Statens Serum Institut

Liposomes are valuable in drug and vaccine delivery. However, due to limited stability in the gastric environment, there is a need to optimize liposomes for oral delivery. This study demonstrates the potential of pectin-coated cationic liposomes for mucosal delivery. Low methoxylated (LM), low methoxylated amidated (LMA), or high methoxylated (HM) pectins were coated onto cationic adjuvant formulation (CAF04) liposomes. The resulting liposomes were characterized to determine their in vitro stability in a simulated intestinal medium, interactions with mucins, and diffusivity across artificial mucus. Subsequently, liposome retention after in situ intestinal perfusion in rats and liposome uptake after incubation with macrophage-like cells were determined. In vitro stability tests in simulated intestinal fluid revealed that the pectin coating protected the liposomes against premature degradation. Mucin interaction studies showed that LM and LMA-pectin coatings created a protective buffer, avoiding excessive complexation with mucin. Diffusivity of the liposomes across artificial mucus revealed that the diffusivity of particles across mucus was influenced by both steric obstructions and interactive barriers. In situ intestinal perfusion demonstrated that pectin-coated liposomes were retained in the intestine, and cellular uptake studies confirmed that the pectin coating did not inhibit the uptake of the liposomes by macrophages. Overall, pectins demonstrated potential as excipients for mucosal delivery systems. In the context of oral liposome-based vaccine formulations, they can mitigate undesirable interactions such as complexation with bile salts and mucins, while preserving the cellular uptake efficiency of the particles.

Annual reformulation and approval of seasonal influenza vaccines necessitate yearly evaluation of their effectiveness. Regulatory agencies, including the European Medicines Agency (EMA), rely on timely, real-world evidence to inform product-specific benefit-risk assessments. We explored the feasibility of conducting annual, brand-specific influenza vaccine effectiveness studies in Denmark, Finland and Sweden, starting with the 2024/25 season. These countries maintain population-wide vaccination, clinical and laboratory registers, linkable via personal identification numbers and updated in near real-time. We discuss suitable study designs and document that cohort studies using a target trial emulation (TTE) framework are feasible in all three countries; register-based test-negative case-control design (TND) studies are currently only feasible in Denmark. Supplementary methods, including regression discontinuity and negative control outcome analyses, can address residual bias. This Nordic collaboration has proven capacity for large-scale register-based studies and its infrastructure is able to address EMA's requirements for timely, robust post-authorisation evidence to guide public health and regulatory decisions.

Antimicrobial resistance (AMR) is recognised as a major global public health threat, with the environment increasingly acknowledged as a key reservoir and dissemination pathway for resistant bacteria and resistance genes. In this study, 148 surface water samples were collected between 2023 and 2024 from six rivers and three canals discharging wastewater into two lake waters in Southern Italy to assess the occurrence and genomic features of extended-spectrum β-lactamase (ESBL)-, AmpC-, and carbapenemase-producing Escherichia coli and Klebsiella pneumoniae. Relevant isolates were obtained using selective culturing, and tested for antimicrobial susceptibility by broth microdilution. Major β-lactam resistance genes were detected by real-time PCR. Whole-genome sequencing (WGS) was performed on presumptive carbapenemase-producing isolates. ESBL- and/or carbapenemase-producing Enterobacterales were detected in 67.6% of samples, yielding a total of 176 non-duplicate isolates. The most prevalent gene was blaCTX-M, detected in 79.3% of positive isolates (96/121), while carbapenemase genes were detected in 20.6% (25/121) of isolates, mainly blaOXA-48 and blaVIM. WGS analysis of carbapenemase PCR-positive isolates revealed occurrence of clinically relevant high-risk clones, such as K. pneumoniae ST512/ST307 carrying blaKPC-3 and E. coli ST10 harbouring blaOXA-244. These findings highlight a potential risk to public health and underscore the importance of integrating environmental compartments into One Health surveillance frameworks for AMR.

Tuberculosis (TB) among refugee minors in low-incidence countries remains underexplored. We estimated the incidence of TB disease among refugee minors compared to Danish-born minors. This nationwide prospective historical cohort study included 31 172 refugee minors (< 18 years) granted residency in Denmark from 1993 to 2015. Each was matched 1:6 with a Danish-born control on age and sex. Follow-up extended from the date of residency until the earliest of: TB diagnosis, the age of 21 years, or study-end (31.12.2015). Data were obtained from Statistics Denmark and the International Reference Laboratory of Mycobacteriology. We conducted descriptive analyses and estimated incidence rates (IRs) using Poisson regression. Refugee minors had a 48 times higher TB IR compared to their Danish-born peers. Notably, refugee minors from sub-Saharan Africa had an IR of 203 per 100 000 person-years. For both refugee minors and their Danish-born peers, pulmonary TB was the most common form, but still more than a third had extrapulmonary manifestations. Among refugee minors, most TB cases were diagnosed more than 2 years after arrival. Our findings underscore the need for national policies and clinical guidelines for TB screening of all refugee minors upon arrival to reduce morbidity and advance TB elimination efforts.

The host genetics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have previously been studied based on cases from the earlier waves of the pandemic in 2020 and 2021, identifying 51 genomic loci associated with infection and/or severity. SARS-CoV-2 has shown rapid sequence evolution, increasing transmissibility, particularly for Omicron variants, which raises the question of whether this affected the host genetic factors. We performed a genome-wide association study of SARS-CoV-2 infection with Omicron variants, including more than 150,000 cases from four cohorts. We identified 13 genome-wide significant loci, of which only five were previously described as associated with SARS-CoV-2 infection. The strongest signal was a single nucleotide polymorphism in an intron of ST6GAL1, a gene affecting immune development and function, connected to three other associated loci (harboring MUC1, MUC5AC and MUC16) through O-glycan biosynthesis. Our study provides robust evidence for individual genetic variation related to glycosylation, translating into susceptibility to SARS-CoV-2 infections with Omicron variants.

A surge in Group A streptococcus (GAS) infections has been described in the post-COVID-19 pandemic period. We reviewed cases with periorbital GAS infections at our institution during a 14-month period, including cases with necrotizing soft tissue infection (NSTI). A single center retrospective case series was performed at the University Hospital of Copenhagen, Rigshospitalet, during January 2023 to February 2024 including all adult patients referred from secondary centers with a suspicion of periorbital NSTI. All cases were treated for periorbital skin and soft tissue infections with culture-confirmed group A streptococci in an eye swab, a tissue sample or blood cultures. Eleven cases with a median age of 72 (range 55-84) years with periorbital GAS infection were included. Four patients had diabetes, and one patient had eyelid surgery prior to the infection. Pre-admission symptoms included pain, swelling in the periorbital area, fever and/or a sore throat. Patients presented with fever, nausea, and/or confusion and clinical exams were noticeable for erythema and edema of the periorbital area with the eyelids fully closed on the affected side. Two cases had septic shock. Based on CT scans, six cases were diagnosed with pre-septal cellulitis and five cases were suspected of post-septal NSTI, which was confirmed by surgical debridement. The GAS isolates from tissue samples or blood cultures in these five cases were of type MLST 28 / emm 1.0 (M1 clone). Treatment included meropenem and clindamycin (n = 11), intravenous immunoglobulin (n = 4), surgical debridement (n = 5) and hyperbaric oxygen therapy (n = 3). One patient died in the intensive care unit. Two patients have permanently reduced visual acuity. We report an accumulation of cases with pre- or post-septal orbital GAS infections in which the majority had no evidence of immunosuppression or a triggering event such as trauma or surgery. All cases of invasive GAS infections were caused by the M1 clone.

Important questions remain regarding differences in geographical and age-specific mortality patterns as the COVID-19 pandemic evolved in consecutive waves, and how COVID-19 mortality compares to seasonal influenza. In a pandemic situation, excess all-cause mortality provides a more complete and robust measure than cause-specific mortality. Data submitted by 26 countries participating in the European Mortality Monitoring (EuroMOMO) network between 2020 and 2023 was analysed to quantify excess all-cause mortality during the COVID-19 pandemic. Excess mortality from this period was compared to previous influenza seasons from 2014 to 2019. Pooled estimates of excess mortality showed four main waves during the COVID-19 pandemic period, most markedly in people aged 65 years and above, with timing and magnitude that varied between countries. Here we show that prior to implementation of control measures and COVID-19 vaccination, excess mortality greatly exceeded typical seasonal influenza mortality, but later during the pandemic was at levels comparable to influenza.

Abstract Background Early life may shape the risk of later IBD development1–4; however, research on molecular neonatal features in individuals who later develop IBD is lacking. We explored metabolomes at birth in individuals who later developed IBD using unique neonatal dried blood spots (DBS). Methods We analysed neonatal DBS samples from 520 individuals with pediatric- or adult-onset IBD (CD = 276, UC = 244) and 1:1 matched controls, based on sample acquisition date, time of sampling (days after birth), gestational age or birth weight, and sex. We performed untargeted metabolomics and employed multivariate analysis, followed by a feature selection method built on conditional logistic regression with a LASSO component to reveal metabolites for further analysis. The following analysis was conducted using conditional logistic regression adjusted for multiple testing based on the total number of selected metabolite features. We also employed genotype and inflammatory marker information available for a subset of the cohort to investigate functional properties of the identified individual metabolites. Results We measured 1,249 metabolites that passed quality control. Although the global metabolomic composition did not differ significantly between cases and controls, the feature selection method revealed 21 neonatal metabolites associated with later CD development and four with UC. These metabolites belonged to the classes of amino acids and derivatives, nucleotides/nucleosides, peptides, and acylcarnitine. We further observed an association between specific neonatal metabolites and age of IBD onset: 7 metabolites associated with pediatric-onset CD, two with adult-onset CD, two with pediatric-onset UC, and two with adult-onset UC. Additionally, several feature-selected metabolites showed positive correlations with inflammatory markers, including IL-4, TNF-α, IL-6, and IFN-γ, and some were linked to genetic variants. Conclusion We identify specific neonatal metabolites in individuals with later development of IBD, related to IBD subtypes and age at diagnosis. This expands on the role of early life in development of IBD and sheds novel light on disease pathogenesis.