Seroprevalence of SARS-CoV-2 and humoral immune responses to COVID-19 mRNA vaccines among people who use drugs - in the light of tailored mitigating strategies.

BACKGROUND: During the initial wave of the COVID-19 pandemic, there was a surprisingly low incidence of SARS-CoV-2 among People Who Use Drugs (PWUD) in Oslo, Norway, despite their heightened vulnerability regarding risk of infection and severe courses of the disease.This study aims to investigate the seroprevalence of SARS-CoV-2 antibodies among PWUD, their antibody responses to relevant virus infections and COVID-19 mRNA vaccines, and their vaccination coverage compared to the general population. METHODS: Conducted as a prospective cohort study, data was collected from residents in six institutions for homeless PWUD and users of a low-threshold clinic for opioid agonist treatment. Ninety-seven participants were recruited for SARS-CoV-2 seroprevalence analysis. Additional two participants with known positive SARS-CoV-2 test results were recruited for further analyses. Twenty-five participants completed follow-up. Data included questionnaires, nasal swabs and blood samples. Data on vaccination coverage was obtained from the National Vaccine Register. Serologic methods included detection of antibodies to relevant virus proteins, neutralizing antibodies to SARS-CoV-2, antibodies to the full-length spike protein, and receptor-binding domain from SARS-CoV-2. RESULTS: Among PWUD, antibodies to SARS-CoV-2 were detected in 2 out of 97 samples before vaccines against SARS-CoV-2 were available, comparable to a 2.8% frequency in population-based screening. Levels of serum antibodies to seasonal coronaviruses and Epstein-Barr-Virus (EBV) in PWUD were similar to population-based levels. After the second vaccine dose, binding and neutralizing antibody levels to SARS-CoV-2 in PWUD were comparable to controls. Eighty-four of PWUD received at least one dose of COVID-19 mRNA vaccine, compared to 89% in the general population. CONCLUSION: Results indicate that PWUD did not exhibit increased SARS-CoV-2 seroprevalence or elevated serum antibodies to seasonal coronaviruses and EBV. Moreover, vaccine responses in PWUD were comparable to controls, suggesting that vaccination is effective in conferring protection against SARS-CoV-2 also in this population.

People who use drugs show no increase in pre-existing T-cell cross-reactivity toward SARS-CoV-2 but develop a normal polyfunctional T-cell response after standard mRNA vaccination.

People who use drugs (PWUD) are at a high risk of contracting and developing severe coronavirus disease 2019 (COVID-19) and other infectious diseases due to their lifestyle, comorbidities, and the detrimental effects of opioids on cellular immunity. However, there is limited research on vaccine responses in PWUD, particularly regarding the role that T cells play in the immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Here, we show that before vaccination, PWUD did not exhibit an increased frequency of preexisting cross-reactive T cells to SARS-CoV-2 and that, despite the inhibitory effects that opioids have on T-cell immunity, standard vaccination can elicit robust polyfunctional CD4+ and CD8+ T-cell responses that were similar to those found in controls. Our findings indicate that vaccination stimulates an effective immune response in PWUD and highlight targeted vaccination as an essential public health instrument for the control of COVID-19 and other infectious diseases in this group of high-risk patients.

The LASSO Program in Oslo: Harm Reduction Using Buprenorphine-Naloxone (Suboxone®) in a Low Threshold Setting.

BACKGROUND: This is a 6-year retrospective quality control study of the LASSO Program (Low Threshold Substitution Treatment in Oslo), using exclusively Suboxone® (buprenorphine-naloxone [BPNX]) in out-patient settings. Adequate abstinence prior to induction is necessary to avoid acute onset opioid withdrawal symptoms; thus, its use in low threshold settings is far less common than methadone. OBJECTIVES: The aim of this study was to determine if BPNX is a safe and feasible medication to use in a low threshold setting. METHODS: The analysis is based on daily supervised BPNX medication. The standardized induction regime started with 4-mg BPNX increasing by 4 mg daily until 16 mg, with individual adjustments based on clinical status. Treatment effect was evaluated by the number of medication induction attempts, treatment length and lag time between initial contact and medication start. Statistical computations were performed with SPSS®. RESULTS: There were 331 out of 394 registered patient inquires that started on BPNX. Two hundred fifty-three patients (76.4%) completed induction on first attempt with 95% Wilson score CIs of (0.716-0.807). The accumulated percentage increased to 85.2% during successive inductions. No significant association was found between lag time and (i) the number of days on medication during the first induction; or (ii) total treatment length. Patients had a median lag time of 5 days, remained in treatment a median of 52.0 days with an average of 3.9 inductions. There were no cases of severe precipitated withdrawal and only 2 cases of adverse reactions among the 1,293 inductions and 25,544 administered dosages. CONCLUSION: This study shows that BPNX is highly effective in treating marginalized heroin addicts in low threshold settings. Even during their first attempt, 76.4% completed induction. There were no cases of severe precipitated withdrawal. Prolonged lag time affected neither the length of first treatment nor the total treatment length. Individualized induction readiness approach and motivation were central to the above results.