.50 for QIVc and £22.00 for QIVr. The base case effectiveness of QIVc was 63.9%. As there are no data comparing the vaccines in the 18 to 64-year-old age group, rVE was varied. Results: For the base case, the rVE of QIVr compared with QIVc must be at least 25% in order for the cost per quality-adjusted life-year gained to be £20,000 or lower. Sensitivity analysis demonstrated that the rVE required for QIVr to be cost-effective was most dependent on the absolute effectiveness of QIVc. Conclusion: At list prices, our analysis predicts that the rVE for QIVr must be at least 25% compared to QIVc in order to be considered cost-effective.

Incidence, circulation, and spatiotemporal analysis of seasonal influenza in Shandong, China, 2008-2019: A retrospective study

BACKGROUND

Understanding the influenza-like illness (ILI) incidence, circulation pattern of virus strains and spatiotemporal pattern of influenza transmission are important for designing control interventions. Based on the 10 years' surveillance data, we aimed to provide a baseline characterization and the epidemiology and dynamics of influenza virus in Shandong.

METHODS

We extracted surveillance and laboratory testing data. We estimated the ILI incidence and analyzed the predominant virus. A wavelet power analysis was used to illustrate the periodicity. In addition, we applied a linear regression model to characterize the correlation of influenza seasonality with longitude.

RESULTS

The average ILI incidence was estimated to be 3744.79 per 1 million (95% confidence interval [CI]: 2558.09-4931.45) during 2009-2018. Influenza A/H1N1 and A/H3N2 strains predominated in the most influenza seasons in Shandong. The annual amplitude of influenza epidemics decreased with longitude (P < 0.05). In contrast, the epidemic peak of influenza emerged earlier in the western region and increased with longitude in influenza A (P < 0.05). The annual peak of the influenza B epidemic lagged a median of 4.2 weeks compared with that of influenza A.

CONCLUSIONS

The development or modification of seasonal influenza vaccination strategies requires the recognition that the incidence is higher in preschool- and school-aged children. Although seasonal influenza circulates annually in Shandong, the predominant virus strain circulation pattern is extremely unpredictable and strengthening surveillance for the predominant virus strain is necessary. Lower longitude inland regions need to take nonpharmaceutical or pharmaceutical interventions in advance during influenza high-occurrence seasons.

Uptake and impact of vaccinating primary school children against influenza: Experiences in the fourth season of the live attenuated influenza vaccination programme, England, 2016/2017

BACKGROUND

In the 2016/2017 influenza season, England was in its fourth season of the roll-out of a live-attenuated influenza vaccine (LAIV) targeted at healthy children aged two to less than 17 years. For the first time, all healthy children aged 2 to 8 years were offered LAIV at national level in 2016/2017. Since the commencement of the programme in 2013/2014, a series of geographically discrete pilot areas have been in place where quadrivalent LAIV was also offered to all school age children. In 2016/2017, these were children aged 8 to 11 years, other than those targeted by the national programme.

METHODS

We evaluated the overall and indirect impact of vaccinating primary school age children, on the population of England, by measuring vaccine uptake levels and comparing cumulative disease incidence through various influenza surveillance schemes, in targeted and non-targeted age groups in pilot and non-pilot areas in 2016/2017.

RESULTS

Our findings indicate that cumulative primary care influenza-like consultations, primary and secondary care swab positivity, influenza confirmed hospitalisations and emergency department attendances in pilot areas were overall lower than those observed in non-pilot areas; however, significant differences were not always observed in both targeted and non-targeted age groups. Excess mortality was higher in pilot areas compared with non-pilot areas.

CONCLUSIONS

These results are similar to earlier seasons of the programme indicating the importance and continuing support of vaccinating all primary school children with LAIV to reduce influenza related illness across the population, although further work is needed to understand the differences in excess mortality.

Clinical spectrum, risk factors, and outcomes of children with laboratory-confirmed influenza infection managed in a single tertiary hospital: A 6-year retrospective cohort study

BACKGROUND

Influenza is a highly contagious disease that causes severe illness each year. Data in the United Arab Emirates are scarce.

OBJECTIVES

To study the seasonality, morbidity, mortality rate, and comorbidities associated with confirmed influenza infection in a tertiary hospital in Al-Ain city, UAE.

METHODS

Retrospective study, from 2012 to 2017, of the electronic medical records in Tawam hospital, of children up to 15 years of age with laboratory-confirmed influenza infection.

RESULTS

There were 1392 children, with the highest number in 2017 (n = 461, 33%). The incidence peaked between October and March. The infection was more common between 1 and 11 years of age (n = 948, 68%). The overall prevalence of influenza A (n = 1144, 82%) was higher than influenza B (n = 276, 19.8%). One-third of the patients required admission. The commonest underlying comorbidity was asthma (n = 170, 12%). The two commonest complications were pneumonia (n = 165, 12%) and acute otitis media (n = 82, 6%).

CONCLUSION

Our findings serve as a benchmark for comparison with reports from other countries and need to be considered when reviewing the national vaccination program.

Burden of influenza disease in children under 2 years of age hospitalized between 2011 and 2020 in France

BACKGROUND

Although influenza viruses cause significant morbidity and mortality worldwide, the impact of these infections on children in France and in other European countries has not been extensively characterized. The primary objective of the present study was to describe the burden of influenza disease on hospitalized children under 2 years of age in France, using data from the national hospital discharge summary database (Programme de Médicalisation des Systèmes d'Information, PMSI).

METHODS

In a retrospective study of hospital admissions for influenza among children under the age of 2 in France, we extracted and analyzed hospital administrative data from the PMSI database (from January 1, 2011, to December 31, 2020).

RESULTS

From 2011 to 2020, 28,507 children under the age of 2 were admitted to hospital with a primary or secondary diagnosis of influenza infection. The hospital admission rate was 205 per 100,000 for children under the age of 2, 276 per 100,000 for children under the age of 12 months, and 135 per 100,000 for children aged between 12 and 23 months. Children under 6 months of age were the most affected (45.4%). An underlying condition was identified for 9.4% of the children, and 2.2% of the children were admitted to the intensive care unit. The death rate was 0.12 per 100,000 for children under 2, 0.11 per 100,000 for children under 12 months, and 0.16 per 100,000 for children aged between 12 and 23 months.

CONCLUSIONS

In France, the burden of influenza disease is significant in children under the age of 2.

Pharmacometric analysis of seasonal influenza epidemics and the effect of vaccination using sentinel surveillance data

The identification of influenza epidemics and assessment of the efficacy of vaccination against this infection are major challenges for the implementation of effective public health strategies, such as vaccination programs. In this study, we developed a new pharmacometric model to evaluate the efficacy of vaccination based on infection surveillance data from the 2010/2011 to 2018/2019 influenza seasons in Japan. A novel susceptible‐infected‐removed plus vaccination model, based on an indirect response structure with the effect of vaccination, was applied to describe seasonal influenza epidemics using a preseasonal collection of data regarding serological H₁ antibody titer positivity and the fraction of virus strains. Using this model, we evaluated K_in (a parameter describing the transmission rate of symptomatic influenza infection) for different age groups. Furthermore, we defined a new parameter (prevention factor) showing the efficacy of vaccination against each viral strain and in different age groups. We found that the prevention factor of vaccination against influenza varied among age groups. Notably, children aged 5–14 years showed the highest K_in value during the 10 influenza seasons and the greatest preventive effect of vaccination (prevention factor = 70.8%). The propagation of influenza epidemics varies in different age groups. Children aged 5–14 years most likely play a leading role in the transmission of influenza. Prioritized vaccination in this age group may be the most effective strategy for reducing the prevalence of influenza in the community.

Estimating the burden of adult hospital admissions due to RSV and other respiratory pathogens in England

Respiratory syncytial virus (RSV) is a common seasonal respiratory virus and an important cause of illness among infants, but the burden of RSV disease is not well described among the older population. The objective of this study was to estimate the age‐specific incidence of hospital admission among over 65 s due to respiratory illnesses attributable to RSV in England to inform optimal vaccine and therapeutic interventions.

We used linear multiple regression to examine the effect of changes in weekly counts of respiratory pathogens on the weekly counts of respiratory hospital admissions. The study population was all patients aged 65 years or over admitted to English hospitals between 2nd August 2010 and 30th July 2017.

RSV was estimated to account for a seasonal annual average of 71 (95% CI 52–90) respiratory admissions per 100 000 in adults age 65–74 and 251 (95% CI 186–316) admissions per 100,000 adults age 75+. Pneumococcus was the pathogen responsible for highest annual average respiratory admission with 448 (95% CI 310–587) admissions per 100,000 adults age 65–74 and 1010 (95% CI 527–1493) admissions per 100,000 adults aged 75+.

This study shows that RSV continues to exert a significant burden of disease among older adults in England. These findings will support development of policy for the use of RSV therapeutics and vaccines in this age group.

Influenza vaccine uptake among at-risk adults (aged 16-64 years) in the UK: a retrospective database analysis

Background

In the UK, annual influenza vaccination is currently recommended for adults aged 16–64 years who are in a clinical at-risk group. Despite recommendations, rates of vaccine uptake in the UK have historically been low and below national and international targets. This study aims to analyse vaccine uptake among adults in clinical at-risk groups from the 2015–2016 influenza season to the present.

Methods

A retrospective analysis of influenza vaccine coverage in the UK was conducted using data extracted from publicly available sources. Clinically at-risk individuals (as defined by Public Health England), including pregnant women, aged 16–64 years, were included in this study.

Results

Influenza vaccination coverage rates across the UK in adults aged 16–64 years in a clinical at-risk group have been consistently low over the past 5 years, with only 48.0, 42.4, 44.1 and 52.4% of eligible patients in England, Scotland, Wales and Northern Ireland receiving their annual influenza vaccination during the 2018–2019 influenza season. Influenza vaccine coverage was lowest in patients with morbid obesity and highest in patients with diabetes in 2018–2019. Coverage rates were below current national ambitions of ≥75% in all clinical risk groups. In these clinical at-risk groups, influenza vaccine coverage decreased between 2015 and 2019, and there was considerable regional variation.

Conclusions

Uptake of the influenza vaccine by adults aged 16–64 years in a clinical at-risk group was substantially below the national ambitions. As a result, many individuals in the UK remain at high risk of developing severe influenza or complications. Given that people who are vulnerable to COVID-19 are also at increased risk of complications from influenza, during the 2020–2021 season, there is a heightened need for healthcare professionals across the UK to address suboptimal vaccine uptake, particularly in at-risk patients. Healthcare professionals and policymakers should consider measures targeted at increasing access to and awareness of the clinical benefits of the influenza vaccine.

The cost-effectiveness of an adjuvanted quadrivalent influenza vaccine in the United Kingdom

In the United Kingdom (UK), both the MF59-adjuvanted quadrivalent influenza vaccine (aQIV) and the high-dose QIV (QIV-HD) are preferred for persons aged 65 years and older but only aQIV is reimbursed by the National Health Service (NHS). The objective was to determine the potential cost-effectiveness of vaccinating adults aged 65 years and above with aQIV compared with QIV-HD in the UK. A dynamic transmission model, calibrated to match infection data from the UK, was used to estimate the impact of vaccination in 10 influenza seasons. Vaccine effectiveness was based on a meta-analysis that concluded the vaccines were not significantly different. Vaccine coverage, physician visits, hospitalizations, deaths, utility losses and NHS costs were estimated using published UK sources. The list price of aQIV was £11.88 while a range of prices were tested for QIV-HD. The price of the trivalent high-dose vaccine (TIV-HD) is £20.00 but a list price for QIV-HD is not yet available. The projected differences between the vaccines in terms of clinical cases and influenza treatment costs are minimal. Our analysis demonstrates that in order to be cost-effective, the price of QIV-HD must be similar to that of aQIV and may range from £7.57 to £12.94 depending on the relative effectiveness of the vaccines. The results of the analysis were most sensitive to variation in vaccine effectiveness and the rate of hospitalization due to influenza. Given the evidence, aQIV is cost-saving unless QIV-HD is priced lower than the existing list price of TIV-HD.

Spotlight influenza: Laboratory-confirmed seasonal influenza in people with acute respiratory illness: a literature review and meta-analysis, WHO European Region, 2004 to 2017

BackgroundAcross the World Health Organization European Region, there are few estimates of the proportion of people seeking medical care for influenza-like illness or acute respiratory infections and who have laboratory-confirmed seasonal influenza infection.MethodsWe conducted a meta-analysis of data extracted from studies published between 2004 and 2017 and from sentinel data from the European surveillance system (TESSy) between 2004 and 2018. We pooled within-season estimates by influenza type/subtype, setting (outpatient (OP)/inpatient (IP)) and age group to estimate the proportion of people tested who have laboratory-confirmed and medically-attended seasonal influenza in Europe.ResultsIn the literature review, the pooled proportion for all influenza types was 33% (95% confidence interval (CI): 30-36), higher among OP 36% (95% CI: 33-40) than IP 24% (95% CI: 20-29). Pooled estimates for all influenza types by age group were: 0-17 years, 26% (22-31); 18-64 years, 41% (32-50); ≥ 65 years, 33% (27-40). From TESSy data, 33% (31-34) of OP and 24% (21-27) of IP were positive. The highest proportion of influenza A was in people aged 18-64 years (22%, 16-29). By subtype, A(H1N1)pdm09 was highest in 18-64 year-olds (16%, 11-21%) whereas A(H3N2) was highest in those ≥ 65 years (10%, 2-22). For influenza B, the highest proportion of infections was in those aged 18-64 years (15%, 9-24).ConclusionsLaboratory-confirmed influenza accounted for approximately one third of all acute respiratory infections for which medical care was sought during the influenza season.

Estimating case fatality risk of severe Yellow Fever cases: systematic literature review and meta-analysis

BACKGROUND

Case fatality risk (CFR), commonly referred to as a case fatality ratio or rate, represents the probability of a disease case being fatal. It is often estimated for various diseases through analysis of surveillance data, case reports, or record examinations. Reported CFR values for Yellow Fever vary, offering wide ranges. Estimates have not been found through systematic literature review, which has been used to estimate CFR of other diseases. This study aims to estimate the case fatality risk of severe Yellow Fever cases through a systematic literature review and meta-analysis.

METHODS

A search strategy was implemented in PubMed and Ovid Medline in June 2019 and updated in March 2021, seeking reported severe case counts, defined by fever and either jaundice or hemorrhaging, and the number of those that were fatal. The searches yielded 1,133 studies, and title/abstract review followed by full text review produced 14 articles reporting 32 proportions of fatal cases, 26 of which were suitable for meta-analysis. Four studies with one proportion each were added to include clinical case data from the recent outbreak in Brazil. Data were analyzed through an intercept-only logistic meta-regression with random effects for study. Values of the I2 statistic measured heterogeneity across studies.

RESULTS

The estimated CFR was 39 % (95 % CI: 31 %, 47 %). Stratifying by continent showed that South America observed a higher CFR than Africa, though fewer studies reported estimates for South America. No difference was seen between studies reporting surveillance data and studies investigating outbreaks, and no difference was seen among different symptom definitions. High heterogeneity was observed across studies.

CONCLUSIONS

Approximately 39 % of severe Yellow Fever cases are estimated to be fatal. This study provides the first systematic literature review to estimate the CFR of Yellow Fever, which can provide insight into outbreak preparedness and estimating underreporting.

Impaired memory B-cell recall responses in the elderly following recurrent influenza vaccination

Influenza is a highly contagious viral respiratory disease that affects million of people worldwide each year. Annual vaccination is recommended by the World Health Organization with the goal of reducing influenza severity and limiting transmission through elicitation of antibodies targeting the hemagglutinin (HA) glycoprotein. The antibody response elicited by current seasonal influenza virus vaccines is predominantly strain-specific, but pre-existing influenza virus immunity can greatly impact the serological antibody response to vaccination. However, it remains unclear how B cell memory is shaped by recurrent annual vaccination over the course of multiple seasons, especially in high-risk elderly populations. Here, we systematically profiled the B cell response in young adult (18-34 year old) and elderly (65+ year old) vaccine recipients that received annual split inactivated influenza virus vaccination for 3 consecutive seasons. Specifically, the antibody serological and memory B-cell compartments were profiled for reactivity against current and historical influenza A virus strains. Moreover, multiparametric analysis and antibody landscape profiling revealed a transient increase in strain-specific antibodies in the elderly, but with an impaired recall response of pre-existing memory B-cells, plasmablast (PB) differentiation and long-lasting serological changes. This study thoroughly profiles and compares the immune response to recurrent influenza virus vaccination in young and elderly participants unveiling the pitfalls of current influenza virus vaccines in high-risk populations.