Stable measurement of chemistry, immunochemistry, and hematology analytes in a heparin-based anticoagulant with iloprost additive: A promising candidate for the polyvalent blood collection tube.

INTRODUCTION: A polyvalent blood collection tube could potentially reduce the number and volume of blood samples drawn from patients and reduce the risk of tube mix-ups in a point-of-care setting in the emergency department and the intensive care unit. METHODS: Four different concentrations of our experimental heparin anticoagulant with iloprost additive (HEP-ILOP 50 nM, 150 nM, 1000 nM, and 10 µM, respectively) were tested for significant differences and bias performance specifications against EDTA for 29 hematology analytes, and the highest concentration (HEP-ILOP 10 µM) against lithium heparin for 14 chemistry and immunochemistry analytes. Samples were drawn from 79 consenting subjects from the Oncology Department (n = 38) and the Intensive and Intermediary Care Unit (n = 41). RESULTS: For hematology analytes, the HEP-ILOP formulation generally provided stable measurement within optimal requirements within 5 h after sampling (mean 104 ± 56 min), with very little difference between the four HEP-ILOP concentrations. Because of differences in platelet and red blood cell swelling between EDTA and HEP-ILOP, all size-dependent analytes required proportional factorization to produce similar results. Platelet count by impedance similarly required factorization, whereas the fluorescent method provided results identical with EDTA. Chemistry and immunochemistry analytes were within optimal requirements except for potassium, lactate dehydrogenase, and glucose, indicating a cytoprotective effect of iloprost reducing cell metabolism and rupture, thereby producing results closer to in vivo conditions. CONCLUSIONS: Our novel dry-sprayed anticoagulant formulation, HEP-ILOP, is a promising candidate for a polyvalent blood collection tube, enabling the analysis of hematology, chemistry, and immunochemistry analytes in the same tube.

Prevalence and duration of anti-SARS-CoV-2 antibodies in healthcare workers.

INTRODUCTION: Knowledge of the seroprevalence and duration of antibodies against SARS-CoV-2 was needed in the early phases of the COVID-19 pandemic and is still necessary for policy makers and healthcare professionals. This information allows us to better understand the risk of reinfection in previously infected individuals. METHODS: We investigated the prevalence and duration of detectable antibodies against SARS-CoV-2 in sequentially collected samples from 379 healthcare professionals. RESULTS: SARS-CoV-2 seroprevalence at inclusion was 5.3% (95% confidence interval (CI): 3.3-8.0%) and 25% of seropositive participants reverted during follow-up. At the end of follow-up, the calculated probability of having detectable antibodies among former seropositive participants was 72.2% (95% CI: 54.2-96.2%). CONCLUSION: Antibodies against SARS-CoV-2 were detectable in a subset of infected individuals for a minimum of 39 weeks. FUNDING: The assays performed at Rigshospitalet were developed with financial support from the Carlsberg Foundation (CF20-0045) and the Novo Nordisk Foundation (NFF205A0063505 and NNF20SA0064201). TRIAL REGISTRATION: The study was registered with the Danish National Committee on Health Research Ethics (H-20022312).

Effect of Influenza Vaccination on Risk of Coronavirus Disease 2019: A Prospective Cohort Study of 46†000 Healthcare Workers.

BACKGROUND: The purpose of this study was to assess whether influenza vaccination has an impact on the risk of coronavirus disease 2019 (COVID-19). METHODS: A cohort of 46 112 healthcare workers were tested for antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and filled in a survey on COVID-19 symptoms, hospitalization, and influenza vaccination. RESULTS: The risk ratio of hospitalization due to SARS-CoV-2 for influenza vaccinated compared with unvaccinated participants was 1.00 for the seasonal vaccination in 2019/2020 (confidence interval, .56-1.78, P = 1.00). Likewise, no clinical effect of influenza vaccination on development of antibodies against SARS-CoV-2 was found. CONCLUSIONS: The present findings indicate that influenza vaccination does not affect the risk of SARS-CoV-2 infection or COVID-19.

Seroprevalence of SARS-CoV-2 antibodies and reduced risk of reinfection through 6 months: a Danish observational cohort study of 44 000 healthcare workers.

OBJECTIVES: Antibodies to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are a key factor in protecting against coronavirus disease 2019 (COVID-19). We examined longitudinal changes in seroprevalence in healthcare workers (HCWs) in Copenhagen and the protective effect of antibodies against SARS-CoV-2. METHODS: In this prospective study, screening for antibodies against SARS-CoV-2 (ELISA) was offered to HCWs three times over 6 months. HCW characteristics were obtained by questionnaires. The study was registered at ClinicalTrials.gov, NCT04346186. RESULTS: From April to October 2020 we screened 44 698 HCWs, of whom 2811 were seropositive at least once. The seroprevalence increased from 4.0% (1501/37 452) to 7.4% (2022/27 457) during the period (p < 0.001) and was significantly higher than in non-HCWs. Frontline HCWs had a significantly increased risk of seropositivity compared to non-frontline HCWs, with risk ratios (RRs) at the three rounds of 1.49 (95%CI 1.34-1.65, p < 0.001), 1.52 (1.39-1.68, p < 0.001) and 1.50 (1.38-1.64, p < 0.001). The seroprevalence was 1.42- to 2.25-fold higher (p < 0.001) in HCWs from dedicated COVID-19 wards than in other frontline HCWs. Seropositive HCWs had an RR of 0.35 (0.15-0.85, p 0.012) of reinfection during the following 6 months, and 2115 out of 2248 (95%) of those who were seropositive during rounds one or two remained seropositive after 4-6 months. The 133 of 2248 participants (5.0%) who seroreverted were slightly older and reported fewer symptoms than other seropositive participants. CONCLUSIONS: HCWs remained at increased risk of infection with SARS-CoV-2 during the 6-month period. Seropositivity against SARS-CoV-2 persisted for at least 6 months in the vast majority of HCWs and was associated with a significantly lower risk of reinfection.

Risk Factors for Being Seronegative following SARS-CoV-2 Infection in a Large Cohort of Health Care Workers in Denmark.

Most individuals seroconvert after infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but being seronegative is observed in 1 to 9%. We aimed to investigate the risk factors associated with being seronegative following PCR-confirmed SARS-CoV-2 infection. In a prospective cohort study, we screened health care workers (HCW) in the Capital Region of Denmark for SARS-CoV-2 antibodies. We performed three rounds of screening from April to October 2020 using an enzyme-linked immunosorbent assay (ELISA) method targeting SARS-CoV-2 total antibodies. Data on all participants' PCR for SARS-CoV-2 RNA were captured from national registries. The Kaplan-Meier method and Cox proportional hazards models were applied to investigate the probability of being seronegative and the related risk factors, respectively. Of 36,583 HCW, 866 (2.4%) had a positive PCR before or during the study period. The median (interquartile range [IQR]) age of 866 HCW was 42 (31 to 53) years, and 666 (77%) were female. After a median of 132 (range, 35 to 180) days, 21 (2.4%) of 866 were seronegative. In a multivariable model, independent risk factors for being seronegative were self-reported asymptomatic or mild infection hazard ratio (HR) of 6.6 (95% confidence interval [CI], 2.6 to 17; P < 0.001) and body mass index (BMI) of ≥30, HR 3.1 (95% CI, 1.1 to 8.8; P = 0.039). Only a few (2.4%) HCW were not seropositive. Asymptomatic or mild infection as well as a BMI above 30 were associated with being seronegative. Since the presence of antibodies against SARS-CoV-2 reduces the risk of reinfection, efforts to protect HCW with risk factors for being seronegative may be needed in future COVID-19 surges. IMPORTANCE Most individuals seroconvert after infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but negative serology is observed in 1 to 9%. We found that asymptomatic or mild infection as well as a BMI above 30 were associated with being seronegative. Since the presence of antibodies against SARS-CoV-2 reduces the risk of reinfection, efforts to protect HCW with risk factors for being seronegative may be needed in future COVID-19 surges.

Impact of Probiotics on the Salivary Microbiota and Salivary Levels of Inflammation-Related Proteins during Short-Term Sugar Stress: A Randomized Controlled Trial.

BACKGROUND: The purpose of the present investigation was to characterize the effect of probiotics on the composition of the salivary microbiota and salivary levels of inflammation-related proteins during short-term sugar stress. We tested the hypotheses that consumption of probiotics may partly counteract the detrimental influence of sugar stress on oral homeostasis. METHODS: The present study was a five-week, blinded, randomized controlled trial with four study arms-A: sucrose and probiotic (n = 20); B: sucrose and placebo (n = 20); C: xylitol and probiotic (n = 20); D: xylitol and placebo (n = 20). Saliva samples were collected at baseline and after two and five weeks. The salivary microbiota was characterized by means of 16S rDNA sequencing, and sequences were referenced against the Human Oral Microbiome Database (HOMD). Neutrophil gelatinase-associated lipocalin (NGAL) and transferrin levels were quantified using immunoassays. RESULTS: Sugar stress induced a significant increase in the relative abundance of the genus Streptococcus from 29.8% at baseline to 42.9% after two weeks. Changes were transient and were completely reversed three weeks after discontinuation of sugar stress. Xylitol and probiotics alone had no effect on the salivary microbiota, whereas the combination of xylitol and probiotics induced a significant decrease in the relative abundance of Streptococcus species from 37.6% at baseline to 23.0% at week 2. Sugar stress significantly increased salivary transferrin levels, and the effect was partly counteracted by concomitant use of probiotics. CONCLUSIONS: The data clearly demonstrate an impact of combined consumption of xylitol and probiotics on the composition of the salivary microbiota. Future studies are needed to evaluate whether the combined use of xylitol and the probiotic strains tested could have clinically protective effects during periods of sugar stress.

Risk of COVID-19 in health-care workers in Denmark: an observational cohort study.

BACKGROUND: Health-care workers are thought to be highly exposed to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We aimed to investigate the prevalence of antibodies against SARS-CoV-2 in health-care workers and the proportion of seroconverted health-care workers with previous symptoms of COVID-19. METHODS: In this observational cohort study, screening was offered to health-care workers in the Capital Region of Denmark, including medical, nursing, and other students who were associated with hospitals in the region. Screening included point-of-care tests for IgM and IgG antibodies against SARS-CoV-2. Test results and participant characteristics were recorded. Results were compared with findings in blood donors in the Capital Region in the study period. FINDINGS: Between April 15 and April 23, 2020, we screened 29 295 health-care workers, of whom 28 792 (98·28%) provided their test results. We identified 1163 (4·04% [95% CI 3·82-4·27]) seropositive health-care workers. Seroprevalence was higher in health-care workers than in blood donors (142 [3·04%] of 4672; risk ratio [RR] 1·33 [95% CI 1·12-1·58]; p<0·001). Seroprevalence was higher in male health-care workers (331 [5·45%] of 6077) than in female health-care workers (832 [3·66%] of 22 715; RR 1·49 [1·31-1·68]; p<0·001). Frontline health-care workers working in hospitals had a significantly higher seroprevalence (779 [4·55%] of 16 356) than health-care workers in other settings (384 [3·29%] of 11 657; RR 1·38 [1·22-1·56]; p<0·001). Health-care workers working on dedicated COVID-19 wards (95 [7·19%] of 1321) had a significantly higher seroprevalence than other frontline health-care workers working in hospitals (696 [4·35%] of 15 983; RR 1·65 [1·34-2·03]; p<0·001). 622 [53·5%] of 1163 seropositive participants reported symptoms attributable to SARS-CoV-2. Loss of taste or smell was the symptom that was most strongly associated with seropositivity (377 [32·39%] of 1164 participants with this symptom were seropositive vs 786 [2·84%] of 27 628 without this symptom; RR 11·38 [10·22-12·68]). The study is registered at ClinicalTrials.gov, NCT04346186. INTERPRETATION: The prevalence of health-care workers with antibodies against SARS-CoV-2 was low but higher than in blood donors. The risk of SARS-CoV-2 infection in health-care workers was related to exposure to infected patients. More than half of seropositive health-care workers reported symptoms attributable to COVID-19. FUNDING: Lundbeck Foundation.

Neutrophil gelatinase associated lipocalin a biomarker for bacterial-induced pharyngeal infection-A pilot study.

OBJECTIVES: Neutrophil gelatinase associated lipocalin (NGAL) is secreted from activated neutrophil granulocytes and is considered an acute phase protein. The aim of this pilot study was to determine whether the NGAL concentration in saliva increases in response to a bacterial throat infection and identify pitfalls, which shall be taken into account in a protocol in a larger hypothesis testing study. METHODS: Saliva samples for measurement of NGAL concentration where obtained from cases with an acute throat infection (n = 21) and controls (n = 24). Among cases, plasma NGAL, plasma CRP, and whole blood leukocytes, were measured as well. RESULTS: There was no significant difference in NGAL saliva concentration between cases and controls overall (p = .31). For both cases and controls, the saliva NGAL concentration decreased significantly after cleansing the mouth with tap water (cases p = .01; controls p = .01). Among cases, a significant positive correlation between saliva NGAL concentrations before mouth cleansing and plasma CRP concentrations (p = .001) was observed. Blood neutrophil granulocyte count presented a nonsignificant positive correlation to saliva NGAL (p = .07). CONCLUSION: We could not demonstrate a simple association between the salivary NGAL concentration and pharyngeal bacterial infection. Furthermore, the salivary NGAL concentrations were higher among some controls than cases, suggesting that cofounders for example, periodontitis, uneven salivary dilution level, or other exogenous factors affect salivary NGAL content.

Salivary microbiota and inflammation-related proteins in patients with psoriasis.

OBJECTIVE: The purpose of the present study was to characterize the composition of the salivary microbiota and quantify salivary levels of inflammation-related proteins (neutrophil gelatinase-associated lipocalin [NGAL] and transferrin) in patients with psoriasis and compare data to those obtained in patients with periodontitis and orally healthy controls, respectively. MATERIALS AND METHODS: Stimulated saliva samples from patients with psoriasis (n = 27), patients with periodontitis (n = 58), and orally healthy controls (n = 52) were characterized by means of next-generation sequencing of the 16S rRNA gene. Salivary levels of NGAL and transferrin were quantified using immunoassays. RESULTS: Linear discriminant effect size analysis showed that 52 (22 psoriasis-associated and 30 periodontitis-associated) and 21 (8 psoriasis-associated and 13 orally healthy control-associated) bacterial taxa differentiated the salivary microbiota in patients with psoriasis from that of patients with periodontitis and orally healthy controls, respectively. Significantly lower mean salivary levels of NGAL (psoriasis: 996 [std. error 320], periodontitis: 2,072 [295], orally healthy controls: 2,551 [345] ng/ml, p < .0001) and transferrin (psoriasis: 4.37 [0.92], periodontitis: 7.25 [0.88], orally healthy controls: 10.02 [0.94] ng/ml, p < .0001) were identified in patients with psoriasis. CONCLUSIONS: Psoriasis associates with characteristics of the salivary microbiota and salivary levels of inflammation-related proteins, which are different from characteristics in patients with periodontitis and orally healthy controls, respectively.