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Background: Fraction of exhaled nitric oxide with an expiratory flow of 50 mL/s (FENO50) is a biomarker of eosinophilic airway inflammation. Liver transplant recipients have an increased risk of pulmonary infections, but little is known about the burden of chronic pulmonary diseases in this group. We aimed to assess the prevalence of elevated FENO50 in liver transplant recipients and compare it to controls from the general population. Methods: FENO50 was measured in 271 liver transplant recipients from The Danish Comorbidity in Liver Transplant Recipients (DACOLT) study and 1,018 age- and sex-matched controls from The Copenhagen General Population Study (CGPS). Elevated FENO50 was defined as ≥25 or ≥50 parts per billion (ppb). The analyses were adjusted for known and suspected confounders. Results: The median age of the liver transplant recipients was 55 years (interquartile range (IQR) 46–64), and 58% were men. The liver transplant recipients had a higher median FENO50 than the controls [16 ppb (IQR 10–26) vs. 13 ppb (IQR 8–18.), p < 0.001]. Furthermore, the liver transplant recipients had a higher prevalence of elevated FENO50 (for FENO50 ≥25 ppb 27% vs. 11%, p < 0.001 and ≥50 ppb 4% vs. 2%, p = 0.02). The results were similar after adjusting for age, sex, smoking status, use of airway medication, and blood eosinophil counts [the adjusted odds ratio (OR) for FENO50 ≥25 ppb was 3.58 (95% CI: 2.50–5.15, p < 0.0001) and the adjusted OR for FENO50 ≥50 ppb was 3.14 (95% CI: 1.37–7.20, p = 0.007)]. Conclusion: The liver transplant recipients had elevated FENO50, implying increased eosinophilic airway inflammation. The clinical impact of this finding needs further investigation., Background: Fraction of exhaled nitric oxide with an expiratory flow of 50 mL/s (FENO50) is a biomarker of eosinophilic airway inflammation. Liver transplant recipients have an increased risk of pulmonary infections, but little is known about the burden of chronic pulmonary diseases in this group. We aimed to assess the prevalence of elevated FENO50 in liver transplant recipients and compare it to controls from the general population. Methods: FENO50 was measured in 271 liver transplant recipients from The Danish Comorbidity in Liver Transplant Recipients (DACOLT) study and 1,018 age- and sex-matched controls from The Copenhagen General Population Study (CGPS). Elevated FENO50 was defined as ≥25 or ≥50 parts per billion (ppb). The analyses were adjusted for known and suspected confounders. Results: The median age of the liver transplant recipients was 55 years (interquartile range (IQR) 46–64), and 58% were men. The liver transplant recipients had a higher median FENO50 than the controls [16 ppb (IQR 10–26) vs. 13 ppb (IQR 8–18.), p < 0.001]. Furthermore, the liver transplant recipients had a higher prevalence of elevated FENO50 (for FENO50 ≥25 ppb 27% vs. 11%, p < 0.001 and ≥50 ppb 4% vs. 2%, p = 0.02). The results were similar after adjusting for age, sex, smoking status, use of airway medication, and blood eosinophil counts [the adjusted odds ratio (OR) for FENO50 ≥25 ppb was 3.58 (95% CI: 2.50–5.15, p < 0.0001) and the adjusted OR for FENO50 ≥50 ppb was 3.14 (95% CI: 1.37–7.20, p = 0.007)]. Conclusion: The liver transplant recipients had elevated FENO50, implying increased eosinophilic airway inflammation. The clinical impact of this finding needs further investigation.

Infection with BK polyomavirus (BKPyV) is a common opportunistic infection after kidney transplantation (KT) and may affect graft function. We aimed to determine the incidence, risk factors, and clinical outcomes of BKPyV DNAemia in a prospective cohort of 601 KT recipients transplanted from 2012 to 2020. BKPyV PCR on plasma was performed at days 60, 90, 180, 270, and 360 post-KT. Any BKPyV DNAemia was defined as a single BKPyV DNA of ≥1000 copies/mL. Severe BKPyV DNAemia was defined as two consecutive BKPyV DNA of ≥10,000 copies/mL. Cumulative incidences were investigated using the Aalen–Johansen estimator, and the risk factors were investigated in Cox proportional hazard models. The incidence of any BKPyV DNAemia and severe BKPyV DNAemia was 21% (18–25) and 13% (10–16) at one year post-KT, respectively. Recipient age > 50 years (aHR, 1.72; 95% CI 1.00–2.94; p = 0.049), male sex (aHR, 1.96; 95% CI 1.17–3.29; p = 0.011), living donors (aHR, 1.65; 95% CI 1.03–2.74; p = 0.045), and >3 HLA-ABDR mismatches (aHR, 1.72; 95% CI 1.01–2.94; p = 0.046) increased the risk of severe BKPyV DNAemia. Any BKPyV DNAemia was associated with an increased risk of graft function decline (aHR, 2.26; 95% CI 1.00–5.12; p = 0.049), and severe BKPyV DNAemia was associated with an increased risk of graft loss (aHR, 3.18; 95% CI 1.06–9.58; p = 0.039). These findings highlight the importance of BKPyV monitoring post-KT.

Objectives We aimed to determine the incidence rate, pathogen composition, and risk factors, particularly airflow limitation, associated with bacterial respiratory infection and pneumonia in a prospective cohort of well-treated people with HIV (PWH) between 2015-2021. Methods We included 1007 PWH from the Copenhagen Comorbidity in HIV infection (COCOMO) study. Spirometry was performed at inclusion. Microbiology samples were collected prospectively. Cumulative incidence was determined by the Aalen-Johansen estimator. Cox proportional hazard models were used to calculate risk factors, adjusted for traditional and HIV-specific variables. Results The incidence rates of first bacterial respiratory infection and pneumonia were 12.4 (95% CI 9.7-15.5) and 5.5 (95% CI: 3.8-7.7) per 1000 person-years, respectively. The cumulative incidence of pneumonia was four times higher in PWH with airflow limitation (11.8% vs 3.2%, P <0.001). Risk factors for bacterial respiratory infection were airflow limitation (hazard ratio [HR] 2.9, [95% CI: 1.7-5.1], P <0.001), smoking (HR 2.3, [95% CI: 1.4-3.8], P <0.001), and previous AIDS-defining event (HR 2.0, [95% CI: 1.2-3.3], P = 0.009). For pneumonia, airflow limitation (HR 2.7, [95% CI: 1.2-6.3], P = 0.016), smoking (HR 2.5, [95% CI: 1.2-5.4], P = 0.016), and older age (HR 1.5, [95% CI: 1.1-2.1], P = 0.015) were identified as risk factors. Conclusions Increased emphasis on airflow limitation prevention, including smoking cessation, may reduce the burden of bacterial respiratory infection and pneumonia in PWH., Objectives: We aimed to determine the incidence rate, pathogen composition, and risk factors, particularly airflow limitation, associated with bacterial respiratory infection and pneumonia in a prospective cohort of well-treated people with HIV (PWH) between 2015-2021. Methods: We included 1007 PWH from the Copenhagen Comorbidity in HIV infection (COCOMO) study. Spirometry was performed at inclusion. Microbiology samples were collected prospectively. Cumulative incidence was determined by the Aalen-Johansen estimator. Cox proportional hazard models were used to calculate risk factors, adjusted for traditional and HIV-specific variables. Results: The incidence rates of first bacterial respiratory infection and pneumonia were 12.4 (95% CI 9.7-15.5) and 5.5 (95% CI: 3.8-7.7) per 1000 person-years, respectively. The cumulative incidence of pneumonia was four times higher in PWH with airflow limitation (11.8% vs 3.2%, P <0.001). Risk factors for bacterial respiratory infection were airflow limitation (hazard ratio [HR] 2.9, [95% CI: 1.7-5.1], P <0.001), smoking (HR 2.3, [95% CI: 1.4-3.8], P <0.001), and previous AIDS-defining event (HR 2.0, [95% CI: 1.2-3.3], P = 0.009). For pneumonia, airflow limitation (HR 2.7, [95% CI: 1.2-6.3], P = 0.016), smoking (HR 2.5, [95% CI: 1.2-5.4], P = 0.016), and older age (HR 1.5, [95% CI: 1.1-2.1], P = 0.015) were identified as risk factors. Conclusions: Increased emphasis on airflow limitation prevention, including smoking cessation, may reduce the burden of bacterial respiratory infection and pneumonia in PWH.

The aim of this study was to provide information about immunity against COVID-19 along with risk factors and behavior among employees in day care facilities and preschools (DCS) in Denmark. In collaboration with the Danish Union of Pedagogues, during February and March 2021, 47,810 members were offered a point-of-care rapid SARS-CoV-2 antibody test (POCT) at work and were invited to fill in an electronic questionnaire covering COVID-19 exposure. Seroprevalence data from Danish blood donors (total Ig enzyme-linked immunosorbent assay [ELISA]) were used as a proxy for the Danish population. A total of 21,018 (45%) DCS employees completed the questionnaire and reported their POCT result {median age, 44.3 years (interquartile range [IQR], [32.7 to 53.6]); females, 84.1%}, of which 20,267 (96.4%) were unvaccinated and included in analysis. A total of 1,857 (9.2%) participants tested seropositive, significantly higher than a seroprevalence at 7.6% (risk ratio [RR], 1.2; 95% confidence interval [CI], 1.14 to 1.27) among 40,541 healthy blood donors (median age, 42 years [IQR, 28 to 53]; males, 51.3%). Exposure at work (RR, 2.9; 95% CI, 2.3 to 3.6) was less of a risk factor than exposure within the household (RR, 12.7; 95% CI, 10.2 to 15.8). Less than 25% of participants reported wearing face protection at work. Most of the participants expressed some degree of fear of contracting COVID-19 both at work and outside work. SARS-CoV-2 seroprevalence was slightly higher in DCS staff than in blood donors, but possible exposure at home was associated with a higher risk than at work. DCS staff expressed fear of contracting COVID-19, though there was limited use of face protection at work. IMPORTANCE Identifying at-risk groups and evaluating preventive interventions in at-risk groups is imperative for the ongoing pandemic as well as for the control of future epidemics. Although DCS staff have a much higher risk of being infected within their own household than at their workplace

Multiomics technologies improve the biological understanding of health status in people living with HIV on antiretroviral therapy (PWH). Still, a systematic and in-depth characterization of metabolic risk profile during successful long-term treatment is lacking. Here, we used multi-omics (plasma lipidomic, metabolomic, and fecal 16 S microbiome) data-driven stratification and characterization to identify the metabolic at-risk profile within PWH. Through network analysis and similarity network fusion (SNF), we identified three groups of PWH (SNF-1-3): healthy (HC)-like (SNF-1), mild at-risk (SNF-3), and severe at-risk (SNF-2). The PWH in the SNF-2 (45%) had a severe at-risk metabolic profile with increased visceral adipose tissue, BMI, higher incidence of metabolic syndrome (MetS), and increased di- and triglycerides despite having higher CD4(+) T-cell counts than the other two clusters. However, the HC-like and the severe at-risk group had a similar metabolic profile differing from HIV-negative controls (HNC), with dysregulation of amino acid metabolism. At the microbiome profile, the HC-like group had a lower alpha-diversity, a lower proportion of men having sex with men (MSM) and was enriched in Bacteroides. In contrast, in at-risk groups, there was an increase in Prevotella, with a high proportion of MSM, which could potentially lead to higher systemic inflammation and increased cardiometabolic risk profile. The multi-omics integrative analysis also revealed a complex microbial interplay of the microbiome-associated metabolites in PWH. Those severely at-risk clusters may benefit from personalized medicine and lifestyle intervention to improve their dysregulated metabolic traits, aiming to achieve healthier aging., QC 20230414

Immune dysfunction resulting from allogeneic haematopoietic stem cell transplantation (aHSCT) predisposes one to an elevated risk of cytomegalovirus (CMV) infection. Changes in metabolism have been associated with adverse outcomes, and in this study, we explored the associations between metabolic profiles and post-transplantation CMV infection using plasma samples collected 7-33 days after aHSCT. We included 68 aHSCT recipients from Rigshospitalet, Denmark, 50% of whom experienced CMV infection between days 34-100 post-transplantation. First, we investigated whether 12 metabolites selected based on the literature were associated with an increased risk of post-transplantation CMV infection. Second, we conducted an exploratory network-based analysis of the complete metabolic and lipidomic profiles in relation to clinical phenotypes and biological pathways. Lower levels of trimethylamine N-oxide were associated with subsequent CMV infection (multivariable logistic regression: OR = 0.63; 95% CI = [0.41; 0.87]; p = 0.01). Explorative analysis revealed 12 clusters of metabolites or lipids, among which one was predictive of CMV infection, and the others were associated with conditioning regimens, age upon aHSCT, CMV serostatus, and/or sex. Our results provide evidence for an association between the metabolome and CMV infection post-aHSCT that is independent of known risk factors.

In the present study, we aimed to investigate the association between soluble CD40 ligand (sCD40L, a marker of platelet activation), soluble thrombomodulin, and syndecan-1 (both well-described markers of endothelial dysfunction) and metabolic syndrome in a large cohort of well-treated people with HIV (PWH) and to elucidate their association with HIV-specific variables. We included 862 PWH with undetectable viral replication. Our hypotheses were tested using uni- and multivariable logistic regression models a priori adjusted for well-known confounders. While no association of soluble thrombomodulin and syndecan-1 with MetS was found, high levels of sCD40L (aOR 1.54 [1.07–2.22]) were associated with excess risk of MetS. Given the previously described association between sCD40L, vascular inflammation and endothelial damage, the results presented in our study may suggest a potential role for sCD40L in the well-known association between cardiometabolic comorbidity and HIV infection., In the present study, we aimed to investigate the association between soluble CD40 ligand (sCD40L, a marker of platelet activation), soluble thrombomodulin, and syndecan-1 (both well-described markers of endothelial dysfunction) and metabolic syndrome in a large cohort of well-treated people with HIV (PWH) and to elucidate their association with HIV-specific variables. We included 862 PWH with undetectable viral replication. Our hypotheses were tested using uni- and multivariable logistic regression models a priori adjusted for well-known confounders. While no association of soluble thrombomodulin and syndecan-1 with MetS was found, high levels of sCD40L (aOR 1.54 [1.07–2.22]) were associated with excess risk of MetS. Given the previously described association between sCD40L, vascular inflammation and endothelial damage, the results presented in our study may suggest a potential role for sCD40L in the well-known association between cardiometabolic comorbidity and HIV infection.

Background: Knowledge of COVID-19 and the pandemic's effects on Danish children's body weight is limited. Objective: Objectives were to investigate (I) risk of weight changes among Danish children with and without SARS-CoV-2, (II) associations between weight changes, psychological symptoms, and long COVID symptoms, and (III) weight distribution pre- and post-pandemic. Methods: A national survey was administered to all Danish children aged 0–18 years, with prior COVID-19 (cases) and matched references including questions on weight, weight changes during the pandemic and long COVID-related symptoms. Descriptive statistics and logistic regression were used. Weight distribution was compared with a pre-pandemic database. Results: In all, 17 627 cases and 54 656 references were included. The 4–18-year-old cases had lower odds of unintended weight gain. The 2–3-year-old cases had higher odds and the 15–18-year-old cases lower odds of weight loss compared to references. Regardless of COVID-19 status, any reported long COVID-related symptom was associated with a change in body weight. No sign of increasing obesity rates was found among Danish children post-pandemic. Conclusion: COVID-19 was associated with higher odds of weight loss in 2–3-year-olds and lower odds of unintended weight gain in 4–18-year-olds. Any long COVID-related symptom was associated with higher odds of weight changes regardless of COVID-19 status.

Background Current evidence on the risk of admission- or medication-requiring psychiatric sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is limited to selected populations, short durations, and loss to follow-up. This study examined if SARS-CoV-2 infection was associated with increased long-term risk of psychiatric admissions and de novo prescription of psychoactive medication in the general population of Denmark. Methods Adults (≥18 years) were assigned to either the control or SARS-CoV-2 group based on polymerase chain reaction (PCR) tests between 1 January 2020 and 27 November 2021. Infected subjects were matched 1:5 to control subjects by propensity score. Incidence rate ratios (IRRs) were calculated. Adjusted Cox regression was applied to the unmatched population with SARS-CoV-2 infection as a time-dependent covariate. Follow-up time was 12 months or until the end of the study. Results A total of 4,585,083 adults were included in the study. Approximately 342,084 had a PCR-confirmed SARS-CoV-2 infection and were matched 1:5 with 1,697,680 controls. The IRR for psychiatric admission was 0.79 in the matched population (95% confidence interval [CI]: 0.73–0.85, p < 0.001). In the unmatched population, the adjusted hazard ratios (aHR) for psychiatric admission were either below 1.00 or with a 95% CI lower limit of 1.01. SARS-CoV-2 infection was associated with an increased risk of de novo prescription of psychoactive medication in both the matched (IRR 1.06, 95% CI: 1.02–1.11, p < 0.01) and unmatched population (HR 1.31, 95% CI: 1.28–1.34, p < 0.001). Conclusions We found a signal of increased use of psychoactive medication, specifically benzodiazepines, among SARS-CoV-2-positive persons, but the risk of psychiatric admissions did not increase., Background Current evidence on the risk of admission- or medication-requiring psychiatric sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is limited to selected populations, short durations, and loss to follow-up. This study examined if SARS-CoV-2 infection was associated with increased long-term risk of psychiatric admissions and de novo prescription of psychoactive medication in the general population of Denmark. Methods Adults (≥18 years) were assigned to either the control or SARS-CoV-2 group based on polymerase chain reaction (PCR) tests between 1 January 2020 and 27 November 2021. Infected subjects were matched 1:5 to control subjects by propensity score. Incidence rate ratios (IRRs) were calculated. Adjusted Cox regression was applied to the unmatched population with SARS-CoV-2 infection as a time-dependent covariate. Follow-up time was 12 months or until the end of the study. Results A total of 4,585,083 adults were included in the study. Approximately 342,084 had a PCR-confirmed SARS-CoV-2 infection and were matched 1:5 with 1,697,680 controls. The IRR for psychiatric admission was 0.79 in the matched population (95% confidence interval [CI]: 0.73-0.85, p < 0.001). In the unmatched population, the adjusted hazard ratios (aHR) for psychiatric admission were either below 1.00 or with a 95% CI lower limit of 1.01. SARS-CoV-2 infection was associated with an increased risk of de novo prescription of psychoactive medication in both the matched (IRR 1.06, 95% CI: 1.02-1.11, p < 0.01) and unmatched population (HR 1.31, 95% CI: 1.28-1.34, p < 0.001). Conclusions We found a signal of increased use of psychoactive medication, specifically benzodiazepines, among SARS-CoV-2-positive persons, but the risk of psychiatric admissions did not increase.

Background The prevalence of chronic non-cancer pain (CNCP) has increased dramatically the past decades, which combined with indiscriminate use of prescribed opioids has become a public health problem. Endocrine dysfunction may be a complication of long-term opioid treatment (L-TOT), but the evidence is limited. This study aimed at investigating the associations between L-TOT and endocrine measures in CNCP patients. Methods Cortisol (spot and after stimulation), thyrotropin (TSH), thyroxin (T4), insulin-like growth factor 1 (IGF-1), prolactin (PRL), 17-hydroxyprogesterone, androstenedione, dehydroepiandrosterone (DHEAS), sex hormone-binding globulin (SHBG), total testosterone (TT) and free testosterone (fT) were measured. Group comparisons were done between CNCP patients in L-TOT and controls as well as between patients on high- or low-dose morphine equivalents. Results Eighty-two CNCP patients (38 in L-TOT and 44 controls not receiving opioids) were included. Low TT (p = 0.004) and fT concentrations (p < 0.001), high SHBG (p = 0.042), low DEAS (p = 0.017) and low IGF-1 (p = 0.003) in men were found when comparing those in L-TOT to controls and high PRL (p = 0.018), low IGF-1 standard deviation score (SDS) (p = 0.006) along with a lesser, but normal cortisol response to stimulation (p = 0.016; p = 0.012) were found when comparing L-TOT to controls. Finally, a correlation between low IGF-1 levels and high opioid dose was observed (p < 0.001). Conclusions Our study not only supports previous findings but even more interestingly disclosed new associations. We recommend future studies to investigate endocrine effects of opioids in larger, longitudinal studies. In the meanwhile, we recommend monitoring endocrine function in CNCP patients when prescribing L-TOT. Significance This clinical study found associations between L-TOT, androgens, growth hormone and prolactin in patients with CNCP compared to controls., Background: The prevalence of chronic non-cancer pain (CNCP) has increased dramatically the past decades, which combined with indiscriminate use of prescribed opioids has become a public health problem. Endocrine dysfunction may be a complication of long-term opioid treatment (L-TOT), but the evidence is limited. This study aimed at investigating the associations between L-TOT and endocrine measures in CNCP patients. Methods: Cortisol (spot and after stimulation), thyrotropin (TSH), thyroxin (T4), insulin-like growth factor 1 (IGF-1), prolactin (PRL), 17-hydroxyprogesterone, androstenedione, dehydroepiandrosterone (DHEAS), sex hormone-binding globulin (SHBG), total testosterone (TT) and free testosterone (fT) were measured. Group comparisons were done between CNCP patients in L-TOT and controls as well as between patients on high- or low-dose morphine equivalents. Results: Eighty-two CNCP patients (38 in L-TOT and 44 controls not receiving opioids) were included. Low TT (p = 0.004) and fT concentrations (p < 0.001), high SHBG (p = 0.042), low DEAS (p = 0.017) and low IGF-1 (p = 0.003) in men were found when comparing those in L-TOT to controls and high PRL (p = 0.018), low IGF-1 standard deviation score (SDS) (p = 0.006) along with a lesser, but normal cortisol response to stimulation (p = 0.016; p = 0.012) were found when comparing L-TOT to controls. Finally, a correlation between low IGF-1 levels and high opioid dose was observed (p < 0.001). Conclusions: Our study not only supports previous findings but even more interestingly disclosed new associations. We recommend future studies to investigate endocrine effects of opioids in larger, longitudinal studies. In the meanwhile, we recommend monitoring endocrine function in CNCP patients when prescribing L-TOT. Significance: This clinical study found associations between L-TOT, androgens, growth hormone and prolactin in patients with CNCP compared to controls. The results support previous studies as well as

Background:People with HIV (PWH) have an increased risk of peripheral artery disease (PAD), but the pathogenesis is unknown. We aimed to determine the associations between markers of endothelial dysfunction and platelet activation and both PAD at baseline and de novo PAD in PWH.Methods:In total, 1012 PWH from the longitudinal Copenhagen Comorbidity in HIV-infection (COCOMO) study and 57 age-matched and sex-matched population controls were included. Plasma samples were collected at baseline and analyzed for soluble thrombomodulin, syndecan-1, and CD40 ligand (sCD40L). The ankle-brachial index was measured at baseline and two-year follow-up in PWH. Logistic and Poisson regression models were used to test associations.Results:PWH had higher concentrations of soluble thrombomodulin (P = 0.03) and syndecan-1 (P < 0.001) and lower concentration of sCD40L (P < 0.001) compared with controls. High concentration of soluble thrombomodulin, but not syndecan-1 or sCD40L, was associated with lower odds of PAD in PWH at baseline after adjustments (adjusted odds ratio: 0.50 [0.28, 0.90], P = 0.02). None of the markers were associated with de novo PAD.Conclusions:PWH had higher concentrations of soluble thrombomodulin and syndecan-1 and lower concentration of sCD40L compared with controls. Soluble thrombomodulin was associated with lower odds of PAD at baseline. Further studies are needed to elucidate the pathogenesis of PAD in people with HIV.

Despite the success of mRNA-based vaccines against infectious diseases (including COVID-19), safety concerns have been raised relating to the lipid nanoparticles (LNPs) used to deliver the mRNA cargo. Antibodies against the polyethylene glycol (PEG) coating on these non-viral vectors are present in the general population and can in some instances induce allergic reactions. Furthermore, treatment with PEGylated therapeutics may increase the plasma concentration of such anti-PEG antibodies. The widespread use of PEGylated nanoparticles for mRNA vaccines concerns researchers and clinicians about a potential rise in future cases of allergic reactions against mRNA vaccines and cross-reactions with other PEGylated therapeutics. To determine if vaccination with Comirnaty increased the plasma concentration of antibodies against LNPs, we investigated the blood plasma concentration of anti-LNP antibodies in healthy individuals before and after vaccination with the mRNA-based COVID-19 vaccine Comirnaty (BNT162b2). Blood samples were acquired from 21 healthy adults before vaccination, 3-4 weeks after the first vaccination dose but before the second dose, and 2-6 months after the second (booster) dose. The blood plasma concentration of antibodies recognizing the LNPs was analyzed using a microscopy-based assay capable of measuring antibody-binding to individual authentic LNPs. No significant increase in anti-LNP antibodies was observed after two doses of Comirnaty. The LNPs used for intramuscular delivery of mRNA in the vaccine against COVID-19, Comirnaty, do, therefore, not seem to induce the generation of anti-vector antibodies.