Association Between Autoimmune Diseases and Monoclonal Gammopathy of Undetermined Significance : An Analysis From a Population-Based Screening Study.

BACKGROUND: Monoclonal gammopathy of undetermined significance (MGUS) is a precursor of multiple myeloma (MM) and related conditions. In previous registry-based, retrospective studies, autoimmune diseases have been associated with MGUS. However, these studies were not based on a screened population and are therefore prone to ascertainment bias. OBJECTIVE: To examine whether MGUS is associated with autoimmune diseases. DESIGN: A cross-sectional study within iStopMM (Iceland Screens, Treats, or Prevents MM), a prospective, population-based screening study of MGUS. SETTING: Icelandic population of adults aged 40 years or older. PATIENTS: 75 422 persons screened for MGUS. MEASUREMENTS: Poisson regression for prevalence ratios (PRs) of MGUS among persons with or without an autoimmune disease, adjusted for age and sex. RESULTS: A total of 10 818 participants had an autoimmune disorder, of whom 599 had MGUS (61 with a prior clinical diagnosis and 538 diagnosed at study screening or evaluation). A diagnosis of an autoimmune disease was not associated with MGUS (PR, 1.05 [95% CI, 0.97 to 1.15]). However, autoimmune disease diagnoses were associated with a prior clinical diagnosis of MGUS (PR, 2.11 [CI, 1.64 to 2.70]). LIMITATION: Registry data were used to gather information on autoimmune diseases, and the homogeneity of the Icelandic population may limit the generalizability of these results. CONCLUSION: The study did not find an association between autoimmune disease and MGUS in a systematically screened population. Previous studies not done in systematically screened populations have likely been subject to ascertainment bias. The findings indicate that recommendations to routinely screen patients with autoimmune disease for MGUS may not be warranted. PRIMARY FUNDING SOURCE: The International Myeloma Foundation and the European Research Council.

Development of a Multivariable Model to Predict the Need for Bone Marrow Sampling in Persons With Monoclonal Gammopathy of Undetermined Significance : A Cohort Study Nested in a Clinical Trial.

BACKGROUND: Monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM) are asymptomatic precursor conditions to multiple myeloma and related disorders. Smoldering multiple myeloma is distinguished from MGUS by 10% or greater bone marrow plasma cells (BMPC) on sampling, has a higher risk for progression, and requires specialist management. OBJECTIVE: To develop a multivariable prediction model that predicts the probability that a person with presumed MGUS has 10% or greater BMPC (SMM or worse by bone marrow criteria) to inform the decision to obtain a bone marrow sample and compare its performance to the Mayo Clinic risk stratification model. DESIGN: iStopMM (Iceland Screens, Treats or Prevents Multiple Myeloma), a prospective population-based screening study of MGUS. (ClinicalTrials.gov: NCT03327597). SETTING: Icelandic population of adults aged 40 years or older. PATIENTS: 1043 persons with IgG, IgA, light-chain, and biclonal MGUS detected by screening and an interpretable bone marrow sample. MEASUREMENTS: Monoclonal gammopathy of undetermined significance isotype; monoclonal protein concentration; free light-chain ratio; and total IgG, IgM, and IgA concentrations were used as predictors. Bone marrow plasma cells were categorized as 0% to 4%, 5% to 9%, 10% to 14%, or 15% or greater. RESULTS: The c-statistic for SMM or worse was 0.85 (95% CI, 0.82 to 0.88), and calibration was excellent (intercept, -0.07; slope, 0.95). At a threshold of 10% predicted risk for SMM or worse, sensitivity was 86%, specificity was 67%, positive predictive value was 32%, and negative predictive value was 96%. Compared with the Mayo Clinic model, the net benefit for the decision to refer for sampling was between 0.13 and 0.30 higher over a range of plausible low-risk thresholds. LIMITATION: The prediction model will require external validation. CONCLUSION: This accurate prediction model for SMM or worse was developed in a population-based cohort of persons with presumed MGUS and may be used to defer bone marrow sampling and referral to hematology. PRIMARY FUNDING SOURCE: International Myeloma Foundation and the European Research Council.

Prior cancer and risk of monoclonal gammopathy of undetermined significance: a population-based study in Iceland and Sweden.

There is some evidence that a prior cancer is a risk factor for the development of multiple myeloma (MM). If this is true, prior cancer should be associated with higher prevalence or increased progression rate of monoclonal gammopathy of undetermined significance (MGUS), the precursor of MM and related disorders. Those with a history of cancer might therefore present a target population for MGUS screening. This two-part study is the first study to evaluate the relationship of MGUS and prior cancers. First, we evaluated whether prior cancers were associated with having MGUS at the time of screening in the Iceland Screens Treats or Prevents Multiple Myeloma (iStopMM) study that includes 75,422 individuals screened for MGUS. Next, we evaluated the association of prior cancer and the progression of MGUS to MM and related disorders in a population-based cohort of 13,790 Swedish individuals with MGUS. A history of prior cancer was associated with a modest increase in the risk of MGUS (odds ratio (OR)= 1.10; 95% confidence interval (CI): 1.00-1.20). This excess risk was limited to prior cancers in the year preceding MGUS screening. A history of prior cancer associated with the progression of MGUS, except for myeloid malignancies which were associated with lower risk of progression (hazard ratio (HR)=0.37; 95%CI: 0.16-0.89; p=0.028). Our findings indicate that a prior cancer are not a significant aetiological factor in plasma cell disorders. The findings do not warrant MGUS screening or different management of MGUS in those with a prior cancer.

Determining hemodilution in diagnostic bone marrow aspirated samples in plasma cell disorders by next-generation flow cytometry: Proposal for a bone marrow quality index.

Hemodilution of bone marrow (BM) aspirates is a limitation of multiparameter flow cytometry (MFC) in plasma cell disorders. There is a need for a validated approach for assessing sample quality and the distribution of non-plasma cell BM populations by MFC could provide a solution. We evaluated BM-associated cell populations, assessed by next-generation flow cytometry (NGF) and white blood cell (WBC) count in 351 BM aspirated samples from 219 participants with plasma cell disorders in the Iceland Screens, Treats, or Prevents MM study (iStopMM), as markers of hemodilution by their discriminatory ability between first and (generally more hemodiluted) second pull BM aspirated samples. The most discriminating markers were used to derive a novel BM quality index (BMQI). Nucleated red blood cells and myeloid precursors provided the greatest discriminatory ability between first vs second pull samples (area under the curve (AUC): 0.87 and 0.85, respectively), significantly better than B cell precursors (AUC = 0.64; p < 0.001), mast cells (AUC = 0.65; p < 0.001), and the BM WBC count (AUC = 0.77; p < 0.05). We generated a novel BMQI that is intrinsic to current NGF protocols, for evaluating quality of diagnostic BM samples and suggest the use of a BMQI scoring system for interpreting results and guiding appropriate actions.

COVID-19 illness severity and 2-year prevalence of physical symptoms: an observational study in Iceland, Sweden, Norway and Denmark.

Background: Although the persistence of physical symptoms after SARS-CoV-2 infection is a major public health concern, evidence from large observational studies beyond one year post diagnosis remain scarce. We aimed to assess the prevalence of physical symptoms in relation to acute illness severity up to more than 2-years after diagnosis of COVID-19. Methods: This multinational study included 64,880 adult participants from Iceland, Sweden, Denmark, and Norway with self-reported data on COVID-19 and physical symptoms from April 2020 to August 2022. We compared the prevalence of 15 physical symptoms, measured by the Patient Health Questionnaire (PHQ-15), among individuals with or without a confirmed COVID-19 diagnosis, by acute illness severity, and by time since diagnosis. We additionally assessed the change in symptoms in a subset of Swedish adults with repeated measures, before and after COVID-19 diagnosis. Findings: During up to 27 months of follow-up, 34.5% participants (22,382/64,880) were diagnosed with COVID-19. Individuals who were diagnosed with COVID-19, compared to those not diagnosed, had an overall 37% higher prevalence of severe physical symptom burden (PHQ-15 score ≥15, adjusted prevalence ratio [PR] 1.37 [95% confidence interval [CI] 1.23-1.52]). The prevalence was associated with acute COVID-19 severity: individuals bedridden for seven days or longer presented with the highest prevalence (PR 2.25 [1.85-2.74]), while individuals never bedridden presented with similar prevalence as individuals not diagnosed with COVID-19 (PR 0.92 [0.68-1.24]). The prevalence was statistically significantly elevated among individuals diagnosed with COVID-19 for eight of the fifteen measured symptoms: shortness of breath, chest pain, dizziness, heart racing, headaches, low energy/fatigue, trouble sleeping, and back pain. The analysis of repeated measurements rendered similar results as the main analysis. Interpretation: These data suggest an elevated prevalence of some, but not all, physical symptoms during up to more than 2 years after diagnosis of COVID-19, particularly among individuals suffering a severe acute illness, highlighting the importance of continued monitoring and alleviation of these targeted core symptoms. Funding: This work was mainly supported by grants from NordForsk (COVIDMENT, grant number 105668 and 138929) and Horizon 2020 (CoMorMent, 847776). See Acknowledgements for further details on funding.

Were cancer patients worse off than the general population during the COVID-19 pandemic? A population-based study from Norway, Denmark and Iceland during the pre-vaccination era.

Background: In a population-based setting, we investigated the risks of testing positive for SARS-CoV-2 and developing severe COVID-19 outcomes among cancer patients compared with the general population. Methods: In nationwide cohorts, we identified all individuals in Norway, Denmark and Iceland who tested positive for SARS-CoV-2 or had a severe COVID-19 outcome (hospitalisation, intensive care, and death) from March until December 2020, using data from national health registries. We estimated standardised incidence ratios (SIRs) with 95% confidence intervals (CIs) comparing cancer patients with the general population. Findings: During the first wave of the pandemic, cancer patients in Norway and Denmark had higher risks of testing SARS-CoV-2 positive compared to the general population. Throughout 2020, recently treated cancer patients were more likely to test SARS-CoV-2 positive. In Iceland, cancer patients experienced no increased risk of testing positive. The risk of COVID-19-related hospitalisation was higher among cancer patients diagnosed within one year of hospitalisation (Norway: SIR = 2.43, 95% CI 1.89-3.09; Denmark: 2.23, 1.96-2.54) and within five years (Norway: 1.58, 1.35-1.83; Denmark: 1.54, 1.42-1.66). Risks were higher in recently treated cancer patients and in those diagnosed with haematologic malignancies, colorectal or lung cancer. Risks of COVID-19-related intensive care and death were higher among cancer patients. Interpretation: Cancer patients were at increased risk of testing positive for SARS-CoV-2 during the first pandemic wave when testing availability was limited, while relative risks of severe COVID-19 outcomes remained increased in cancer patients throughout 2020. Recent cancer treatment and haematologic malignancy were the strongest risk factors. Funding: Nordic Cancer Union.

Physical and cognitive impact following SARS-CoV-2 infection in a large population-based case-control study.

BACKGROUND: Persistent symptoms are common after SARS-CoV-2 infection but correlation with objective measures is unclear. METHODS: We invited all 3098 adults who tested SARS-CoV-2 positive in Iceland before October 2020 to the deCODE Health Study. We compared multiple symptoms and physical measures between 1706 Icelanders with confirmed prior infection (cases) who participated, and 619 contemporary and 13,779 historical controls. Cases participated in the study 5-18 months after infection. RESULTS: Here we report that 41 of 88 symptoms are associated with prior infection, most significantly disturbed smell and taste, memory disturbance, and dyspnea. Measured objectively, cases had poorer smell and taste results, less grip strength, and poorer memory recall. Differences in grip strength and memory recall were small. No other objective measure associated with prior infection including heart rate, blood pressure, postural orthostatic tachycardia, oxygen saturation, exercise tolerance, hearing, and traditional inflammatory, cardiac, liver, and kidney blood biomarkers. There was no evidence of more anxiety or depression among cases. We estimate the prevalence of long Covid to be 7% at a median of 8 months after infection. CONCLUSIONS: We confirm that diverse symptoms are common months after SARS-CoV-2 infection but find few differences between cases and controls in objective parameters measured. These discrepancies between symptoms and physical measures suggest a more complicated contribution to symptoms related to prior infection than is captured with conventional tests. Traditional clinical assessment is not expected to be particularly informative in relating symptoms to a past SARS-CoV-2 infection.

Persistent symptoms are commonly reported after SARS-CoV-2 infection, and this is often described as long Covid. We compared different symptoms reported following SARS-CoV- 2 infection with the results obtained during various medical evaluations that are often used to assess health, such as blood tests, smell tests, taste tests, hearing tests, etc. We compared symptoms and test results between 1,706 Icelanders who had been infected previously with SARS-CoV-2 infection (cases) and 14,398 individuals who had not been infected (controls). Out of 88 assessed symptoms, 41 were more common in cases than controls. However, relatively few differences were seen in the results obtained from the various medical evaluations (cases had poorer smell and taste test results, slightly less grip strength, and slightly poorer memory recall than controls). The differences seen between symptoms and results of medical evaluations suggests that conventional clinical tests may not be informative in relating symptoms to a past SARS-CoV-2 infection.

Liver injury in patients with COVID-19 in comparison to patients with the pandemic influenza A (H1N1) 2009: a population-based study.

BACKGROUND: Elevated liver tests in patients with COVID-19 are widely reported. Population-based studies utilizing a validated analysis of drug-induced liver injury (DILI), with a control group of other viral illnesses and follow-up are largely lacking. MATERIALS AND METHODS: All hospitalized patients in Iceland with SARS-CoV-2 in 2020 and pandemic influenza A (H1N1) in 2009 were included in this retrospective, population-based study. Liver tests were compared between the two groups and the correlation to inflammatory markers and persistence of alanine aminotransferase (ALT) elevations were assessed. Potential DILI cases were reviewed using the Roussel Uclaf Causality Assessment Method (RUCAM). RESULTS: 225 SARS-CoV-2-positive and 73 influenza A (H1N1)-positive patients were included. Liver test values were similar between the groups, except for aspartate aminotransferase (AST) which was significantly lower in COVID-19, with a mean difference of 26 U/L (95%CI 4.2-47). Ferritin elevation was positively correlated with ALT, AST and alkaline phosphatase. No patient had persistently elevated ALT in COVID-19 and none had a probable DILI. Only 3 patients had a possible DILI according to the RUCAM. CONCLUSIONS: Elevated liver enzymes are not specific for COVID-19. Hyperferritinemia was associated with elevated liver tests. DILI was very rare in COVID-19 and an unlikely cause of elevated liver enzymes in COVID-19. Abnormal liver tests are nonpersistent and generally not clinically important in these patients.

Prevalence of smoldering multiple myeloma based on nationwide screening.

Smoldering multiple myeloma (SMM) is an asymptomatic precursor to multiple myeloma. Here we define the epidemiological characteristics of SMM in the general population in Iceland. The iStopMM study (ClinicalTrials.gov ID: NCT03327597 ) is a nationwide screening study for multiple myeloma precursors where all residents in Iceland 40 years or older were invited to participate. SMM was defined as 10-60% bone marrow plasma cells and/or monoclonal (M) protein concentration ≥3 g dl-1, in the absence of myeloma-defining events. Of the 80,759 who gave informed consent to participate, 75,422 (93%) were screened. The prevalence of SMM in the total population was 0.53% (95% confidence interval (CI) = 0.49-0.57%) in individuals 40 years or older. In men and women, the prevalence of SMM was 0.67% (95% CI = 0.62-0.73%) and 0.39% (95% CI = 0.35-0.43%), respectively; it increased with age in both sexes. For the 193 individuals with SMM, median age was 70 years (range 44-92 years) and 60% were males. The mean M protein concentration of individuals with SMM was 0.62 g dl-1 (range 0.01-3.5 g dl-1) and 73% had 11-20% bone marrow plasma cell infiltration. The high prevalence of SMM has implications for future treatment policies in multiple myeloma as the evidence supporting treatment initiation at the SMM stage is emerging.

Respiratory function and CT abnormalities among survivors of COVID-19 pneumonia: a nationwide follow-up study.

INTRODUCTION: Considering the pulmonary burden caused by acute COVID-19, questions remain of respiratory consequences after recovery. The aim of the study was to describe respiratory function of COVID-19 pneumonia survivors at mid-term follow-up (median 68 days) and assess whether impairments were predicted by acute illness severity or residual CT abnormalities. METHODS: Residents of Iceland that had COVID-19 and oxygen saturation ≤94% from 28 February 2020 to 30 April 2021 were offered a clinical follow-up visit with an interview, a 6 min walk test (6MWT), spirometry with gas exchange measurement and chest CT. The results of these examinations were described, grouped by the level of care during acute illness. The associations of disease severity and CT abnormalities at follow-up with subjective dyspnoea, 6MWT results and lung function test results were estimated with regression analyses. RESULTS: Of 190 eligible patients, 164 (86%) participated in the study. Of those, 32 had never been admitted to hospital, 103 were admitted to hospital without intensive care and 29 had required intensive care. At a follow-up, need for intensive care during acute illness was associated with shorter walking distance on 6MWT, lower oxygen saturation and lower DLCO. Imaging abnormalities at follow-up were observed for most participants (74%) and the magnitude of these changes was associated with decrements in 6MWT distance, oxygen saturation, forced vital capacity and DLCO. CONCLUSIONS: The findings show that impaired exercise capacity and lung physiology at follow-up were primarily observed for patients with COVID-19 pneumonia that required intensive care treatment and/or had persistent imaging abnormalities.

Development of a prognostic model of COVID-19 severity: a population-based cohort study in Iceland.

BACKGROUND: The severity of SARS-CoV-2 infection varies from asymptomatic state to severe respiratory failure and the clinical course is difficult to predict. The aim of the study was to develop a prognostic model to predict the severity of COVID-19 in unvaccinated adults at the time of diagnosis. METHODS: All SARS-CoV-2-positive adults in Iceland were prospectively enrolled into a telehealth service at diagnosis. A multivariable proportional-odds logistic regression model was derived from information obtained during the enrollment interview of those diagnosed between February 27 and December 31, 2020 who met the inclusion criteria. Outcomes were defined on an ordinal scale: (1) no need for escalation of care during follow-up; (2) need for urgent care visit; (3) hospitalization; and (4) admission to intensive care unit (ICU) or death. Missing data were multiply imputed using chained equations and the model was internally validated using bootstrapping techniques. Decision curve analysis was performed. RESULTS: The prognostic model was derived from 4756 SARS-CoV-2-positive persons. In total, 375 (7.9%) only required urgent care visits, 188 (4.0%) were hospitalized and 50 (1.1%) were either admitted to ICU or died due to complications of COVID-19. The model included age, sex, body mass index (BMI), current smoking, underlying conditions, and symptoms and clinical severity score at enrollment. On internal validation, the optimism-corrected Nagelkerke's R2 was 23.4% (95%CI, 22.7-24.2), the C-statistic was 0.793 (95%CI, 0.789-0.797) and the calibration slope was 0.97 (95%CI, 0.96-0.98). Outcome-specific indices were for urgent care visit or worse (calibration intercept -0.04 [95%CI, -0.06 to -0.02], Emax 0.014 [95%CI, 0.008-0.020]), hospitalization or worse (calibration intercept -0.06 [95%CI, -0.12 to -0.03], Emax 0.018 [95%CI, 0.010-0.027]), and ICU admission or death (calibration intercept -0.10 [95%CI, -0.15 to -0.04] and Emax 0.027 [95%CI, 0.013-0.041]). CONCLUSION: Our prognostic model can accurately predict the later need for urgent outpatient evaluation, hospitalization, and ICU admission and death among unvaccinated SARS-CoV-2-positive adults in the general population at the time of diagnosis, using information obtained by telephone interview.

HLA alleles, disease severity, and age associate with T-cell responses following infection with SARS-CoV-2.

Memory T-cell responses following SARS-CoV-2 infection have been extensively investigated but many studies have been small with a limited range of disease severity. Here we analyze SARS-CoV-2 reactive T-cell responses in 768 convalescent SARS-CoV-2-infected (cases) and 500 uninfected (controls) Icelanders. The T-cell responses are stable three to eight months after SARS-CoV-2 infection, irrespective of disease severity and even those with the mildest symptoms induce broad and persistent T-cell responses. Robust CD4+ T-cell responses are detected against all measured proteins (M, N, S and S1) while the N protein induces strongest CD8+ T-cell responses. CD4+ T-cell responses correlate with disease severity, humoral responses and age, whereas CD8+ T-cell responses correlate with age and functional antibodies. Further, CD8+ T-cell responses associate with several class I HLA alleles. Our results, provide new insight into HLA restriction of CD8+ T-cell immunity and other factors contributing to heterogeneity of T-cell responses following SARS-CoV-2 infection.

Defining new reference intervals for serum free light chains in individuals with chronic kidney disease: Results of the iStopMM study.

Serum free light chain (FLC) concentration is greatly affected by kidney function. Using a large prospective population-based cohort, we aimed to establish a reference interval for FLCs in persons with chronic kidney disease (CKD). A total of 75422 participants of the iStopMM study were screened with serum FLC, serum protein electrophoresis and immunofixation. Estimated glomerular filtration rate (eGFR) was calculated from serum creatinine. Central 99% reference intervals were determined, and 95% confidence intervals calculated. Included were 6461 (12%) participants with measured FLCs, eGFR < 60 mL/min/1.73 m2, not receiving renal replacement therapy, and without evidence of monoclonality. Using current reference intervals, 60% and 21% had kappa and lambda FLC values outside the normal range. The FLC ratio was outside standard reference interval (0.26-1.65) in 9% of participants and outside current kidney reference interval (0.37-3.10) in 0.7%. New reference intervals for FLC and FLC ratio were established. New reference intervals for the FLC ratio were 0.46-2.62, 0.48-3.38, and 0.54-3.30 for eGFR 45-59, 30-44, and < 30 mL/min/1.73 m2 groups, respectively. The crude prevalence of LC-MGUS in CKD patients was 0.5%. We conclude that current reference intervals for FLC and FLC ratio are inaccurate in CKD patients and propose new eGFR based reference intervals to be implemented.

Longitudinal changes in inflammatory biomarkers among patients with COVID-19: A nationwide study in Iceland.

OBJECTIVES: All SARS-CoV-2-positive persons in Iceland were prospectively monitored and those who required outpatient evaluation or were admitted to hospital underwent protocolized evaluation that included a standardized panel of biomarkers. The aim was to describe longitudinal changes in inflammatory biomarkers throughout the infection period of patients with COVID-19 requiring different levels of care. DESIGN: Registry-based study. SETTING: Nationwide study in Iceland. PATIENTS: All individuals who tested positive for SARS-CoV-2 by real-time polymerase chain reaction (RT-PCR) from February 28 to December 31, 2020 in Iceland and had undergone blood tests between 5 days before and 21 days following onset of symptoms. MEASUREMENTS AND MAIN RESULTS: Data were collected from the electronic medical record system of Landspitali-The National University Hospital of Iceland. Data analyses were descriptive and the evolution of biomarkers was visualized using locally weighted scatterplot smoothing curves stratified by the worst clinical outcome experienced by the patient: outpatient evaluation only, hospitalization, and either intensive care unit (ICU) admission or death. Of 571 included patients, 310 (54.3%) only required outpatient evaluation or treatment, 202 (35.4%) were hospitalized, and 59 (10.3%) were either admitted to the ICU or died. An early and persistent separation of the mean lymphocyte count and plasma C-reactive protein (CRP) and ferritin levels was observed between the three outcome groups, which occurred prior to hospitalization for those who later were admitted to ICU or died. Lower lymphocyte count, and higher CRP and ferritin levels correlated with worse clinical outcomes. Patients who were either admitted to the ICU or died had sustained higher white blood cell and neutrophil counts, and elevated plasma levels of procalcitonin and D-dimer compared with the other groups. CONCLUSIONS: Lymphocyte count and plasma CRP and ferritin levels might be suitable parameters to assess disease severity early during COVID-19 and may serve as predictors of worse outcome.

Reconstruction of a large-scale outbreak of SARS-CoV-2 infection in Iceland informs vaccination strategies.

OBJECTIVES: The spread of SARS-CoV-2 is dependent on several factors, both biological and behavioural. The effectiveness of nonpharmaceutical interventions can be attributed largely to changes in human behaviour, but quantifying this effect remains challenging. Reconstructing the transmission tree of the third wave of SARS-CoV-2 infections in Iceland using contact tracing and viral sequence data from 2522 cases enables us to directly compare the infectiousness of distinct groups of persons. METHODS: The transmission tree enables us to model the effect that a given population prevalence of vaccination would have had on the third wave had one of three different vaccination strategies been implemented before that time. This allows us to compare the effectiveness of the strategies in terms of minimizing the number of cases, deaths, critical cases, and severe cases. RESULTS: We found that people diagnosed outside of quarantine (Rˆ=1.31) were 89% more infectious than those diagnosed while in quarantine (Rˆ=0.70) and that infectiousness decreased as a function of time spent in quarantine before diagnosis, with people diagnosed outside of quarantine being 144% more infectious than those diagnosed after ≥3 days in quarantine (Rˆ=0.54). People of working age, 16 to 66 years (Rˆ=1.08), were 46% more infectious than those outside of that age range (Rˆ=0.74). DISCUSSION: We found that vaccinating the population in order of ascending age or uniformly at random would have prevented more infections per vaccination than vaccinating in order of descending age, without significantly affecting the expected number of deaths, critical cases, or severe cases.

The first wave of COVID-19 and concurrent social restrictions were not associated with a negative impact on mental health and psychiatric well-being.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic and efforts to contain it have substantially affected the daily lives of most of the world's population. OBJECTIVE: We describe the impact of the first COVID-19 wave and associated social restrictions on the mental health of a large adult population. METHODS: We performed a cohort study nested in a prospective randomized clinical trial, comparing responses during the first COVID-19 wave to previous responses. We calculated the odds ratio (OR) of the population moving up one severity category on validated instruments used to measure stress (PSS-10), anxiety (GAD-7), depression (PHQ-9), and Satisfaction With Life Scale (SWLS). Responses were linked to inpatient and outpatient ICD-10 codes from registries. Models were adjusted for age, sex, comorbidities, and pre-existing diagnoses of mental illness. RESULTS: Of 63,848 invited participants, 42,253 (66%) responded. The median age was 60 (inter-quartile range 53-68) and 19,032 (45%) were male. Responses during the first wave of COVID-19 did not suggest increased stress (OR 0.97; 95% confidence interval [CI], 0.93-1.01; p = 0.28) or anxiety (OR 1.01; 95% CI, 0.96 to 1.05; p = 0.61), but were associated with decreased depression (OR 0.89; 95% CI, 0.85-0.93, p < 0.0001) and increased satisfaction with life (OR 1.12; 95% CI, 1.08-1.16, p < 0.0001). A secondary analysis of repeated measures data showed similar results. CONCLUSIONS: Social restrictions were sufficient to contain the pandemic but did not negatively impact validated measures of mental illness or psychiatric well-being. However, responses to individual questions showed signs of fear and stress. This may represent a normal, rather than pathological, population response to a stressful situation.

Obstructive sleep apnea is an independent risk factor for severe COVID-19: a population-based study.

STUDY OBJECTIVES: Obstructive sleep apnea (OSA) has been proposed as a risk factor for severe COVID-19. Confounding is an important consideration as OSA is associated with several known risk factors for severe COVID-19. Our aim was to assess the association of OSA with hospitalization due to COVID-19 using a population-based cohort with detailed information on OSA and comorbidities. METHODS: Included were all community-dwelling Icelandic citizens 18 years of age and older diagnosed with SARS-CoV-2 infection in 2020. Data on demographics, comorbidities, and outcomes of COVID-19 was obtained from centralized national registries. Diagnosis of OSA was retrieved from the centralized Sleep Department Registry at Landspitali - The National University Hospital. Severe COVID-19 was defined as the composite outcome of hospitalization and death. The associations between OSA and the outcome were expressed as odds ratios (OR) with 95% confidence intervals (95% CI), calculated using logistic regression models and inverse probability weighting. RESULTS: A total of 4,756 individuals diagnosed with SARS-CoV-2 infection in Iceland were included in the study (1.3% of the Icelandic population), of whom 185 had a diagnosis of OSA. In total, 238 were hospitalized or died, 38 of whom had OSA. Adjusted for age, sex, and BMI, OSA was associated with poor outcome (OR 2.2, 95% CI 1.4-3.5). This association was slightly attenuated (OR 2.0, 95% CI 2.0, 1.2-3.2) when adjusted for demographic characteristics and various comorbidities. CONCLUSIONS: OSA was associated with twofold increase in risk of severe COVID-19, and the association was not explained by obesity or other comorbidities.