Masked face recognition with BF-FaceNet and multi-view features (preprint)

Wearing masks in accordance with scientific guidelines is the most economically-effective protective measure for preventing respiratory diseases, such as COVID-19 and influenza, by interrupting viral transmission and safeguarding one's own health. In fact, researchers found that wearing masks can effectively reduce the infection rate of COVID-19 by 65%. However, this brings great inconvenience to face recognition, and human face recognition accuracy under occlusion conditions is low. Therefore, this paper proposes masked face recognition with BF-FaceNet and multi-view features. Firstly, in order to extract fine-grained features of the face region, ResNet50 is replaced by BoTNet as the backbone network of FaceNet. Secondly, a non-masked map is generated to accurately locate the non-masked area. Meanwhile, the face attention augmentation model (FAAM) is designed to extract local face features of the non-masked map. Thirdly, by combining loss function Ltriplet with Lattention, joint loss function Lface is proposed to improve the accuracy of masked recognition. Finally, experimental results on the publicly-available masked face dataset, SMFRD, demonstrate a significant improvement in recognition accuracy using our proposed algorithm compared to other methods.

Emerging role of mesenchymal stem/stromal cells (MSCs) and MSCs-derived exosomes in bone- and joint-associated musculoskeletal disorders: a new frontier.

Exosomes are membranous vesicles with a 30 to 150 nm diameter secreted by mesenchymal stem/stromal cells (MSCs) and other cells, such as immune cells and cancer cells. Exosomes convey proteins, bioactive lipids, and genetic components to recipient cells, such as microRNAs (miRNAs). Consequently, they have been implicated in regulating intercellular communication mediators under physiological and pathological circumstances. Exosomes therapy as a cell-free approach bypasses many concerns regarding the therapeutic application of stem/stromal cells, including undesirable proliferation, heterogeneity, and immunogenic effects. Indeed, exosomes have become a promising strategy to treat human diseases, particularly bone- and joint-associated musculoskeletal disorders, because of their characteristics, such as potentiated stability in circulation, biocompatibility, low immunogenicity, and toxicity. In this light, a diversity of studies have indicated that inhibiting inflammation, inducing angiogenesis, provoking osteoblast and chondrocyte proliferation and migration, and negative regulation of matrix-degrading enzymes result in bone and cartilage recovery upon administration of MSCs-derived exosomes. Notwithstanding, insufficient quantity of isolated exosomes, lack of reliable potency test, and exosomes heterogeneity hurdle their application in clinics. Herein, we will deliver an outline respecting the advantages of MSCs-derived exosomes-based therapy in common bone- and joint-associated musculoskeletal disorders. Moreover, we will have a glimpse the underlying mechanism behind the MSCs-elicited therapeutic merits in these conditions.

Impact of the Covid-19 pandemic on inpatient health care in Switzerland – a retrospective study using admission data of all Swiss hospitals (preprint)

Background: As part of the Covid-19-restrictions in Switzerland, a federal ban on non-urgent examinations and treatments was applied to all hospitals during six weeks in spring 2020 (“spring lockdown”). The aim of this study was to comprehensively investigate the consequences of the Covid-19 pandemic on Swiss inpatient admissions based on data of all hospitals, focusing on selected procedures of different medical urgency.  Methods: The study includes all acute care inpatient cases (including Covid-19 cases, excluding cases in psychiatry and rehabilitation) according to the Swiss Medical Statistics of Hospitals. Besides the total number of admissions, subdivided by regions, hospital types and age groups, we focused on selected procedures representing different medical urgency: elective surgeries, cancer surgeries, and emergencies. Procedures were selected based on expert interviews. We compared the number of admissions during spring lockdown and for the whole years 2020 and 2021 in absolute numbers and in percentage changes to the corresponding periods in 2019 (baseline year).  Results: During spring lockdown, the number of admissions decreased by 47,156 (32.2%) without catch-up effect by the end of 2020 (-72,817 admissions/-5.8%). With procedure-specific decreases of up to 86%, the decline in admissions was largest for elective surgery, a decline that was only fully reversed in the case of a few procedures, such as joint arthroplasty. Strikingly, admissions due to emergencies also substantially decreased during spring lockdown (stroke -14%; acute myocardial infarction STEMI: -9%, NSTEMI: -26%). Results for the selected procedures in cancer surgery showed no consistent pattern. In 2021, admission numbers for most procedures reached or even exceeded those in 2019.  Conclusions: The substantial reduction in admissions, particularly in elective procedures, may reflect the impact of the triage in favor of anticipated Covid-19-cases during spring lockdown. By the end of 2020, admissions were still at lower levels relative to the previous, pre-pandemic year. The numbers in 2021 reached the same levels as those in 2019, which suggests that the Covid-19 pandemic only temporarily impacted inpatient health care in Switzerland. Long-term consequences of the observed reduction in admissions for emergencies and cancer surgery need to be investigated at the individual level.

N1-methylpseudouridine-incorporated mRNA enhances exogenous protein expression and suppresses immunogenicity in primary human fibroblast-like synoviocytes (preprint)

Studies conducted using murine arthritis models have indicated that the use of in vitro -transcribed messenger RNA (IVT mRNA) is an effective therapeutic approach for joint diseases. However, the use of IVT mRNA in human synovial cells has not been widely studied. Recently, the outbreak of the novel coronavirus disease has accelerated the development of innovative mRNA vaccines such as those containing a modified nucleic acid, N 1 -methylpseudouridine-5′-triphosphate (m1ψ). IVT mRNA is an attractive tool for biological experiments and drug discovery. To verify the protein expression of IVT mRNA in vitro , primary cultured human fibroblast-like synoviocytes (FLS) were transfected with enhanced green fluorescent protein (EGFP) mRNA with or without m1ψ incorporation. EGFP was detected using western blotting and fluorescence microscopy. A multiplex assay was performed to comprehensively understand IVT mRNA-induced immunogenicity. FLS transfected EGFP mRNA containing m1ψ generated higher levels of EGFP than unmodified EGFP mRNA or control RNAs. The multiplex assay of the FLS culture supernatant revealed that concentrations of IL-6, TNF-α, and CXCL10 were upregulated by unmodified EGFP mRNA, whereas they were suppressed by EGFP mRNA with m1ψ. Overall, m1ψ incorporation enhanced protein expression and decreased cytokine expressions in primary cultured FLS. The findings may contribute to arthritis research.

COVID-19 in patients with chronic inflammatory rheumatic joint disease. / Covid-19 hos pasienter med kronisk inflammatorisk leddsykdom.

BACKGROUND: Since patients with chronic inflammatory rheumatic joint diseases may be more prone to infections, we wished to investigate the incidence of COVID-19 in this group, and explore the possible significance of factors related to the rheumatic disease, the patient or the treatment. MATERIAL AND METHOD: Altogether 27 907 patients registered in the Norwegian Arthritis Registry (NorArthritis) were linked to the Norwegian Surveillance System for Communicable Diseases and the Norwegian Intensive Care and Pandemic Registry in order to find the incidence of COVID-19 in 2020, and the proportion of patients who were hospitalised. A standardised incidence ratio (SIR) was calculated by comparing with sex and age-specific incidence in the general population. Logistic regression analysis was used to investigate whether diagnosis, age, sex, disease activity, comorbidity or drug therapy had any bearing on the incidence. RESULTS: A total of 185 of the patients in NorArthritis tested positive for COVID-19, of whom 10 % were hospitalised. The incidence was lower than in the general population (SIR 0.84; 95 % confidence interval (CI): 0.72-0.97, P = 0.02). Young age and low disease activity were associated with higher incidence of infection. The other factors had no significant effect. INTERPRETATION: The fact that the incidence of COVID-19 was lower than in the general population, and that within the group it was lower in those with moderate/high disease activity and greater age, is most likely attributable to patients of advanced age with chronic active disease having protected themselves against infection to a greater degree.

Risk of severe COVID-19 outcomes associated with immune-mediated inflammatory diseases and immune modifying therapies: a nationwide cohort study in the OpenSAFELY platform (preprint)

BackgroundIt is unclear if people with immune-mediated inflammatory diseases (IMIDs) (joint, bowel and skin) and on immune modifying therapy have increased risk of serious COVID-19 outcomes. MethodsWith the approval of NHS England we conducted a cohort study, using OpenSAFELY, analysing routinely-collected primary care data linked to hospital admission, death and previously unavailable hospital prescription data. We used Cox regression (adjusting for confounders) to estimate hazard ratios (HR) comparing risk of COVID-19-death, death/critical care admission, and hospitalisation (March to September 2020) in: 1) people with IMIDs compared to the general population; and 2) people with IMIDs on targeted immune modifying drugs (e.g., biologics) compared to standard systemic treatment (e.g., methotrexate). FindingsWe identified 17,672,065 adults; of 1,163,438 (7%) with IMIDs, 19,119 people received targeted immune modifying drugs, and 200,813 received standard systemics. We saw evidence of increased COVID-19-death (HR 1.23, 95%CI 1.20, 1.27), and COVID-19 hospitalisation (HR 1.32, 95%CI 1.29, 1.35) in individuals with IMIDs overall compared to individuals without IMIDs of the same age, sex, deprivation and smoking status. We saw no evidence of increased COVID-19 deaths with targeted compared to standard systemic treatments (HR 1.03, 95%CI 0.80, 1.33). There was no evidence of increased COVID-19-related death in those prescribed TNF inhibitors, IL-12/23, IL7, IL-6 or JAK inhibitors compared to standard systemics. Rituximab was associated with increased COVID-19 death (HR 1.68, 95%CI 1.11, 2.56); however, this finding may relate to confounding. InterpretationCOVID-19 death and hospitalisation was higher in people with IMIDs. We saw no increased risk of adverse COVID-19 outcomes in those on most targeted immune modifying drugs for IMIDs compared to standard systemics. RESEARCH IN CONTEXTO_ST_ABSEvidence before this studyC_ST_ABSWe searched PubMed on May 19th, 2021, using the terms "COVID-19", "SARS-CoV-2" and "rheumatoid arthritis", "psoriatic arthritis" "ankylosing spondylitis", "Crohns disease" "ulcerative colitis" "hidradenitis suppurativa" and "psoriasis", to identify primary research articles examining severe COVID-19 outcome risk in individuals with immune-mediated inflammatory diseases (IMIDs) and those on immune modifying therapy. The studies identified (including matched cohort studies and studies in disease-specific registries) were limited by small sample sizes and number of outcomes. Most studies did not show a signal of increased adverse COVID-19 outcomes in those on targeted therapies, with the exception of rituximab. Additionally, disease- specific registries are subject to selection bias and lack denominator populations. Added value of the studyIn our large population-based study of 17 million individuals, including 1 million people with IMIDs and just under 200,000 receiving immune modifying medications, we saw evidence that people with IMIDs had an increased risk of COVID-19-related death compared to the general population after adjusting for potential confounders (age, sex, deprivation, smoking status) (HR 1.23, 95%CI 1.20, 1.27). We saw differences by IMID type, with COVID-19-related death being increased by the most in people with inflammatory joint disease (HR 1.47, 95%CI 1.40, 1.54). We also saw some evidence that those with IMIDs were more likely, compared to the general population, to have COVID-19-related critical care admission/death (HR 1.24, 95%CI 1.21, 1.28) and hospitalisation (HR 1.32, 95%CI 1.29, 1.35). Compared to people with IMIDs taking standard systemics, we saw no evidence of differences in severe COVID-19-related outcomes with TNF inhibitors, IL-17 inhibitors, IL-12/23 inhibitors, IL-6 inhibitors and JAK inhibitors. However, there was some evidence that rituximab was associated with an increased risk of COVID-19-related death (HR 1.68, 95%CI 1.11, 2.56) and death/critical care admission (HR 1.92, 95%CI 1.31, 2.81). We also saw evidence of an increase in COVID-19-related hospital admissions in people prescribed rituximab (HR 1.59, 95%CI 1.16, 2.18) or JAK inhibition (HR 1.81, 95%CI 1.09, 3.01) compared to those on standard systemics, although this could be related to worse underlying health rather than the drugs themselves, and numbers of events were small. This is the first study to our knowledge to use high-cost drug data on medicines supplied by hospitals at a national scale in England (to identify targeted therapies). The availability of these data fills an important gap in the medication record of those with more specialist conditions treated by hospitals creating an important opportunity to generate insights to these conditions and these medications Implications of all of the available evidenceOur study offers insights into future risk mitigation strategies and SARS-CoV-2 vaccination priorities for individuals with IMIDs, as it highlights that those with IMIDs and those taking rituximab may be at risk of severe COVID-19 outcomes. Critically, our study does not show a link between most targeted immune modifying medications compared to standard systemics and severe COVID-19 outcomes. However, the increased risk of adverse COVID-19 outcomes that we saw in people with IMIDs and those treated with rituximab merits further study.

Associations of Health, Lifestyle and Psycho-Social Factors With Sleep Quality During the Early Phase of the COVID-19 Pandemic: A Focus on UK Older Adults Deemed Clinically Extremely Vulnerable (preprint)

Background: Sleep quality is crucial for health and wellbeing in all ages and sleep abnormalities may contribute to multimorbidity in older adults. The impact of pandemic-related disruptions to sleep quality in older adults, particularly those deemed “clinically extremely vulnerable” to COVID-19-related complications (COVID-19CEV) remains unknown.Methods: In this cross-sectional study, conducted during the first UK lockdown (April- June 2020), we surveyed 5558 adults aged 50 years and over (of whom 523 met criteria for COVID-19CEV) with assessments of sleep quality, health/medical, lifestyle, psychosocial and sociodemographic factors. We identified associations between these factors and sleep quality and explored interactions of COVID-19CEV status with factors significantly associated with sleep quality to identify potential moderating variables.Findings: 37% of participants reported poor sleep quality which was associated with younger age, female sex and multimorbidity. Significant associations with poor sleep included, among health/medical factors: COVID-19CEV status, higher BMI, arthritis, pulmonary disease, and mental health disorders; .and the following lifestyle and psychosocial factors: living alone, higher alcohol consumption, an unhealthy diet and higher depressive and anxiety symptoms. r Moderators of the COVID-19CEV status - sleep quality relationship included marital status, loneliness, anxiety and diet. Within this subgroup, less anxious and less lonely males, as well as females with healthier diets, reported better sleep quality. Interpretation: Sleep quality in older adults was compromised during the sudden unprecedented nation-wide lockdown due to distinct health/medical, lifestyle and psychosocial factors. Male and female older adults with COVID-19CEV status may benefit from targeted mental health and dietary interventions, respectively. Results inform tailored interventions and policy for older adults deemed COVID-19CEV. Funding Information: This study was sponsored by Imperial College London and partly funded by the ICHT BRC.Declaration of Interests: Dr. Middleton reports clinical trial grants from Janssen R&D, Novartis and Takeda outside the submitted work. All authors declare no competing interests related to this study.Ethics Approval Statement: Data collected as in this study are anonymized and kept strictlyconfidential in accordance with the UK General Data Protection Regulations (2016). The CCRR study was ethically approved by the Imperial College London Joint Research Compliance Office (20IC5942) and by the Health Research Authority (16/EM/0213).

Appropriateness for SARS-CoV-2 Vaccination for Otolaryngologist and Head and Neck Surgeons in case of Pregnancy, Breastfeeding or Childbearing potential: YO-IFOS and CEORL-HNS joint clinical consensus statement (preprint)

Purpose: SARS-CoV-2 vaccines are a key step in fighting the pandemic. Nevertheless, their rapid development did not allow for testing among specific population subgroups such as pregnant and breastfeeding women, or elaborating specific guidelines for healthcare personnel working in high infection risk specialties, such as otolaryngology (ORL). This clinical consensus statement (CCS) aims to offer guidance for SARS-CoV-2 vaccination to this high-risk population based on the best evidence available. Methods: : A multidisciplinary international panel of 33 specialists judged statements through a 2-rounds modified Delphi method survey. Statements were designed to encompass the following topics: risk of SARS-Cov-2 infection and use of protective equipment in ORL; SARS-Cov-2 infection and vaccines and respective risks for the mother/child dyad; and counseling for SARS-CoV-2 vaccination in pregnant, breastfeeding, or fertile healthcare workers (PBFHW). All ORL PBFHW were considered as the target audience. Results: : Of the 13 statements, 7 reached consensus or strong consensus, 2 reached noConsensus and 2 reached near-consensus. According to the statements with strong consensus Otorhinolaryngologists – Head & Neck Surgeons who are pregnant, breastfeeding or with childbearing potential should have the opportunity to receive SARS-Cov-2 vaccination. Moreover, personal protective equipment (PPE) should still be used even after the vaccination. Conclusion: Until prospective evaluations on these topics are available, ORL-HNS must be considered a high infection risk specialty. While the use of PPE remains pivotal, ORL PBFHW should be allowed access to SARS-CoV-2 vaccination provided they receive up-to-date information.

Estimation of SARS-CoV-2 antibody prevalence through integration of serology and incidence data (preprint)

Serology tests for SARS-CoV-2 provide a paradigm for estimating the number of individuals who have had infection in the past (including cases that are not detected by routine testing, which has varied over the course of the pandemic and between jurisdictions). Classical statistical approaches to such estimation do not incorporate case counts over time, and may be inaccurate due to uncertainty about the sensitivity and specificity of the serology test. In this work, we provide a joint Bayesian model for case counts and serological data, integrating uncertainty through priors on the sensitivity and specificity. We also model the Phases of the pandemic with exponential growth and decay. This model improves upon maximum likelihood estimates by conditioning on more data, and by taking into account the epidemiological trajectory. We apply our model to the greater Vancouver area, British Columbia, Canada with data acquired during Phase 1 of the pandemic.

Risk-mitigating behaviours in people with inflammatory skin and joint disease during the COVID-19 pandemic differ by treatment type: a cross-sectional patient survey.

BACKGROUND: Registry data suggest that people with immune-mediated inflammatory diseases (IMIDs) receiving targeted systemic therapies have fewer adverse coronavirus disease 2019 (COVID-19) outcomes compared with patients receiving no systemic treatments. OBJECTIVES: We used international patient survey data to explore the hypothesis that greater risk-mitigating behaviour in those receiving targeted therapies may account, at least in part, for this observation. METHODS: Online surveys were completed by individuals with psoriasis (globally) or rheumatic and musculoskeletal diseases (RMDs) (UK only) between 4 May and 7 September 2020. We used multiple logistic regression to assess the association between treatment type and risk-mitigating behaviour, adjusting for clinical and demographic characteristics. We characterized international variation in a mixed-effects model. RESULTS: Of 3720 participants (2869 psoriasis, 851 RMDs) from 74 countries, 2262 (60·8%) reported the most stringent risk-mitigating behaviour (classified here under the umbrella term 'shielding'). A greater proportion of those receiving targeted therapies (biologics and Janus Kinase inhibitors) reported shielding compared with those receiving no systemic therapy [adjusted odds ratio (OR) 1·63, 95% confidence interval (CI) 1·35-1·97]. The association between targeted therapy and shielding was preserved when standard systemic therapy was used as the reference group (OR 1·39, 95% CI 1·23-1·56). Shielding was associated with established risk factors for severe COVID-19 [male sex (OR 1·14, 95% CI 1·05-1·24), obesity (OR 1·37, 95% CI 1·23-1·54), comorbidity burden (OR 1·43, 95% CI 1·15-1·78)], a primary indication of RMDs (OR 1·37, 95% CI 1·27-1·48) and a positive anxiety or depression screen (OR 1·57, 95% CI 1·36-1·80). Modest differences in the proportion shielding were observed across nations. CONCLUSIONS: Greater risk-mitigating behaviour among people with IMIDs receiving targeted therapies may contribute to the reported lower risk of adverse COVID-19 outcomes. The behaviour variation across treatment groups, IMIDs and nations reinforces the need for clear evidence-based patient communication on risk-mitigation strategies and may help inform updated public health guidelines as the pandemic continues.

Incidence and case fatality rate of COVID-19 in patients with inflammatory articular diseases.

OBJECTIVE: To describe the incidence and fatality of coronavirus disease 2019 (COVID-19) and identify risk factors to fatality in patients with inflammatory articular diseases (IAD). METHODS: This is a cross-sectional observational study of IAD patients and COVID-19 with controls matched for age, sex, and RT-PCR. A control group was used to compare the cumulative incidence (CI) and case fatality rate (CFR). The main outcomes of the study were CI and CFR. Other variables included comorbidities, treatments, and characteristics of the COVID-19. Multiple logistic regression analysis was performed to investigate risk factors for fatality in patients with IAD. RESULTS: Of the 1537 patients who fulfilled the inclusion criteria, 23/1537 (1.49%) had IAD 13 (0.8%) had rheumatoid arthritis (RA), 5 psoriatic arthritis (PsA) (0.3%) and 5 axial spondyloarthritis (0.3%). There were no significant differences in CI of COVID-19 and CFR in patients with IAD compared with COVID-19 patients without IAD. In RT-PCR positive patients, the CI of COVID-19 in PsA and AS was higher. Of the 23 IAD patients, 2 RA patients (8.6%) died. The patients did no show characteristics of the COVID-19 disease different from the population. In multivariate analysis, the factor associated with fatality in patients with IAD was older age (OR [95% CI], 1.1 [1.0-1.2]). CONCLUSION: COVID-19 CI, fatality rate and other features do not seem to be increased in IAD patients. Older age was associated with fatality in patients with IAD.

Incidence and clinical course of COVID-19 in patients with rheumatologic diseases: A population-based study.

OBJECTIVES: Patients with rheumatologic diseases might be more susceptible to COVID-19 and carry a poorer prognosis. The aim of this study is to examine the incidence and outcomes of all COVID-19 patients with rheumatologic conditions in Hong Kong. METHODS: This is a population-based retrospective study. All patients tested positive for SARS-CoV-2 by PCR with a previous diagnosis of rheumatologic diseases were reviewed. The incidence of COVID-19 in patients with rheumatologic conditions was calculated and compared to the general population in Hong Kong. Descriptive data of those rheumatologic patients with COVID-19 and the clinical course of the index infection were presented. RESULTS: Up till 27 May 2020, there were 1067 cases of COVID-19 diagnosed in Hong Kong which had a population of 7.5 million. Out of the 39,835 patients with underlying rheumatologic diseases, we identified 5 PCR confirmed COVID-19 cases. The estimated incidence of COVID-19 was 0.0126% patients with rheumatologic diseases, compared to 0.0142% in the general population. All 5 patients had inflammatory arthropathies. One patient was on hydroxychloroquine and sulphasalazine, and one was on methotrexate. None of the 3534 patients on b/tsDMARDs was infected. Four patients had leucopenia/lymphopenia and stool viral PCR was positive in 3 patients. All patients made uneventful recovery without complications or flare of underlying diseases. CONCLUSIONS: We found no alarming signals of increased frequency or severity of COVID-19 in patients with rheumatologic diseases, although extrapolation of the results to other populations with different infection control strategies should be made with caution.

Facemasks prevent influenza-like illness: implications for COVID-19 (preprint)

The coronavirus disease 2019 (COVID-19) pandemic is causing a huge toll on individuals, families, communities and societies across the world. Currently, whether wearing facemasks in public should be a measure to prevent transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) remains contraversial.1 This is largely because there have been no randomized controlled trials (RCTs) for coronavirus to directly support this. However, lessons may be taken from published RCTs examining influenza-like illness (ILI).2,3 Recent studies suggested that SARS-CoV-2 shares similar transmission route with influenza virus,4 and the incidence of community transmission of SARS-CoV-2 in individuals with ILI is high.5 Therefore, we undertook this meta-analysis of RCTs examining the efficacy of wearing facemasks to prevent ILI in community settings, irrespective of confirmatory testing for the causative virus. We undertook a systematic literature search for RCTs related to facemasks and ILI between 1966 and April 2020 using PUBMED, EMBASE, and Cochrane library. RCTs undertaken in community (not hospital) settings comparing wearing and not wearing facemasks for ILI were included. Incidence of ILI (e.g., fever, cough, headache, sore throat, aches or pains in muscles or joints) was estimated per group. Relative risk (RR) and 95% confidence interval (CI) were calculated. We screened 899 related abstracts and eventually included 8 RCTs (Figure S1). Basic characteristics and quality of included RCTs are listed in Supplement. Participants wearing facemasks had a significantly lower risk of developing ILI than those not wearing facemasks (pooled RR=0.81, 95% CI: 0.70-0.95) and there was no heterogeneity (Figure 1). The decreased risk of ILI was more pronounced if everyone wore facemask irrespective of whether they were infected or not (RR=0.77, 95% CI: 0.65-0.91), compared to those wearing facemasks when infected (RR=0.95, 95% CI: 0.58-1.56) or uninfected (RR=1.26, 95% CI: 0.69-2.31). This study shows that wearing facemasks, irrespective of infection status, is effective in preventing ILI spread in the community. This situation mirrors what is happening now in public settings where we do not know who has been infected and who has not. Although there are no RCTs of facemasks for SARS-CoV-2, as with other simple measures such as social distancing and handwashing, these data support the recommendation to wear facemasks in public to further reduce transmission of SARS-CoV-2 and flatten the curve of this pandemic, especially when social distancing is impractical, such as shopping, or travelling with public transport for work that cannot be done from home.