Introduction In recent years, migration to and within the European Union and European Economic Area has increased significantly. In Catalonia, an increasing influx of migrants arriving through unsafe routes has been documented, often exposing them to a higher risk of infectious diseases and other health conditions. This study describes a community-based intervention carried out in Catalonia, Spain, to assess the health needs in newly arrived migrants who entered Europe through its southern border.Methods Combining rapid clinical screening, tuberculosis (TB)-specific measures and sociocultural integration strategies, this intervention aimed to facilitate healthcare access and prevent the spread of communicable diseases in a vulnerable population.Results A total of 262 male migrants, with a median age of 23 years, arrived, predominantly from Mali (55.7%), Mauritania (22.9%) and Senegal (20.2%). During clinical screening, 92 individuals (35%) required medical attention after reporting various symptoms. Remarkably, syndromic screening facilitated the diagnosis and treatment of one malaria case and two schistosomiasis cases. Nine TB awareness workshops were conducted to strengthen prevention efforts and facilitate active TB surveillance.Conclusion This experience highlights the necessity of rapid, coordinated and culturally adapted public health responses to ensure equitable healthcare and outbreak prevention.

Antimicrobial resistance (AMR) remains a major global public health concern requiring coordinated surveillance and technological innovation. In Catalonia, AMR surveillance is conducted through the Microbiological Reporting System of Catalonia (MRSC) and will be integrated into the Epidemiological Surveillance Information System (SIVEC), enabling automated and real-time monitoring. This study aimed to evaluate the current landscape of AMR surveillance and laboratory capacity across clinical microbiology laboratories (CMLs). All CMLs participating in the MRSC were invited to complete a structured survey assessing diagnostic capacity, resistance mechanism (RM) detection, laboratory information systems (LIS), and reporting practices. Surveillance data from invasive isolates (one per patient and episode) collected between 2016 and 2023 were analysed. CMLs were classified by complexity (L1–L3) according to phenotypic, molecular and genomic capabilities. Temporal trends in resistance were assessed using logistic regression models. By 2023, 53 CMLs participated compared with 28 in 2016, reflecting a marked increase in coverage. A total of 87,556 invasive isolates and 694,289 susceptibility tests were reported. Escherichia coli was the most frequently notified microorganism (37,999 isolates), followed by Klebsiella pneumoniae (12,626) and methicillin-susceptible Staphylococcus aureus (10,464). All laboratories followed EUCAST criteria, although only 56.6

Background:Nirsevimab, a long-acting monoclonal antibody against respiratory syncytial virus (RSV), was recently introduced in Catalonia (Spain, 2023-2024 season onwards) and Italy (2024-2025 season). The United Kingdom (UK) instead introduced maternal RSV vaccination (RSVpreF) in the 2024-2025 season. Our aim was to analyse emergency department (ED) attendances and admissions to hospital following RSVpreF and nirsevimab introduction, with hospitals in Iceland and Romania, where no intervention was introduced, used as comparators. Methods:Multi-national retrospective analysis of ED attendances and admissions for all diagnoses, respiratory diagnoses excluding bronchiolitis, and bronchiolitis from all hospitals in Catalonia (Spain), four UK hospitals (Bristol, Edinburgh, Glasgow, and Leicester), and one hospital in Italy (Rome), Romania (Bucharest), and Iceland (Reykjavík) from April 2018 to March 2025. Bronchiolitis diagnoses in the 2024-2025 season were compared to previous pre-intervention seasons (2018-2023, excluding the 2020-2021 COVID-19 year) by applying a generalised linear model in Poisson regression to obtain risk ratios (RR) and 95% confidence intervals (95% CI). Findings:In the 2024-2025 season, in Catalonia, there was a reduction in the RR for bronchiolitis ED attendances and admissions in infants of age <6 months (RR 0.45; 95% CI 0.43-0.47 and RR 0.40; 95% CI 0.37-0.43, respectively). This was not seen in Rome, where the RR for ED attendances with bronchiolitis in infants of age <6 months was 1.09 (95% CI 0.92-1.30) and the RR for admissions was 1.12 (95% CI 0.83-1.52). In the UK, for infants of age <6 months with bronchiolitis, there was a significant but modest reduction in 1 out of 4 hospitals for ED attendances (Leicester; RR 0.91, 95% CI 0.85-0.97) and in 2 out of 4 hospitals for admissions (Leicester; RR 0.80, 95% CI 0.69-0.94 and Edinburgh; RR 0.85, 95% CI 0.76-0.95). Interpretation:In Catalonia, there was a sustained reduction in bronchiolitis ED attendances and admissions for infants in the 2024-2025 season. However, no substantial reduction in bronchiolitis ED attendances or admissions was observed in Rome or the UK. These differences are likely to relate to the reduced uptake of RSV prevention products in these settings compared to Catalonia. Funding:None.

BACKGROUND:Streptococcus pyogenes (group A Streptococcus, GAS) is a common pediatric pathogen causing a wide range of diseases with significant morbidity and mortality. GAS infections exhibit strong seasonal patterns, and the invasive forms (iGAS) have historically been associated with influenza. Since September 2022, a global outbreak of both iGAS and noninvasive GAS infections has been reported. METHODS:This is a retrospective observational multicentric study of children (<15 years) with iGAS in Catalonia (Spain) from week 40 of 2022 to week 24 of 2023. We collected clinical, epidemiologic and microbiologic data on iGAS, scarlet fever and acute respiratory infection diagnoses between 2013 and the study period. Seasonal comparisons were assessed using Kruskal-Wallis and Wilcoxon tests, and correlations between weekly time series were evaluated using Spearman coefficients. RESULTS:Among 135 pediatric iGAS cases, the median age was 3.7 years (interquartile range, 1.6-5.9), mostly healthy. Fever was the most common symptom (92.6%), and pneumonia was the most prevalent diagnosis (40.7%). Viral coinfection occurred in 59.3% of the cases, with influenza A/B being the most prevalent. One-third (35.6%) required intensive care; the case fatality rate was 3.0%. We found a significant correlation between pediatric iGAS infections and influenza A/B circulation (ρ = 0.85) in the context of significantly higher scarlet fever incidence compared with pandemic and pre-pandemic seasons. Weaker correlations were identified between iGAS infections and the other acute viral infections studied. CONCLUSIONS:Pediatric iGAS during the 2022-2023 outbreak was strongly associated with influenza activity, suggesting that influenza might contribute to the epidemiology of pediatric iGAS in a context of increased GAS circulation.

INTRODUCTION:Autochthonous dengue transmission is increasingly being reported in temperate regions of Europe, particularly in areas with established Aedes albopictus populations and high population mobility. We describe a locally acquired dengue outbreak identified in Vila-seca (Tarragona, north-eastern Spain), which involved eight confirmed cases, two of which were asymptomatic, and the associated public health response. MATERIALS AND METHODS:Following the notification of two non-travel-associated dengue cases in September 2024 at Hospital Universitari de Tarragona Joan XXIII, epidemiological, virological, and entomological investigations were conducted led by Public Health Agency of Catalonia with the collaboration of microbiology departments of Hospital Universitari Vall d'Hebron and Hospital Clínic of Barcelona. Active case finding, contact tracing, laboratory confirmation, viral sequencing, and vector surveillance were implemented in the affected area of Vila-seca (Spain). RESULTS:A total of eight confirmed dengue cases were identified. The index cases were two residents without travel history who presented with fever, rash, and myalgia and tested positive for dengue virus (DENV). Four additional cases were detected through active surveillance, including three household contacts employed at a nearby entertainment resort and one resident living approximately 160 meters from the index household. Two further epidemiologically linked cases were identified among French tourists following international alerts. All patients recovered, and no additional cases were detected after November 2024, coinciding with decreased vector activity. Virological analysis confirmed local transmission of DENV-1, genotype V (clade D.2). Entomological surveys demonstrated widespread Ae. albopictus presence in public and private settings, prompting immediate vector control interventions, although no infected mosquitoes were detected. CONCLUSION:This outbreak illustrates the growing risk of DENV transmission in non-endemic European settings with intense tourist and occupational mobility. Rapid diagnostics, genomic surveillance, coordinated vector control, and timely international communication are essential to limit transmission and protect both residents and travellers, reinforcing the importance of a One Health approach.

Background Despite being a low-incidence area, Catalonia experiences substantial migration flows from countries with high tuberculosis (TB) burden, potentially making it a focal point for various Mycobacterium tuberculosis complex (MTBC) lineages.Aim We aimed to characterize the spatial structure of MTBC (sub)lineages in Catalonia, assess their associations with clinical and epidemiological factors, and identify spatiotemporal hotspots of cases belonging to the same sublineage.Methods Whole-genome sequencing (WGS) was performed on 783 MTBC isolates collected across Catalonia from December 2021 to June 2023. Lineages and sublineages were assigned using SNP-based typing. Associations with clinical presentation, country of origin, and migration timing were evaluated using logistic regression and Fisher's exact test. SaTScan was used to identify space-time clusters of selected (sub)lineages.Results Lineage 4/Euro-American predominated (83%), with L4.1.2/Haarlem, L4.3/LAM, and L4.10/PGG3 widely distributed, particularly among Spanish-born individuals and long-term migrants. L1/EAI, L2/Beijing, L3/CAS, and L4.1.1/X showed geographically restricted patterns, predominantly linked to migrants from India, Pakistan, China, and Peru. L1/EAI, L3/CAS, and L4.10/PGG3 were significantly associated with extrapulmonary TB. Sublineage diversity increased from sparsely to densely populated areas. Spatiotemporal analysis identified four significant clusters involving L1/EAI, L3/CAS, and L4.10/PGG3 across seven counties, mainly within the Barcelona Metropolitan Area, with L4.10/PGG3 showing the strongest clustering.Conclusion L4 sublineages predominate in Catalonia, whereas L1/EAI, L2/Beijing, and L3/CAS are more geographically restricted and predominantly associated with migrants. The presence of sublineage-specific hotspots in dense urban areas highlights the role of migration dynamics and urbanization in shaping TB transmission.

Invasive group A streptococcal (iGAS) infections resurged across Europe in late 2022. We aimed to describe the incidence, clinical characteristics, and outcomes of iGAS in Catalonia over two epidemic seasons (2022/23 and 2023/24), and to identify risk factors associated with mortality. A prospective study was conducted including all confirmed iGAS cases reported to the Microbiological Reporting System of Catalonia between October 2022 and October 2024. Epidemiological and clinical data were collected from medical files and incidence rates (IRs) calculated. Multivariable logistic regression was used to assess risk factors associated with mortality. A total of 589 laboratory-confirmed iGAS cases were included; 416 cases (70.6

Enterovirus (EV) infections are common and often mild or asymptomatic but can occasionally cause serious illness in children. Routine clinical surveillance typically underestimates the full spectrum of circulating EVs, whereas wastewater-based epidemiology captures a broader viral diversity and may serve as an early warning tool. We conducted a 5-year surveillance (2020-2024) in Barcelona, Spain, combining biweekly wastewater sampling with clinical EV reporting during the SARS-CoV-2 pandemic and subsequent relaxation of restrictions. We quantified EV genome copies in sewage by RT-qPCR and performed partial VP1 sequencing on wastewater concentrates and on clinical specimens. Over the study period, wastewater EV loads broadly paralleled reported case trends, with good correlations over the years except in 2022. A monotonic relationship was observed for certain EV type trends, including CVA6, CVB2, CVB3, E11, and EV-D68, but there was low robustness in their predictive capacity for clinical cases. Overall, deep sequencing revealed 122 distinct EV types in wastewater versus 92 types in clinical samples; 66 types were found in both sources, whereas 56 types appeared only in sewage. Sequences from wastewater and clinical sources showed high genetic similarity. Dominant EV types shifted over time highlighting the virus dynamics. These findings demonstrate that integrating WS with clinical surveillance yields a more comprehensive picture of EV circulation, uncovering hidden viral diversity and enabling early detection of emerging public health threats.

BACKGROUND:We estimated vaccine effectiveness (VE) of the COVID-19 monovalent XBB.1.5 vaccine recommended in Spain in October 2023 for ≥60-year-olds against medically attended COVID-19 and COVID-19 hospitalization, during winter and summer epidemic waves. RESEARCH DESIGN AND METHODS:Patients ≥60-year-olds consulting in primary-care or requiring hospitalization due to respiratory infection were systematically RT-PCR tested for SARS-CoV-2 and classified as cases if PCR-positive or controls if PCR-negative. Logistic regression compared autumnal vaccination ≥14 days before onset in cases and controls adjusting for sex, age group, comorbidities, region in Spain and week; VE=(1-Odds Ratio)x100. RESULTS:We included 1,141/3,286 and 1,386/5,260 cases/controls from primary-care and hospitals. During the winter wave, VE (95% Confidence Interval) was 28% (5;47%) against medically attended COVID-19 [45% (-31;80%) during XBB.1.5 dominance; 26% (-2;46%) during BA.2.86] and 39% (24;51%) against hospitalization [73% (41;89%) during XBB.1.5; 37% (17;48%) during BA.2.86]. During the summer wave, VE decreased; -6% (-33;15%) against infection [21% (-11;44%) during BA.2.86; -39% (-91;-1%) during KP.3] and 6% (-14;22%) against hospitalization [8% (-20;30%) during BA.2.86; 5% (-35;21%) during KP.3]. CONCLUSIONS:COVID-19 VE was moderate during the 2023/24 winter wave, higher during XBB.1.5 dominance and against hospitalization. Effectiveness was null during the summer wave, likely reflecting waning immunity and SARS-CoV-2 variant substitution.

OBJECTIVES:To evaluate the effect of the selective pressure exerted by nirsevimab on human respiratory syncytial virus (HRSV) in Catalonia (2023-2024) by analysing viral mutations, diversity, and evolutionary dynamics, based on viruses characterised from non-immunised and previously immunised patients. METHODS:Respiratory samples were collected through the SIVIC sentinel network and three hospitals in Catalonia. HRSV-positive samples underwent whole-genome sequencing (WGS), or F gene sequencing when WGS was not feasible. Viral diversity, phylogenetics, and selection pressure were assessed. RESULTS:A total of 251 WGS (HRSV-A: 165; HRSV-B: 86) and 27 F gene sequences (HRSV-A: 13; HRSV-B: 14) were obtained for the non-immunised group. For immunised cases, 79 WGS (HRSV-A: 67; HRSV-B: 12) and 12 F sequences (HRSV-A: 10; HRSV-B: 2) were analysed. Lineage distribution remained similar between groups. Nucleotide diversity was similar for HRSV-A groups, though reduced in immunised HRSV-B. Selection pressure analyses suggested a shift toward neutral evolution in immunised samples. Mutations N63S, K65R, I206T, and K209E (HRSV-A) and K68E, R209Q, and S211N (HRSV-B) were detected in nirsevimab epitope, with K209E and K68E absent in non-immunised samples. CONCLUSIONS:Nirsevimab immunisation may influence HRSV evolution, particularly in HRSV-B. Continued genomic surveillance is crucial for early mAb-resistant mutants detection.

Background Respiratory syncytial virus (RSV) causes substantial morbidity in infants < 1 year. In October 2023, Spain recommended the monoclonal antibody nirsevimab to all children born since 1 April 2023, at birth or as catch-up if born before October 2023. Aim We estimated nirsevimab effectiveness in preventing RSV hospitalisations during the 2023/24 season. Methods We conducted a nationwide population-based matched case–control study. Cases were children hospitalised for lower respiratory tract infection who were RSV PCR-positive. For each case, we selected four population density controls born in the same province and date (±2 days). We defined at-birth immunisation as receiving nirsevimab during the first 2 weeks of life, and catch-up immunisation within 30 days from campaign onset. Causal intention-to-treat (ITT) and per-protocol (PP) effectiveness was estimated using inverse-probability-of-immunisation weighted conditional logistic regression. Results We included 406 cases and 1,623 controls in catch-up and 546 cases and 2,182 controls in at-birth immunisation studies. Effectiveness in preventing RSV hospitalisations for catch-up immunisation was 71% (95% confidence interval (CI): 65–76) by ITT and 80% (95% CI: 75–84) PP. Effectiveness for at-birth immunisation was 78% (95% CI: 73–82) by ITT and 83% (95% CI: 79–87) PP. Effectiveness was similar for ICU admission, need of mechanical ventilation, and RSV viral subgroups A and B. Children born pre-term or with birthweight < 2,500 g showed lower PP effectiveness of 60–70%. Conclusions Population-level nirsevimab immunoprophylaxis in children in their first RSV season was very effective in preventing RSV hospitalisations, ICU admission and mechanical ventilation, with reduced but still high effectiveness for pre-term and low-birthweight children.

Between July and October 2025, among the total 117 influenza A(H1N1)pdm09 strains characterised in Catalonia, 20% to 100% per week were carrying the NA:S247N substitution. The mutation, conferring reduced susceptibility to oseltamivir, was phenotypically confirmed (IC50 between 0.82 and 1.63 nM, compared to median IC50 of 0.3 nM for susceptible strains). An increased proportion of S247N variants was also observed in sequence data (10,944 sequences) from other parts of Spain and five of 35 submitting countries across Europe.

To analyse the effect of nirsevimab immunoprophylaxis on RSV-associated outcomes after two consecutive epidemic seasons in infants born and Living in Catalonia, Spain. We conducted a population-based retrospective cohort study including all infants born in Catalonia between April 2023 and March 2024. We established two cohorts (immunised with nirsevimab and non-immunised). We estimated adjusted cumulative incidences (CInc) curves for RSV-associated hospital admissions, paediatric intensive care unit (PICU) admissions, emergency department (ED) visits for bronchiolitis, and RSV infections and bronchiolitis registered in primary care from October 2023 to mid-February 2025 using inverse probability-weighted Kaplan–Meier methods. Marginal risk differences and risk ratios (RR) with 95

Background:Nirsevimab, a novel monoclonal antibody with a long half-life, has received European Union approval to prevent lower respiratory tract infections (LRTIs) caused by respiratory syncytial virus (RSV) during the first season of exposure. It was implemented in Catalonia (Spain) in the 2023-2024 season. Our main objective was to analyse the impact of the nirsevimab on LRTIs presenting to the Emergency Department (ED) in Catalonia (Spain) by comparing presentations to those at five sites in the United Kingdom (UK) and Rome (Italy). Methods:In this multi-national retrospective analysis of emergency department attendances and admissions, we retrospectively collected information for all diagnoses, respiratory diagnoses excluding bronchiolitis, and bronchiolitis, for different age groups from 68 hospitals in Catalonia (Spain), one hospital in Rome (Italy), and four hospitals in the UK (Bristol, Leicester, Glasgow, and Edinburgh), from May 1st, 2018, to April 30th 2024. Applying a generalised linear model (GLM) in Poisson regression, we obtained the risk ratio (RR) and 95% confidence intervals (CI) of bronchiolitis in 2023-2024 season compared to the mean of all previous seasons. We analysed data in annual bins, from May 1st to April 30th, excluding 2020-21 as a COVID year, for a total of 5 years of data. Findings:Data was available for 1,574,392 ED attendances (96,028 for bronchiolitis) and 255,689 hospital admissions (27,691 for bronchiolitis). In the 2023-2024 season, in Catalonia there was a reduction in the RR for bronchiolitis hospital admissions in the youngest infants aged <6 months (0.52, 95% CI: 0.48-0.55). There was also a reduction in Catalonia in the RR for hospital attendances for bronchiolitis in nirsevimab eligible age groups (0-11 months), with a RR of 0.56 (95% CI: 0.54-0.58) for infants <6 m and 0.93 (95% CI: 0.89-0.97) for infants 6-11 m. None of the other sites or age groups showed a significant reduction in the RR for attendances or admissions for the 2023-2024 season compared to previous years. Interpretation:Nirsevimab had a clear impact in reducing attendances and admissions for infants with bronchiolitis aged <6 months in Catalonia. However, the impact on older infants was less clear. Funding:None.

BACKGROUND:In Catalonia, infants <6 months old were eligible to receive nirsevimab, a novel monoclonal antibody against respiratory syncytial virus (RSV). We aimed to analyze nirsevimab's effectiveness in hospital-related outcomes of the seasonal cohort (born during the RSV epidemic from October to January 2024) and compared them with the catch-up cohort (born from April to September 2023). METHODS:Retrospective cohort study of all infants born between October 1, 2023, and January 21, 2024, according to their immunization with nirsevimab (immunized and nonimmunized). We followed individuals until the earliest of an outcome-hospital emergency visits, hospital admission or pediatric intensive care unit (PICU) admission due to RSV-associated or all-causes bronchiolitis-death or the end of the study. We used the Kaplan-Meier estimator and fitted Cox regression models using a calendar time scale to estimate hazard ratios (HRs) and their 95% confidence interval (CI). Sensitivity analysis was performed through matching. RESULTS:Among 15,341 infants, a dose of nirsevimab led to an adjusted HR for hospital admission, PICU admission and emergency visits due to RSV bronchiolitis of 0.26 (95% CI: 0.17-0.39), 0.15 (95% CI: 0.07-0.28) and 0.46 (95% CI: 0.23-0.90), respectively. For all-causes bronchiolitis, the former adjusted HRs were 0.45 (95% CI: 0.31-0.63), 0.23 (95% CI: 0.13-0.41) and 0.49 (95% CI: 0.35-0.68), respectively. CONCLUSIONS:Nirsevimab was associated with reductions of 74% and 85% hospitalizations and PICU admissions regarding RSV-associated bronchiolitis, respectively. These percentages are slightly lower than those for the catch-up cohort. This information may help the implementation of RSV-immunization campaigns by public health authorities.

Respiratory syncytial virus (RSV) causes most of the cases of bronchiolitis and thousands of deaths annually, particularly in infants less than 6 months old. In Catalonia (Spain), infants born between April 2023 and March 2024 aged 0–6 months during their first RSV season have been candidates to receive nirsevimab, the novel monoclonal antibody against RSV, since October 2023. We aimed to analyse the dynamics of all-causes bronchiolitis diagnoses and RSV community infections in the current season and compare them to pre-nirsevimab epidemics. We collected epidemiological data from the Information System for Surveillance of Infections in Catalonia (SIVIC) on daily all-causes bronchiolitis clinical diagnoses and RSV-confirmed cases provided by rapid antigen tests in primary care practices. We calculated the rate ratio (RR) for the incidence of all-causes bronchiolitis for children aged 0-11 m-old with respect to 12-35 m-old between September 2014 and January 2024. We analysed the RR of the incidence of RSV-confirmed infection for 0-11 m-old and 12-35 m-old with respect to the > 35 m-old, from January 2021 to January 2024. We then computed the relative difference of the RR, designated as percentage of reduction of risk, between season 2023/2024 and former epidemics. With a global coverage recorded rate for nirsevimab of 82.2