Maxim Kan

Research problem and specific questions People who inject drugs (PWID) face significant health risks, including blood-borne infections such as HIV, hepatitis B (HBV), hepatitis C (HCV) and premature mortality. Globally, there are 13. 9 million PWID, with 1.6 million and 6.8 million living with HIV and HCV, respectively. Despite expanded harm-reduction efforts in Sweden, including needle and syringe programs (NSP) and take-home naloxone (THN) distribution to prevent opioid overdose deaths, Sweden still lacks comprehensive national research describing PWID health trajectories over time and how NSP-based interventions translate into infection control, reduced mortality, and improved continuity of care. In 2016, the WHO and UNAIDS presented global strategies to eliminate HIV and HCV as a public health threat by 2030. Aligned with these targets, we address a knowledge gap using two national quality registers (InfCare NSP linked to InfCare Hepatitis) and a patient- and peer co-created implementation pilot at the three largest NSP in Sweden (Stockholm, Malmö, Gothenburg). This project will generate actionable evidence through three complementary studies. Specific research questions: How have active HCV infection and HCV treatment uptake and cure changed over time among NSP participants in Sweden, and are trends consistent across regions and calendar periods? (Study I) At which steps (diagnosis → treatment start → cure → follow-up) are PWID most often lost to follow-up, and which individual- and region-level factors predict attrition, cure, and reinfection? (Study I) How have all-cause and cause-specific mortality changed among NSP participants from 2013–2026? (Study II) Is participation in Take-Home Naloxone (THN) programs associated with lower opioid overdose mortality when modelled as a time-varying exposure and accounting for regional trends? (Study II) Which barriers and facilitators do NSP participants and staff identify for reduced bloodborne infections, mortality and optimisation of HCV treatment (initiation, retention, prevention of reinfection), and can a co-created, user-led intervention be implemented with acceptable feasibility and acceptability in routine NSP practice? (Study III) Data and methods Study I and II use data from two national quality registers (InfCare NSP and InfCare Hepatitis). InfCare NSP covers >98% of NSP participants nationwide (with 13,700 individuals enrolled and over 500,000 visits, December 2025), and includes repeated visit data, HIV/HBV/HCV testing history, and participation in interventions such as THN. InfCare Hepatitis adds clinical information on HCV care, enabling national assessment of the hepatitis care cascade among PWID. Analyses will use longitudinal and quasi-experimental approaches to assess time trends and policy-relevant shifts (e.g., changes in HCV treatment guidelines, introduction of THN), and survival/competing-risk methods for mortality outcomes. Sensitivity analyses will assess robustness to NSP expansion by (i) restricting analyses to early-adopting regions with continuous registration since 2013, and (ii) defining fixed-entry cohorts based on enrolment period. Study III is a mixed-methods pilot project at the three largest Swedish NSP (Stockholm, Malmö, Gothenburg), which annually serve 55% (n=2,500) of the country’s NSP patients. Through interviews and co-creation workshops with service users, researchers and staff, micro-interventions will be developed to reduce blood-borne infections and excess mortality, and evaluated for feasibility and acceptability. Societal relevance and utilisation This project is the first national-level analysis of NSP participants, with implications for science, clinical practice, and policymaking. By adding a co-created pilot for structured patient- and user involvement, the project translates national evidence into implementable service improvements. It aligns with Forte’s priorities, addressing drug-related mortality emphasized by UNAIDS, WHO, and the EU. Findings will support policymakers, program managers, and clinicians in strengthening harm reduction, hepatitis care pathways, and overdose prevention. Plan for project realisation The project follows a three-year timeline (2027–2029), and pre-study work-up in 2026 includes ethics amendment and register extraction planning. In 2027, the focus will be on data management and analysis for Study I, followed by manuscript writing. In 2028, Study I dissemination, Study II analysis, and manuscript writing will take place. In 2029, Study III pilot implementation, evaluation, and dissemination will be completed. Results will be disseminated continuously to researchers, policymakers, and healthcare. The experienced interdisciplinary team has unique expertise and access to data, maximizing the project’s scientific and societal impact.

Research problem and specific questions: This project addresses the public health challenge of understanding how migration status, social stratification, and gender influence health outcomes among people who inject drugs (PWID) in Sweden. Despite Sweden’s commitment to harm reduction, disparities persist, particularly among migrants and socioeconomically disadvantaged individuals. Key research questions: 1. How do injection risk behaviors differ by migration status, gender, and social stratification at enrollment and over time? 2. How do migration status, gender, and social stratification influence access to needle and syringe program (NSP) services and coverage across Sweden? Data and method: For quantitative analysis, the project will use data from the Swedish NSP quality register, InfC are NSP, covering 2013-2025. It is used by 20 of 21 Swedish regions, capturing 98% of all PWID in Swedish NSP (N=13,000). Methods such as propensity score matching (PSM), marginal structural models (MSM), and difference-in-differences (DiD) will be used to strengthen findings and inform policy recommendations. Semistructured interviews will be used for qualitative analysis. Societal relevance and utilisation: This research includes groups often treated as low priority, ignored, and carrying multiple stigmas, both as immigrants and injecting drug users. Women in these categories are extremely vulnerable, facing compounded challenges due to hepatitis, HIV, mental illness, and social exclusion. They are difficult to reach with harm reduction interventions. The results are relevant for actors such as the Public Health Agency, decision-makers, healthcare, and service providers, who need to implement evidencebased guidelines to reach this vulnerable and often care-demanding group. By focusing on migration, social stratification, and gender, the project aims to reduce disparities in access to healthcare and promote the inclusion of marginalized groups. Plan for project realisation: The project will be conducted over three years (2026–2028). Data collection, analysis, and manuscript preparation will be carried out according to the work plan. Findings will be disseminated through published manuscripts, scientific conferences, and meetings with stakeholders such as the Public Health Agency and regional NSP coordinators. Principal Investigator with expertise in harm reduction and advanced quantitative methods, will collaborate with different experts to ensure the project’s success.

Estimating the size and coverage of hard-to reach and stigmatized (“hidden”) populations such as people who inject drugs (PWID) remains a major challenge for public health e.g. prevention, policy and programming. Today, the estimated number of PWID in Sweden varies between 8,000-10,000 that was calculated using multiplier methods, which combine data from needle exchange programs, treatment entries, and survey data to estimate the hidden population of PWID. This pilot study aims to integrate brief, standardized questions in routine clinical data collection at needle and syringe program (NSP) sites (harm reduction services) in Sweden to help estimate network size, thereby providing necessary data for more precise service demand and program coverage estimations. The goal of this project is to assess the feasibility and utility of collecting such data for future use in population size estimation and service coverage analysis that could be applied also to other hard-to reach populations. The project will provide proof-of-concept for a scalable, low-burden data collection method that could be expanded nationally. The results will support improved epidemiological surveillance and more targeted harm reduction planning. Specific Aims: 1) To develop and pilot test a short module of network size questions tailored for PWID in needle and syringe exchange harm reduction programs (NSP)

2) To assess the feasibility and acceptability of integrating network questions into NSP service routines. 3) To evaluate the potential of collected network data for estimating PWID population size and NSP coverage (using the network scale-up method or other methods).

During the COVID-19 pandemic, Sweden saw a rise in immune-mediated inflammatory diseases (IMIDs) such as inflammatory bowel disease, rheumatoid arthritis, asthma and psoriasis —a trend that has persisted beyond 2022. While viral infections may trigger IMIDs, the role of SARS-CoV-2 infection remains unclear. Emerging factors like mRNA vaccines, reduced social contact, and health care disruptions require investigation but are difficult to assess through clinical trials. The proposed research project leverages Sweden’s unique population registers and biobank data to explore links between SARS-CoV-2 infection, vaccination, social contact, and new-onset IMIDs. We will analyze data from 53 national registers in the SWECOV database (15.7 million individuals, 1990–2024), linked with repeated autoantibody measurements from the COMMUNITY cohort, which includes 2,267 individuals (2020–2024). Five substudies over 3 years will examine: (1) temporal trends in IMIDs (2) effects of SARS-Cov-2 infection by frequency/severity 3) COVID-19 vaccination effects by vaccine type/dose, (4) social isolation via occupation/household factors, and (5) immune markers (autoantibodies) pre- and post-infection or vaccination. This project will clarify mechanisms behind rising autoimmunity and improve our understanding of immunology and peripandemic disease trends, thereby informing clinical practice and public health policy e.g. the need for tailored follow-up care and surveillance.