Executive summary - Diagnosis, treatment and prophylaxis of influenza virus infection - Consensus statement of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), the Spanish Society of Pediatric Infectious Diseases (SEIP), the Spanish Association of Vaccinology (AEV), the Spanish Society of Family and Community Medicine (SEMFYC) and the Spanish Society of Preventive Medicine, Public Health and Health Management (SEMPSPGS).

The influenza virus has accompanied humans since time immemorial, in the form of annual epidemics and occasional pandemics. It is a respiratory infection with multiple repercussions on people's lives at an individual and social level, as well as representing a significant burden on the health system. This Consensus Document arises from the collaboration of various Spanish scientific societies involved in influenza virus infection. The conclusions drawn are based on the highest quality evidence available in the scientific literature and, failing that, on the opinion of the experts convened. The Consensus Document addresses the clinical, microbiological, therapeutic, and preventive aspects (with respect to the prevention of transmission and in relation to vaccination) of influenza, for both adult and pediatric populations. This Consensus Document aims to help facilitate the clinical, microbiological, and preventive approach to influenza virus infection and, consequently, to reduce its important consequences on the morbidity and mortality of the population.

Immunodominance hierarchy after seasonal influenza vaccination.

Current influenza vaccines elicit humoral immune responses against the haemagglutinin (HA) protein of influenza viruses. Different antigenic sites have been identified in the HA head as the main target of haemagglutination inhibition (HAI) antibodies (Sb, Sa, Cb, Ca1 and Ca2). To determine immunodominance (ID) of each site, we performed HAI assays against a panel of mutant viruses, each one lacking one of the classically defined antigenic sites and compared it to wild type (Wt). Agglutinating antibodies were measured before and after vaccination in two different regimens: Quadrivalent Influenza Vaccine (QIV) in young adults; or Adjuvanted Trivalent influenza Vaccine (ATIV) in elderly. Our results showed abs before vaccination were significantly reduced against all antigenic sites in the elderly and only against Sb and Ca2 in young adults compared to the Wt. Humoral response to vaccination was significantly reduced against all viruses compared to the Wt for the ATIV and only against Sb and Ca2 for the QIV. The strongest reduction was observed in all cases against Sb followed by Ca2. We concluded that ID profile was clearly dominated by Sb followed by Ca2. Additionally, the antibody response evolved with age, increasing the response towards less immunodominant epitopes of HA head. Adjuvants can positively influence ID hierarchy broadening responses towards multiple antigenic sites of HA head.

National influenza surveillance systems in five European countries: a qualitative comparative framework based on WHO guidance.

BACKGROUND: Influenza surveillance systems vary widely between countries and there is no framework to evaluate national surveillance systems in terms of data generation and dissemination. This study aimed to develop and test a comparative framework for European influenza surveillance. METHODS: Surveillance systems were evaluated qualitatively in five European countries (France, Germany, Italy, Spain, and the United Kingdom) by a panel of influenza experts and researchers from each country. Seven surveillance sub-systems were defined: non-medically attended community surveillance, virological surveillance, community surveillance, outbreak surveillance, primary care surveillance, hospital surveillance, mortality surveillance). These covered a total of 19 comparable outcomes of increasing severity, ranging from non-medically attended cases to deaths, which were evaluated using 5 comparison criteria based on WHO guidance (granularity, timing, representativeness, sampling strategy, communication) to produce a framework to compare the five countries. RESULTS: France and the United Kingdom showed the widest range of surveillance sub-systems, particularly for hospital surveillance, followed by Germany, Spain, and Italy. In all countries, virological, primary care and hospital surveillance were well developed, but non-medically attended events, influenza cases in the community, outbreaks in closed settings and mortality estimates were not consistently reported or published. The framework also allowed the comparison of variations in data granularity, timing, representativeness, sampling strategy, and communication between countries. For data granularity, breakdown per risk condition were available in France and Spain, but not in the United Kingdom, Germany and Italy. For data communication, there were disparities in the timeliness and accessibility of surveillance data. CONCLUSIONS: This new framework can be used to compare influenza surveillance systems qualitatively between countries to allow the identification of structural differences as well as to evaluate adherence to WHO guidance. The framework may be adapted for other infectious respiratory diseases.

Coinfections of influenza and other respiratory viruses are associated to children.

INTRODUCTION: Coinfections of influenza and other respiratory viruses (ORVs) are frequent in the epidemic season. The aim of this study was to examine the demographic and virological variables associated with coinfections by influenza and ORVs. MATERIALS AND METHODS: We analysed respiratory samples of patients with laboratory-confirmed influenza using molecular diagnostic methods obtained in 8 consecutive influenza seasons (2011-2012 to 2018-2019). We analysed data focusing on different variables: age, sex, type of patient (hospitalized/sentinel) and detected type/subtype of influenza. RESULTS: Coinfections of influenza and ORVs were detected in 17.8% of influenza-positive samples. The probability of detecting coinfection was significantly higher in young children (0-4 years; OR: 2.7; 95% CI: 2.2-3.4), children (5-14 years; OR: 1.6; 95% CI: 1.2-2.1) and patients infected with the A(H3N2) subtype (OR: 1.4; 95% CI: 1.14-1.79). Also, we found a significantly higher frequency of coinfections involving influenza and 2 or more other respiratory viruses in young children (0-4 years; OR: 0.5; 95% CI: 0.32-0.8), adults (40-64 years; OR: 0.5; 95% CI: 0.3-0.9) and women (OR: 0.7; 95% CI: 0.5-0.9). DISCUSSION: These results show that coinfections of influenza and ORVs are more frequent in young children and children, and in cases involving the A(H3N2) influenza subtype. Our findings can be useful to guide the use of multiplex diagnostic methods in laboratories with limited resources.

A comparison of coronavirus disease 2019 and seasonal influenza surveillance in five European countries: France, Germany, Italy, Spain and the United Kingdom.

BACKGROUND: In response to the coronavirus disease (COVID-19) outbreak that unfolded across Europe in 2020, the World Health Organisation (WHO) called for repurposing existing influenza surveillance systems to monitor COVID-19. This analysis aimed to compare descriptively the extent to which influenza surveillance systems were adapted and enhanced and how COVID-19 surveillance could ultimately benefit or disrupt routine influenza surveillance. METHODS: We used a previously developed framework in France, Germany, Italy, Spain and the United Kingdom to describe COVID-19 surveillance and its impact on influenza surveillance. The framework divides surveillance systems into seven subsystems and 20 comparable outcomes of interest and uses five evaluation criteria based on WHO guidance. Information on influenza and COVID-19 surveillance systems were collected from publicly available resources shared by European and national public health agencies. RESULTS: Overall, non-medically attended, virological, primary care and mortality surveillance were adapted in most countries to monitor COVID-19, although community, outbreak and hospital surveillance were reinforced in all countries. Data granularity improved, with more detailed demographic and medical information recorded. A shift to systematic notification for cases and deaths enhanced both geographic and population representativeness, although the sampling strategy benefited from the roll out of widespread molecular testing. Data communication was greatly enhanced, contributing to improved public awareness. CONCLUSIONS: Well-established influenza surveillance systems are a key component of pandemic preparedness, and their upgrade allowed European countries to respond to the COVID-19 pandemic. However, uncertainties remain on how both influenza and COVID-19 surveillance can be jointly and durably implemented.

Influenza hospitalizations in children under 1 year old in Spain: the importance of maternal immunization.

This study estimates the burden of influenza in infants up to 12 months of age in Spain over 8 seasons (2009/10-2016/17). The survey was conducted by reviewing the Spanish Surveillance System for Hospital Data. Over the eight seasons, 5,618 hospital admissions were recorded for patients younger than 12 months that included codes related to influenza in any diagnostic position (487-488 ICD-9-CM and J9, J10 and J11 CIE 10). In total, 2,363 admissions (42.1%) were female patients whose median age was 3.05 months. Patients younger than 6 months accounted for 3,856 admissions (68.6%). Among them, 59.2% were male, and 40.8% were female (p < .05). Overall, 37.1% (2,084 patients) were younger than 2 months. The hospitalization rate for the entire period studied was 156.09 admissions per 100,000 children under 12 months of age (95% CI: 152.4-160.6). The average duration of hospitalization was 6.6 days (95% CI: 6.4-6.8). Eighteen deaths were recorded for hospitalized patients over the entire period. Of these, 12 patients (66.7%) were younger than 6 months. There is a significant burden of influenza disease in children under 1 year of age in Spain, mainly in children under 6 months of age. Improvements to prevention strategies through increased vaccination coverage in family environments and vaccination strategies involving pregnant woman can contribute decisively and effectively to reducing these hospitalizations.

Vaccination of healthcare personnel in Europe: Update to current policies.

We investigated and compared current national vaccination policies for health-care personnel (HCP) in Europe with results from our previous survey. Data from 36 European countries were collected using the same methodology as in 2011. National policies for HCP immunization were in place in all countries. There were significant differences in terms of number of vaccinations, target HCP and healthcare settings, and implementation regulations (recommended or mandatory vaccinations). Vaccination policies against hepatitis B and seasonal influenza were present in 35 countries each. Policies for vaccination of HCP against measles, mumps, rubella and varicella existed in 28, 24, 25 and 19 countries, respectively; and against tetanus, diphtheria, pertussis and poliomyelitis in 21, 20, 19, and 18 countries, respectively. Recommendations for hepatitis A immunization existed in 17 countries, and against meningococcus B, meningococcus C, meningococcus A, C, W, Y, and tuberculosis in 10, 8, 17, and 7 countries, respectively. Mandatory vaccination policies were found in 13 countries and were a pre-requisite for employment in ten. Comparing the vaccination programs of the 30 European countries that participated in the 2011 survey, we found that more countries had national vaccination policies against measles, mumps, rubella, hepatitis A, diphtheria, tetanus, poliomyelitis, pertussis, meningococcus C and/or meningococcus A, C, W, Y; and more of these implemented mandatory vaccination policies for HCP. In conclusion, European countries now have more comprehensive national vaccination programs for HCP, however there are still gaps. Given the recent large outbreaks of vaccine-preventable diseases in Europe and the occupational risk for HCP, vaccination policies need to be expanded and strengthened in several European countries. Overall, vaccination policies for HCP in Europe should be periodically re-evaluated in order to provide optimal protection against vaccine-preventable diseases and infection control within healthcare facilities for HCP and patients.

Human T-lymphotropic virus type 1 infection and disease in Spain.

: Human T-lymphotropic virus type 1 (HTLV-1) infection is a neglected disease despite roughly 15 million people are chronically infected worldwide. Lifelong less than 10% of carriers develop life-threatening diseases, mostly a subacute myelopathy known as tropical spastic paraparesis (TSP) and a lymphoproliferative disorder named adult T-cell leukemia (ATL). HTLV-1 is efficiently transmitted perinatally (breastfeeding), sexually (more from men to women) and parenterally (transfusions, injection drug user (IDU), and transplants). To date there is neither prophylactic vaccine nor effective antiviral therapy. A total of 327 cases of HTLV-1 infection had been reported at the HTLV-1 Spanish registry until December 2016, of whom 34 had been diagnosed with TSP and 25 with ATL. Overall 62% were Latin American immigrants and 13% were persons of African origin. The incidence of HTLV-1 in Spain has remained stable for nearly a decade with 20-25 new cases yearly. Of the 21 newly diagnosed HTLV-1 cases during year 2016, one was a native Spaniard pregnant woman, and four presented with symptomatic disease, including three with ATL and one with TSP. Underdiagnosis of HTLV-1 in Spain must be high (iceberg model), which may account for the disproportionate high rate of symptomatic cases (almost 20%) and the late recognition of preventable HTLV-1 transmissions in special populations, such as newborns and transplant recipients. Our current estimate is of 10 000 persons living with HTLV-1 infection in Spain. Given the large flux of immigrants and visitors from HTLV-1 endemic regions to Spain, the expansion of HTLV-1 screening policies is warranted. At this time, it seems worth recommending HTLV testing to all donor/recipient organ transplants and pregnant women regardless place of birth. Although current leukoreduction procedures largely prevent HTLV-1 transmission by blood transfusions, HTLV testing of all first-time donors should be cost-effective contributing to unveil asymptomatic unaware HTLV-1 carriers.

Influenza vaccination: key facts for general practitioners in Europe-a synthesis by European experts based on national guidelines and best practices in the United Kingdom and the Netherlands.

Currently there is no influenza vaccination guidance for European general practitioners. Furthermore, although the European Council recommends a target seasonal influenza vaccination rate of 75% in the elderly (65 years and above) and in anyone aged >6 months with a chronic medical condition, there remain wide discrepancies throughout Europe. A harmonised guideline regarding not only vaccination strategy but also for the consistent diagnosis of influenza across Europe is essential to support a common approach for the implementation of seasonal influenza vaccination across Europe. This document is based on pre-existing guidelines available in the UK and Netherlands and has been approved by a group of European experts for use throughout Europe. As well as providing a standardised influenza diagnosis, it also reviews the current recommendations for influenza vaccination, the types of vaccine available, the contraindications, vaccine use in special populations (in pregnancy, children, and in those with egg allergy), and concomitant administration with other vaccines. The effectiveness, safety, and timing of the seasonal influenza vaccine are also reviewed. A second section provides practical guidance for general practitioners for the implementation of a seasonal influenza vaccination program, including the selection and notification of those eligible for vaccination, as well as suggestions for the organisation of a vaccination programme. Finally, suggested responses to common patient misconceptions and frequently asked questions are included. The aim of this article is to harmonise the diagnosis of seasonal influenza and the approach of European general practitioners to seasonal influenza vaccination in order to better identify influenza outbreaks and to move towards reaching the target vaccination rate of 75% throughout Europe.

IgM levels in plasma predict outcome in severe pandemic influenza.

BACKGROUND: Little is known on the participation of immunoglobulin isotypes and subclasses in the pathogenesis of the severe disease caused by the pandemic influenza virus (influenza A(H1N1)pdm09). OBJECTIVES: (1) To evaluate the association between plasma levels of IgG1, IgG2, IgG3, IgG4, IgA, IgM, IgE and outcome in patients with severe pandemic influenza. (2) To evaluate the association between immunoglobulin and cytokine levels in these patients. STUDY DESIGN: 40 critically ill patients with community acquired pneumonia and influenza A(H1N1)pdm09 infection were recruited from November 2010 to February 2011. Plasma samples were collected during the first 24h following admission to the ICU. Immunoglobulins and 17 major cytokines were profiled in plasma. RESULTS: 15 patients died (37.5%). When the association between clinical variables and prognosis was assessed, prior immunosuppression, APACHE II score, levels of IgG2 and levels of IgM were associated with outcome in a univariate Cox regression analysis. Kaplan Meier analysis showed that patients with levels of IgG2 and IgM < 59 and<58 mg/dl respectively died earlier. Multivariate Cox regression analysis showed that APACHE II score and levels of IgM were the best predictors of outcome, being levels of IgM a protective factor against mortality. IgM was the immunoglobulin showing the largest number of negative correlations with cytokine levels. CONCLUSIONS: Our results support a central role of IgM in preventing uncontrolled inflammatory response and mortality in severe pandemic influenza. Early assessment of IgM could contribute to guide clinical decisions in these patients.

Beneficial role of endogenous immunoglobulin subclasses and isotypes in septic shock.

PURPOSE: There is increasing evidence on the relationship between endogenously produced immunoglobulins and the clinical outcome in septic shock (SS). MATERIALS AND METHODS: Levels of immunoglobulin G (IgG) subclasses, immunoglobulin A (IgA), immunoglobulin M (IgM), and immunoglobulin E were measured in plasma from 42 patients with SS and in 36 patients with systemic inflammatory response syndrome at diagnosis. Association of immunoglobulins levels with disease severity and outcome was evaluated. RESULTS: Eighteen patients with SS finally died. Both patients with systemic inflammatory response syndrome and SS showed subnormal levels of total IgG, IgG2, and IgM. Patients with SS who died showed the lowest levels of total IgG and IgG1. Total IgG, IgG1, IgG2, IgG3, IgG4, and IgA correlated inversely with Acute Physiology and Chronic Health Evaluation II score in SS. Univariate Cox regression analysis showed that levels of IgG1, IgG2, IgG3, IgM, IgA, and total IgG were inversely associated to the probability of death at 28 days. Multivariate analysis showed that IgG1, total IgG, IgM, and IgA behaved as independent protective factors against mortality (hazard ratio, P): 0.23, 0.026; 0.16, 0.028; 0.11, 0.042; 0.05, 0.010, respectively, whereas IgG3 showed a protective trend also. CONCLUSIONS: Our study evidenced that, in addition to IgG1, other major endogenous immunoglobulins isotypes and subclasses seem to play a beneficial role in SS.

Critical COPD respiratory illness is linked to increased transcriptomic activity of neutrophil proteases genes.

BACKGROUND: Gene expression profiling (GEP) in cells obtained from peripheral blood has shown that this is a very useful approach for biomarker discovery and for studying molecular pathogenesis of prevalent diseases. While there is limited literature available on gene expression markers associated with Chronic Obstructive Pulmonary Disease (COPD), the transcriptomic picture associated with critical respiratory illness in this disease is not known at the present moment. FINDINGS: By using Agilent microarray chips, we have profiled gene expression signatures in the whole blood of 28 COPD patients hospitalized with different degrees of respiratory compromise.12 of them needed of admission to the ICU, whilst 16 were admitted to the Respiratory Medicine Service. GeneSpring GX 11.0 software was used for performing statistical comparisons of transcript levels between ICU and non-ICU patients. Ingenuity pathway analysis 8.5 (IPA) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to select, annotate and visualize genes by function and pathway (gene ontology). T-test showed evidence of 1501 genes differentially expressed between ICU and non-ICU patients. IPA and KEGG analysis of the most representative biological functions revealed that ICU patients had increased levels of neutrophil gene transcripts, being [cathepsin G (CTSG)], [elastase, neutrophil expressed (ELANE)], [proteinase 3 (PRTN3)], [myeloperoxidase (MPO)], [cathepsin D (CTSD)], [defensin, alpha 3, neutrophil-specific (DEFA3)], azurocidin 1 (AZU1)], and [bactericidal/permeability-increasing protein (BPI)] the most representative ones. Proteins codified by these genes form part of the azurophilic granules of neutrophils and are involved in both antimicrobial defence and tissue damage. This "neutrophil signature" was paralleled by the necessity of advanced respiratory and vital support, and the presence of bacterial infection. CONCLUSION: Study of transcriptomic signatures in blood suggests an essential role of neutrophil proteases in COPD patients with critical respiratory illness. Measurement and modulation of the expression of these genes could present an option for clinical monitoring and treatment of severe COPD exacerbations.

Interleukin-6 is a potential biomarker for severe pandemic H1N1 influenza A infection.

Pandemic H1N1 influenza A (H1N1pdm) is currently a dominant circulating influenza strain worldwide. Severe cases of H1N1pdm infection are characterized by prolonged activation of the immune response, yet the specific role of inflammatory mediators in disease is poorly understood. The inflammatory cytokine IL-6 has been implicated in both seasonal and severe pandemic H1N1 influenza A (H1N1pdm) infection. Here, we investigated the role of IL-6 in severe H1N1pdm infection. We found IL-6 to be an important feature of the host response in both humans and mice infected with H1N1pdm. Elevated levels of IL-6 were associated with severe disease in patients hospitalized with H1N1pdm infection. Notably, serum IL-6 levels associated strongly with the requirement of critical care admission and were predictive of fatal outcome. In C57BL/6J, BALB/cJ, and B6129SF2/J mice, infection with A/Mexico/4108/2009 (H1N1pdm) consistently triggered severe disease and increased IL-6 levels in both lung and serum. Furthermore, in our lethal C57BL/6J mouse model of H1N1pdm infection, global gene expression analysis indicated a pronounced IL-6 associated inflammatory response. Subsequently, we examined disease and outcome in IL-6 deficient mice infected with H1N1pdm. No significant differences in survival, weight loss, viral load, or pathology were observed between IL-6 deficient and wild-type mice following infection. Taken together, our findings suggest IL-6 may be a potential disease severity biomarker, but may not be a suitable therapeutic target in cases of severe H1N1pdm infection due to our mouse data.

Trends in the prevalence and distribution of HTLV-1 and HTLV-2 infections in Spain.

BACKGROUND: Although most HTLV infections in Spain have been found in native intravenous drug users carrying HTLV-2, the large immigration flows from Latin America and Sub-Saharan Africa in recent years may have changed the prevalence and distribution of HTLV-1 and HTLV-2 infections, and hypothetically open the opportunity for introducing HTLV-3 or HTLV-4 in Spain. To assess the current seroprevalence of HTLV infection in Spain a national multicenter, cross-sectional, study was conducted in June 2009. RESULTS: A total of 6,460 consecutive outpatients attending 16 hospitals were examined. Overall, 12% were immigrants, and their main origin was Latin America (4.9%), Africa (3.6%) and other European countries (2.8%). Nine individuals were seroreactive for HTLV antibodies (overall prevalence, 0.14%). Evidence of HTLV-1 infection was confirmed by Western blot in 4 subjects (prevalence 0.06%) while HTLV-2 infection was found in 5 (prevalence 0.08%). Infection with HTLV types 1, 2, 3 and 4 was discarded by Western blot and specific PCR assays in another two specimens initially reactive in the enzyme immunoassay. All but one HTLV-1 cases were Latin-Americans while all persons with HTLV-2 infection were native Spaniards. CONCLUSIONS: The overall prevalence of HTLV infections in Spain remains low, with no evidence of HTLV-3 or HTLV-4 infections so far.

A combined score of pro- and anti-inflammatory interleukins improves mortality prediction in severe sepsis.

Identification of patients at increased risk of death is dramatically important in severe sepsis. Cytokines have been widely assessed as potential biomarkers in this disease, but none of the cytokines studied has evidenced a sufficient specificity or sensitivity to be routinely employed in clinical practice. In this pilot study, we profiled 17 immune mediators in the plasma of 29 consecutively recruited patients with severe sepsis or septic shock, during the first 24h following admission to the ICU, by using a Bio-Plex Human Cytokine 17-Plex Panel (Bio-Rad). Patients were 66.1year old in average. Twelve patients of our cohort died during hospitalization at the ICU, eight of them in the first 72h due to multiorganic dysfunction syndrom (MODS). Levels in plasma of three pro-inflammatory mediators (IL-6, IL-8, MCP-1) and of an immunosuppressive one (IL-10) were higher in those patients with fatal outcome. We developed a combined score with those cytokines showing to better predict mortality in our cohort based on the results of Cox regression analysis. This way, IL-6, IL-8 and IL-10 were included in the score. Patients were split into two groups based on the percentile 75 (P75) of the plasma levels of these three interleukins. Those patients showing at least one interleukin value higher than P75 were given the value "1". Those patients showing IL-6, IL-8, IL-10 levels below P75 were given the value "0". Hazard ratios for mortality at day 3 and day 28th obtained with the combined score were 2-3-fold higher than those obtained with the individual interleukins values. In conclusion, we have described a combined cytokine score associated with a worse outcome in patients with sepsis, which may represent a new avenue to be explored for guiding treatment decisions in this disease.

Socio-economic modelling of rotavirus vaccination in Castilla y Leon, Spain.

Rotavirus is one of the main causes of acute gastroenteritis in infants and young children. Furthermore, rotavirus is the leading cause of hospitalization and death from acute gastroenteritis among infants and young children worldwide. Although death due to rotavirus is rare in industrialized regions such as Spain, the rotavirus disease burden and its economic impact is severe. This study aims to assess systematic vaccination against rotavirus economically and socially in a Spanish region. Economic cost-effectiveness and cost-benefit assessment through a choice tree was designed. We estimated health provider costs, economic costs and quality-adjusted life years (QALYs) lost due to rotavirus infections. The study includes a fictitious cohort of 100,000 children from Castilla y Leon who were also administered the rotavirus vaccine together with diphtheria and tetanus toxoids and pertussis (DTP) . The study adopted a society and health care system perspective. A sensitivity analysis was developed to assess the uncertainty of some variables. According to the estimated incidence rate for children in Castilla y Leon, rotavirus immunization is projected to prevent 45% of cases with RotaTeq and 57% with Rotarix. The respective cost per QALY is about Euro 75,000 and 50,000 from the perspective of the health care system. Routine infant vaccination in Castilla y Leon using either rotavirus vaccine is not profitable from the payer's perspective and is not cost-effective under basic case assumptions unless the vaccine is available at a lower cost.

Early natural killer cell counts in blood predict mortality in severe sepsis.

INTRODUCTION: Host immunity should play a principal role in determining both the outcome and recovery of patients with sepsis that originated from a microbial infection. Quantification of the levels of key elements of the immune response could have a prognostic value in this disease. METHODS: In an attempt to evaluate the quantitative changes in the status of immunocompetence in severe sepsis over time and its potential influence on clinical outcome, we monitored the evolution of immunoglobulins (Igs) (IgG, IgA and IgM), complement factors (C3 and C4) and lymphocyte subsets (CD4+ T cells, CD8+ T cells, B cells (CD19+) and natural killer (NK) cells (CD3-CD16+CD56+)) in the blood of 50 patients with severe sepsis or septic shock at day 1, day 3 and day 10 following admission to the ICU. RESULTS: Twenty-one patients died, ten of whom died within the 72 hours following admission to the ICU. The most frequent cause of death (n = 12) was multiorgan dysfunction syndrome. At day 1, survivors showed significantly higher levels of IgG and C4 than those who ultimately died. On the contrary, NK cell levels were significantly higher in the patients who died. Survivors exhibited a progressive increase from day 1 to day 10 on most of the immunological parameters evaluated (IgG, IgA, IgM, C3, CD4+, CD8+ T cells and NK cells). Multivariate Cox regression analysis, including age, sex, APACHE II score, severe sepsis or septic shock status and each one of the immunological parameters showed that NK cell counts at day 1 were independently associated with increased risk of death at 28 days (hazard ratio = 3.34, 95% CI = 1.29 to 8.64; P = 0.013). Analysis of survival curves provided evidence that levels of NK cells at day 1 (> 83 cells/mm³) were associated with early mortality. CONCLUSIONS: Our results demonstrate the prognostic role of NK cells in severe sepsis and provide evidence for a direct association of early counts of these cells in blood with mortality.

Direct association between pharyngeal viral secretion and host cytokine response in severe pandemic influenza.

BACKGROUND: Severe disease caused by 2009 pandemic influenza A/H1N1virus is characterized by the presence of hypercytokinemia. The origin of the exacerbated cytokine response is unclear. As observed previously, uncontrolled influenza virus replication could strongly influence cytokine production. The objective of the present study was to evaluate the relationship between host cytokine responses and viral levels in pandemic influenza critically ill patients. METHODS: Twenty three patients admitted to the ICU with primary viral pneumonia were included in this study. A quantitative PCR based method targeting the M1 influenza gene was developed to quantify pharyngeal viral load. In addition, by using a multiplex based assay, we systematically evaluated host cytokine responses to the viral infection at admission to the ICU. Correlation studies between cytokine levels and viral load were done by calculating the Spearman correlation coefficient. RESULTS: Fifteen patients needed of intubation and ventilation, while eight did not need of mechanical ventilation during ICU hospitalization. Viral load in pharyngeal swabs was 300 fold higher in the group of patients with the worst respiratory condition at admission to the ICU. Pharyngeal viral load directly correlated with plasma levels of the pro-inflammatory cytokines IL-6, IL-12p70, IFN-γ, the chemotactic factors MIP-1ß, GM-CSF, the angiogenic mediator VEGF and also of the immuno-modulatory cytokine IL-1ra (p < 0.05). Correlation studies demonstrated also the existence of a significant positive association between the levels of these mediators, evidencing that they are simultaneously regulated in response to the virus. CONCLUSIONS: Severe respiratory disease caused by the 2009 pandemic influenza virus is characterized by the existence of a direct association between viral replication and host cytokine response, revealing a potential pathogenic link with the severe disease caused by other influenza subtypes such as H5N1.