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The SARS-CoV-2 Omicron variant has dominated the COVID-19 pandemic since late 2021, bringing [greater than or equal to]3 waves of increasingly immunity-evasive Omicron subvariants. An early wave of the Omicron [...]

Background Within a year of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, vaccines inducing a robust humoral and cellular immune response were implemented worldwide. However, emergence of novel variants and waning vaccine-induced immunity led to implementation of additional vaccine boosters. Methods This prospective study evaluated the temporal profile of cellular and serological responses in a cohort of 639 SARS-CoV-2–vaccinated participants, of whom a large proportion experienced a SARS-CoV-2 infection. All participants were infection naïve at the time of their first vaccine dose. Proportions of SARS-CoV-2 spike–specific T cells were determined after each vaccine dose using the activation-induced marker assay, while levels of circulating SARS-CoV-2 antibodies were determined by the Meso Scale serology assay. Results We found a significant increase in SARS-CoV-2 spike–specific CD4+ and CD8+ T-cell responses following the third dose of a SARS-CoV-2 messenger RNA vaccine as well as enhanced CD8+ T-cell responses after the fourth dose. Furthermore, increased age was associated with a poorer response. Finally, we observed that SARS-CoV-2 infection boosts both the cellular and humoral immune response, relative to vaccine-induced immunity alone. Conclusions Our findings highlight the boosting effect on T-cell immunity of repeated vaccine administration. The combination of multiple vaccine doses and SARS-CoV-2 infections maintains population T-cell immunity, although with reduced levels in the elderly. [ABSTRACT FROM AUTHOR]

The prevalence of hepatitis C (HCV) among psychiatric patients is elevated compared to the background population in many studies, but the prevalence among Danish psychiatric patients is unknown. The aim of the study was to determine the HCV prevalence and the proportion of the psychiatric patient population that remains to be diagnosed and treated in a Danish setting. During a 5-month period, patients attending the psychiatric emergency room in Vejle, Denmark, were offered point-of-care anti-HCV testing. Previous hepatitis C tests for all patients attending the Psychiatric Department in the study period were extracted from the national laboratory database (DANVIR). We combined the survey and register data in a capture–recapture estimate of undiagnosed patients with HCV. During the study 24.9% (589 of 2364) patients seen at the psychiatric department attended the emergency room. The prevalence of anti-HCV among those tested in the emergency room was 1.6%. The laboratory register identified 595/2364 patients previously tested for anti-HCV with a positive prevalence of 6.1%. The undiagnosed anti-HCV positives among the 1483 never tested was estimated to 1.1%. Thus the total estimated prevalence of anti-HCV was 2.3% (54/2364, 95% CI 1.7%–3.0%) in the population, of whom 70.4% had been diagnosed, and 72.2% of diagnosed patients had received treatment or cleared HCV. Combining survey and register data showed that the WHO target of 90% diagnosed and 80% treated was not met. To eliminate HCV in the psychiatric population, both undiagnosed and untreated patients must be targeted. [ABSTRACT FROM AUTHOR]

The emergence of the SARS-CoV-2 Omicron variant BA.1 (B.1.1.529) in late 2021 caused immediate apprehension because it readily outcompeted the already highly transmissible Delta variant. The high number of spike [...]

Background: In solid organ transplant (SOT) recipients, the humoral response following COVID-19 vaccination is reduced, as a result of their immunosuppressed treatment. In this study, we investigated antibody concentrations after booster vaccinations until the fifth dose, the latter by monovalent or bivalent BA1 or BA4/5 vaccines. In addition, we evaluated the efficacy of vaccination by recording breakthrough infections, hospitalizations, and deaths. Method: This prospective cohort study included 438 SOT recipients (>18 years) vaccinated with mRNA vaccines against COVID-19 from January 2021 until March 2023. Blood samples were drawn before and after each vaccination and tested for SARS-CoV-2 spike RBD IgG antibodies with the lowest and highest cut-off at 7.1 and 5,680 BAU/mL, respectively. Vaccine information, breakthrough infections, and hospitalizations were collected from the medical records. Results: Most participants received BNT162b2 and 61.4% received five vaccine doses. The response proportion in SOT recipients increased from 86.7% after the fourth dose to 93.0% following the fifth dose. Antibody concentration decreased with 142.7 BAU/mL between the third and fourth dose (median 132 days, Quartile 1: 123, Quartile 3: 148) and 234.3 BAU/mL between the fourth and fifth (median 250 days, Quartile 1: 241, Quartile 3: 262) dose among those without breakthrough infection (p=0.34). When comparing the Omicron BA.1 or Omicron BA.4/BA.5 adapted vaccines, no significant differences in antibody concentration were found, but 20.0% of SOT recipients receiving a monovalent fifth vaccine dose had a breakthrough infection compared to 4.0% and 7.9% among those who received BA.1 and BA.4/BA.5 adapted vaccines, respectively (p=0.04). Since January 2021, 240 (54.8%) participants had a breakthrough infection, and 22 were hospitalized, but no deaths were observed. Conclusions: The fifth COVID-19 vaccine dose raised antibody response to 93.0% of the study population. Additional booster doses, as well as bivalent vaccines, led to higher levels of antibody concentration in SOT recipients. We found a lower incidence of breakthrough infections among SOT recipients after receiving a bivalent vaccine as a fifth dose compared to those receiving a monovalent dose. Antibody concentrations did not wane when the time between doses was prolonged from four to eight months. [ABSTRACT FROM AUTHOR]

Background Continuous evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outpaces monovalent vaccine cross-protection to new viral variants. Consequently, bivalent coronavirus disease 2019 (COVID-19) vaccines including Omicron antigens were developed. The contrasting immunogenicity of the bivalent vaccines and the impact of prior antigenic exposure on new immune imprinting remains to be clarified. Methods In the large prospective ENFORCE cohort, we quantified spike-specific antibodies to 5 Omicron variants (BA.1 to BA.5) before and after BA.1 or BA.4/5 bivalent booster vaccination to compare Omicron variant-specific antibody inductions. We evaluated the impact of previous infection and characterized the dominant antibody responses. Results Prior to the bivalent fourth vaccine, all participants (N = 1697) had high levels of Omicron-specific antibodies. Antibody levels were significantly higher in individuals with a previous polymerase chain reaction positive (PCR+) infection, particularly for BA.2-specific antibodies (geometric mean ratio [GMR] 6.79, 95% confidence interval [CI] 6.05–7.62). Antibody levels were further significantly boosted in all individuals by receiving either of the bivalent vaccines, but greater fold inductions to all Omicron variants were observed in individuals with no prior infection. The BA.1 bivalent vaccine generated a dominant response toward BA.1 (adjusted GMR 1.31, 95% CI 1.09–1.57) and BA.3 (1.32, 1.09–1.59) antigens in individuals with no prior infection, whereas the BA.4/5 bivalent vaccine generated a dominant response toward BA.2 (0.87, 0.76–0.98), BA.4 (0.85, 0.75–0.97), and BA.5 (0.87, 0.76–0.99) antigens in individuals with a prior infection. Conclusions Vaccination and previous infection leave a clear serological imprint that is focused on the variant-specific antigen. Importantly, both bivalent vaccines induce high levels of Omicron variant-specific antibodies, suggesting broad cross-protection of Omicron variants. [ABSTRACT FROM AUTHOR]

Vibrio vulnificus is a zoonotic pathogen that can cause death by septicaemia in farmed fish (mainly eels) and humans. The zoonotic strains that have been isolated from diseased eels and humans after eel handling belong to clade E (or serovar E (SerE)), a clonal complex within the pathovar (pv.) piscis. The aim of this study was to evaluate the accuracy of MALDI‐TOF mass spectrometry (MS) in the identification of SerE, using the other two main pv. piscis‐serovars (SerA and SerI) from eels as controls. MALDI‐TOF data were compared with known serologic and genetic data of five pv. piscis isolates or strains, and with the non pv. piscis reference strain. Based on multiple spectra analysis, we found serovar‐specific peaks that were of ~3098 Da and ~ 4045 Da for SerE, of ~3085 Da and ~ 4037 Da for SerA, and of ~3085 Da and ~ 4044 Da for SerI. Therefore, our results demonstrate that MALDI‐TOF can be used to identify SerE and could also help in the identification of the other serovars of the species. This means that zoonosis due to V. vulnificus could be prevented by using MALDI‐TOF, as action can be taken immediately after the isolation of a possible zoonotic V. vulnificus strain. [ABSTRACT FROM AUTHOR]

Simple Summary: Enriching the places were captive fish live, i.e., tanks, ponds or cages, has demonstrated potential to improve the wellbeing of the fish, which is a matter of increasing concern in the aquaculture sector. Enriching strategies are diverse but studies on the feasibility of their implementation in real farming scenarios are scarce. Here, the feasibility of using structural enrichment in the form of plastic shelters to improve the welfare of rainbow trout was studied in an organic fish farm. It was demonstrated that the use of simple plastic shelters is technically feasible, since the shelters induced little extra work in the farm routines and had no negative effects on fish performance, health or mortality. However, different to laboratory-based studies, the fish did not develop a clear shelter-seeking behavioral response when disturbed. This could be related to the short duration of the study, and therefore, it is recommended that enrichment in real scenarios should be tested covering a relevant part of the life cycle of the fish. Physical enrichment can improve the welfare of captive fish. Previous research has shown that fish often show preference for enriched environments, which can also result in improvements in growth performance. However, effects of enrichment are not always positive and the design and extent of the enrichment needs to be carefully considered. In this regard, information in real aquaculture scenarios is limited. The aim of this study was to serve as a proof of concept to test the feasibility of using simple PVC immersed shelters as a tool for better welfare in an organic rainbow trout farm. Our shelters induced little extra work in farm routines and had no negative effects on fish performance, health or mortality. The behavioral assessment pointed to a preference for sheltered areas in undisturbed conditions. However, no benefits were observed in terms of stress responses during standardized stress tests, and fish showed no obvious shelter-seeking behavior after disturbance. The results in terms of shelter-seeking behavior were probably limited by the short duration of the experiment, which was due to the farm's routines and needs. It is recommended that strategies for enrichment in real scenarios should be tested covering a relevant part of the life cycle of the fish in captivity, to fully account for their potential to improve welfare in aquaculture. [ABSTRACT FROM AUTHOR]

Flavobacteria are among the most important pathogens in freshwater salmonid aquaculture worldwide. Due to concerns regarding development of antibiotic resistance, phage therapy has been proposed as a solution to decrease pathogen load. However, application of phages is challenged by the development of phage resistance, and knowledge of the mechanisms and implications of phage resistance is therefore required. To study this, 27 phage‐resistant isolates of F. psychrophilum were genome sequenced and characterized to identify genetic modifications and evaluate changes in phenotypic traits, including virulence against rainbow trout. Phage‐resistant isolates showed reduction or loss of gliding motility, proteolytic activity, and adhesion to surfaces, and most isolates were completely non‐virulent against rainbow trout fry. Genomic analysis revealed that most phage‐resistant isolates had mutations in genes associated with gliding motility and virulence. Reversal of these mutations in a sub‐set of isolates led to regained motility, proteolytic activity, virulence and phage susceptibility. Although costly, the fast generation of phage resistance driven by single, reversible mutations likely represents a flexible and efficient phage defence mechanism in F. psychrophilum. The results further suggest that phage administration in aquaculture systems to prevent F. psychrophilum outbreaks selects for non‐virulent phage‐resistant phenotypes. [ABSTRACT FROM AUTHOR]

The study aimed to determine adjusted all‐cause mortality and cause of death in persons with chronic hepatitis B virus (HBV) infection compared with age‐ and sex‐matched persons from the general population. We used nationwide registers to identify persons aged ≥18 years with chronic HBV infection in 2002–2017 in Denmark and included 10 age‐ and sex‐matched controls for each. Follow‐up was from 6 months after diagnosis until death, emigration, or 31 December 2017. Mortality rate ratios (MRRs) adjusted for age, sex, employment, origin and comorbidity were calculated using Poisson regression. Unadjusted cause‐specific mortality rate ratios with 95% confidence intervals were calculated assuming a Poisson distribution. A total of 6988 persons with chronic HBV infection and 69,847 controls were included. During a median follow‐up of 7.7 years (range 0.0–15.5), 315 (5%) persons with—and 1525 (2%) without—chronic HBV infection died. The adjusted all‐cause MRR was 1.5 (95% CI 1.2–2.0). Persons with chronic HBV infection had increased mortality due to liver disease including hepatocellular carcinoma (MRR 12.3 [8.6–17.7]), external causes (MRR 3.3 [2.5–4.7]), endocrine disease (MRR 3.2 [1.8–5.4]), genitourinary disease (MRR 3.2 [1.2–7.6]) and neoplasms (except hepatocellular carcinoma; MRR 1.6 [1.2–2.0]). In conclusion, this study showed an increased all‐cause mortality in persons with chronic HBV infection in comparison with age‐ and sex‐matched persons without chronic HBV infection which remained after adjustment for several confounding factors. Excess mortality was mainly associated with liver disease, but also external factors, endocrine disease, genitourinary disease and neoplasms (excluding hepatocellular carcinoma). [ABSTRACT FROM AUTHOR]