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Obesity is a major risk factor for COVID-19 severity; however, the mechanisms underlying this relationship are not fully understood. Since obesity influences the plasma proteome, we sought to identify circulating proteins mediating the effects of obesity on COVID-19 severity in humans. Here, we screened 4,907 plasma proteins to identify proteins influenced by body mass index (BMI) using Mendelian randomization (MR). This yielded 1,216 proteins, whose effect on COVID-19 severity was assessed, again using MR. We found that a standard deviation increase in nephronectin (NPNT) was associated with increased odds of critically ill COVID-19 (OR = 1.71,P= 1.63 × 10−10). The effect was driven by an NPNT splice isoform. Mediation analyses supported NPNT as a mediator. In single-cell RNA-sequencing,NPNTwas expressed in alveolar cells and fibroblasts of the lung in individuals who died of COVID-19. Finally, decreasing body fat mass and increasing fat-free mass were found to lower NPNT levels. These findings provide actionable insights into how obesity influences COVID-19 severity.

Metabolic processes can influence disease risk and provide therapeutic targets. By conducting genome-wide association studies of 1,091 blood metabolites and 309 metabolite ratios, we identified associations with 690 metabolites at 248 loci; and associations with 143 metabolite ratios at 69 loci. Integrating metabolite-gene and gene expression information identified 94 effector genes for 109 metabolites and 48 metabolite ratios. Using Mendelian Randomization (MR), we identified 22 metabolites and 20 metabolite ratios having estimated causal effect on 12 traits and diseases, including orotate for estimated bone mineral density, alpha-hydroxyisovalerate for body mass index and ergothioneine for inflammatory bowel disease and asthma. We further measured orotate level in a separate cohort and demonstrated that, consistent with MR, orotate levels were positively associated with incident hip fractures. This study provides a valuable resource describing the genetic architecture of metabolites and delivers insights into their roles in common diseases, thereby offering opportunities for therapeutic targets.

Obesity strongly increases the risk of cardiometabolic diseases, yet the underlying mediators of this relationship are not fully understood. Given that obesity has broad effects on circulating protein levels, we investigated circulating proteins that mediate the effects of obesity on coronary artery disease (CAD), stroke, and type 2 diabetes—since doing so may prioritize targets for therapeutic intervention. By integrating proteome-wide Mendelian randomization (MR) screening 4,907 plasma proteins, colocalization, and mediation analyses, we identified seven plasma proteins, including collagen type VI α3 (COL6A3). COL6A3 was strongly increased by body mass index (BMI) (β= 0.32, 95% CI: 0.26–0.38,P= 3.7 × 10-8per s.d. increase in BMI) and increased the risk of CAD (OR = 1.47, 95% CI:1.26–1.70,P= 4.5 × 10-7per s.d. increase in COL6A3). Notably, COL6A3 is cleaved at its C-terminus to produce endotrophin, which was found to mediate this effect on CAD. In single-cell RNA sequencing of adipose tissues and coronary arteries,COL6A3was highly expressed in cell types involved in metabolic dysfunction and fibrosis. Finally, we found that body fat reduction can reduce plasma levels of COL6A3-derived endotrophin, thereby highlighting a tractable way to modify endotrophin levels. In summary, we provide actionable insights into how circulating proteins mediate the effect of obesity on cardiometabolic diseases and prioritize endotrophin as a potential therapeutic target.

Background Pneumocystis jirovecii pneumonia (PCP) is an opportunistic infection commonly affecting immunocompromised people. Diagnosis usually requires invasive techniques to obtain respiratory specimens. Minimally invasive detection tests have been proposed, but their operating characteristics are poorly described. Objectives To systematically review and meta-analyse the performance of minimally invasive PCP detection tests to inform diagnostic algorithms. Data sources Medline, Embase, Cochrane Library (inception to 15 October 2020). Study eligibility criteria Studies of minimally invasive PCP detection tests were included if they contained a minimum of ten PCP cases. Participants Adults at risk of PCP. Tests Non-invasive PCP detection tests. Reference standard Diagnosis using the combination of clinical and radiographical features with invasive sampling. Assessment of risk bias Using the QUADAS-2 tool. Methods We used bivariate and, when necessary, univariate analysis models to estimate diagnostic test sensitivity and specificity. Results Fifty-two studies were included; most studies (40) comprised exclusively human immunodeficiency virus (HIV) -infected individuals; nine were mixed (HIV and non-HIV), two were non-HIV and one study did not report HIV status. Sampling sites included induced sputum, nasopharyngeal aspirate, oral wash and blood. The four testing modalities evaluated were cytological staining, fluorescent antibody, PCR and lactate dehydrogenase. Induced sputum had the most data available; this modality was both highly sensitive at 99% (95% CI 51%–100%) and specific at 96% (95% CI 88%–99%). Induced sputum cytological staining had moderate sensitivity at 50% (95% CI 39%–61%) and high specificity at 100% (95% CI 100%–100%), as did fluorescent antibody testing with sensitivity 74% (95% CI 62%–87%) and specificity 100% (95% CI 91%–100%). Conclusion There are several promising minimally invasive PCP diagnostic tests available, some of which may reduce the need for invasive respiratory sampling. Understanding the operating characteristics of these tests can augment current diagnostic strategies and help establish a more confident clinical diagnosis of PCP. Further studies in non-HIV infected populations are needed.

Objectives Increased iron stores have been associated with elevated risks of different infectious diseases, suggesting that iron supplementation may increase the risk of infections. However, these associations may be biased by confounding or reverse causation. This is important, since up to 19% of the population takes iron supplementation. We used Mendelian randomization (MR) to bypass these biases and estimate the causal effect of iron on infections. Methods As instrumental variables, we used genetic variants associated with iron biomarkers in two genome-wide association studies (GWASs) of European ancestry participants. For outcomes, we used GWAS results from the UK Biobank, FinnGen, the COVID-19 Host Genetics Initiative or 23andMe, for seven infection phenotypes: ‘any infections’, combined, COVID-19 hospitalization, candidiasis, pneumonia, sepsis, skin and soft tissue infection (SSTI) and urinary tract infection (UTI). Results Most of our analyses showed increasing iron (measured by its biomarkers) was associated with only modest changes in the odds of infectious outcomes, with all 95% odds ratios confidence intervals within the 0.88 to 1.26 range. However, for the three predominantly bacterial infections (sepsis, SSTI, UTI), at least one analysis showed a nominally elevated risk with increased iron stores (P Conclusion Using MR, we did not observe an increase in risk of most infectious diseases with increases in iron stores. However for bacterial infections, higher iron stores may increase odds of infections. Hence, using genetic variation in iron pathways as a proxy for iron supplementation, iron supplements are likely safe on a population level, but we should continue the current practice of conservative iron supplementation during bacterial infections or in those at high risk of developing them.

ObjectiveObservational studies on cognition found that vitamin D supplementation is associated with improved cognition. Further, recent Mendelian randomization (MR) studies have shown that increased vitamin D levels, as measured by 25-hydroxyvitamin D [25(OH)D], may protect against Alzheimer’s disease. Thus, it is possible that 25OHD may protect against Alzheimer’s disease by improving cognition.MethodsTo evaluate this hypothesis, we began by performing an observational study by testing the association of 25OHD levels with 5 cognitive outcomes related to memory and executive function, adjusting for age, sex, BMI, smoking status and nutritional risk index in 26,787 older individuals (median age 62). Since such observational analyses can be biased by confounding, we next performed two-sample mendelian randomization (MR) analyses testing the effect of 25(OH)D on cognitive outcomes, since this method helps to protect against bias from confounding.ResultsObservational studies suggested a strong protective association between 25(OH)D and cognitive measures. However, in MR analyses, we found no estimated effect of 25(OH)D on these outcomes.ConclusionThese findings suggest that associations between 25(OH)D levels and cognition are likely to be biased by confounding and that the relationship between 25(OH)D levels and Alzheimer’s disease is not due to the effect of 25(OH)D on cognition.

A phase III randomised, placebo-controlled, trial to directly compare the efficacy and safety of low-dose TMP-SMX (10 mg/kg/day of TMP) with the standard of care (15 mg/kg/day of TMP) among patients with PJP, for a composite primary outcome of change of treatment, new mechanical ventilation, or death. The trial will be undertaken at 16 Canadian hospitals. Data will be analysed as intention to treat. Primary and secondary outcomes will be compared using logistic regression adjusting for stratification and presented with 95% CI.This study has been conditionally approved by the McGill University Health Centre; Ethics approval will be obtained from all participating centres. Results will be submitted for publication in a peer-reviewed journal.NCT04851015.

To identify circulating proteins influencing Coronavirus Disease 2019 (COVID-19) susceptibility and severity, we undertook a two-sample Mendelian randomization (MR) study, rapidly scanning hundreds of circulating proteins while reducing bias due to reverse causation and confounding. In up to 14,134 cases and 1.2 million controls, we found that an s.d. increase in OAS1 levels was associated with reduced COVID-19 death or ventilation (odds ratio (OR) = 0.54, P = 7 × 10−8), hospitalization (OR = 0.61, P = 8 × 10−8) and susceptibility (OR = 0.78, P = 8 × 10−6). Measuring OAS1 levels in 504 individuals, we found that higher plasma OAS1 levels in a non-infectious state were associated with reduced COVID-19 susceptibility and severity. Further analyses suggested that a Neanderthal isoform of OAS1 in individuals of European ancestry affords this protection. Thus, evidence from MR and a case–control study support a protective role for OAS1 in COVID-19 adverse outcomes. Available pharmacological agents that increase OAS1 levels could be prioritized for drug development. A variant of the OAS1 gene, which encodes an enzyme that is critical for the innate immune response to viral infections, is associated with decreased risk of death in patients with COVID-19.

Background: Obesity is associated with increased risk of multiple sclerosis (MS); however, the underlying mechanisms remain unclear. Objective: To determine the extent to which decreased vitamin D bioavailability and altered levels of adiponectin and leptin mediate the association between obesity and MS. Methods: We performed Mendelian randomization (MR) analyses to estimate the effects on MS of body mass index (BMI), 25-hydroxyvitamin D (25OHD), adiponectin, and leptin levels in a cohort of 14,802 MS cases and 26,703 controls. We then estimated the proportion of the effect of obesity on MS explained by these potential mediators. Results: Genetic predisposition to higher BMI was associated with increased MS risk (odds ratio (OR) = 1.33 per standard deviation (SD), 95% confidence interval (CI) = 1.09–1.63), while higher 25OHD levels reduced odds of MS (OR = 0.72 per SD, 95% CI = 0.60–0.87). In contrast, we observed no effect of adiponectin or leptin. In MR mediation analysis, 5.2% of the association between BMI and MS was attributed to obesity lowering 25OHD levels (95% CI = 0.3%–31.0%). Conclusions: This study found that a minority of the increased risk of MS conferred by obesity is mediated by lowered vitamin D levels, while leptin and adiponectin had no effect. Consequently, vitamin D supplementation would only modestly reverse the effect of obesity on MS.

Randomized controlled trials (RCT) established the mortality reduction by tocilizumab (Actemra), baricitinib (Olumiant), and sarilumab (Kevzara) in hospitalized COVID-19 patients. However, uncertainty remains about which treatment performs best in patients receiving corticosteroids.To estimate probabilities of noninferiority between baricitinib and sarilumab compared to tocilizumab in patients treated with corticosteroids.PubMed, Embase, Cochrane Library, and MedRxiv.Eligible RCTs assigning hospitalized adults with COVID-19 treated with corticosteroids to tocilizumab or baricitinib or sarilumab versus standard of care or placebo (control).Reviewers independently abstracted published data and assessed study quality with the Risk of Bias 2 tool. Unpublished data, if required, were requested from authors of included studies. The outcome of interest was all-cause mortality at 28 days.Twenty-seven RCTs with 13 549 patients were included. Overall, the risk of bias was low. Bayesian pairwise meta-analyses were used to aggregate results of each treatment versus control. The average odds ratio for mortality was 0.78 (95% credible interval [CrI]: 0.65, 0.94) for tocilizumab; 0.78 (95% CrI: 0.56, 1.03) for baricitinib; and 0.91 (95% CrI: 0.60, 1.40) for sarilumab. The certainty of evidence (GRADE) ranged from moderate to low. Bayesian meta-regressions with multiple priors were used to estimate probabilities of noninferiority (margin of 13% greater effect by tocilizumab). Compared to tocilizumab, there were ≤94% and 90% probabilities of noninferiority with baricitinib and sarilumab, respectively.All but two studies included data with only indirect evidence for the comparison of interest.Among hospitalized COVID-19 treated with corticosteroids, there are high probabilities that both baricitinib and sarilumab are associated with similar mortality reductions in comparison to tocilizumab.

Background Deaths following Staphylococcus aureus bacteremia (SAB) may be related or unrelated to the infection. In SAB therapeutics research, the length of follow-up should be optimized to capture most attributable deaths and minimize nonattributable deaths. We performed a secondary analysis of a systematic review to describe attributable mortality in SAB over time. Methods We systematically searched Medline, Embase, and Cochrane Database of Systematic Reviews from 1 January 1991 to 7 May 2021 for human observational studies of SAB. To be included in this secondary analysis, the study must have reported attributable mortality. Two reviewers extracted study data and assessed risk of bias independently. Pooling of study estimates was not performed due to heterogeneity in the definition of attributable deaths. Results Twenty-four observational cohort studies were included. The median proportion of all-cause deaths that were attributable to SAB was 77% (interquartile range [IQR], 72%–89%) at 1 month and 62% (IQR, 58%–75%) at 3 months. At 1 year, this proportion was 57% in 1 study. In 2 studies that described the rate of increase in mortality over time, 2-week follow-up captured 68 of 79 (86%) and 48 of 57 (84%) attributable deaths that occurred by 3 months. By comparison, 1-month follow-up captured 54 of 57 (95%) and 56 of 60 (93%) attributable deaths that occurred by 3 months in 2 studies. Conclusions The proportion of deaths that are attributable to SAB decreases as follow-up lengthens. Follow-up duration between 1 and 3 months seems optimal if evaluating processes of care that impact SAB mortality. Clinical Trials Registration PROSPERO CRD42021253891.

Background Bloodstream infections (BSIs) with methicillin-susceptible Staphylococcus aureus (MSSA) are associated with significant morbidity and mortality. Our objective in this study was to determine the efficacy of synergistic treatment with daptomycin when given with either cefazolin or cloxacillin for the treatment of MSSA BSI. Methods A randomized, double-blind, placebo-controlled trial was performed at 2 academic hospitals in Montreal, Canada. Patients aged ≥18 years with MSSA BSI receiving either cefazolin or cloxacillin monotherapy were considered for inclusion. In addition to the standard-of-care treatment, participants received a 5-day course of adjunctive daptomycin or placebo. The primary outcome was the duration of MSSA BSI in days. Results Of 318 participants screened, 115 were enrolled and 104 were included in the intention-to-treat analysis (median age, 67 years; 34.5% female). The median duration of bacteremia was 2.04 days among patients who received daptomycin vs 1.65 days in those who received placebo (absolute difference, 0.39 days; P = .40). In a modified intention-to-treat analysis that involved participants who remained bacteremic at the time of enrollment, we found a median duration of bacteremia of 3.06 days among patients who received daptomycin vs 3.0 days in those who received placebo (absolute difference, 0.06 days; P = .77). Ninety-day mortality in the daptomycin arm was 18.9% vs 17.7% in the placebo arm (P = 1.0). Conclusions Among patients with MSSA BSIs, the administration of adjunctive daptomycin therapy to standard-of-care treatment did not shorten the duration of bacteremia and should not be routinely considered. Clinical Trials Registration NCT02972983.

BackgroundThe benefits of remdesivir in the treatment of hospitalized patients with Covid-19 remain debated with the National Institutes of Health and the World Health Organization providing contradictory recommendations for and against use.MethodsWe performed a systematic review of randomized controlled trials (RCTs) of remdesivir for the treatment of hospitalized patients with COVID-19. The primary outcome was mortality, stratified by oxygen use (none, supplemental oxygen without mechanical ventilation, and mechanical ventilation). We conducted a frequentist random effects meta-analysis on the risk ratio (RR) scale and, to better contextualize the probabilistic benefits, we also performed a bayesian random effects meta-analysis on the risk difference scale.ResultsWe identified 8 randomized trials, totaling 9157 participants. The RR for mortality comparing remdesivir versus control was 0.71 (95% confidence interval [CI] 0.42-1.22; I2=0.0%) in the patients who did not require supplemental oxygen; 0.83 (95%CI 0.73-0.95; I2=0.0%) for nonventilated patients requiring oxygen; and 1.19 (95%CI 0.98-1.44 I2=0.0%) in the setting of mechanical ventilation. Using neutral priors, the probabilities that remdesivir reduces mortality were 74.7%, 96.9% and 8.9%, respectively. The probability that remdesivir reduced mortality by more than 1% was 88.1% for nonventilated patients requiring oxygen.ConclusionBased on this meta-analysis, there is a high probability that remdesivir reduces mortality for nonventilated patients with COVID-19 requiring supplemental oxygen therapy.

Precise estimates of mortality in Staphylococcus aureus bacteraemia (SAB) are important to convey prognosis and guide the design of interventional studies.We performed a systematic review and meta-analysis to estimate all-cause mortality in SAB and explore mortality change over time.The MEDLINE and Embase databases, as well as the Cochrane Database of Systematic Reviews, were searched from January 1, 1991 to May 7, 2021.Human observational studies on patients with S. aureus bloodstream infection were included.The study analyzed data of patients with a positive blood culture for S. aureus.Two independent reviewers extracted study data and assessed risk of bias using the Newcastle-Ottawa Scale. A generalized, linear, mixed random effects model was used to pool estimates.A total of 341 studies were included, describing a total of 536,791 patients. From 2011 onward, the estimated mortality was 10.4% (95% CI, 9.0%-12.1%) at 7 days, 13.3% (95% CI, 11.1%-15.8%) at 2 weeks, 18.1% (95% CI, 16.3%-20.0%) at 1 month, 27.0% (95% CI, 21.5%-33.3%) at 3 months, and 30.2% (95% CI, 22.4%-39.3%) at 1 year. In a meta-regression model of 1-month mortality, methicillin-resistant S. aureus had a higher mortality rate (adjusted OR (aOR): 1.04; 95% CI, 1.02-1.06 per 10% increase in methicillin-resistant S. aureus proportion). Compared with prior to 2001, more recent time periods had a lower mortality rate (aOR: 0.88; 95% CI, 0.75-1.03 for 2001-2010; aOR: 0.82; 95% CI, 0.69-0.97 for 2011 onward).SAB mortality has decreased over the last 3 decades. However, more than one in four patients will die within 3 months, and continuous improvement in care remains necessary.

Deaths followingWe systematically searched Medline, Embase, and Cochrane Database of Systematic Reviews from 1 January 1991 to 7 May 2021 for human observational studies of SAB. To be included in this secondary analysis, the study must have reported attributable mortality. Two reviewers extracted study data and assessed risk of bias independently. Pooling of study estimates was not performed due to heterogeneity in the definition of attributable deaths.Twenty-four observational cohort studies were included. The median proportion of all-cause deaths that were attributable to SAB was 77% (interquartile range [IQR], 72%-89%) at 1 month and 62% (IQR, 58%-75%) at 3 months. At 1 year, this proportion was 57% in 1 study. In 2 studies that described the rate of increase in mortality over time, 2-week follow-up captured 68 of 79 (86%) and 48 of 57 (84%) attributable deaths that occurred by 3 months. By comparison, 1-month follow-up captured 54 of 57 (95%) and 56 of 60 (93%) attributable deaths that occurred by 3 months in 2 studies.The proportion of deaths that are attributable to SAB decreases as follow-up lengthens. Follow-up duration between 1 and 3 months seems optimal if evaluating processes of care that impact SAB mortality.PROSPERO CRD42021253891.

Predicting COVID-19 severity is difficult, and the biological pathways involved are not fully understood. To approach this problem, we measured 4,701 circulating human protein abundances in two independent cohorts totaling 986 individuals. We then trained prediction models including protein abundances and clinical risk factors to predict adverse COVID-19 outcomes in 417 subjects and tested these models in a separate cohort of 569 individuals. For severe COVID-19, a baseline model including age and sex provided an area under the receiver operator curve (AUC) of 65% in the test cohort. Selecting 92 proteins from the 4,701 unique protein abundances improved the AUC to 88% in the training cohort, which remained relatively stable in the testing cohort at 86%, suggesting good generalizability. Proteins selected from different adverse COVID-19 outcomes were enriched for cytokine and cytokine receptors, but more than half of the enriched pathways were not immune-related. Taken together, these findings suggest that circulating proteins measured at early stages of disease progression are reasonably accurate predictors of adverse COVID-19 outcomes. Further research is needed to understand how to incorporate protein measurement into clinical care.

Pneumocystis jirovecii pneumonia (PCP) is a common opportunistic infection causing more than 400000 cases annually worldwide. Although antiretroviral therapy has reduced the burden of PCP in persons with human immunodeficiency virus (HIV), an increasing proportion of cases occur in other immunocompromised populations. In this review, we synthesize the available randomized controlled trial (RCT) evidence base for PCP treatment. We identified 14 RCTs that were conducted 25–35 years ago, principally in 40-year-old men with HIV. Trimethoprim-sulfamethoxazole, at a dose of 15–20 mg/kg per day, is the treatment of choice based on historical practice rather than on quality comparative, dose-finding studies. Treatment duration is similarly based on historical practice and is not evidence based. Corticosteroids have a demonstrated role in hypoxemic patients with HIV but have yet to be studied in RCTs as an adjunctive therapy in non-HIV populations. The echinocandins are potential synergistic treatments in need of further investigation.

The authors reply: We appreciate the interest of Dr. Zhang and colleagues in our manuscript. The main difference between our publication and that of Zhang et al. (1), was that we assessed all rare predicted loss-of-function variants (pLOFs) meeting the same criteria in cases and controls, which is a well-established paradigm in the field (2). On the other hand, Zhang et al. included specific variants which were experimentally confirmed only in cases, but not controls, precluding a valid case-control comparison.We matched patients as closely as possible to the previous study, and the inclusion of more severe cases (WHO grades 7-10) should only strengthen the signal against population controls. The use of population controls is standard in such settings and has minimal impact on power, because only a small proportion of individuals exposed to SARS-Cov-2 develop severe disease (3). Additionally, for the pLOF model we report adequate power even for an odds ratio of 5.5, which is considerably lower than the one reported by Zhang et al. We tested the same dominant model as Zhang et al., even though LOF variants in these genes have only been reported to cause disease under recessive inheritance (4).We have serious concerns about confounding by ancestry in the analysis by Zhang et al. in which the pLOF carriers were mostly European, but functionally validated missense variants were found in various nationalities from Asia, Europe, Latin America, and the Middle East. Because the rates of pLOFs vary considerably across populations, adjusting for only 3 principal components of ancestry in rare-variant association tests of multi-ethnic cohorts does not provide adequate control for population structure.While we noted that age differences may contribute to the discrepancies between the two studies, Zhang et al. do not discuss the role of age in the interpretation of their results stating: "Inborn errors of TLR3- and IRF7-dependent type I IFN immunity at eight loci were found in as many as 23 patients (3.5%) of various ages (17 to 77 years) and ancestries (various nationalities from Asia, Europe, Latin America, and the Middle East) and in patients of both sexes." We also note that the patients with autoantibodies were not excluded from the primary analysis by Zhang et al., but this was done only in the post-hoc analysis.Most importantly, our negative findings are in full agreement with the recently published independent study of 586,157 individuals, including 20,952 cases of COVID-19 (4,928 hospitalized and 1,304 requiring ventilation or resulting in death) (5). There were no significant associations with any of the 13 candidate genes examined either individually or in aggregate, or when comparisons included all hospitalized cases or only the most severe cases. Indeed, none of the associations displayed even marginal significance. Therefore, consistent with our study, these findings do not support substantial contributions of inborn errors in type I IFN immunity to COVID-19 severity.These negative results underscore the importance of proper study design, selection of appropriate genetic models, adequate control for genetic ancestry, and adherence to unbiased methods for genetic discovery rather than focusing only on a candidate biological pathway.

A recent report found that rare predicted loss-of-function (pLOF) variants across 13 candidate genes in TLR3- and IRF7-dependent type I IFN pathways explain up to 3.5% of severe COVID-19 cases. We performed whole-exome or whole-genome sequencing of 1,864 COVID-19 cases (713 with severe and 1,151 with mild disease) and 15,033 ancestry-matched population controls across 4 independent COVID-19 biobanks. We tested whether rare pLOF variants in these 13 genes were associated with severe COVID-19. We identified only 1 rare pLOF mutation across these genes among 713 cases with severe COVID-19 and observed no enrichment of pLOFs in severe cases compared to population controls or mild COVID-19 cases. We found no evidence of association of rare LOF variants in the 13 candidate genes with severe COVID-19 outcomes.

Background Increased vitamin D levels, as reflected by 25-hydroxy vitamin D (25OHD) measurements, have been proposed to protect against COVID-19 based on in vitro, observational, and ecological studies. However, vitamin D levels are associated with many confounding variables, and thus associations described to date may not be causal. Vitamin D Mendelian randomization (MR) studies have provided results that are concordant with large-scale vitamin D randomized trials. Here, we used 2-sample MR to assess evidence supporting a causal effect of circulating 25OHD levels on COVID-19 susceptibility and severity. Methods and findings Genetic variants strongly associated with 25OHD levels in a genome-wide association study (GWAS) of 443,734 participants of European ancestry (including 401,460 from the UK Biobank) were used as instrumental variables. GWASs of COVID-19 susceptibility, hospitalization, and severe disease from the COVID-19 Host Genetics Initiative were used as outcome GWASs. These included up to 14,134 individuals with COVID-19, and up to 1,284,876 without COVID-19, from up to 11 countries. SARS-CoV-2 positivity was determined by laboratory testing or medical chart review. Population controls without COVID-19 were also included in the control groups for all outcomes, including hospitalization and severe disease. Analyses were restricted to individuals of European descent when possible. Using inverse-weighted MR, genetically increased 25OHD levels by 1 standard deviation on the logarithmic scale had no significant association with COVID-19 susceptibility (odds ratio [OR] = 0.95; 95% CI 0.84, 1.08; p = 0.44), hospitalization (OR = 1.09; 95% CI: 0.89, 1.33; p = 0.41), and severe disease (OR = 0.97; 95% CI: 0.77, 1.22; p = 0.77). We used an additional 6 meta-analytic methods, as well as conducting sensitivity analyses after removal of variants at risk of horizontal pleiotropy, and obtained similar results. These results may be limited by weak instrument bias in some analyses. Further, our results do not apply to individuals with vitamin D deficiency. Conclusions In this 2-sample MR study, we did not observe evidence to support an association between 25OHD levels and COVID-19 susceptibility, severity, or hospitalization. Hence, vitamin D supplementation as a means of protecting against worsened COVID-19 outcomes is not supported by genetic evidence. Other therapeutic or preventative avenues should be given higher priority for COVID-19 randomized controlled trials., In a Mendelian randomization analysis, Guillaume Butler-Laporte, Tomoki Nakanishi, and colleages study genetic evidence for a relationship between vitamin D and COVID-19 outcomes., Author summary Why was this study done? Vitamin D levels have been associated with COVID-19 outcomes in multiple observational studies, though confounders are likely to bias these associations. By using genetic instruments that limit such confounding, Mendelian randomization studies have consistently obtained results concordant with vitamin D supplementation randomized trials. This provides a rationale to undertake vitamin D Mendelian randomization studies for COVID-19 outcomes. What did the researchers do and find? We used the genetic variants obtained from the largest consortium of COVID-19 cases and controls, and the largest study on genetic determinants of vitamin D levels. We used Mendelian randomization to estimate the effect of increased vitamin D on COVID-19 outcomes, while limiting confounding. In multiple analyses, our results consistently showed no evidence for an association between genetically predicted vitamin D level and COVID-19 susceptibility, hospitalization, or severe disease. What do these findings mean? Using Mendelian randomization to reduce confounding that has traditionally biased vitamin D observational studies, we did not find evidence that vitamin D supplementation in the general population would improve COVID-19 outcomes. These findings, together with recent randomized controlled trial data, suggest that other therapies should be prioritized for COVID-19 trials.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), a respiratory illness that can result in hospitalization or death. We used exome sequence data to investigate associations between rare genetic variants and seven COVID-19 outcomes in 586,157 individuals, including 20,952 with COVID-19. After accounting for multiple testing, we did not identify any clear associations with rare variants either exome wide or when specifically focusing on (1) 13 interferon pathway genes in which rare deleterious variants have been reported in individuals with severe COVID-19, (2) 281 genes located in susceptibility loci identified by the COVID-19 Host Genetics Initiative, or (3) 32 additional genes of immunologic relevance and/or therapeutic potential. Our analyses indicate there are no significant associations with rare protein-coding variants with detectable effect sizes at our current sample sizes. Analyses will be updated as additional data become available, and results are publicly available through the Regeneron Genetics Center COVID-19 Results Browser.

Variability in SARS-CoV-2 susceptibility and COVID-19 disease severity between individuals is partly due to genetic factors. Here, we identify 4 genomic loci with suggestive associations for SARS-CoV-2 susceptibility and 19 for COVID-19 disease severity. Four of these 23 loci likely have an ethnicity-specific component. Genome-wide association study (GWAS) signals in 11 loci colocalize with expression quantitative trait loci (eQTLs) associated with the expression of 20 genes in 62 tissues/cell types (range: 1:43 tissues/gene), including lung, brain, heart, muscle, and skin as well as the digestive system and immune system. We perform genetic fine mapping to compute 99% credible SNP sets, which identify 10 GWAS loci that have eight or fewer SNPs in the credible set, including three loci with one single likely causal SNP. Our study suggests that the diverse symptoms and disease severity of COVID-19 observed between individuals is associated with variants across the genome, affecting gene expression levels in a wide variety of tissue types., Graphical abstract, D’Antonio et al. characterize associations between GWAS signals for COVID-19 disease and eQTLs in 69 human tissues to identify causal variants and their underlying molecular mechanisms. They show that diverse symptoms and disease severity of COVID-19 are associated with variants affecting gene expression in a wide variety of tissues.

Summary Background: Vancomycin is often used as empiric therapy for methicillin-resistant Staphylococcus aureus (MRSA), but can be associated with clinically important adverse events including renal failure. MRSA colonization swabs are primarily used for infection control; their use as a diagnostic test to inform the decision to add empiric vancomycin therapy has not been well elucidated. Methods: We performed a Medline and Embase systematic review for peer-reviewed studies reporting the diagnostic accuracy of using MRSA colonization status to predict MRSA infections. Meta-analysis was performed using Cochrane guidelines. Grey literature was excluded. Findings: 29 studies were included involving 24225 patients. In cases where the pathogen is not known to be S. aureus, specificities were greater than 85% for bacteremia, lower respiratory tract infections, skin and soft tissue infections (SSTI), and all infections pooled together. Sensitivities ranged between 54.0% and 77.5%. In cases where the pathogen is known to be S. aureus, we found studies on bacteremia and SSTI and arrived at pooled estimates of sensitivities ranging between 56.6% and 56.9%, and of specificities greater than 91%. Most importantly, for most infections in settings where the prevalence of MRSA as a causative organism is below 15%, the negative predictive value of a negative MRSA colonization swab exceeds 90%. Interpretations: In settings of low-moderate MRSA prevalence, negative MRSA screening swabs may prevent unnecessary vancomycin use. More research is needed to assess if this strategy can mitigate the cost of screening in areas with a low MRSA colonization rate.

Background & objectives The echinocandins, amphotericin B preparations, voriconazole, and fluconazole are approved for the treatment of invasive candidiasis, though it remains unclear which agent is most effective. In order to answer this question, we performed a systematic review and network meta-analysis of the randomized controlled trials (RCT) which evaluated these agents in comparison. Methods Four electronic databases were searched from database inception to October 8, 2020. RCTs comparing triazoles, echinocandins, or amphotericin B for the treatment of invasive candidiasis or candidemia were included. Random effect Bayesian network meta-analysis methods were used to compare treatment outcomes. Results Thirteen RCTs met inclusion criteria. Of the 3528 patients included from these trials, 1531 were randomized to receive an echinocandin, 944 to amphotericin B, and 1053 to a triazole. For all forms of invasive candidiasis, echinocandins were associated with the highest rate of treatment success when compared to amphotericin B (OR 1.41, 95% CI 1.04 - 1.92) and the triazoles (OR 1.82, 95% CI 1.35 - 2.51). Rank probability analysis favoured echinocandins as the most effective choice 98% of the time. Overall survival did not significantly differ between groups. Conclusions Among patients with invasive candidiasis, echinocandins had the best clinical outcomes and should remain the first-line agents in the treatment of invasive candidiasis.

Despite advances in COVID-19 management, it is unclear how to recognize patients who evolve towards death. This would allow for better risk stratification and targeting for early interventions. However, the explosive increase in correlates of COVID-19 severity complicates biomarker prioritisation. To identify early biological predictors of mortality, we performed an immunovirological assessment (SARS-CoV-2 viral RNA, cytokines and tissue injury markers, antibody responses) on plasma samples collected from 144 hospitalised COVID-19 patients 11 days after symptom onset and used to test models predicting mortality within 60 days of symptom onset. In the discovery cohort (n=61, 13 fatalities), high SARS-CoV-2 vRNA, low RBD-specific IgG levels, low SARS-CoV-2-specific antibody-dependent cellular cytotoxicity, and elevated levels of several cytokines and lung injury markers were strongly associated with increased mortality in the entire cohort and the subgroup on mechanical ventilation. Model selection revealed that a three-variable model of vRNA, age and sex was very robust at identifying patients who will succumb to COVID-19 (AUC=0.86, adjusted HR for log-transformed vRNA=3.5; 95% CI: 2.0-6.0). This model remained robust in an independent validation cohort (n=83, AUC=0.85). Quantification of plasma SARS-CoV-2 RNA can help understand the heterogeneity of disease trajectories and identify patients who may benefit from new therapies.

A locus containing OAS1/2/3 has been identified as a risk locus for severe COVID-19 among Europeans ancestry individuals, with a protective haplotype of ∼75 kilobases derived from Neanderthals. Here, we show that among several potentially causal variants at this locus, a splice variant of OAS1 occurs in people of African ancestry independently of the Neanderthal haplotype and confers protection against COVID-19 of a magnitude similar to that seen in individuals without African ancestry.

Importance Nasopharyngeal swab nucleic acid amplification testing (NAAT) is the noninvasive criterion standard for diagnosis of coronavirus disease 2019 (COVID-19). However, it requires trained personnel, limiting its availability. Saliva NAAT represents an attractive alternative, but its diagnostic performance is unclear. Objective To assess the diagnostic accuracy of saliva NAAT for COVID-19. Data Sources In this systematic review, a search of the MEDLINE and medRxiv databases was conducted on August 29, 2020, to find studies of diagnostic test accuracy. The final meta-analysis was performed on November 17, 2020. Study Selection Studies needed to provide enough data to measure salivary NAAT sensitivity and specificity compared with imperfect nasopharyngeal swab NAAT as a reference test. An imperfect reference test does not perfectly reflect the truth (ie, it can give false results). Studies were excluded if the sample contained fewer than 20 participants or was neither random nor consecutive. The Quality Assessment of Diagnostic Accuracy Studies 2 tool was used to assess the risk of bias. Data Extraction and Synthesis Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guideline was followed for the systematic review, with multiple authors involved at each stage of the review. To account for the imperfect reference test sensitivity, we used a bayesian latent class bivariate model for the meta-analysis. Main Outcomes and Measures The primary outcome was pooled sensitivity and specificity. Two secondary analyses were performed: one restricted to peer-reviewed studies, and a post hoc analysis limited to ambulatory settings. Results The search strategy yielded 385 references, and 16 unique studies were identified for quantitative synthesis. Eight peer-reviewed studies and 8 preprints were included in the meta-analyses (5922 unique patients). There was significant variability in patient selection, study design, and stage of illness at which patients were enrolled. Fifteen studies included ambulatory patients, and 9 exclusively enrolled from an outpatient population with mild or no symptoms. In the primary analysis, the saliva NAAT pooled sensitivity was 83.2% (95% credible interval [CrI], 74.7%-91.4%) and the pooled specificity was 99.2% (95% CrI, 98.2%-99.8%). The nasopharyngeal swab NAAT had a sensitivity of 84.8% (95% CrI, 76.8%-92.4%) and a specificity of 98.9% (95% CrI, 97.4%-99.8%). Results were similar in secondary analyses. Conclusions and Relevance These results suggest that saliva NAAT diagnostic accuracy is similar to that of nasopharyngeal swab NAAT, especially in the ambulatory setting. These findings support larger-scale research on the use of saliva NAAT as an alternative to nasopharyngeal swabs.

A recent report found that rare predicted loss-of-function (pLOF) variants across 13 candidate genes in TLR3- and IRF7-dependent type I IFN pathways explain up to 3.5% of severe COVID-19 cases. We performed whole-exome or whole-genome sequencing of 1,934 COVID-19 cases (713 with severe and 1,221 with mild disease) and 15,251 ancestry-matched population controls across four independent COVID-19 biobanks. We then tested if rare pLOF variants in these 13 genes were associated with severe COVID-19. We identified only one rare pLOF mutation across these genes amongst 713 cases with severe COVID-19 and observed no enrichment of pLOFs in severe cases compared to population controls or mild COVID-19 cases. We find no evidence of association of rare loss-of-function variants in the proposed 13 candidate genes with severe COVID-19 outcomes.

Background There has been uncertainty about the safety or benefit of angiotensin-converting enzyme (ACE) inhibitors during the COVID-19 pandemic. We used Mendelian randomization using genetic determinants of serum-ACE levels to test whether decreased ACE levels increase susceptibility to SARS-CoV-2 infection or COVID-19 severity, while reducing potential bias from confounding and reverse causation in observational studies. Methods Genetic variants strongly associated with ACE levels, which were nearby the ACE gene, were identified from the ORIGIN trial and a separate genome-wide association study (GWAS) of ACE levels from the AGES cohort. The ORIGIN trial included 4147 individuals of European and Latino ancestries. Sensitivity analyses were performed using a study of 3200 Icelanders. Cohorts from the COVID-19 Host Genetics Initiative GWAS of up to 960 186 individuals of European ancestry were used for COVID-19 susceptibility, hospitalization and severe-disease outcome. Results Genetic variants were identified that explain between 18% and 37% of variance in ACE levels. Using genetic variants from the ORIGIN trial, a standard-deviation decrease in ACE levels was not associated with an increase in COVID-19 susceptibility [odds ratio (OR): 1.02, 95% confidence interval (CI): 0.90, 1.15], hospitalization (OR: 0.86, 95% CI: 0.68, 1.08) or severe disease (OR: 0.74, 95% CI: 0.51, 1.06). Using genetic variants from the AGES cohort, the result was similar for susceptibility (OR: 0.98, 95% CI: 0.89, 1.09), hospitalization (OR: 0.86, 95% CI: 0.66, 1.11) and severity (OR: 0.75, 95% CI: 0.50, 1.14). Multiple-sensitivity analyses led to similar results. Conclusion Genetically decreased serum ACE levels were not associated with susceptibility to, or severity of, COVID-19 disease. These data suggest that individuals taking ACE inhibitors should not discontinue therapy during the COVID-19 pandemic.

Background Invasive aspergillosis (IA) is a rare but highly lethal complication after orthotopic liver transplantation (OLT). Targeted antifungal prophylaxis has been proposed as a strategy to prevent IA among orthotopic liver transplant recipient (OLTr), but limited data is available to support its efficacy. Method We conducted a single center, retrospective, before and after cohort study, comparing IA incidences among OLTr who did not receive antifungal prophylaxis after transplantation (cohort 1) to OLTr who received targeted antifungal prophylaxis after liver transplantation (cohort 2). Patients in cohort 2 received caspofungin prophylaxis if they presented one of the following risk factors: retransplantation, acute liver failure, dialysis or Aspergillus colonization prior to transplantation. The primary outcome was IA at 90 days after transplantation. Results A total of 391 OLTr were included in the study; 181 patients in the cohort 1 (no prophylaxis) and 210 patients in the cohort 2 (targeted prophylaxis). Among patients in cohort 2, 19% (40/ 210) were considered at high risk for IA and 85% (34/40) of those received caspofungin prophylaxis. The incidence of IA at 90 days was 3.3% (6/ 181) and 0.5% (1/ 210), in cohort 1 and 2 respectively (OR 0.14; 95%CI 0.01-0.83; P= 0.03). Ninety-day mortality was similar among the two cohorts (3.9% (7/181) and 2.4% (5/210) in cohort 1 and 2, respectively (OR 0.61; 95% 0.18-1.93; P=0.40)). The 90-day mortality among the OLTs with IA was 71% (5/7). Conclusion Targeted caspofungin prophylaxis was associated with lower rate of IA.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) causes coronavirus disease-19 (COVID-19), a respiratory illness that can result in hospitalization or death. We investigated associations between rare genetic variants and seven COVID-19 outcomes in 543,213 individuals, including 8,248 with COVID-19. After accounting for multiple testing, we did not identify any clear associations with rare variants either exome-wide or when specifically focusing on (i) 14 interferon pathway genes in which rare deleterious variants have been reported in severe COVID-19 patients; (ii) 167 genes located in COVID-19 GWAS risk loci; or (iii) 32 additional genes of immunologic relevance and/or therapeutic potential. Our analyses indicate there are no significant associations with rare protein-coding variants with detectable effect sizes at our current sample sizes. Analyses will be updated as additional data become available, with results publicly browsable athttps://rgc-covid19.regeneron.com.

Proteins detectable in peripheral blood may influence COVID-19 susceptibility or severity. However, understanding which circulating proteins are etiologically involved is difficult because their levels may be influenced by COVID-19 itself and are also subject to confounding factors. To identify circulating proteins influencing COVID-19 susceptibility and severity we undertook a large-scale two-sample Mendelian randomization (MR) study, since this study design can rapidly scan hundreds of circulating proteins and reduces bias due to reverse causation and confounding. We identified genetic determinants of 931 circulating proteins in 28,461 SARS-CoV-2 uninfected individuals, retaining only single nucleotide polymorphism near the gene encoding the circulating protein. We found that a standard deviation increase in OAS1 levels was associated with reduced COVID-19 death or ventilation (N = 4,336 cases / 623,902 controls; OR = 0.54, P = 7×10−8), COVID-19 hospitalization (N = 6,406 / 902,088; OR = 0.61, P = 8×10−8) and COVID-19 susceptibility (N = 14,134 / 1,284,876; OR = 0.78, P = 8×10−6). Results were consistent in multiple sensitivity analyses. We then measured OAS1 levels in 504 patients with repeated plasma samples (N=1039) with different COVID-19 outcomes and found that increased OAS1 levels in a non-infectious state were associated with protection against very severe COVID-19, hospitalization and susceptibility. Further analyses suggested that a Neanderthal isoform of OAS1 affords this protection. Thus, evidence from MR and a case-control study supported a protective role for OAS1 in COVID-19 outcomes. Available medicines, such as phosphodiesterase-12 inhibitors, increase OAS1 and could be explored for their effect on COVID-19 susceptibility and severity.

Differentiating cellulitis from pseudocellulitis is challenging, and misdiagnosis leads to unnecessary antimicrobial use and increased healthcare expenditure. Clinical diagnosis remains the criterion standard and may involve expert consultation. Our objective was to evaluate the usefulness of a handheld infrared thermometer to improve diagnostic certainty in cases of suspected cellulitis.We conducted a cross-sectional study from August 2018 to January 2020 at a tertiary-care hospital in Montreal, Canada. We enrolled adult patients with suspected limb cellulitis. Using the infrared thermometer, we compared the average temperature of the affected area with that of the contralateral limb, and we used Youden's method to determine the optimal temperature difference which best differentiated cellulitis from pseudocellulitis as determined by an independent and blinded infectious diseases specialist. We used bootstrapping to estimate 95% confidence intervals for the sensitivity, specificity, and area under the receiver operating curve.Of 65 patients screened for enrolment, 52 patients were recruited (median age: 64 years, IQR 52-76); 39 of these were diagnosed with cellulitis and 13 were not. The mean temperature difference between affected and unaffected limbs was 2.6°C (95%CI 2.1-3.1°C) for patients with cellulitis and 0.4°C (95%CI -1.2°C to 2.1°C) for patients without (p 0.001). An average temperature difference between limbs of 0.8°C or more was 95% sensitive (95%CI 74-100%) and 69% specific (95%CI 44-95%) for the diagnosis of cellulitis (c-statistic 0.82).In this proof-of-concept single-centre study, a handheld infrared thermometer was a useful aid to differentiate cellulitis from pseudocellulitis.

Background Infectious diseases are causally related to a large array of noncommunicable diseases (NCDs). Identifying genetic determinants of infections and antibody-mediated immune responses may shed light on this relationship and provide therapeutic targets for drug and vaccine development. Methods We used the UK biobank cohort of up to 10 000 serological measurements of infectious diseases and genome-wide genotyping. We used data on 13 pathogens to define 46 phenotypes: 15 seropositivity case–control phenotypes and 31 quantitative antibody measurement phenotypes. For each of these, we performed genome-wide association studies (GWAS) using the fastGWA linear mixed model package and human leukocyte antigen (HLA) classical allele and amino acid residue associations analyses using Lasso regression for variable selection. Results We included a total of 8735 individuals for case–control phenotypes, and an average (range) of 4286 (276–8555) samples per quantitative analysis. Fourteen of the GWAS yielded a genome-wide significant (P, Using the UK Biobank cohort, we performed genome-wide association studies on 31 antibodies to 13 human pathogens known to be involved in non-communicable diseases. Our study highlights the important role of the HLA region in infectious disease immunity.

Background The effect of participation in a clinical trial on concomitant off-study investigational drug use has not been described. We sought to determine if participation in the Daptomycin as Adjunctive Therapy for Staphylococcus aureus bacteremia (DASH) trial increased overall daptomycin prescribing at study sites. Methods We retrospectively analyzed daptomycin use for 8 years preceding the trial, off-study daptomycin use during the trial itself (31 months), and daptomycin use for 6 fiscal months after trial completion. We used a segmented linear regression analysis of an interrupted time series to analyze changes in each drug’s defined daily doses (DDD) per 1000 patient-days. As a control, we analyzed use of linezolid over these periods and also accounted for rates of methicillin-resistant S. aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) infections. Results For 1.5 years before the DASH trial, daptomycin use was decreasing by –0.30 DDD per 1000 patient-days per fiscal period (95% CI, –0.52 to –0.07). Following the initiation of the study, there was a statistically significant increase in daptomycin use of 0.28 DDD per 1000 patient-days per fiscal period (95% CI, 0.03 to 0.52), despite low, stable rates of MRSA and VRE infections. Following trial completion, daptomycin use decreased back toward prestudy rates. Use of linezolid remained stable throughout. Conclusions Despite the DASH trial being a negative study, it impacted the prescribing habits of local clinicians during recruitment. Trialists should be aware of potential off-target study effects, and prescribers should be wary of early uptake of interventions before definitive study results., We performed a randomized controlled trial on adjunctive daptomycin in S. aureus bacteremia. Without external funding or advertisement, and despite showing no benefits to daptomycin, we noticed a clear change in off-study daptomycin use in our hospital during the trial.