Full-length sequence analysis of hepatitis C virus genotype 3b strains and development of an in vivo infectious 3b cDNA clone.

IMPORTANCE: HCV genotype 3b is a difficult-to-treat subtype, associated with accelerated progression of liver disease and resistance to antivirals. Moreover, its prevalence has significantly increased among persons who inject drugs posing a serious risk of transmission in the general population. Thus, more genetic information and antiviral testing systems are required to develop novel therapeutic options for this genotype 3 subtype. We determined the complete genomic sequence and complexity of three genotype 3b isolates, which will be beneficial to study its biology and evolution. Furthermore, we developed a full-length in vivo infectious cDNA clone of genotype 3b and showed its robustness and genetic stability in human-liver chimeric mice. This is, to our knowledge the first reported infectious cDNA clone of HCV genotype 3b and will provide a valuable tool to evaluate antivirals and neutralizing antibodies in vivo, as well as in the development of infectious cell culture systems required for further research.

Use of molnupiravir: A Danish nationwide drug utilization study.

PURPOSE: To describe utilization patterns, characteristics of users and prescribers of the new oral antiviral medication, molnupiravir, indicated for mild-to-moderate COVID-19. METHODS: Using nationwide registries, we identified all Danish adults who filled a prescription for molnupiravir from December 16th, 2021, to August 31st, 2022. We described weekly incidence rates and patient characteristics over time, prescriber characteristics as well as time between molnupiravir initiation and a positive SARs-CoV-2 test. Patient characteristics were compared to matched, untreated SARS-CoV-2 positive reference groups. RESULTS: By August 31st, 2022, 5847 individuals had filled a prescription for molnupiravir. The incidence rate gradually increased to 16 weekly prescriptions per 1000 RT-PCR SARS-CoV-2 positives. Users of molnupiravir were most often men (55% vs. 45% women). The majority (81%) had a positive RT-PCR SARS-CoV-2 test and few (2.9%) redeemed molnupiravir outside the recommended window of 5 days from the positive test result. Compared to matched, untreated SARS-CoV-2 positive reference groups, users of molnupiravir had a median age of 74 years versus 49 years, a higher proportion resided in a nursing home (12% vs. 1.5%) and had a higher number of comorbidities (median of 3 vs. 0); most commonly hypertension (38%), chronic lung disease (35%), diabetes (20%) and mood disorders (20%). General practitioners were the primary prescribers of molnupiravir (91%). CONCLUSIONS: Molnupiravir was mainly prescribed by general practitioners to RT-PCR SARS-CoV-2 positive individuals who had a potentially increased risk of severe COVID-19. Though some off-label prescribing occurred, our study indicates a high level of adherence to contemporary guidelines.

Experience with sotrovimab treatment of SARS-CoV-2-infected patients in Denmark.

AIMS: To evaluate the experience with use of sotrovimab following severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in high-risk groups. METHODS: In a nationwide, population-based cohort study, we identified all individuals treated with sotrovimab (N = 2933) and stratified them by 4 high-risk groups: (A) malignant haematological disease, (B) solid organ transplantation, (C) anti-CD20 therapy ≤1 year and (D) other risks. Cox regression analysis was used to calculate hazard ratios for hospitalization, death and associated prognostic factors. RESULTS: Of 2933 sotrovimab-treated individuals, 83% belonged to high-risk groups (37.6% haematological malignancy, 27.4% solid organ transplantation and 17.5% treatment with anti-CD20 ≤1 year). Only 17.8% had other risks (11.8% were pregnant, 10.7% primary immunodeficiency, 21.2% other malignancy, 4.3% received anti-CD20 >1 year and 52.0% other/unknown causes). Within 90 days of infusion, 30.2% were hospitalized and 5.3% died. The main prognostic factors were the predefined high-risk groups, mainly malignant haematological disease and age ≥65 years. Number of COVID-19 vaccines (≥3) was associated with a decreased risk of hospitalization. The Delta but not the Omicron BA.2 variant was associated with a higher risk of death compared to the BA.1 variant. CONCLUSION: More than 90% of the patients treated with sotrovimab belonged to the very high-risk groups as described in the Danish guidelines. Sotrovimab-treated individuals remained at a high risk of hospitalization and death which was strongly associated with the underlying immunocompromised state and age. Having received >3 COVID-19 vaccines was association with decreased risk of death and hospitalization.

A multi-level intervention to eliminate hepatitis C from the Region of Southern Denmark: the C-Free-South project.

Denmark has signed the WHO strategy to eliminate hepatitis C virus (HCV). In the absence of a national strategy for elimination, a local action plan was developed in the Region of Southern Denmark (RSD). The aim of the strategy is to diagnose 90% of HCV-infected persons and treat 80% of those diagnosed by 2025. The strategy was developed by reviewing Danish data on HCV epidemiology and drug use to identify key populations for screening, linkage to care, and treatment. Based on available published data from 2016, an estimated 3028 persons in the RSD were HCV-RNA positive (population prevalence 0.21%). Of these, 1002 were attending clinical care, 1299 were diagnosed but not in clinical care, and 727 were undiagnosed. Three different interventions targeting the HCV-infected population and two interventions for HCV surveillance are planned to achieve elimination. The "C-Free-South" strategy aims to eliminate HCV in our region by identifying (90%) and treating (80%) of infected persons by the end of 2025, 5 years earlier than the WHO elimination target date.

Hepatitis C time trends in reported cases and estimates of the hidden population born before 1965, Denmark and Sweden, 1990 to 2020.

BackgroundAccording to the World Health Organization, hepatitis C virus (HCV) infection should be under control by 2030.AimOur aim was to describe the size and temporal changes in reported cases of chronic HCV infection in Denmark and Sweden and to estimate the size of the hidden (undiagnosed) population born before 1965.MethodsWe extracted all HCV infections reported to national surveillance systems in Denmark and Sweden from 1990 to 2020. Prediction of the size of the hidden HCV-infected population was restricted to the cohort born before 1965 and cases reported up to 2017. We applied a model based on removal sampling from binomial distributions, estimated the yearly probability of diagnosis, and deducted the original HCV-infected population size.ResultsDenmark (clinician-based) reported 10 times fewer hepatitis C cases annually than Sweden (laboratory and clinician-based), peaking in 2007 (n = 425) and 1992 (n = 4,537), respectively. In Denmark, the birth year distribution was monophasic with little change over time. In recent years, Sweden has had a bimodal birth year distribution, suggesting ongoing infection in the young population. In 2017, the total HCV-infected population born before 1965 was estimated at 10,737 living persons (95% confidence interval (CI): 9,744-11,806), including 5,054 undiagnosed, in Denmark and 16,124 (95% CI: 13,639-18,978), including 10,580 undiagnosed, in Sweden.ConclusionsThe reporting of HCV cases in Denmark and Sweden was different. For Denmark, the estimated hidden population was larger than the current national estimate, whereas in Sweden the estimate was in line with the latest published numbers.

Inferior cure rate in pilot study of 4-week glecaprevir/pibrentasvir treatment with or without ribavirin of chronic hepatitis C.

BACKGROUND & AIMS: Shortening the treatment duration for chronic hepatitis C may increase feasibility and reduce the cost of cure. The aims of this study were to compare 4 weeks of glecaprevir/pibrentasvir (GLE/PIB) treatment with and without ribavirin for patients with chronic hepatitis C and favourable baseline characteristics and to monitor the development of resistance-associated substitutions (RAS) and re-treatment outcomes if treatment failed. METHODS: We performed an open-label single-centre randomized controlled trial, in which patients with chronic hepatitis C were randomized 1:1 to GLE/PIB ± ribavirin, stratified by genotype 3. The main inclusion criteria were treatment-naive patients, aged 18-49 with all genotypes accepted, and absence of liver fibrosis, determined by liver stiffness measurement less than 8 kPa. Viral genome sequences were determined by deep sequencing at baseline and at the time of relapse. RESULTS: A total of 32 patients started treatment. Sustained virological response at week 12 (SVR12) was 59% (10/17) for GLE/PIB without ribavirin and 73% (11/15) for GLE/PIB with ribavirin. Drug target-specific NS5A RAS were detected at baseline for 45% (5/11) of patients with treatment failure and for 14% (3/21) of patients who achieved SVR12. Ten failure patients were retreated 12 weeks with sofosbuvir-based regimens; all have been cured. CONCLUSIONS: In this pilot study of 4-week treatment with GLE/PIB with and without ribavirin, we found that baseline RAS were more frequent in patients with virological failure. Development of RAS did occur after short treatment but did not result in retreatment failure with a different regimen. EudraCT no: 2017-005179-21.

Hepatitis C elimination among people who inject drugs: Challenges and recommendations for action within a health systems framework.

The burden of hepatitis C infection is considerable among people who inject drugs (PWID), with an estimated prevalence of 39%, representing an estimated 6.1 million people who have recently injected drugs living with hepatitis C infection. As such, PWID are a priority population for enhancing prevention, testing, linkage to care, treatment and follow-up care in order to meet World Health Organization (WHO) hepatitis C elimination goals by 2030. There are many barriers to enhancing hepatitis C prevention and care among PWID including poor global coverage of harm reduction services, restrictive drug policies and criminalization of drug use, poor access to health services, low hepatitis C testing, linkage to care and treatment, restrictions for accessing DAA therapy, and the lack of national strategies and government investment to support WHO elimination goals. On 5 September 2017, the International Network of Hepatitis in Substance Users (INHSU) held a roundtable panel of international experts to discuss remaining challenges and future priorities for action from a health systems perspective. The WHO health systems framework comprises six core components: service delivery, health workforce, health information systems, medical procurement, health systems financing, and leadership and governance. Communication has been proposed as a seventh key element which promotes the central role of affected community engagement. This review paper presents recommended strategies for eliminating hepatitis C as a major public health threat among PWID and outlines future priorities for action within a health systems framework.

Model projections on the impact of HCV treatment in the prevention of HCV transmission among people who inject drugs in Europe.

BACKGROUND & AIMS: Prevention of hepatitis C virus (HCV) transmission among people who inject drugs (PWID) is critical for eliminating HCV in Europe. We estimated the impact of current and scaled-up HCV treatment with and without scaling up opioid substitution therapy (OST) and needle and syringe programmes (NSPs) across Europe over the next 10 years. METHODS: We collected data on PWID HCV treatment rates, PWID prevalence, HCV prevalence, OST, and NSP coverage from 11 European settings. We parameterised an HCV transmission model to setting-specific data that project chronic HCV prevalence and incidence among PWID. RESULTS: At baseline, chronic HCV prevalence varied from <25% (Slovenia/Czech Republic) to >55% (Finland/Sweden), and <2% (Amsterdam/Hamburg/Norway/Denmark/Sweden) to 5% (Slovenia/Czech Republic) of chronically infected PWID were treated annually. The current treatment rates using new direct-acting antivirals (DAAs) may achieve observable reductions in chronic prevalence (38-63%) in 10 years in Czech Republic, Slovenia, and Amsterdam. Doubling the HCV treatment rates will reduce prevalence in other sites (12-24%; Belgium/Denmark/Hamburg/Norway/Scotland), but is unlikely to reduce prevalence in Sweden and Finland. Scaling-up OST and NSP to 80% coverage with current treatment rates using DAAs could achieve observable reductions in HCV prevalence (18-79%) in all sites. Using DAAs, Slovenia and Amsterdam are projected to reduce incidence to 2 per 100 person years or less in 10 years. Moderate to substantial increases in the current treatment rates are required to achieve the same impact elsewhere, from 1.4 to 3 times (Czech Republic and France), 5-17 times (France, Scotland, Hamburg, Norway, Denmark, Belgium, and Sweden), to 200 times (Finland). Scaling-up OST and NSP coverage to 80% in all sites reduces treatment scale-up needed by 20-80%. CONCLUSIONS: The scale-up of HCV treatment and other interventions is needed in most settings to minimise HCV transmission among PWID in Europe. LAY SUMMARY: Measuring the amount of HCV in the population of PWID is uncertain. To reduce HCV infection to minimal levels in Europe will require scale-up of both HCV treatment and other interventions that reduce injecting risk (especially OST and provision of sterile injecting equipment).

Effect of direct-acting antivirals on the titers of human pegivirus 1 during treatment of chronic hepatitis C patients.

Coinfections with human pegivirus 1 (HPgV-1) are common in chronic hepatitis C virus (HCV) patients. However, little is known about whether HPgV-1 is affected by direct-acting antivirals during HCV treatment. Metagenomic analysis and reverse transcriptase-quantitative PCR (RT-qPCR) were performed on RNA from the plasma of 88 selected chronic HCV patients undergoing medical treatment. Twenty (23%) of these HCV patients had HPgV-1 coinfections and were followed by RT-qPCR during treatment and follow-up to investigate HPgV-1 RNA titers. Recovered sequences could be assembled to complete HPgV-1 genomes, and most formed a genotype 2 subclade. All HPgV-1 viral genomic regions were under negative purifying selection. Glecaprevir/pibrentasvir treatment in five patients did not consistently lower the genome titers of HPgV-1. In contrast, a one log10 drop of HPgV-1 titers at week 2 was observed in 10 patients during treatment with sofosbuvir-containing regimens, sustained to the end of treatment (EOT) and in two cases decreasing to below the detection limit of the assay. For the five patients treated with ledipasvir/sofosbuvir with the inclusion of pegylated interferon, titers decreased to below the detection limit at week 2 and remained undetectable to EOT. Subsequently, the HPgV-1 titer rebounded to pretreatment levels for all patients. In conclusion, we found that HCV treatment regimens that included the polymerase inhibitor sofosbuvir resulted in decreases in HPgV-1 titers, and the addition of pegylated interferon increased the effect on patients with coinfections. This points to the high specificity of protease and NS5A inhibitors toward HCV and the more broad-spectrum activity of sofosbuvir and especially pegylated interferon. IMPORTANCE: Human pegivirus 1 coinfections are common in hepatitis C virus (HCV) patients, persisting for years. However, little is known about how pegivirus coinfections are affected by treatment with pangenotypic direct-acting antivirals (DAAs) against HCV. We identified human pegivirus by metagenomic analysis of chronic HCV patients undergoing protease, NS5A, and polymerase inhibitor treatment, in some patients with the addition of pegylated interferon, and followed viral kinetics of both viruses to investigate treatment effects. Only during HCV DAA treatment regimens that included the more broad-spectrum drug sofosbuvir could we detect a consistent decline in pegivirus titers that, however, rebounded to pretreatment levels after treatment cessation. The addition of pegylated interferon gave the highest effect with pegivirus titers decreasing to below the assay detection limit, but without clearance. These results reveal the limited effect of frontline HCV drugs on the closest related human virus, but sofosbuvir appeared to have the potential to be repurposed for other viral diseases.

Combining cross-sectional survey and register data improved the estimate of hepatitis C prevalence among patients attending a psychiatric emergency department in Denmark.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Comparison of the medical students' perceived self-efficacy and the evaluation of the observers and patients.

BACKGROUND: The accuracy of self-assessment has been questioned in studies comparing physicians' self-assessments to observed assessments; however, none of these studies used self-efficacy as a method for self-assessment. The aim of the study was to investigate how medical students' perceived self-efficacy of specific communication skills corresponds to the evaluation of simulated patients and observers. METHODS: All of the medical students who signed up for an Objective Structured Clinical Examination (OSCE) were included. As a part of the OSCE, the student performance in the "parent-physician interaction" was evaluated by a simulated patient and an observer at one of the stations. After the examination the students were asked to assess their self-efficacy according to the same specific communication skills. The Calgary Cambridge Observation Guide formed the basis for the outcome measures used in the questionnaires. A total of 12 items was rated on a Likert scale from 1-5 (strongly disagree to strongly agree). We used extended Rasch models for comparisons between the groups of responses of the questionnaires. Comparisons of groups were conducted on dichotomized responses. RESULTS: Eighty-four students participated in the examination, 87% (73/84) of whom responded to the questionnaire. The response rate for the simulated patients and the observers was 100%. Significantly more items were scored in the highest categories (4 and 5) by the observers and simulated patients compared to the students (observers versus students: -0.23; SE:0.112; p=0.002 and patients versus students:0.177; SE:0.109; p=0.037). When analysing the items individually, a statistically significant difference only existed for two items. CONCLUSION: This study showed that students scored their communication skills lower compared to observers or simulated patients. The differences were driven by only 2 of 12 items. The results in this study indicate that self-efficacy based on the Calgary Cambridge Observation guide seems to be a reliable tool.

Retrieval of patients with hepatitis C who were lost to follow-up in Southern Denmark.

BACKGROUND: The goal of the C-Free-South project is to eliminate hepatitis C (HCV) in the Region of Southern Denmark (1.2 million inhabitants). One target group consists of people with HCV who had received care but were lost to follow-up. The study aim was to evaluate program efficacy in locating these patients and getting them into care. METHODS: Patients were contacted if they were HCV-RNA positive and age 18+ years, registered in the clinical hepatitis database as of November 1, 2019, and had no scheduled HCV-related appointment. They were contacted at 2-month intervals by phone or letter. For patients who did not respond, we asked their general practitioner to refer them, if possible. RESULTS: We identified 69 (7%) patients in the database who were listed as untreated and not being followed up. We successfully contacted 54 (78%), and the remaining 15 (22%) did not respond to our contacts. To date, 45 (65%) had initiated treatment, one (1%) had rejected treatment, and eight (12%) did not show up to their appointments. Among those receiving treatment, 20 (44%) responded after the first contact, 18 (40%) after the second contact, and 7 (16%) after informing the general practitioner. CONCLUSION: An intensified and persistent effort made it possible to reach most HCV patients lost to follow-up. All new contact attempts increased the possibility that patients would receive treatment. Nevertheless, 22% of HCV patients lost to follow-up did not respond to repeated contact attempts.

Peer-delivered point-of-care testing and linkage to treatment for hepatitis C virus infection among marginalized populations through a mobile clinic in Copenhagen, Denmark.

BACKGROUND: Globally, many people with hepatitis C virus (HCV) infection are marginalized and have very limited access to traditional healthcare services, including HCV testing and treatment. Models of care attuned to the needs of the marginalized population at risk are needed. This study aimed to evaluate the testing and treatment uptake of a community-based, peer-led model of care offering point-of-care testing. METHODS: In this interventional cohort study, people at risk of HCV infection were recruited between May 2019 and December 2021 at a community-based, peer-led mobile clinic. During a single visit, participants were offered a point-of-care HCV antibody test, and, if antibodies were detected, an additional RNA test. Participants with detectable HCV RNA were linked with peer-assisted referral to a 'fast-track' clinic at a major hospital. The primary outcomes were the number of people engaged in testing and the proportion who initiated treatment and achieved a sustained virologic response (SVR). RESULTS: We tested 728 individuals. Of those, 208 (29%) were positive for HCV antibodies, and 114 (15%) were HCV RNA detectable. Of the 114, 80 (70%) initiated treatment, and 79 (99%) achieved SVR. The main reason for not initiating treatment was non-Danish citizenship with no legal access to health care. CONCLUSION: This study found that a peer-led point-of-care service is a model of care that can engage marginalized groups in HCV testing and linkage to treatment.

Hepatitis C screening and linkage to care with a mobile clinic in Southern Denmark.

BACKGROUND: Knowing the prevalence of hepatitis C (HCV) in risk groups is essential for elimination. The aim of the study was to assess HCV prevalence among people with different risk profiles and the feasibility of linking people with HCV to care. METHODS: In Southern Denmark we tested people who were using shelters, cafés, and facilities for marginalized populations and the general population. We established a mobile clinic for HCV testing offering point-of-care HCV-antibody (HCV-Ab), point-of-care HCV RNA testing, and dried blood spot (DBS) testing. People with HCV infection were linked to care. RESULTS: Among 802 tested persons, we found an HCV-Ab /HCV RNA prevalence of 13% (n = 101) /3% (n = 24). We found a prevalence of 20% (n = 97)/5% (n = 24) among 475 persons tested at locations attended by people who inject drugs but 0%/0% when testing the general population. Of 24 people who were HCV RNA positive, 83% (n = 20) initiated treatment, 13% (n = 3) spontaneously cleared their infection, and one was lost to follow-up. CONCLUSION: General population testing has limited utility while focus on settings attended by people with increased HCV risk is more feasible. Linkage of people with a current HCV infection to care is feasible.

Immunological Characteristics of Patients Receiving Ultra-Short Treatment for Chronic Hepatitis C.

Reducing the treatment duration for chronic hepatitis C could be an important tool in the effort to reach the elimination goals set by the World Health Organization. The current challenge is to predict the target group who will achieve sustained virological response at week 12 (SVR12) with shorter treatment duration. The aim of this exploratory study was to characterize immune subsets with focus on inhibitory receptors in patients who experienced SVR12 or virological relapse following four weeks treatment with glecaprevir/pibrentasvir with or without ribavirin. A total of 32 patients were included in this study of whom 21 achieved SVR12 and 11 had virological relapse. All available samples at baseline (n = 31) and end of treatment (EOT) (n = 30) were processed for flow cytometric analysis in order to measure the expression of PD-1, 2B4, BY55, CTLA-4, TIM-3 and LAG-3 on 12 distinct T cell subsets. At baseline, patients with SVR12 (n=21) had numerically lower frequencies of inhibitory receptors for 83% (60/72) of the investigated T-cell subtypes. The most significant difference observed between the two groups was a lower frequency of stem cell-like memory T-cells CD4+PD1+ in the SVR group (p = 0.007). Furthermore, we observed a significant positive correlation between baseline viral load and the expression of PD-1 on the total CD8+ T-cells and effector memory T-cells CD4+ and CD8+ for patients with virological relapse. This study suggests a measurable immunologic phenotype at baseline of patients achieving SVR12 after short treatment compared to patients with virological relapse.

Four Weeks Treatment with Glecaprevir/Pibrentasvir + Ribavirin-A Randomized Controlled Clinical Trial.

Enhancing treatment uptake for hepatitis C to achieve the elimination goals set by the World Health Organization could be achieved by reducing the treatment duration. The aim of this study was to compare the sustained virological response at week 12 (SVR12) after four weeks of glecaprevir/pibrentasvir (GLE/PIB) + ribavirin compared to eight weeks of GLE/PIB and to estimate predictors for SVR12 with four weeks of treatment through a multicenter open label randomized controlled trial. Patients were randomized 2:1 (4 weeks:8 weeks) and stratified by genotype 3 and were treatment naïve of all genotypes and without significant liver fibrosis. A total of 27 patients were analyzed for predictors for SVR12, including 15 from the first pilot phase of the study. In the 'modified intention to treat' group, 100% (7/7) achieved cure after eight weeks and for patients treated for four weeks the SVR12 was 58.3% (7/12). However, patients with a baseline viral load <2 mill IU/mL had 93% SVR12. The study closed prematurely due to the low number of included patients due to the COVID-19 pandemic. Our results suggest that viral load should be taken into account when considering trials of short course treatment.

Levels of SARS-CoV-2 antibodies among fully vaccinated individuals with Delta or Omicron variant breakthrough infections.

SARS-CoV-2 variants of concern have continuously evolved and may erode vaccine induced immunity. In this observational cohort study, we determine the risk of breakthrough infection in a fully vaccinated cohort. SARS-CoV-2 anti-spike IgG levels were measured before first SARS-CoV-2 vaccination and at day 21-28, 90 and 180, as well as after booster vaccination. Breakthrough infections were captured through the Danish National Microbiology database. incidence rate ratio (IRR) for breakthrough infection at time-updated anti-spike IgG levels was determined using Poisson regression. Among 6076 participants, 127 and 364 breakthrough infections due to Delta and Omicron variants were observed. IRR was 0.29 (95% CI 0.15-0.56) for breakthrough infection with the Delta variant, comparing the highest and lowest quintiles of anti-spike IgG. For Omicron, no significant differences in IRR were observed. These results suggest that quantitative level of anti-spike IgG have limited impact on the risk of breakthrough infection with Omicron.

Characteristics associated with serological COVID-19 vaccine response and durability in an older population with significant comorbidity: the Danish Nationwide ENFORCE Study.

OBJECTIVES: To identify individual characteristics associated with serological COVID-19 vaccine responsiveness and the durability of vaccine-induced antibodies. METHODS: Adults without history of SARS-CoV-2 infection from the Danish population scheduled for SARS-CoV-2 vaccination were enrolled in this parallel group, phase 4 study. SARS-CoV-2 Spike IgG and Spike-ACE2-receptor-blocking antibodies were measured at days 0, 21, 90, and 180. Vaccine responsiveness was categorized according to Spike IgG and Spike-ACE2-receptor-blocking levels at day 90 after first vaccination. Nondurable vaccine response was defined as day-90 responders who no longer had significant responses by day 180. RESULTS: Of 6544 participants completing two vaccine doses (median age 64 years; interquartile range: 54-75), 3654 (55.8%) received BTN162b2, 2472 (37.8%) mRNA-1273, and 418 (6.4%) ChAdOx1 followed by an mRNA vaccine. Levels of both types of antibodies increased from baseline to day 90 and then decreased to day 180. The decrease was more pronounced for levels of Spike-ACE2-receptor-blocking antibodies than for Spike IgG. Proportions with vaccine hyporesponsiveness and lack of durable response were 5.0% and 12.1% for Spike IgG and 12.7% and 39.6% for Spike-ACE2-receptor-blocking antibody levels, respectively. Male sex, vaccine type, and number of comorbidities were associated with all four outcomes. Additionally, age ≥75 years was associated with hyporesponsiveness for Spike-ACE2-receptor-blocking antibodies (adjusted odds ratio: 1.59; 95% confidence interval: 1.25-2.01) but not for Spike IgG. DISCUSSION: Comorbidity, male sex, and vaccine type were risk factors for hyporesponsiveness and nondurable response to COVID-19 vaccination. The functional activity of vaccine-induced antibodies declined with increasing age and had waned to pre-second-vaccination levels for most individuals after 6 months.

[From treating in the dark towards eliminating hepatitis C].

Before the hepatitis C virus (HCV) was identified, patients with hepatitis C were treated with interferon. Alanine aminotranferase levels decreased in 25-50% of treated patients, but only 10-20% had been cured, i.e. became HCV-RNA-negative. Cure rates were improved to 40-60% by prolonging the duration of therapy and adding ribavirin, but it was not until the introduction of direct acting antivirals, that a cure for all patients was achieved. The time is now to eliminate hepatitis C, and in this review we argue, that it will require outreach and point-of-care testing and treating, but we expect Denmark to fulfil the WHO elimination goals before 2030.