Validation of dried blood spot sampling for detecting SARS-CoV-2 antibodies and total immunoglobulins in a large cohort of asymptomatic young adults.

BACKGROUND: Detecting antibody responses following infection with SARS-CoV-2 is necessary for sero-epidemiological studies and assessing the role of specific antibodies in disease, but serum or plasma sampling is not always viable due to logistical challenges. Dried blood spot sampling (DBS) is a cheaper, simpler alternative and samples can be self-collected and returned by post, reducing risk for SARS-CoV-2 exposure from direct patient contact. The value of large-scale DBS sampling for the assessment of serological responses to SARS-CoV-2 has not been assessed in depth and provides a model for examining the logistics of using this approach to other infectious diseases. The ability to measure specific antigens is attractive for remote outbreak situations where testing may be limited or for patients who require sampling after remote consultation. METHODS: We compared the performance of SARS-CoV-2 anti-spike and anti-nucleocapsid antibody detection from DBS samples with matched serum collected by venepuncture in a large population of asymptomatic young adults (N = 1070) living and working in congregate settings (military recruits, N = 625); university students, N = 445). We also compared the effect of self-sampling (ssDBS) with investigator-collected samples (labDBS) on assay performance, and the quantitative measurement of total IgA, IgG and IgM between DBS eluates and serum. RESULTS: Baseline seropositivity for anti-spike IgGAM antibody was significantly higher among university students than military recruits. Strong correlations were observed between matched DBS and serum samples in both university students and recruits for the anti-spike IgGAM assay. Minimal differences were found in results by ssDBS and labDBS and serum by Bland Altman and Cohen kappa analyses. LabDBS achieved 82.0% sensitivity and 98.2% specificity and ssDBS samples 86.1% sensitivity and 96.7% specificity for detecting anti-spike IgGAM antibodies relative to serum samples. For anti-SARS-CoV-2 nucleocapsid IgG there was qualitatively 100% agreement between serum and DBS samples and weak correlation in ratio measurements. Strong correlations were observed between serum and DBS-derived total IgG, IgA, and IgM. CONCLUSIONS: This is the largest validation of DBS against paired serum for SARS-CoV-2 specific antibody measurement and we have shown that DBS retains performance from prior smaller studies. There were no significant differences regarding DBS collection methods, suggesting that self-collected samples are a viable sampling collection method. These data offer confidence that DBS can be employed more widely as an alternative to classical serology.

Correlation between post-vaccination titres of anti-Spike antibodies and protection against breakthrough SARSCoV-2 infection in 7530 UK adults

Background: A robust correlate of vaccine-induced protection against SARS-CoV-2 infection has yet to be found. Aim(s): To explore whether post-vaccination combined IgG, IgA, and IgM responses to the SARS-CoV-2 trimeric spike glycoprotein (anti-S IgGAM) can predict protection against breakthrough SARS-CoV-2 infection. Method(s): In this prospective population-based study, we used dried blood spots to determine post-vaccination anti-S IgGAM responses in SARS-CoV-2-vaccinated UK adults. Using receiver operating characteristic (ROC) curve analysis, we assessed the ability of anti-S IgGAM titres (adjusted for days since vaccination) to predict postvaccination incident SARS-CoV-2 infection. After adjusting for household and behavioural factors reflecting risk of SARS-CoV-2 exposure, we compared the area under the ROC curve (AUROC) between minimally and fully adjusted models. Finding(s): Between Jan 12, 2021, and Jan 31, 2022, 300 (4.0%) of 7530 participants reported a breakthrough SARS-CoV-2 infection during 18 weeks of follow-up (220 [4.4%] ChAdOx1 nCoV-19 [ChadOx1] recipients and 75 [3.1%] BNT162b2 recipients). Anti-S IgGAM titres were modestly predictive of breakthrough infection (overall: AUROC 0.582 [95% CI 0.550-0.614];ChAdOx1: 0.564 [0.526-0.602];BNT162b2: 0.562 [0.488-0.636]). Adjustment for exposure factors significantly improved discrimination (overall: 0.666 [0.633-0.699], p<0.0001;ChAdOx1: 0.656 [0.617-0.695], p<0.0001;BNT162b1: 0.709 [0.649-0.769], p=0.0012). Conclusion(s): Anti-S IgGAM titres correlate with protection against SARS-CoV-2 infection in vaccinated adults, but exposure factors contribute significantly to risk.

Determinants of pre-vaccination SARS-CoV-2 seropositivity: a population-based longitudinal study (COVIDENCE UK)

Background: Prospective population-based studies investigating multiple determinants of pre-vaccination antibody responses to SARS-CoV-2 are lacking. Aim(s): To study factors associated with SARS-CoV-2 seropositivity. Method(s): We did a prospective population-based study in SARS-CoV-2 vaccine-naive UK adults recruited from May to November 2020, without a positive swab test result for SARS-CoV-2 prior to enrolment. Information on 88 potential sociodemographic, behavioural, nutritional, clinical, and pharmacological risk factors was obtained through online questionnaires, and combined IgG/IgA/IgM responses to SARS-CoV-2 spike glycoprotein were determined in dried blood spots. Result(s): 1696 (15.2%) of 11,130 participants were seropositive. Factors independently associated with higher risk of seropositivity included frontline health/care occupation (adjusted OR 1.86, 95% CI 1.48-2.33), international travel (1.20, 1.07-1.35), number of visits to shops and other indoor public places (>=5 vs 0/week: 1.29, 1.06-1.57, Ptrend=0.01), BMI >=25 vs <25 kg/m2 (1.24, 1.11-1.39), South Asian vs White ethnicity (1.65, 1.10-2.49), alcohol consumption >=15 vs 0 units/week (1.23, 1.04-1.46), sex hormone therapy (1.25, 1.02-1.52), and use of vitamin D supplements (1.16, 1.03-1.30). Postgraduate degree (vs primary or secondary level: 0.82, 0.67-0.99), light physical exercise (0.80, 0.70-0.93, for >=10 vs 0-4 h/week), passive smoking (0.59, 0.37-0.95), and prescribed paracetamol use (0.70, 0.52-0.96) were independently associated with lower risk. Conclusion(s): Our findings confirm ethnic, occupational, and lifestyle determinants of SARS-CoV-2 seropositivity and identify additional risk factors.

Determinants of antibody responses to primary courses and booster doses of SARS-CoV-2 vaccines in 9,101 UK adults

Background: Antibody responses to SARS-CoV-2 vaccines vary for reasons that are poorly understood. AIM: To determine factors modifying antibody responses to SARS-CoV-2 vaccination. Method(s): We tested for anti-Spike (S) antibodies before and after 2 doses of ChAdOx1 or BNT162b2 given to UK adults December 2020-July 2021. Participant characteristics and outcomes were captured by online questionnaires. Logistic regression was used to estimate odds of seronegativity after vaccination. For those who were seronegative after 2 vaccine doses, repeat testing was offered following a booster dose of BNT162b2 or mRNA-1273. Result(s): Anti-S antibodies were undetectable in 378/9101 (4.2%) participants after 2 vaccine doses. Increased risk of post-vaccination seronegativity associated with administration of ChAdOx1 vs BNT162b2 (aOR 7.0, 95% CI 4.411.2), shorter interval between vaccine doses (aOR 1.6, 1.2-2.1, 6-10 vs >10 weeks), poor vs excellent general health (aOR 3.3, 1.5-7.5), immunodeficiency (aOR 6.8, 2.6-17.4) and immunosuppressant use (aOR 3.8, 2.4-5.8). Odds of seronegativity were lower for participants who were SARS-CoV-2 seropositive pre-vaccination (aOR 0.2, 0.0-0.7) and for those taking vitamin D supplements (aOR 0.7, 0.5-0.9). Of 247 participants who were seronegative following 2 vaccine doses, 8 (3.2%) remained seronegative post-booster: all were immunosuppressed. Conclusion(s): We identify multiple determinants of antibody responses to SARS-CoV-2 vaccines, many of which are modifiable. Booster doses of BNT162b2 or mRNA-1273 were highly effective in achieving seroconversion in those who failed to mount anti-S responses following two doses of ChAdOx1 or BNT162b2.

Is there an international right to truth in the post-truth world?

This article raises questions on the political and legal side of lies and truths: (1) is there a human right to (know) the truth? (2) Is there a human right to (dissemi-nate) lies? They are important issues today as the governments in too many parts of the world aim to suppress political voices by ostracizing and outlawing disinformation in communications and the media. So far this happens in the context of countering COVID-19 conspiracies and anti-vax movements, but generally designed to tackle any socially important information. On the other hand, the world indeed stands bewildered at the current outbursts of false news and the governments search for ways and means to diminish their social harm. The article provides a viewpoint for what the international law says on lies and truths in global affairs. © 2022 Intellect Ltd Viewpoint. English language.

Second SARS-CoV-2 Booster Vaccination Significantly Reduces Haemodialysis Patients' Susceptibility to Infection With Omicron Variant

Background: Patients requiring haemodialysis (HD) have disproportionately poorer outcomes from SARS-CoV-2 infection and vaccines afford an opportunity to improve this. However, the efficacy of booster doses on infection with emerging variants remains unclear in this population. Method(s): We report the real-world impact of SARS-CoV-2 booster vaccinations in an ethnically diverse urban cohort of 1172 patients receiving in-centre HD who were routinely screened for SARS-CoV-2 infection by weekly nasopharyngeal PCR between 1st December 2021 and 31st March 2022, during dominant UK prevalence of B.1.1.529 variant ("Omicron"). Where possible, genomic sequencing was performed as standard of care. Result(s): At the start of the observation period, 896 (76.5%) had received 3 doses of SARS-CoV-2 vaccine and only 87 (7.4%) were unvaccinated. By end of study 664 (59.5%) had received 4 vaccine doses. 305 patients had PCR positive SARS-CoV-2 infection, with Omicron variant confirmed in all but one of samples successfully tested. Clinical course of infection was mild: around half of patients asymptomatic, only 1 in 20 hospitalised, case fatality 3%. Three or more vaccine doses significantly associated with reduced risk of SARS-CoV-2 PCR positivity compared to unvaccinated status, together with White ethnicity and lower deprivation index (Cox regression p<0.03). However, 2 booster doses further reduced the risk of infection by around a third compared to 1 boost, independent of age, gender and comorbidity. Conclusion(s): A second SARS-CoV-2 booster vaccine further reduces the risk of Omicron infection in haemodialysis patients. As such, a double-boost policy could significantly reduce the burden and associated spread of SARS-CoV-2 infection in this vulnerable population.

Association between vitamin D deficiency and extended duration of COVID-19 symptoms

Introduction and ObjectivesVitamin D (VD) is involved in immunity and inflammation through mechanisms such as renin inhibition and inflammatory cytokine reduction. There is already evidence to suggest that VDD may increase COVID-19 infection susceptibility, however research assessing the impact of VDD on COVID-19 symptom duration is limited. The aim of this research was to determine whether VDD is a significant independent risk factor for extended durations of COVID-19 symptoms.MethodsThe study included 392 healthcare workers who isolated due to COVID-19 symptoms during the first wave of the pandemic (12th to 22nd May 2020) as part of the convalescent immunity (COCO) study. Data on 8 symptom types and duration of symptoms were collected, including patients’ demographics and co-morbidities. Anti-SARS-Cov-2 antibodies were measured using a combined IgG, IgA and IgM ELISA (The Binding Site). Vitamin D status was determined by measurement of serum 25(OH)D3 using the AB SCIEX Triple Quad 4500 mass spectrometry system. VDD was defined as serum 25(OH)D3 <30 nmol/L.ResultsThrough univariate analysis of VDD and non-VDD staff, we initially showed VDD to be significantly associated with longer durations of body aches (median 7 days, IQR 5–14 vs. median 5 days, IQR 3–7.5;p=0.0075) and fatigue (median 12 days, IQR 7–14 vs. median 7 days, IQR 4–14;p=0.0127). VDD did not influence the duration of the other 6 symptoms analysed, such as cough and fever. Using binary logistic regression models, we confirm that VDD is a significant independent risk factor for extended durations of fatigue (OR 2.089, 95% CI 1.087–4.011;p=0.027) and body aches (OR 3.069, 95% CI 1.538–6.124;p=0.001). Additionally, VDD staff experienced a significantly greater quantity of symptoms compared to non-VDD staff (median 5, IQR 4–7 versus median 4, IQR 3–6;p=0.0030).ConclusionsThis is one of the first studies to investigate the influence of VDD on COVID-19 symptom duration. Our results indicate that VDD is a significant independent risk factor for a longer duration of body aches and fatigue. Larger studies are required to confirm these results and determine if VD supplementation could shorten symptoms.

Rapid flow cytometric whole blood assay for assessment of SARS-CoV-2-reactive T cell immunity

As of November 2021, the viral pathogen severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causing the coronavirus disease 2019 (COVID-19), has infected more than 250 million individuals worldwide and killed over 5 million people. In addition to known risk groups, also cancer patients are at increased risk for severe disease progression. Therefore, understanding the nature of the accompanying immune response is essential, especially the role of T cells for successful virus defense but also during immunopathology leading to severe disease outcomes. Furthermore, as neutralizing antibodies are reported to decay within months post infection or vaccination or are even absent due to cancer treatment, SARS-CoV-2-specific T cell persistence is discussed as an indicator of long-term protective immunity. Especially, in immunocompromised cancer patients, levels of SARS-CoV-2-specifc antibodies may not be efficiently detected. Therefore, we developed a rapid and easy flow cytometric assay for the analysis of SARS-CoV-2-reactive CD4+ and CD8+ T cells directly from whole blood.

CLL-VR: A UK study of vaccine responses in patients with B-cell chronic lymphocytic leukaemia

B-cell chronic lymphocytic leukaemia (CLL) is associated with immune suppression and patients are at increased risk following SARS-CoV-2 infection. The Chronic Lymphocytic Leukaemia-Vaccine Response (CLL-VR) study was designed to assess immune responses following the introduction of Covid-19 vaccination in UK. Five hundred patients with CLL were recruited nationally through NHS and charity communications. Phlebotomy blood samples were taken from local patients ( n = 100) and dried blood spot samples were collected via post from participants across the UK ( n = 400). Ninety-six age-matched control subjects were also recruited locally. Samples were taken at 2-3 weeks following the first, second and third primary vaccine doses. Antibody and cellular responses against spike protein, and neutralising antibody titre to delta and omicron variant, were measured. Total serum immunoglobulin level was also determined. Responses were analysed according to clinical history, serum immunoglobulin level and vaccine type received. Donors with a clinical or serological history of prior natural infection were excluded from the analysis. Twenty percent (70/353) of participants developed a measurable antibody response after the first vaccination and this increased to 67% (323/486) following the second dose and 80% (202/254) after a third dose. The response rate in healthy controls plateaued at 100% after only two doses. The magnitude of the antibody response was also 3.7-fold lower following the second vaccine compared to controls ( n = 244;490 vs. 1821 U/ml, p < 0.0001) but increased markedly to 3114 U/ ml after third dose ( n = 51). No difference was observed in relation to the initial vaccine platform received. Multivariate analysis on 486 participants showed that BTKi therapy, history of recurrent infection and low serum antibody levels of IgA or IgM were independent prognostic markers for poor antibody response. Among participants with a detectable antibody response, a marked reduction in the ability to neutralise the delta and omicron variants of concern was noted compared to healthy controls following both the second and third dose of vaccine. Cellular responses were assessed following the second vaccine by IFN-g ELISPOT ( n = 91). Patients who had received the ChAdOx1 vaccine had similar levels to controls ( p = 0.39), while those who had received BNT162b2 had lower levels ( p < 0.0001). Five patients with poor spike-specific antibody responses to vaccination subsequently developed breakthrough infection with SARS-CoV-2 delta variant. Antibody responses and neutralisation remained poor following recovery from infection although T-cell responses were strong and only one patient required hospital admission. CLL-VR is the largest vaccine study conducted in patients with CLL and reveals diminished but comparable antibody responses to both the ChAdOx1 and BNT162b2 vaccines with some improvement following third primary dose of mRNA vaccine. In contrast T-cell responses following second dose are greater in those who received ChAdOx1 platform. Low neutralising activity against the delta and omicron variants highlights an ongoing risk for this vulnerable population despite repeated vaccination and reveals the need for alternative approaches to protection including prophylactic monoclonal antibody therapy..

Computer-Supported Cooperative Work - Revisited

Due to the COVID-19 lockdowns and the related mandated work for home, we have seen a massive increase of the use of collaboration tools in various work settings in the last 18 months. Whereas this might have been a new terrain for some, IT-supported work and the related research domain Computer-Supported Cooperative Work (CSCW) have been around for decades. In this article we briefly review what CSCW has to offer for the currently increasing demand in setting up remote collaboration - and share our own observations about what happened when collaboration tools have been introduced in the pandemic. As a summary, we present some learnings from the experience - both for the current state of CSCW research and for future work. © 2021 Bullinger-Hoffmann, published by De Gruyter.

Vaccine Efficacy after Rituximab Exposure: First Interim Analysis of Virtue Project on Behalf of West Midlands Research Consortium, UK

[Formula presented] Background: Anti-CD20 B cell depleting agents are amongst the most commonly used immunotherapeutics employed in the treatment of haematological malignancy and autoimmune diseases. By inducing peripheral B cell aplasia, anti-CD20 depleting agents are hypothesised to significantly impair serological responses to neoantigens, including the SARS-CoV-2 spike glycoprotein within SARS-CoV-2 vaccines. Seropositivity following SARS-CoV-2 is the strongest, measurable correlate of protection from severe COVID-19. Understanding the kinetics of B cell reconstitution and vaccine responsiveness following exposure to B cell depleting agents is essential to maximise vaccine efficacy in patients vulnerable to severe COVID-19. Methods: 80 patients with underlying haematological malignancy and 38 patients with underlying rheumatological disease previously treated with anti-CD20 B cell depleting agents were studied following their second dose of a SARS-CoV-2 vaccine (median time to sampling: 46.5d, IQR: 33.8-63.3). Lymphocyte subset (CD4, CD8, CD19, CD56/16) enumeration was performed using 6 colour flow cytometry (BD Trucount). Total anti-SARS-CoV-2 spike glycoprotein antibodies were measured by enzyme-linked immunosorbent assay (The Binding Site, Human Anti-IgG/A/M SARS-CoV-2-ELISA). The relationship between immune reconstitution following B cell depletion and vaccine responsiveness was explored. Results: In the haematology cohort (median age 70y, IQR 60.3-76.0, 62.5% male), overall seropositivity following vaccination was 60.0%. Individuals on active chemotherapy had significantly lower seroprevalence than those vaccinated following the completion of chemotherapy (22.7% vs 74.1%, p<0.0001). In the rheumatology cohort (median age 65y, IQR 58.3-70.8, 39.9% male), overall seropositivity was 69.4%. In both cohorts, vaccine non-responders had significantly smaller populations of peripheral CD19+ B cells (haematology: 0.20 vs 0.02 x10 9/L, p=0.004, rheumatology: 0.07 vs 0.01 x10 9/L, p=0.03). The magnitude of the antibody response following vaccination did not differ between recipients of Tozinameran and Vaxzeveria in either cohort. Vaccine responsiveness was lower in the first 6 months following B cell depletion therapy;42.9% in the haematology cohort and 33.3% in the rheumatology cohort, increasing to 100% and 75% respectively in individuals receiving their second dose 6-12 months following B cell depletion (Figure 1). B cell reconstitution in the 7-12 month window following B cell depletion was faster in haematology compared to rheumatology patients (77.8% v 22.2% achieving normal B cell count, p=0.005) and associated with improved vaccine responsiveness. However, persistent immunodeficiency occurred in some haematology patients following completion of treatment: 25% of patients who had completed therapy at least 36 months previously failed to respond to vaccination. In this cohort of vaccine non-responders, 83.3% of individuals had B cell numbers within the normal range. These patients had all previously been treated for follicular lymphoma suggesting a specific mechanism for long-range secondary immunodeficiency in these patients. Conclusions: Serological responsiveness to SARS-CoV-2 vaccines is poor during active chemotherapy for haematological malignancy and in the first 6 months following B cell depletion, regardless of underlying disease. Vaccine responsiveness significantly improves in the 7-12 month window following B cell depletion. Compared to haematology patients, B cell reconstitution is slower in rheumatology patients and associated with reduced vaccine responsiveness, possibly due to the use of additional concurrent disease-modifying anti-rheumatic therapies. Furthermore, long-term secondary immunodeficiency occurs in a minority of haematology patients. To maximise the efficacy from SARS-CoV-2 booster vaccination and optimal utilisation of available vaccine doses, immunisations should be delivered at least 6 months following the administration of anti-CD20 depleting drugs. Figure 1: Kinetics of return f vaccine responsiveness following B cell depletion in haematology and rheumatology patients. [Formula presented] Disclosures: Paneesha: Roche: Honoraria;Janssen: Honoraria;Gilead: Honoraria;Bristol Myers Squibb: Honoraria;AbbVie: Honoraria;Celgene: Honoraria. Drayson: Abingdon Health: Current holder of individual stocks in a privately-held company.

Antibody responses after first and second Covid-19 vaccination in patients with chronic lymphocytic leukaemia.

B-cell chronic lymphocytic leukaemia (CLL) is associated with immunosuppression and patients are at increased clinical risk following SARS-CoV-2 infection. Covid-19 vaccines offer the potential for protection against severe infection but relatively little is known regarding the profile of the antibody response following first or second vaccination. We studied spike-specific antibody responses following first and/or second Covid-19 vaccination in 299 patients with CLL compared with healthy donors. 286 patients underwent extended interval (10-12 week) vaccination. 154 patients received the BNT162b2 mRNA vaccine and 145 patients received ChAdOx1. Blood samples were taken either by venepuncture or as dried blood spots on filter paper. Spike-specific antibody responses were detectable in 34% of patients with CLL after one vaccine (n = 267) compared to 94% in healthy donors with antibody titres 104-fold lower in the patient group. Antibody responses increased to 75% after second vaccine (n = 55), compared to 100% in healthy donors, although titres remained lower. Multivariate analysis showed that current treatment with BTK inhibitors or IgA deficiency were independently associated with failure to generate an antibody response after the second vaccine. This work supports the need for optimisation of vaccination strategy in patients with CLL including the potential utility of booster vaccines.

COVID-19: Seroprevalence and Vaccine Responses in UK Dental Care Professionals.

Dental care professionals (DCPs) are thought to be at enhanced risk of occupational exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, robust data to support this from large-scale seroepidemiological studies are lacking. We report a longitudinal seroprevalence analysis of antibodies to SARS-CoV-2 spike glycoprotein, with baseline sampling prior to large-scale practice reopening in July 2020 and follow-up postimplementation of new public health guidance on infection prevention control (IPC) and enhanced personal protective equipment (PPE). In total, 1,507 West Midlands DCPs were recruited into this study in June 2020. Baseline seroprevalence was determined using a combined IgGAM enzyme-linked immunosorbent assay and the cohort followed longitudinally for 6 mo until January/February 2021 through the second wave of the coronavirus disease 2019 pandemic in the United Kingdom and vaccination commencement. Baseline seroprevalence was 16.3%, compared to estimates in the regional population of 6% to 7%. Seropositivity was retained in over 70% of participants at 3- and 6-mo follow-up and conferred a 75% reduced risk of infection. Nonwhite ethnicity and living in areas of greater deprivation were associated with increased baseline seroprevalence. During follow-up, no polymerase chain reaction-proven infections occurred in individuals with a baseline anti-SARS-CoV-2 IgG level greater than 147.6 IU/ml with respect to the World Health Organization international standard 20-136. After vaccination, antibody responses were more rapid and of higher magnitude in those individuals who were seropositive at baseline. Natural infection with SARS-CoV-2 prior to enhanced PPE was significantly higher in DCPs than the regional population. Natural infection leads to a serological response that remains detectable in over 70% of individuals 6 mo after initial sampling and 9 mo from the peak of the first wave of the pandemic. This response is associated with protection from future infection. Even if serological responses wane, a single dose of the Pfizer-BioNTech 162b vaccine is associated with an antibody response indicative of immunological memory.

Motivations and Barriers for the Use of Face Coverings during the COVID-19 Pandemic: Messaging Insights from Focus Groups

Widespread use of face coverings is a key public health strategy to prevent the spread of COVID-19. However, few studies have examined why Americans use or do not use face coverings, and little is known about the most effective messaging strategies. This study explored perceptions of face coverings, including motivations and barriers for use, and examined reactions to messaging promoting the use of face coverings. Six virtual focus groups were conducted with 34 North Carolina residents in July 2020. Participants reported high compliance with face covering recommendations but often did not wear them around family, friends, and colleagues. The most prevalent motivation for the use of face coverings was to protect or respect other people, including high-risk populations and individuals. Other motivators were self-protection, responsibility, desire for control, requirements, and expert advice. Barriers included physical and social discomfort, confusion or misinformation, low perceived susceptibility to COVID-19, and perceptions of identity and autonomy. Even among individuals who frequently wear face coverings, there are opportunities to improve compliance. Messaging should highlight how face coverings protect the wearer and others around them, normalize the use of face coverings in social settings, and emphasize requirements. Positive messages that focus on unity, personal experiences and the rationale for face coverings are recommended.

Validation of a combined ELISA to detect IgG, IgA and IgM antibody responses to SARS-CoV-2 in mild or moderate non-hospitalised patients.

BACKGROUND: Frequently SARS-CoV-2 results in mild or moderate disease with potentially lower concentrations of antibodies compared to those that are hospitalised. Here, we validated an ELISA using SARS-CoV-2 trimeric spike glycoprotein, with targeted detection of IgG, IgA and IgM (IgGAM) using serum and dried blood spots (DBS) from adults with mild or moderate disease. METHODS: Targeting the SARS-CoV-2 trimeric spike, a combined anti-IgG, IgA and IgM serology ELISA assay was developed using 62 PCR-confirmed non-hospitalised, mild or moderate COVID-19 samples, ≥14 days post symptom onset and 624 COVID-19 negative samples. The assay was validated using 73 PCR-confirmed non-hospitalised, mild or moderate COVID-19 samples, ≥14 days post symptom onset and 359 COVID-19 negative serum samples with an additional 81 DBSs. The assay was further validated in 226 PCR-confirmed non-hospitalised, mild or moderate COVID-19 samples, ≥14 days post symptom onset and 426 COVID-19 negative clinical samples. RESULTS: A sensitivity and specificity of 98.6% (95% CI, 92.6-100.0), 98.3% (95% CI, 96.4-99.4), respectively, was observed following validation of the SARS-CoV-2 ELISA. No cross-reactivities with endemic coronaviruses or other human viruses were observed, and no change in results were recorded for interfering substances. The assay was stable at temperature extremes and components were stable for 15 days once opened. A matrix comparison showed DBS to correlate with serum results. Clinical validation of the assay reported a sensitivity of 94.7% (95% CI, 90.9-97.2%) and a specificity of 98.4% (95% CI, 96.6-99.3%). CONCLUSIONS: The human anti-IgGAM SARS-CoV-2 ELISA provides accurate and sensitive detection of SARS-CoV-2 antibodies in non-hospitalised adults with mild or moderate disease. The use of dried blood spots makes the assay accessible to the wider community.