Risk factors for severe outcomes following 2009 influenza A (H1N1) infection: a global pooled analysis

Diet switch pre-vaccination improves immune response and metabolic status in formerly obese mice

Metabolic disease is epidemiologically linked to severe complications upon influenza virus infection, thus vaccination is a priority in this high-risk population. Yet, vaccine responses are less effective in these same hosts. Here we examined how the timing of diet switching from a high-fat diet to a control diet affected influenza vaccine efficacy in diet-induced obese mice. Our results demonstrate that the systemic meta-inflammation generated by high-fat diet exposure limited T cell maturation to the memory compartment at the time of vaccination, impacting the recall of effector memory T cells upon viral challenge. This was not improved with a diet switch post-vaccination. However, the metabolic dysfunction of T cells was reversed if weight loss occurred 4 weeks before vaccination, restoring a functional recall response. This corresponded with changes in the systemic obesity-related biomarkers leptin and adiponectin, highlighting the systemic and specific effects of diet on influenza vaccine immunogenicity.

Host obesity impacts genetic variation in influenza A viral populations

Obesity is well established as a risk factor for many noncommunicable diseases; however, its consequences for infectious disease are poorly understood. Here, we investigated the impact of host obesity on influenza A virus (IAV) genetic variation using a diet-induced obesity ferret model and the A/Hong Kong/1073/1999 (H9N2) strain. Using a co-caging study design, we investigated the maintenance, generation, and transmission of intrahost IAV genetic variation by sequencing viral genomic RNA obtained from nasal wash samples over multiple days of infection. We found evidence for an enhanced role of positive selection acting on de novo mutations in obese hosts that led to nonsynonymous changes that rose to high frequency. In addition, we identified numerous cases of mutations throughout the genome that were specific to obese hosts and that were preserved during transmission between hosts. Despite detection of obese-specific variants, the overall viral genetic diversity did not differ significantly between obese and lean hosts. This is likely due to the high supply rate of de novo variation and common evolutionary adaptations to the ferret host regardless of obesity status, which we show are mediated by variation in the hemagglutinin and polymerase genes (PB2 and PB1). We also identified defective viral genomes (DVGs) that were found uniquely in either obese or lean hosts, but the overall DVG diversity and dynamics did not differ between the two groups. Our study suggests that obesity may result in a unique selective environment impacting intrahost IAV evolution, highlighting the need for additional genetic and functional studies to confirm these effects.IMPORTANCEObesity is a chronic health condition characterized by excess adiposity leading to a systemic increase in inflammation and dysregulation of metabolic hormones and immune cell populations. Influenza A virus (IAV) is a highly infectious pathogen responsible for seasonal and pandemic influenza. Host risk factors, including compromised immunity and pre-existing health conditions, can contribute to increased infection susceptibility and disease severity. During viral replication in a host, the negative-sense single-stranded RNA genome of IAV accumulates genetic diversity that may have important consequences for viral evolution and transmission. Our study provides the first insight into the consequences of host obesity on viral genetic diversity and adaptation, suggesting that host factors associated with obesity alter the selective environment experienced by a viral population, thereby impacting the spectrum of genetic variation.

Diet-induced obesity affects influenza disease severity and transmission dynamics in ferrets

Obesity, and the associated metabolic syndrome, is a risk factor for increased disease severity with a variety of infectious agents, including influenza virus. Yet, the mechanisms are only partially understood. As the number of people, particularly children, living with obesity continues to rise, it is critical to understand the role of host status on disease pathogenesis. In these studies, we use a diet-induced obese ferret model and tools to demonstrate that, like humans, obesity resulted in notable changes to the lung microenvironment, leading to increased clinical disease and viral spread to the lower respiratory tract. The decreased antiviral responses also resulted in obese animals shedding higher infectious virus for a longer period, making them more likely to transmit to contacts. These data suggest that the obese ferret model may be crucial to understanding obesity's impact on influenza disease severity and community transmission and a key tool for therapeutic and intervention development for this high-risk population.

Updated antimicrobial dosing recommendations for obese patients

The prevalence of obesity has increased considerably in the last few decades. Pathophysiological changes in obese patients lead to pharmacokinetic (PK) and pharmacodynamic (PD) alterations that can condition the correct exposure to antimicrobials if standard dosages are used. Inadequate dosing in obese patients can lead to toxicity or therapeutic failure. In recent years, additional antimicrobial PK/PD data, extended infusion strategies, and studies in critically ill patients have made it possible to obtain data to provide a better dosage in obese patients. Despite this, it is usually difficult to find information on drug dosing in this population, which is sometimes contradictory. This is a comprehensive review of the dosing of different types of antimicrobials (antibiotics, antifungals, antivirals, and antituberculosis drugs) in obese patients, where the literature on PK and possible dosing strategies in obese adults was critically assessed.

Defining the balance between optimal immunity and immunopathology in influenza virus infection

Influenza A viruses remain a global threat to human health, with continued pandemic potential. In this Review, we discuss our current understanding of the optimal immune responses that drive recovery from influenza virus infection, highlighting the fine balance between protective immune mechanisms and detrimental immunopathology. We describe the contribution of innate and adaptive immune cells, inflammatory modulators and antibodies to influenza virus-specific immunity, inflammation and immunopathology. We highlight recent human influenza virus challenge studies that advance our understanding of susceptibility to influenza and determinants of symptomatic disease. We also describe studies of influenza virus-specific immunity in high-risk groups following infection and vaccination that inform the design of future vaccines to promote optimal antiviral immunity, particularly in vulnerable populations. Finally, we draw on lessons from the COVID-19 pandemic to refocus our attention to the ever-changing, highly mutable influenza A virus, predicted to cause future global pandemics.

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.

Maternal and perinatal health research during emerging and ongoing epidemic threats: a landscape analysis and expert consultation

INTRODUCTION

Pregnant women and their offspring are often at increased direct and indirect risks of adverse outcomes during epidemics and pandemics. A coordinated research response is paramount to ensure that this group is offered at least the same level of disease prevention, diagnosis, and care as the general population. We conducted a landscape analysis and held expert consultations to identify research efforts relevant to pregnant women affected by disease outbreaks, highlight gaps and challenges, and propose solutions to addressing them in a coordinated manner.

METHODS

Literature searches were conducted from 1 January 2015 to 22 March 2022 using Web of Science, Google Scholar and PubMed augmented by key informant interviews. Findings were reviewed and Quid analysis was performed to identify clusters and connectors across research networks followed by two expert consultations. These formed the basis for the development of an operational framework for maternal and perinatal research during epidemics.

RESULTS

Ninety-four relevant research efforts were identified. Although well suited to generating epidemiological data, the entire infrastructure to support a robust research response remains insufficient, particularly for use of medical products in pregnancy. Limitations in global governance, coordination, funding and data-gathering systems have slowed down research responses.

CONCLUSION

Leveraging current research efforts while engaging multinational and regional networks may be the most effective way to scale up maternal and perinatal research preparedness and response. The findings of this landscape analysis and proposed operational framework will pave the way for developing a roadmap to guide coordination efforts, facilitate collaboration and ultimately promote rapid access to countermeasures and clinical care for pregnant women and their offspring in future epidemics.

Sex differences in systemic inflammation and immune function in diet-induced obesity rodent models: A systematic review

Understanding sex differences in immunological responses in the context of obesity is important to improve health outcomes. This systematic review aimed to investigate sex differences in systemic inflammation, immune cell phenotype, and function in diet-induced obesity (DIO) animal models. A systematic search in Medline, Embase, and CINAHL from inception to April 2023 was conducted, using a combination of the following concepts: sex, obesity, cytokines, and immune cell phenotypes/function. Forty-one publications reporting on systemic inflammation (61%), cell phenotype (44%), and/or function (7%) were included. Females had lower systemic inflammation compared with males in response to DIO intervention and a higher proportion of macrophage (M)2-like cells compared with males that had a higher proportion of M1-like in adipose tissue. Although there were no clear sex differences in immune function, high-fat DIO intervention remains an important factor in the development of immune dysfunction in both males and females, including disturbances in cytokine production, proliferation, and migration of immune cells. Yet, the mechanistic links between diet and obesity on such immune dysfunction remain unclear. Future studies should investigate the role of diet and obesity in the functionality of immune cells and employ adequate methods for a high-quality investigation of sex differences in this context.

The pathogenesis of influenza in intact alveoli: virion endocytosis and its effects on the lung's air-blood barrier

Lung infection by influenza A virus (IAV) is a major cause of global mortality from lung injury, a disease defined by widespread dysfunction of the lung's air-blood barrier. Endocytosis of IAV virions by the alveolar epithelium - the cells that determine barrier function - is central to barrier loss mechanisms. Here, we address the current understanding of the mechanistic steps that lead to endocytosis in the alveolar epithelium, with an eye to how the unique structure of lung alveoli shapes endocytic mechanisms. We highlight where future studies of alveolar interactions with IAV virions may lead to new therapeutic approaches for IAV-induced lung injury.

The 2020 immunization programme landscape: Piloting an assessment metric to evaluate the maturity of national immunization programmes across the life course

BACKGROUND

The World Health Organization (WHO) encourages countries to provide appropriate vaccinations for children, adolescents, and relevant adult populations. Childhood programme have been the focus of global investments, but recent pandemics have increasingly demonstrated the value of life course vaccination. Our objective is to compare national life course immunization programmatic maturity prior to mass COVID-19 vaccine introduction, the largest adult vaccination programme, globally. As coverage estimates (typically used to assess childhood programmes) are not available for adult vaccinations, this analysis pilots a standardized quantitative metric of programmatic maturity.

METHODS

Through consultation with vaccination experts, we developed a standardized approach to assess national immunization programme maturity across the life course. In accordance with expert input, five vaccines were selected to represent delivery across the life course: diphtheria tetanus toxoid and pertussis (DTP); measles (MCV) second dose; human papillomavirus (HPV) final dose; pneumococcal conjugate (PCV) final dose; and seasonal influenza annual dose. Experts recommended inclusion of the following indicators for each vaccine: a legal mandate (national policy), experience delivering the vaccine (programme duration), and vaccine use (uptake for relevant populations). We developed a metric accordingly that provides up to 5 points per vaccine ("vaccine specific maturity score") which when summed forms the "life course maturity score", with a maximum score of 25. We analysed the prevalence of national policies, experience, and use by region and World Bank income group.

RESULTS

More than 55% of the 194 WHO Member States had childhood vaccine policies for all three of the vaccines considered (DTP, MCV, and PCV) compared to 60% for HPV (proxy for adolescent vaccination programme) and 52% for seasonal influenza (proxy for adult vaccination programme). Childhood vaccination programmes (e.g., MCV and DTP) had the highest vaccine specific maturity scores, while seasonal influenza and HPV vaccination programmes had much lower scores. The national life course maturity scores ranged from 1 to 23, with a global median of 12 (IQR: 8; 16).

DISCUSSION

The piloted metric provides an overview of the maturity of life course immunization programmes. The metric is structured to be a flexible, rapid resource that can be used to assess other combinations of vaccines across the life course. The findings from this paper provide a baseline of immunization programme maturity for childhood, adolescent, and adult vaccination programmes immediately prior to the COVID-19 vaccine introduction. This maturity score, or adaptations of this approach, could be used to monitor the trajectory of national immunization programme maturity across the life course in the years ahead.

Risk factors for prolonged mechanical ventilation in critically ill patients with influenza-related acute respiratory distress syndrome

BACKGROUND

Patients with influenza-related acute respiratory distress syndrome (ARDS) are critically ill and require mechanical ventilation (MV) support. Prolonged mechanical ventilation (PMV) is often seen in these cases and the optimal management strategy is not established. This study aimed to investigate risk factors for PMV and factors related to weaning failure in these patients.

METHODS

This retrospective cohort study was conducted by eight medical centers in Taiwan. All patients in the intensive care unit with virology-proven influenza-related ARDS requiring invasive MV from January 1 to March 31, 2016, were included. Demographic data, critical illness data and clinical outcomes were collected and analyzed. PMV is defined as mechanical ventilation use for more than 21 days.

RESULTS

There were 263 patients with influenza-related ARDS requiring invasive MV enrolled during the study period. Seventy-eight patients had PMV. The final weaning rate was 68.8% during 60 days of observation. The mortality rate in PMV group was 39.7%. Risk factors for PMV were body mass index (BMI) > 25 (kg/m2) [odds ratio (OR) 2.087; 95% confidence interval (CI) 1.006-4.329], extracorporeal membrane oxygenation (ECMO) use (OR 6.181; 95% CI 2.338-16.336), combined bacterial pneumonia (OR 4.115; 95% CI 2.002-8.456) and neuromuscular blockade use over 48 h (OR 2.8; 95% CI 1.334-5.879). In addition, risk factors for weaning failure in PMV patients were ECMO (OR 5.05; 95% CI 1.75-14.58) use and bacteremia (OR 3.91; 95% CI 1.20-12.69).

CONCLUSIONS

Patients with influenza-related ARDS and PMV have a high mortality rate. Risk factors for PMV include BMI > 25, ECMO use, combined bacterial pneumonia and neuromuscular blockade use over 48 h. In addition, ECMO use and bacteremia predict unsuccessful weaning in PMV patients.

Prevention of influenza complications in patients with liver disease: a retrospective cohort study

Introduction

Patients with chronic liver disease are highly prone to acquiring influenza infection diseases and experiencing associated complications. National and international guidelines recommend the influenza vaccine for patients with liver disorders to reduce the risk of influenza complications. Our study aims to evaluate the risk of flu complications faced by patients with liver disease and assess influenza vaccination coverage.

Methods

The archive of hospital discharge forms was used to define the list of Apulian patients with liver disease, considering data from 2017 through 2022. The vaccination status of these patients was assessed via data collected from the Regional Immunization Database. We focused on influenza vaccine shots administered during the 2020/21, 2021/22, and 2022/23 flu seasons.

Results

A declining trend across the flu seasons was observed, with a VC of 49.5% in the 2020/21 flu season, 48.1% in the 2021/22 season, and 45.0% in the 2022/23 season. Subjects with multiple comorbidities have higher vaccination rates. Additionally, the multivariate models demonstrate that vaccination compliance increases with age and is strongly associated with having received a previous influenza vaccine shot.

Conclusion

The VC rates reported in our study are unsatisfactory and did not reach the minimum achievable goal (75%) the Italian Ministry of Health set. A multifactorial approach is required to raise the immunization rates and therefore protect the patients from the influenza-associated risk of collateral liver damage; the role of gastroenterologists and hepatologists is crucial, as their responsibilities should extend beyond patient care to the prevention of complications after infectious diseases.

Obesity amplifies influenza virus-driven disease severity in male and female mice

Influenza virus-induced respiratory pneumonia remains a major public health concern. Obesity, metabolic diseases, and female sex are viewed as independent risk factors for worsened influenza virus-induced lung disease severity. However, lack of experimental models of severe obesity in female mice limits discovery-based studies. Here, via utility of thermoneutral housing (30 °C) and high-fat diet (HFD) feeding, we induced severe obesity and metabolic disease in female C57BL/6 mice and compared their responses to severely obese male C57BL/6 counterparts during influenza virus infection. We show that lean male and female mice have similar lung edema, inflammation, and immune cell infiltration during influenza virus infection. At standard housing conditions, HFD-fed male, but not female, mice exhibit severe obesity, metabolic disease, and exacerbated influenza disease severity. However, combining thermoneutral housing and HFD feeding in female mice induces severe obesity and metabolic disease, which is sufficient to amplify influenza virus-driven disease severity to a level comparable to severely obese male counterparts. Lastly, increased total body weights of male and female mice at time of infection correlated with worsened influenza virus-driven disease severity metrics. Together, our findings confirm the impact of obesity and metabolic disease as key risk factors to influenza disease severity and present a novel mouse experimental model suitable for future mechanistic interrogation of sex, obesity, and metabolic disease traits in influenza virus-driven disease severity.

Association of Chronic Medical Conditions With Severe Outcomes Among Nonpregnant Adults 18-49 Years Old Hospitalized With Influenza, FluSurv-NET, 2011-2019

Background

Older age and chronic conditions are associated with severe influenza outcomes; however, data are only comprehensively available for adults ≥65 years old. Using data from the Influenza Hospitalization Surveillance Network (FluSurv-NET), we identified characteristics associated with severe outcomes in adults 18-49 years old hospitalized with influenza.

Methods

We included FluSurv-NET data from nonpregnant adults 18-49 years old hospitalized with laboratory-confirmed influenza during the 2011-2012 through 2018-2019 seasons. We used bivariate and multivariable logistic regression to determine associations between select characteristics and severe outcomes including intensive care unit (ICU) admission, invasive mechanical ventilation (IMV), and in-hospital death.

Results

A total of 16 140 patients aged 18-49 years and hospitalized with influenza were included in the analysis; the median age was 39 years, and 26% received current-season influenza vaccine before hospitalization. Obesity, asthma, and diabetes mellitus were the most common chronic conditions. Conditions associated with a significantly increased risk of severe outcomes included age group 30-39 or 40-49 years (IMV, age group 30-39 years: adjusted odds ratio [aOR], 1.25; IMV, age group 40-49 years: aOR, 1.36; death, age group 30-39 years: aOR, 1.28; death, age group 40-49 years: aOR, 1.69), being unvaccinated (ICU: aOR, 1.18; IMV: aOR, 1.25; death: aOR, 1.48), and having chronic conditions including extreme obesity and chronic lung, cardiovascular, metabolic, neurologic, or liver diseases (ICU: range aOR, 1.22-1.56; IMV: range aOR, 1.17-1.54; death: range aOR, 1.43-2.36).

Conclusions

To reduce the morbidity and mortality associated with influenza among adults aged 18-49 years, health care providers should strongly encourage receipt of annual influenza vaccine and lifestyle/behavioral modifications, particularly among those with chronic medical conditions.

Rethinking Immunological Risk: A Retrospective Cohort Study of Severe SARS-Cov-2 Infections in Individuals With Congenital Immunodeficiencies

BACKGROUND

Debates on the allocation of medical resources during the coronavirus disease 2019 (COVID-19) pandemic revealed the need for a better understanding of immunological risk. Studies highlighted variable clinical outcomes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in individuals with defects in both adaptive and innate immunity, suggesting additional contributions from other factors. Notably, none of these studies controlled for variables linked with social determinants of health.

OBJECTIVE

To determine the contributions of determinants of health to risk of hospitalization for SARS-CoV-2 infection among individuals with inborn errors of immunodeficiencies.

METHODS

This is a retrospective, single-center cohort study of 166 individuals with inborn errors of immunity, aged 2 months through 69 years, who developed SARS-CoV-2 infections from March 1, 2020, through March 31, 2022. Risks of hospitalization were assessed using a multivariable logistic regression analysis.

RESULTS

The risk of SARS-CoV-2-related hospitalization was associated with underrepresented racial and ethnic populations (odds ratio [OR] 4.50; 95% confidence interval [95% CI] 1.57-13.4), a diagnosis of any genetically defined immunodeficiency (OR 3.32; 95% CI 1.24-9.43), obesity (OR 4.24; 95% CI 1.38-13.3), and neurological disease (OR 4.47; 95% CI 1.44-14.3). The COVID-19 vaccination was associated with reduced hospitalization risk (OR 0.52; 95% CI 0.31-0.81). Defects in T cell and innate immune function, immune-mediated organ dysfunction, and social vulnerability were not associated with increased risk of hospitalization after controlling for covariates.

CONCLUSIONS

The associations between race, ethnicity, and obesity with increased risk of hospitalization for SARS-CoV-2 infection indicate the importance of variables linked with social determinants of health as immunological risk factors for individuals with inborn errors of immunity.

The Effect of Bifidobacterium animalis subsp. lactis Bl-04 on Influenza A Virus Infection in Mice

Influenza A virus infection is a major global disease requiring annual vaccination. Clinical studies indicate that certain probiotics may support immune function against influenza and other respiratory viruses, but direct molecular evidence is scarce. Here, mice were treated with a placebo or Bifidobacterium animalis subsp. lactis Bl-04 (Bl-04) orally via food (cereal) and also by gavage and exposed to Influenza A virus H1N1 (H1N1). The symptoms of the infection were observed, and tissues and digesta were collected for viral load RT-qPCR, transcriptomics, and microbiomics. The treatment decreased the viral load by 48% at day 3 post-infection in lungs and symptoms of infection at day 4 compared to placebo. Tissue transcriptomics showed differences between the Bl-04 and placebo groups in the genes in the Influenza A pathway in the intestine, blood, and lungs prior to and post-infection, but the results were inconclusive. Moreover, 16S rRNA gene profiling and qPCR showed the presence of Bl-04 in the intestine, but without major shifts in the microbiome. In conclusion, Bl-04 treatment may influence the host response against H1N1 in a murine challenge model; however, further studies are required to elucidate the mechanism of action.

Influenza vaccine coverage among healthcare workers: A cluster analysis from a cross-sectional survey

OBJECTIVES

Influenza vaccination is recommended for healthcare workers (HCWs). However, in a 1500-bed tertiary care university hospital in France, influenza vaccine coverage among HCWs was 23% in 2017.

PATIENTS AND METHODS

We performed a cross-sectional study between 05/09/2018 and 25/09/2018 among HCWs, randomly selected independent of their vaccination status, to estimate influenza vaccination coverage rate during the 2017-2018 season, and explore factors influencing vaccination, using a questionnaire. Multivariable regression analysis to assess factors associated with vaccine uptake and hierarchical clustering on principal components to identify HCW profiles regarding factors influencing vaccine uptake, were performed after multiple imputation.

RESULTS

977 HCWs were included (68% participation rate), primarily females (84%), nurses (38%) of 18-39 years old. Influenza vaccination coverage rate reached 33[30-36]%. Frequent vaccination (aOR 39.27[21.52-74.51]) and personal/family medical history of influenza (aOR 3.33[1.16-10.02]) were independently associated with vaccination. In HCWs' patterns of influenza vaccination status, three clusters were identified: 1) (n = 438) mostly vaccinated (70%); 2) (n = 507) most unvaccinated (97%); and 3) (n = 32) unvaccinated HCWs lacking knowledge on influenza and influenza vaccine. Among the 148 (15%) HCWs reluctant to receive the vaccine the following year, 23 (16%) received it for the 2017-2018 season, while 125 (84%) did not, mostly stating they had doubts about the vaccine (82%).

CONCLUSION

This work identifies determinants of vaccine uptake and highlights HCWs profiles associated with factors influencing vaccination and a subgroup of HCWs flexible about having the vaccine during the upcoming seasonal campaign. This result opens up perspectives toward improved vaccination coverage among HCWs.

Reduced risk of pneumonia and influenza infection after bariatric surgery: a retrospective cohort study among patients with nondiabetic obesity in Taiwan

BACKGROUND

Bariatric surgery is associated with significant improvements in immunity in individuals with obesity, but the exact efficacy in reducing pneumonia and influenza infections is unclear.

OBJECTIVE

To investigate the association between bariatric surgery and the risk of pneumonia and influenza infection.

SETTING

Nondiabetic patients who underwent bariatric surgery and matched controls were identified from the National Health Insurance Research Database of Taiwan.

METHODS

We identified 1648 nondiabetic patients who underwent bariatric surgery from the National Health Insurance Research Database of Taiwan in 2001-2009. These patients were matched by propensity score with 4881 nondiabetic patients with obesity who did not undergo bariatric surgery. We followed the surgical and control cohorts until death, any diagnosis of pneumonia or influenza, or December 31, 2012. The Cox proportional hazards regression model was used to calculate the relative risk of pneumonia and influenza infection in those who underwent bariatric surgery compared with those who did not.

RESULTS

Overall, there was a .87-fold (95% CI, .78-.98) reduced risk of pneumonia and influenza infection in the surgical group versus the control group. Four years after bariatric surgery, a sustainable effect of the surgery was observed, and the risk of pneumonia and influenza infection was .83-fold reduced in the surgical group (95% CI, .73-.95). Individuals with obesity who underwent bariatric surgery had a reduced risk of pneumonia and influenza infection compared with matched control individuals.

CONCLUSION

Individuals with obesity who underwent bariatric surgery had a reduced risk of pneumonia and influenza infection compared with matched control individuals.

NK cells vs. obesity: A tale of dysfunction & redemption

Natural killer (NK) cells are critical in protecting the body against infection and cancer. NK cells can rapidly respond to these threats by directly targeting the infected or transformed cell using their cytotoxic machinery or by initiating and amplifying the immune response via their production of cytokines. Additionally, NK cells are resident across many tissues including adipose, were their role extends from host protection to tissue homeostasis. Adipose resident NK cells can control macrophage polarization via cytokine production, whilst also regulating stressed adipocyte fate using their cytotoxic machinery. Obesity is strongly associated with increased rates of cancer and a heightened susceptibility to severe infections. This is in part due to significant obesity-related immune dysregulation, including defects in both peripheral and adipose tissue NK cells. In this review, we detail the literature to date on NK cells in the setting of obesity - outlining the consequences, mechanisms and therapeutic interventions.

Diet-induced obesity impacts influenza disease severity and transmission dynamics in ferrets

Obesity, and the associated metabolic syndrome, is a risk factor for increased disease severity with a variety of infectious agents, including influenza virus. Yet the mechanisms are only partially understood. As the number of people, particularly children, living with obesity continues to rise, it is critical to understand the role of host status on disease pathogenesis. In these studies, we use a novel diet-induced obese ferret model and new tools to demonstrate that like humans, obesity resulted in significant changes to the lung microenvironment leading to increased clinical disease and viral spread to the lower respiratory tract. The decreased antiviral responses also resulted in obese animals shedding higher infectious virus for longer making them more likely to transmit to contacts. These data suggest the obese ferret model may be crucial to understanding obesity's impact on influenza disease severity and community transmission, and a key tool for therapeutic and intervention development for this high-risk population.

Teaser

A new ferret model and tools to explore obesity's impact on respiratory virus infection, susceptibility, and community transmission.

Obesity exacerbates influenza-induced respiratory disease via the arachidonic acid-p38 MAPK pathway

Obesity is a risk factor for severe influenza, and asthma exacerbations caused by respiratory viral infections. We investigated mechanisms that increase the severity of airway disease related to influenza in obesity using cells derived from obese and lean individuals, and in vitro and in vivo models. Primary human nasal epithelial cells (pHNECs) derived from obese compared with lean individuals developed increased inflammation and injury in response to influenza A virus (IAV). Obese mice infected with influenza developed increased airway inflammation, lung injury and elastance, but had a decreased interferon response, compared with lean mice. Lung arachidonic acid (AA) levels increased in obese mice infected with IAV; arachidonic acid increased inflammatory cytokines and injury markers in response to IAV in human bronchial epithelial (HBE) cells. Obesity in mice, and AA in HBE cells, increased activation of p38 MAPK signaling following IAV infection; inhibiting this pathway attenuated inflammation, injury and tissue elastance responses, and improved survival. In summary, obesity increases disease severity in response to influenza infection through activation of the p38 MAPK pathway in response to altered arachidonic acid signaling.

The Role of Obesity in Breast Cancer Pathogenesis

Research has shown that obesity increases the risk for type 2 diabetes mellitus (Type 2 DM) by promoting insulin resistance, increases serum estrogen levels by the upregulation of aromatase, and promotes the release of reactive oxygen species (ROS) by macrophages. Increased circulating glucose has been shown to activate mammalian target of rapamycin (mTOR), a significant signaling pathway in breast cancer pathogenesis. Estrogen plays an instrumental role in estrogen-receptor-positive breast cancers. The role of ROS in breast cancer warrants continued investigation, in relation to both pathogenesis and treatment of breast cancer. We aim to review the role of obesity in breast cancer pathogenesis and novel therapies mediating obesity-associated breast cancer development. We explore the association between body mass index (BMI) and breast cancer incidence and the mechanisms by which oxidative stress modulates breast cancer pathogenesis. We discuss the role of glutathione, a ubiquitous antioxidant, in breast cancer therapy. Lastly, we review breast cancer therapies targeting mTOR signaling, leptin signaling, blood sugar reduction, and novel immunotherapy targets.

Host obesity impacts genetic variation in influenza A viral populations

Obesity is a chronic health condition characterized by excess adiposity leading to a systemic increase in inflammation and dysregulation of metabolic hormones and immune cell populations. Obesity is well established as a risk factor for many noncommunicable diseases; however, its consequences for infectious disease are poorly understood. Influenza A virus (IAV) is a highly infectious pathogen responsible for seasonal and pandemic influenza. Host risk factors, including compromised immunity and pre-existing health conditions, can contribute to increased infection susceptibility and disease severity. During viral replication in a host, the negative sense single stranded RNA genome of IAV accumulates genetic diversity that may have important consequences for viral evolution and transmission. Here, we investigated the impact of host obesity on IAV genetic variation using a diet induced obesity ferret model. We infected obese and lean male ferrets with the A/Hong Kong/1073/1999 (H9N2) IAV strain. Using a co-caging study design, we investigated the maintenance, generation, and transmission of intrahost IAV genetic variation by sequencing viral genomic RNA obtained from nasal wash samples over multiple days of infection. We found evidence for an enhanced role of positive selection acting on de novo mutations in obese hosts that led to nonsynonymous changes that rose to high frequency. In addition, we identified numerous cases of recurrent low-frequency mutations throughout the genome that were specific to obese hosts. Despite these obese-specific variants, overall viral genetic diversity did not differ significantly between obese and lean hosts. This is likely due to the high supply rate of de novo variation and common evolutionary adaptations to the ferret host regardless of obesity status, which we show are mediated by variation in the hemagglutinin (HA) and polymerase genes (PB2 and PB1). As with single nucleotide variants, we identified a class of defective viral genomes (DVGs) that were found uniquely in either obese or lean hosts, but overall DVG diversity and dynamics did not differ between the two groups. Our study provides the first insight into the consequences of host obesity on viral genetic diversity and adaptation, suggesting that host factors associated with obesity alter the selective environment experienced by a viral population, thereby impacting the spectrum of genetic variation.

Epidemiology and Outcomes of HIN1 Pneumonia in ICU

Introduction

Pandemic influenza H1N1/09 emerged for the first time in April 2009 and has spread widely across India since then. The number of cases have increased over time with the increasing need for respiratory support, causing significant morbidity and mortality. We evaluated the clinical course and outcomes of patients infected with Influenza A (H1N1) admitted to three multidisciplinary intensive care units (ICU) in Chennai.

Materials and methods

We performed a combined retrospective and prospective observational study of all patients admitted with H1N1 pneumonia at three multidisciplinary ICUs in Chennai from October 1, 2018, to January 31, 2019. Data including demographics, risk factors, and clinical courses were recorded. Outcome data including mortality was tracked up to 28 days.

Results

A total of 167 patients were admitted during the study period of which 154 were included in this analysis. The mean age of presentation was 58.2 ± 15.6 years and 59.1% of them were males. The mean acute physiology and chronic health evaluation (APACHE) IV and sequential organ failure assessment (SOFA) scores were 62.8 ± 23.2 and 5.8 ± 3.9 respectively. Oxygen delivery devices were required in 25.3% for a mean duration of 26.5 ± 5.7 hours. Non-invasive ventilation or high-flow nasal cannula (HFNC) was needed in 33.1% of patients for 59.9 ± 64.5 hours. The proportion of patients requiring mechanical ventilation was 41.6%. Rescue measures in the form of proning, use of inhaled nitric oxide (iNO), and extracorporeal membrane oxygenation (ECMO) were initiated for refractory hypoxemia in 26.6%, 14.1%, and 6.3% respectively. The mean duration of ventilator support was 8.5 ± 8 days. Tracheostomy was required in 20.3% of patients and 7.8% were ventilator dependent at 28 days. The mean ICU and Hospital length of stay were 8.3 ± 10.3 and 12.2 ± 14.1 days respectively and overall 28-day mortality was 20.1%.

Conclusion

A significant proportion of H1N1 patients admitted to the ICU required high-level respiratory support including non-invasive ventilation (NIV), HFNC, or invasive ventilation. Deployment of rescue therapies was common and the overall mortality rate was similar to those reported from Western countries.

How to cite this article

Golagana V, Venkataraman R, Mani AK, Rajan ER, Ramakrishnan N, Vidyasagar DD. Epidemiology and Outcomes of HIN1 Pneumonia in ICU. Indian J Crit Care Med 2023;27(7):470-474.

Chronic allergic asthma induces T-cell exhaustion and impairs virus clearance in mice

BACKGROUND

Allergic asthma, one of the most common types of asthma, is thought to be highly susceptible to respiratory viral infections; however, its pathological mechanism needs to be elucidated. Recent studies have found impaired T-cell function in asthmatic mice. Therefore, we aimed to investigate the way by which asthma induction affects T-cell exhaustion in the lungs and assess the relationship between T-cell exhaustion and influenza viral infection.

METHODS

Chronic allergic asthma mice were induced by intranasal injection of ovalbumin for 6 weeks and asthmatic features and T cell populations in lung or airway were assessed. To determine the influenza virus susceptibility, control and asthma mice were challenged with the human influenza virus strain A/Puerto Rico/8/1934 H1N1 and evaluated the survival rate, lung damage, and virus titer.

RESULTS

Six weeks of OVA sensitization and challenge successfully induced chronic allergic asthma in a mouse model showing significant increase of sera IgE level and broncho-pathological features. A significant decrease in interferon-γ-producing T-cell populations and an increase in exhausted T-cell populations in the lungs of OVA-induced asthmatic mice were observed. Asthmatic mice were more susceptible to influenza virus infection than control mice showing lower survival rate and higher virus titer in lung, and a positive correlation existed between T-cell exhaustion in the lung and virus titer.

CONCLUSIONS

Asthma induction in mice results in the exhaustion of T-cell immunity, which may contribute to the defective capacity of viral protection. This study demonstrates a correlation between asthma conditions and viral susceptibility by investigating the functional characteristics of T-cells in asthma. Our results provide insights into the development of strategies to overcome the dangers of respiratory viral disease in patients with asthma.

Prevalence and Clinical Outcomes of Respiratory Syncytial Virus vs Influenza in Adults Hospitalized With Acute Respiratory Illness From a Prospective Multicenter Study

BACKGROUND

Current understanding of severe respiratory syncytial virus (RSV) infections in adults is limited by clinical underrecognition. We compared the prevalence, clinical characteristics, and outcomes of RSV infections vs influenza in adults hospitalized with acute respiratory illnesses (ARIs) in a prospective national surveillance network.

METHODS

Hospitalized adults who met a standardized ARI case definition were prospectively enrolled across 3 respiratory seasons from hospitals participating across all sites of the US Hospitalized Adult Influenza Vaccine Effectiveness Network (2016-2019). All participants were tested for RSV and influenza using real-time reverse-transcription polymerase chain reaction assay. Multivariable logistic regression was used to test associations between laboratory-confirmed infection and characteristics and clinical outcomes.

RESULTS

Among 10 311 hospitalized adults, 6% tested positive for RSV (n = 622), 18.8% for influenza (n = 1940), and 75.1% negative for RSV and influenza (n = 7749). Congestive heart failure (CHF) or chronic obstructive pulmonary disease (COPD) was more frequent with RSV than influenza (CHF: 37.3% vs 28.8%, P < .0001; COPD: 47.6% vs 35.8%, P < .0001). Patients with RSV more frequently had longer admissions (odds ratio [OR], 1.38; 95% confidence interval [CI], 1.06-1.80) for stays >1 week) and mechanical ventilation (OR, 1.45; 95% CI, 1.09-1.93) compared with influenza but not compared with the influenza-negative group (OR, 1.03; 95% CI, .82-1.28 and OR, 1.17; 95% CI, .91-1.49, respectively).

CONCLUSIONS

The prevalence of RSV across 3 seasons was considerable. Our findings suggest that those with RSV have worse outcomes compared with influenza and frequently have cardiopulmonary conditions. This study informs future vaccination strategies and underscores a need for RSV surveillance among adults with severe ARI.

Rethinking immunologic risk: a retrospective cohort study of severe SARS-CoV-2 infections in individuals with congenital immunodeficiencies

Background

Debates on the allocation of medical resources during the COVID-19 pandemic revealed the need for a better understanding of immunologic risk. Studies highlighted variable clinical outcomes of SARS-CoV-2 infections in individuals with defects in both adaptive and innate immunity, suggesting additional contributions from other factors. Notably, none of these studies controlled for variables linked with social determinants of health.

Objective

To determine the contributions of determinants of health to risk of hospitalization for SARS-CoV-2 infection among individuals with inborn errors of immunodeficiencies.

Methods

This is a retrospective, single-center cohort study of 166 individuals with inborn errors of immunity, aged two months through 69 years, who developed SARS-CoV-2 infections from March 1, 2020 through March 31, 2022. Risks of hospitalization was assessed using a multivariable logistic regression analysis.

Results

The risk of SARS-CoV-2-related hospitalization was associated with underrepresented racial and ethnic populations (odds ratio [OR] 5.29; confidence interval [CI], 1.76-17.0), a diagnosis of any genetically-defined immunodeficiency (OR 4.62; CI, 1.60-14.8), use of B cell depleting therapy within one year of infection (OR 6.1; CI, 1.05-38.5), obesity (OR 3.74; CI, 1.17-12.5), and neurologic disease (OR 5.38; CI, 1.61-17.8). COVID-19 vaccination was associated with reduced hospitalization risk (OR 0.52; CI, 0.31-0.81). Defective T cell function, immune-mediated organ dysfunction, and social vulnerability were not associated with increased risk of hospitalization after controlling for covariates.

Conclusions

The associations between race, ethnicity, and obesity with increased risk of hospitalization for SARS-CoV-2 infection indicate the importance of variables linked with social determinants of health as immunologic risk factors for individuals with inborn errors of immunity.

Highlights

What is already known about this topic? Outcomes of SARS-CoV-2 infections in individuals with inborn errors of immunity (IEI) are highly variable. Prior studies of patients with IEI have not controlled for race or social vulnerability. What does this article add to our knowledge ? For individuals with IEI, hospitalizations for SARS-CoV-2 were associated with race, ethnicity, obesity, and neurologic disease. Specific types of immunodeficiency, organ dysfunction, and social vulnerability were not associated with increased risk of hospitalization. How does this study impact current management guidelines? Current guidelines for the management of IEIs focus on risk conferred by genetic and cellular mechanisms. This study highlights the importance of considering variables linked with social determinants of health and common comorbidities as immunologic risk factors.

The Impact of Coronavirus Disease 2019 on Viral, Bacterial, and Fungal Respiratory Infections

Although coronavirus disease 2019 (COVID-19) remains an ongoing threat, concerns regarding other respiratory infections remain. Throughout the COVID-19 pandemic various epidemiologic trends have been observed in other respiratory viruses including a reduction in influenza and respiratory syncytial virus infections following onset of the COVID-19 pandemic. Observations suggest that infections with other respiratory viruses were reduced with social distancing, mask wearing, eye protection, and hand hygiene practices. Coinfections with COVID-19 exist not only with other respiratory viruses but also with bacterial pneumonias and other nosocomial and opportunistic infections. Coinfections have been associated with increased severity of illness and other adverse outcomes.

Factors associated with poor outcomes in patients with severe acute respiratory infections in Bahrain

Background

Severe acute respiratory tract infection (SARI) is a major global health threat. This study aimed to examine risk factors associated with poor outcomes in patients with SARI.

Methods

All patients who met World Health Organization's (WHO) SARI case definition and were admitted to Salmaniya Medical Complex from January 2018 to December 2021 were included. Epidemiological and virological data were obtained and analyzed.

Results

Of 1159 patients with SARI included, 731 (63.1%) patients were below 50 years, and 357 (30.8%) tested positive for viral pathogens. The most prevalent virus was Flu-A (n = 134, 37.5%), SARS-CoV2 (n = 118, 33%), RSV (n = 51, 14.3%), Flu B (n = 49,13.7%), other viruses (n = 3, 0.8%), and combined infection (n = 2, 0.6%). Six hundred fifty-eight (56.8%) patients had comorbidities, mainly diabetes (n = 284, 43%) and heart disease (n = 217, 33%). 183 (16%) patients were admitted to ICU, 110 (9%) needed mechanical ventilation, and 80 (7%) patients died.The odds of ICU admission were higher for patients with hematological (OR 5.9, 95% CI 3.1-11.1) and lung diseases (OR 2.7, 95% CI 1.6-4.6). The odds of mechanical ventilation were higher among patients with lung disease (OR 3.1, 95% 1.7-5.5). The mortality odds were higher among patients above 50 (OR 2.4, 95% CI 1.4-4.1) and chronic kidney disease (OR 2.5, 95% CI 1.1-5.2).

Conclusions

Being 50 years or above or having kidney, lung, or heart diseases was associated with worse SARI outcomes. Efforts and actions in developing better strategies to vaccinate individuals at high risk and early diagnosis and treatment should help in reducing the burden of SARI.

Beyond energy balance regulation: The underestimated role of adipose tissues in host defense against pathogens

Although the adipose tissue (AT) is a central metabolic organ in the regulation of whole-body energy homeostasis, it is also an important endocrine and immunological organ. As an endocrine organ, AT secretes a variety of bioactive peptides known as adipokines - some of which have inflammatory and immunoregulatory properties. As an immunological organ, AT contains a broad spectrum of innate and adaptive immune cells that have mostly been studied in the context of obesity. However, overwhelming evidence supports the notion that AT is a genuine immunological effector site, which contains all cell subsets required to induce and generate specific and effective immune responses against pathogens. Indeed, AT was reported to be an immune reservoir in the host's response to infection, and a site of parasitic, bacterial and viral infections. In addition, besides AT's immune cells, preadipocytes and adipocytes were shown to express innate immune receptors, and adipocytes were reported as antigen-presenting cells to regulate T-cell-mediated adaptive immunity. Here we review the current knowledge on the role of AT and AT's immune system in host defense against pathogens. First, we will summarize the main characteristics of AT: type, distribution, function, and extraordinary plasticity. Second, we will describe the intimate contact AT has with lymph nodes and vessels, and AT immune cell composition. Finally, we will present a comprehensive and up-to-date overview of the current research on the contribution of AT to host defense against pathogens, including the respiratory viruses influenza and SARS-CoV-2.

Algorithms for management of patients with severe A/H1N1 influenza: from diagnosis to respiratory support techniques. Guidelines

In 2022, the incidence of swine (A/H1N1) influenza markedly increased. It causes acute lung injury similar to that caused by SARS-CoV-2. These practice guidelines focus on the management of patients with severe influenza: from the diagnostic algorithm to the specifics of therapy and the use of respiratory support techniques. The guidelines provide recommendations on the rational pharmacotherapy principles: antiviral, antibacterial, mucoactive, anticoagulant, and symptomatic. The need to avoid prescribing drugs that may worsen the condition of patients with A/H1N1 influenza that are effective in other viral lung diseases, including SARS-CoV-2, has been pointed out. A detailed review of the criteria for initiation and principles of respiratory support is given.

Obesity Induces an Impaired Placental Antiviral Immune Response in Pregnant Women Infected with Zika Virus

Obesity is increasing in incidence worldwide, especially in women, which can affect the outcome of pregnancy. During this period, viral infections represent a risk to the mother, the placental unit, and the fetus. The Zika virus (ZIKV) outbreak in Brazil has been the cause of congenital Zika syndrome (CZS), with devastating consequences such as microcephaly in newborns. Herein, we analyzed the impact of maternal overweight/obesity on the antiviral factors' expression in the placental tissue of Zika-infected mothers. We accessed placentas from women with and without obesity from 34 public health units (São Paulo) and from Zika-infected mothers with and without obesity from the Clinical Cohort Study of ZIKV pregnant women (Rio de Janeiro, Brazil). We first verified that obesity, without infection, did not alter the constitutive transcriptional expression of antiviral factors or IFN type I/III expression. Interestingly, obesity, when associated with ZIKV infection, showed a decreased transcriptional expression of RIG-I and IFIH1 (MDA-5 protein precursor gene). At the protein level, we also verified a decreased RIG-I and IRF-3 expression in the decidual placenta from the Zika-infected obese group, regardless of microcephaly. This finding shows, for the first time, that obesity associated with ZIKV infection leads to an impaired type I IFN downstream signaling pathway in the maternal-fetal interface.

The Impact of Comorbidities and Obesity on the Severity and Outcome of COVID-19 in Hospitalized Patients-A Retrospective Study in a Hungarian Hospital

Patients with comorbidities and obesity are more likely to be hospitalized with coronavirus disease 2019 (COVID-19), to have a higher incidence of severe pneumonia and to also show higher mortality rates. Between 15 March 2020 and 31 December 2021, a retrospective, single-center, observational study was conducted among patients requiring hospitalization for COVID-19 infection. Our aim was to investigate the impact of comorbidities and lifestyle risk factors on mortality, the need for intensive care unit (ICU) admission and the severity of the disease among these patients. Our results demonstrated that comorbidities and obesity increased the risk for all investigated endpoints. Age over 65 years and male sex were identified as independent risk factors, and cardiovascular diseases, cancer, endocrine and metabolic diseases, chronic kidney disease and obesity were identified as significant risk factors. Obesity was found to be the most significant risk factor, associated with considerable odds of COVID-19 mortality and the need for ICU admission in the under-65 age group (aOR: 2.95; p < 0.001 and aOR: 3.49, p < 0.001). In our study, risk factors that increased mortality and morbidity among hospitalized patients were identified. Detailed information on such factors may support therapeutic decision making, the proper targeting of vaccination campaigns and the effective overall management of the COVID-19 epidemic, hence reducing the burden on the healthcare system.

COVID-19: Reducing the risk via diet and lifestyle

This review shows that relatively simple changes to diet and lifestyle can significantly, and rapidly, reduce the risks associated with coronavirus disease 2019 (COVID-19) in terms of infection risk, severity of disease, and even disease-related mortality. A wide range of interventions including regular exercise, adequate sleep, plant-based diets, maintenance of healthy weight, dietary supplementation, and time in nature have each been shown to have beneficial effects for supporting more positive health outcomes with COVID-19, in addition to promoting better overall health. This paper brings together literature from these areas and presents the argument that non-pharmaceutical approaches should not be overlooked in our response to COVID-19. It is noted that, in several cases, interventions discussed result in risk reductions equivalent to, or even greater than, those associated with currently available vaccines. Where the balance of evidence suggests benefits, and the risk is minimal to none, it is suggested that communicating the power of individual actions to the public becomes morally imperative. Further, many lives could be saved, and many harms from the vaccine mandates avoided, if we were willing to embrace this lifestyle-centred approach in our efforts to deal with COVID-19.

Impact of the COVID-19 Pandemic on the Success of Bariatric Surgeries in Patients with Severe Obesity

INTRODUCTION

SARS-CoV-2 infection (COVID-19) pandemic may influence the weight outcomes of bariatric surgeries (BS). Here, we intended to compare the weight outcome of patients who underwent BS before and during the pandemic time.

METHODS

In a retrospective, single-center study, the information of two groups of patients; first COVID-19 group (n = 51) consisted of those that underwent BS during the pandemic and completed a year of follow-up, second non-COVID-19 group included 50 patients who underwent BS and were followed up before the pandemic. All the patients' anthropometric and obesity-related disease data were compared between groups.

RESULTS

Weight loss and the decrease of body mass index 1 year after the surgery, as well as excess weight loss and total weight loss, were significantly higher in the non-COVID-19 group compared to the COVID-19 group (p < 0.05). Although the rate of remission for diabetes mellitus, hypertension, and dyslipidemia was higher in the non-COVID-19 group, the differences were not statistically significant (p > 0.05).

CONCLUSION

We showed a significantly poorer weight outcome at the 1-year follow-up of the BS during the pandemic compared to the pre-pandemic. These results need further investigations to determine the preventive measures and management by evaluating the associated factors.

B cell contribution to immunometabolic dysfunction and impaired immune responses in obesity

Obesity increases the risk of type 2 diabetes mellitus, cardiovascular disease, fatty liver disease, and cancer. It is also linked with more severe complications from infections, including COVID-19, and poor vaccine responses. Chronic, low-grade inflammation and associated immune perturbations play an important role in determining morbidity in people living with obesity. The contribution of B cells to immune dysregulation and meta-inflammation associated with obesity has been documented by studies over the past decade. With a focus on human studies, here we consolidate the observations demonstrating that there is altered B cell subset composition, differentiation, and function both systemically and in the adipose tissue of individuals living with obesity. Finally, we discuss the potential factors that drive B cell dysfunction in obesity and propose a model by which altered B cell subset composition in obesity underlies dysfunctional B cell responses to novel pathogens.

Viral pulmonary infection in pregnancy - Including COVID-19, SARS, influenza A, and varicella

The COVID-19 pandemic has been at the forefront of medicine over the last few years. Pregnant women are often exposed to infectious agents that can be harmful not only to the mother but also to the foetus. Moreover, changes during pregnancy means that pregnant women have increased vulnerability to viral infections, especially pulmonary infections. Epidemiological studies have shown a link between maternal viral infections and miscarriage, preterm birth as well as congenital defects. With potential poor outcomes for both women and their newborns, having a good understanding of the presentation and management of these viral pulmonary infections is essential. The increased risk of adverse outcomes has been highlighted during the COVID-19, SARS and H1N1 influenza pandemics.

Allergic sensitization impairs lung resident memory CD8 T-cell response and virus clearance

BACKGROUND

Patients with asthma often suffer from frequent respiratory viral infections and reduced virus clearance. Lung resident memory T cells provide rapid protection against viral reinfections.

OBJECTIVE

Because the development of resident memory T cells relies on the lung microenvironment, we investigated the impact of allergen sensitization on the development of virus-specific lung resident memory T cells and viral clearance.

METHODS

Mice were sensitized with house dust mite extract followed by priming with X47 and a subsequent secondary influenza infection. Antiviral memory T-cell response and protection to viral infection was assessed before and after secondary influenza infection, respectively. Gene set variation analysis was performed on data sets from the U-BIOPRED asthma cohort using an IFN-γ-induced epithelial cell signature and a tissue resident memory T-cell signature.

RESULTS

Viral loads were higher in lungs of sensitized compared with nonsensitized mice after secondary infection, indicating reduced virus clearance. X47 priming induced fewer antiviral lung resident memory CD8 T cells and resulted in lower pulmonary IFN-γ levels in the lungs of sensitized as compared with nonsensitized mice. Using data from the U-BIOPRED cohort, we found that patients with enrichment of epithelial IFN-γ-induced genes in nasal brushings and bronchial biopsies were also enriched in resident memory T-cell-associated genes, had more epithelial CD8 T cells, and reported significantly fewer exacerbations.

CONCLUSIONS

The allergen-sensitized lung microenvironment interferes with the formation of antiviral resident memory CD8 T cells in lungs and virus clearance. Defective antiviral memory response might contribute to increased susceptibility of patients with asthma to viral exacerbations.

Factors associated with influenza vaccination coverage and willingness in the elderly with chronic diseases in Shenzhen, China

Elderly individuals with chronic illnesses are more prone to get influenza. We aimed to investigate the factors associated with influenza coverage and willingness in chronic disease patients aged ≥60 years in Longhua district, Shenzhen City of southern China. Data collected in October 2020 were used in this work. The immunization status of older persons with chronic conditions and their willingness to receive the vaccine were assessed. Multivariable logistic regression was employed to determine the respective independent factors related to vaccination coverage and willingness for influenza. Only 4.8% of 5045 people were immunized against influenza, whereas 92.7% of the individuals agreed to receive the vaccine. Individuals between the ages of 70 and 79 (adjusted OR [aOR] 1.47, P = .012), those with higher education levels (aOR 1.53, P = .005 for high school; aOR 2.44, P < .001 for college or above), those who use of a family doctor (aOR 2.91, P < .001), those who frequently have physical examinations once a year (aOR 2.52, P < .001), and those who have never smoked (aOR 1.62, P = .018) were positively associated with the influenza vaccination. Meanwhile, older age was adversely linked with influenza vaccination willingness (aOR 0.68 for 70-79 years, P = .003; aOR 0.55 for≥80 years, P = .025) in contrast to those aged 60-69. High willingness to get vaccinated was more frequent in people with a high school diploma (aOR 1.33, P = .037). In this work, we observed that the coverage is poor but the immunization desire is high regarding influenza vaccination. Interestingly, older age was associated with higher coverage and lower willingness. These suggest that raising immunization rates among older people with chronic conditions and strengthening health education for caregivers should be the primary concerns.

Targeting T cell (oxidative) metabolism to improve immunity to viral infection in the context of obesity

Disorders of systemic metabolism can influence immunity. Individuals with obesity are known to have increased inflammation, increased risk to select autoimmune diseases, impaired response to several infections, and impaired vaccine response. For example, over the last decade, it has become clear that individuals with obesity have increased risk of morbidity and mortality from influenza infection. Unsurprisingly, this finding is also observed in the current COVID-19 pandemic: individuals with obesity, particularly severe obesity, have increased risk of poor outcomes from SARS-CoV-2 infection, including increased rates of hospitalization, ICU admission, mechanical ventilation, and death. Several studies have now demonstrated a critical role for T cells in the context of obesity-associated immune dysfunction in response to viral infection, and one mechanism for this may be altered T cell metabolism. Indeed, recent studies have shown that activated T cells from obese mice have an altered metabolic profile characterized by increased glucose oxidation, both in vitro and in vivo following viral infection. For that reason, treatments that target abnormal immune cell metabolism in obesity may improve outcomes to viral infection. To that end, several recent studies have shown that use of the metabolic drug, metformin, can reverse abnormal T cell metabolism and restore T cell immunity, as well as survival, in response to viral infection. These findings will be discussed in detail here.

Burden of influenza hospitalization among high-risk groups in the United States

Background

Seasonal influenza poses a substantial clinical and economic burden in the United States and vulnerable populations, including the elderly and those with comorbidities, are at elevated risk for influenza-related medical complications.

Methods

We conducted a retrospective cohort study using the IQVIA PharMetrics® Plus claims database in two stages. In Stage 1, we identified patients with evidence of medically-attended influenza during influenza seasons from October 1, 2014 to May 31, 2018 (latest available data for Stage 1) and used a multivariable logistic regression model to identify patient characteristics that predicted 30-day influenza-related hospitalization. The findings from Stage 1 informed high-risk subgroups of interest for Stage 2, where we selected cohorts of influenza patients during influenza seasons from October 1, 2014 to March 1, 2019 and used 1:1 propensity score matching to patients without influenza with similar high-risk characteristics to compare influenza-attributable rates of all-cause hospital and emergency department (ED) visits during follow-up (30-day and in the index influenza season).

Results

In Stage 1, more than 1.6 million influenza cases were identified, of which 18,509 (1.2%) had a hospitalization. Elderly age was associated with 9 times the odds of hospitalization (≥65 years vs. 5–17 years; OR = 9.4, 95% CI 8.8–10.1) and select comorbidities were associated with 2–3 times the odds of hospitalization. In Stage 2, elderly influenza patients with comorbidities had 3 to 7 times higher 30-day hospitalization rates compared to matched patients without influenza, including patients with congestive heart failure (41.0% vs.7.9%), chronic obstructive pulmonary disease (34.6% vs. 6.1%), coronary artery disease (22.8% vs. 3.8%), and late-stage chronic kidney disease (44.1% vs. 13.1%; all p < 0.05).

Conclusions

The risk of influenza-related complications is elevated in the elderly, especially those with certain underlying comorbidities, leading to excess healthcare resource utilization. Continued efforts, beyond currently available vaccines, are needed to reduce influenza burden in high-risk populations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-022-08586-y.

Histological characteristics of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinases-1 in asthmatic murine model during A(H1N1)pdm09 infection

Pandemic influenza virus A(H1N1)pdm09 infection occurred in healthy children and young adults, but asthmatic patients presented more rapid progression of respiratory distress and plastic bronchitis. To investigate the pathogenesis of worsening respiratory symptoms after A(H1N1)pdm09 infection, we focused on matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinases-1 (TIMP-1). MMP-9 and TIMP-1 levels in bronchoalveolar lavage fluid and serum from mice with and without asthma were evaluated after A(H1N1)pdm09 or seasonal A(H1N1) infection. MMP-9 levels were more elevated in Asthma/A(H1N1)pdm09-infected mice than in non-Asthma/A(H1N1)pdm09-infected mice on both 3 and 7 days post-infection. Immunohistochemical findings in this pneumonia model showed that MMP-9 and TIMP-1 positive cells were observed in blood vessels and bronchus of lung tissue in severe pathological findings of pneumonia with asthma. Microscopically, shedding cells and secretions were conspicuous in the trachea on days 3 and 7 post-infection, in the A(H1N1)pdm09-infected mice with asthma. Our results suggest that MMP-9 and TIMP-1 expressions are related to severe pneumonia in the A(H1N1)pdm09 infection with asthma, leading to cause epithelial cell shedding.

MAGI1 inhibits interferon signaling to promote influenza A infection

We have shown that membrane-associated guanylate kinase with inverted domain structure-1 (MAGI1), a scaffold protein with six PSD95/DiscLarge/ZO-1 (PDZ) domains, is involved in the regulation of endothelial cell (EC) activation and atherogenesis in mice. In addition to causing acute respiratory disease, influenza A virus (IAV) infection plays an important role in atherogenesis and triggers acute coronary syndromes and fatal myocardial infarction. Therefore, the aim of this study is to investigate the function and regulation of MAGI1 in IAV-induced EC activation. Whereas, EC infection by IAV increases MAGI1 expression, MAGI1 depletion suppresses IAV infection, suggesting that the induction of MAGI1 may promote IAV infection. Treatment of ECs with oxidized low-density lipoprotein (OxLDL) increases MAGI1 expression and IAV infection, suggesting that MAGI1 is part of the mechanistic link between serum lipid levels and patient prognosis following IAV infection. Our microarray studies suggest that MAGI1-depleted ECs increase protein expression and signaling networks involve in interferon (IFN) production. Specifically, infection of MAGI1-null ECs with IAV upregulates expression of signal transducer and activator of transcription 1 (STAT1), interferon b1 (IFNb1), myxovirus resistance protein 1 (MX1) and 2'-5'-oligoadenylate synthetase 2 (OAS2), and activate STAT5. By contrast, MAGI1 overexpression inhibits Ifnb1 mRNA and MX1 expression, again supporting the pro-viral response mediated by MAGI1. MAGI1 depletion induces the expression of MX1 and virus suppression. The data suggests that IAV suppression by MAGI1 depletion may, in part, be due to MX1 induction. Lastly, interferon regulatory factor 3 (IRF3) translocates to the nucleus in the absence of IRF3 phosphorylation, and IRF3 SUMOylation is abolished in MAGI1-depleted ECs. The data suggests that MAGI1 inhibits IRF3 activation by maintaining IRF3 SUMOylation. In summary, IAV infection occurs in ECs in a MAGI1 expression-dependent manner by inhibiting anti-viral responses including STATs and IRF3 activation and subsequent MX1 induction, and MAGI1 plays a role in EC activation, and in upregulating a pro-viral response. Therefore, the inhibition of MAGI1 is a potential therapeutic target for IAV-induced cardiovascular disease.

Pandemics, past and present: The role of biological anthropology in interdisciplinary pandemic studies

Biological anthropologists are ideally suited for the study of pandemics given their strengths in human biology, health, culture, and behavior, yet pandemics have historically not been a major focus of research. The COVID‐19 pandemic has reinforced the need to understand pandemic causes and unequal consequences at multiple levels. Insights from past pandemics can strengthen the knowledge base and inform the study of current and future pandemics through an anthropological lens. In this paper, we discuss the distinctive social and epidemiological features of pandemics, as well as the ways in which biological anthropologists have previously studied infectious diseases, epidemics, and pandemics. We then review interdisciplinary research on three pandemics–1918 influenza, 2009 influenza, and COVID‐19–focusing on persistent social inequalities in morbidity and mortality related to sex and gender; race, ethnicity, and Indigeneity; and pre‐existing health and disability. Following this review of the current state of pandemic research on these topics, we conclude with a discussion of ways biological anthropologists can contribute to this field moving forward. Biological anthropologists can add rich historical and cross‐cultural depth to the study of pandemics, provide insights into the biosocial complexities of pandemics using the theory of syndemics, investigate the social and health impacts of stress and stigma, and address important methodological and ethical issues. As COVID‐19 is unlikely to be the last global pandemic, stronger involvement of biological anthropology in pandemic studies and public health policy and research is vital.

Association between visceral fat and influenza infection in Japanese adults: A population-based cross-sectional study

Background

Several studies have reported that obesity is associated with influenza infection; however, the role of visceral fat remains unclear. The aim of this study was to investigate the association between visceral fat and influenza infection in community-dwelling Japanese adults.

Methods

A cross-sectional study was performed using data from an annual community-based health check-up conducted from May to June in 2019. In total, 1,040 Japanese adults aged 20–89 years were enrolled in this study. Influenza infection status was determined by participants’ responses to a self-administered questionnaire. The visceral fat area (VFA) was measured using a bioimpedance-type visceral fat meter. Participants were classified into four groups using the following cut-off points: VFA < 100 cm² was set as the reference category according to the Japanese criteria, 100 ≤ VFA < 150 cm², 150 ≤ VFA < 200 cm², and 200 cm² ≤ VFA. Logistic regression models were used to assess the association between VFA and influenza infection.

Results

In total, 119 participants had influenza infections in the past year. In the multivariate adjusted model, a higher VFA was significantly associated with increased influenza infection; the adjusted odds ratio for 200 cm² ≤ VFA was 5.03 [95% confidence interval (CI): 1.07–23.6], that for 150 ≤ VFA < 200 cm² was 1.97 (95% CI: 0.71–5.45), and that for 100 ≤ VFA < 150 cm² was 1.62 (95% CI: 0.84–3.12), compared with that for VFA < 100 cm² (p for trend = 0.049). These findings were confirmed in the same cohort the following year.

Conclusions

Our results suggest that visceral fat accumulation is associated with influenza infection. Large-scale prospective studies using diagnostic information for influenza infection are required to confirm this association.

Dietary Cholesterol Causes Inflammatory Imbalance and Exacerbates Morbidity in Mice Infected with Influenza A Virus

Influenza is a common cause of pneumonia-induced hospitalization and death, but how host factors function to influence disease susceptibility or severity has not been fully elucidated. Cellular cholesterol levels may affect the pathogenesis of influenza infection, as cholesterol is crucial for viral entry and replication, as well as immune cell proliferation and function. However, there is still conflicting evidence on the extent to which dietary cholesterol influences cholesterol metabolism. In this study, we examined the effects of a high-cholesterol diet in modulating the immune response to influenza A virus (IAV) infection in mice. Mice were fed a standard or a high-cholesterol diet for 5 wk before inoculation with mouse-adapted human IAV (Puerto Rico/8/1934), and tissues were collected at days 0, 4, 8, and 16 postinfection. Cholesterol-fed mice exhibited dyslipidemia characterized by increased levels of total serum cholesterol prior to infection and decreased triglycerides postinfection. Cholesterol-fed mice also displayed increased morbidity compared with control-fed mice, which was neither a result of immunosuppression nor changes in viral load. Instead, transcriptomic analysis of the lungs revealed that dietary cholesterol caused upregulation of genes involved in viral-response pathways and leukocyte trafficking, which coincided with increased numbers of cytokine-producing CD4⁺ and CD8⁺ T cells and infiltrating dendritic cells. Morbidity as determined by percent weight loss was highly correlated with numbers of cytokine-producing CD4⁺ and CD8⁺ T cells as well as granulocytes. Taken together, dietary cholesterol promoted IAV morbidity via exaggerated cellular immune responses that were independent of viral load.

Engaging Remote Aboriginal Communities in COVID-19 Public Health Messaging via Crowdsourcing

Health comunication is a critical component of pandemic mitigation, but mainstream prevention messaging often lacks social, cultural and linguistic relevance to vulnerable populations. This community case study presents a novel, highly participatory pandemic prevention communication campaign that engaged individuals in remote Aboriginal communities of the Northern Territory of Australia directly in prevention messaging via crowdsourcing, and distributed videos to remote area post-codes via targeted Facebook advertising. Facebook metrics, administrative campaign data and national statistics are used to assess campaign reach and engagement. The case study discusses lessons learned from the campaign, including how seeking unscripted COVID-19 prevention video messaging can support community ownership of pandemic messaging, rapid content generation, and a high level of Facebook user engagement. It also discusses the effectiveness of targeting remote area post-codes via Facebook advertising both to reach the target audience, and to support quality improvement assessments to inform health communication decision-making in a low resource setting.