Typology of e-commerce shoppers: the case of COVID-19

Purpose: The spread of coronavirus disease (COVID-19) has drastically changed the entire market structure and shopping behaviors across the world. While shoppers rushed toward e-commerce platforms during the pandemic, the key debate that rose was on how this behavior will evolve post COVID-19. The purpose of this study was to explore the different categories of e-commerce platforms' users and propose a distinctive customer typology in the era of the COVID-19 pandemic. Design/methodology/approach: An exploratory qualitative research design was adopted because of the novelty of the subject. In total, 43 participants were interviewed, including 27 consumers and 16 experts in the field of e-commerce. Findings: Based on the findings, this study distinguishes between two stages of e-commerce usage during the pandemic. Furthermore, this study identifies four key typologies of e-commerce shoppers that are expected to form at the end of the coronavirus: duty-bound, e-watcher, makeshift and onli-vorous shoppers. The characteristics and businesses strategies pertaining to each of the identified groups are discussed. Originality/value: To the best of the authors' knowledge, this research is among the first to identify the different stages, while proposing an innovative typology of e-commerce platform post COVID-19. This study also offers useful recommendations to deal with similar future crises. © 2023, Emerald Publishing Limited.

Neutralizing antibodies against SARS-CoV-2 are higher but decline faster in mRNA vaccinees compared to individuals with natural infection.

BACKGROUND: Waning protection against emerging SARS-CoV-2 variants by pre-existing antibodies elicited due to current vaccination or natural infection is a global concern. Whether this is due to the waning of immunity to SARS-COV-2 remains unclear. AIM: We aimed to investigate the dynamics of antibody isotype responses among vaccinated naïve (VN) and naturally infected (NI) individuals. METHODS: We followed up antibody levels in COVID-19 mRNA-vaccinated subjects without prior infection (VN, n = 100) in two phases: phase-I (P-I) at ~ 1.4 and phase-II (P-II) at ~ 5.3 months. Antibody levels were compared to those of unvaccinated and naturally infected subjects (NI, n = 40) at ~ 1.7 (P-1) and 5.2 (P-II) months post-infection. Neutralizing antibodies (NTAb), anti-S-RBD-IgG, -IgM, and anti-S-IgA isotypes were measured. RESULTS: The VN group elicited significantly greater antibody responses (p < 0.001) than the NI group at P-I, except for IgM. In the VN group, a significant waning in antibody response was observed in all isotypes. There was about ~ a 4-fold decline in NTAb levels (p < 0.001), anti-S-RBD-IgG (~5-folds, p < 0.001), anti-S-RBD-IgM (~6-folds, p < 0.001), and anti-S1-IgA (2-folds, p < 0.001). In the NI group, a significant but less steady decline was notable in S-RBD-IgM (~2-folds, p < 0.001), and a much smaller but significant difference in NTAb (<2-folds, p < 0.001) anti-S-RBD IgG (<2-folds, p = 0.005). Unlike the VN group, the NI group mounted a lasting anti-S1-IgA response with no significant decline. Anti-S1-IgA, which were ~ 3 folds higher in VN subjects compared to NI in P-1 (p < 0.001), dropped to almost the same levels, with no significant difference observed between the two groups in P-II. CONCLUSION: While double-dose mRNA vaccination boosted antibody levels, vaccinated individuals' 'boost' was relatively short-lived.

Evaluating the Effectiveness of Extracorporeal Shockwave Lithotripsy (ESWL) for Ureteric Stones During COVID-19 Pandemic - A Single Centre Experience

Aim Reliance on ESWL for treating ureteric stone has increased during the COVID-19 pandemic. We examined the outcomes for ureteric stones treated with our on-site lithotripter to assess the success rate and determine the variables that could affect the outcome results. Method A retrospective review using electronic records and images of patients who underwent ESWL for ureteric stones (January to December 2020). Univariate and multivariate analysis used to determine stone-free rate predictors (Stone Free rate/SFR: No residual stones on post-ESWL imagining). Results A total of 36 patients underwent ESWL for ureteric stones. Mean age was 58 years (21–90), and mean stone size was 8 mm (5–20). Stones were located in the proximal (67%) or lower ureter (33%). Overall SFR was 64% (67% proximal, 33% distal). 64% of patients required only one session to be stone free, with 60% stone free after two sessions. Stones <10mm had a SFR of 67%, compared to 58% for stone >10 mm. The only statistically significant predictor was stone size (longest dimension, p=0.04). No statistical significance with stone location (P=0.09), skin-to-stone distance (SSD) (P=0.7), stone density (P=0.3) or stone volume (P=0.3). In treatment failure, time to definitive ureteroscopy was 4 weeks. Conclusion Our overall SFR was slightly lower than expected but comparable to available literature. This data highlights the importance of patient selection for ESWL and would be useful in counselling about local success rate. More than half of the patients required only one session for stone clearance and stone size was the only significant predictor for successful ESWL.

Validation of a Novel Fluorescent Lateral Flow Assay for Rapid Qualitative and Quantitative Assessment of Total Anti-SARS-CoV-2 S-RBD Binding Antibody Units (BAU) from Plasma or Fingerstick Whole-Blood of COVID-19 Vaccinees.

Background: Limited commercial LFA assays are available to provide a reliable quantitative measurement of the total binding antibody units (BAU/mL) against the receptor-binding domain of the SARS-CoV-2 spike protein (S-RBD). Aim: This study aimed to evaluate the performance of the fluorescence LFA FinecareTM 2019-nCoV S-RBD test along with its reader (Model No.: FS-113) against the following reference methods: (i) the FDA-approved GenScript surrogate virus-neutralizing assay (sVNT); and (ii) three highly performing automated immunoassays: BioMérieux VIDAS®3, Ortho VITROS®, and Mindray CL-900i®. Methods: Plasma from 488 vaccinees was tested by all aforementioned assays. Fingerstick whole-blood samples from 156 vaccinees were also tested by FinecareTM. Results and conclusions: FinecareTM showed 100% specificity, as none of the pre-pandemic samples tested positive. Equivalent FinecareTM results were observed among the samples taken from fingerstick or plasma (Pearson correlation r = 0.9, p < 0.0001), suggesting that fingerstick samples are sufficient to quantitate the S-RBD BAU/mL. A moderate correlation was observed between FinecareTM and sVNT (r = 0.5, p < 0.0001), indicating that FinecareTM can be used for rapid prediction of the neutralizing antibody (nAb) post-vaccination. FinecareTM BAU results showed strong correlation with VIDAS®3 (r = 0.6, p < 0.0001) and moderate correlation with VITROS® (r = 0.5, p < 0.0001) and CL-900i® (r = 0.4, p < 0.0001), suggesting that FinecareTM can be used as a surrogate for the advanced automated assays to measure S-RBD BAU/mL.

And Still She Rises: Policies for Improving Women's Health for a More Equitable Post-Pandemic World.

The COVID-19 pandemic has spawned crises of violence, hunger and impoverishment. Maternal and Infant Health Canada (MIHCan) conducted this policy action study to explore how changes that have arisen during the COVID-19 pandemic may catalyze potential improvements in global women's health toward the creation of a more equitable post-pandemic world. In this mixed methods study, 280 experts in women's health responded to our survey and 65 subsequently participated in focus groups, including professionals from India, Egypt/Sudan, Canada and the United States/Mexico. From the results of this study, our recommendations include augmenting mental health through more open dialogue, valuing and compensating those working on the frontlines through living wages, paid sick leave and enhanced benefits and expanding digital technology that facilitates flexible work locations, thereby freeing time for improving the wellbeing of caregivers and families and offering telemedicine and telecounseling, which delivers greater access to care. We also recommend bridging the digital divide through the widespread provision of reliable and affordable internet services and digital literacy training. These policy recommendations for employers, governments and health authorities aim to improve mental and physical wellbeing and working conditions, while leveraging the potential of digital technology for healthcare provision for those who identify as women, knowing that others will benefit. MIHCan took action on the recommendation to improve mental health through open conversation by facilitating campaigns in all study regions. Despite the devastation of the pandemic on global women's health, implementing these changes could yield improvements for years to come.

Incidence and Prevalence of Paediatric Inflammatory Bowel Disease Continues to Increase in the South of England.

OBJECTIVE: The incidence of paediatric inflammatory bowel disease (IBD) has been increasing over 25 years; however, contemporary trends are not established and the impact of COVID-19 on case rates is unclear. METHODS: Data from Southampton Children's hospital prospective IBD database were retrieved for 2002-2021. Incidence rates were calculated based on referral area populations and temporal trends analysed. Disease prevalence for those aged <18 years was calculated for 2017-2021. Monoclonal prescriptions were reported. RESULTS: In total, 1150 patients were included (mean age at diagnosis 12.63 years, 40.5% female). An estimated 704 patients had Crohn's disease (61.2%), 385 had ulcerative colitis (33.5%), and 61 had IBD unclassified (5.3%). Overall IBD incidence increased, ß = 0.843, P = 3 × 10 -6 , driven by Crohn's disease, ß = 0.732, P = 0.00024 and ulcerative colitis, ß = 0.816, P = 0.000011. There was no change in IBDU incidence, ß = 0.230, P = 0.33. From 2002-2021, 51 patients were diagnosed <6 years of age, 160 patients aged 6 to <10 years and 939 patients aged 10 to <18 years of age. Increased incidence was observed in patients aged 10 to <18 years of age (ß = 0.888, P = 1.8 × 10 -7 ). There was no significant change in incidence of IBD in <6 years (ß = 0.124, P = 0.57), or 6 to <10 years (ß = 0.146, P = 0.54). IBD prevalence increased by an average of 1.71%/year from 2017 to 2021, ß = 0.979, P = 0.004. The number of new monoclonal prescriptions increased from 6 in 2007 to 111 in 2021. CONCLUSIONS: IBD incidence continues to increase in Southern England. Compounding prevalence and increased monoclonal usage has implications for service provision.

Psychological impact of the COVID-19 pandemic on health care workers.

OBJECTIVE: This study aims to assess the magnitude of depression, anxiety, and stress among health care workers by the coronavirus disease (COVID-19) in Almadinah Almunawwarah, KSA. METHODS: This cross-sectional study examined 122 health care workers between April and May 2020 through the electronic use of the Hospital Anxiety and Depression (HAD) questionnaire, and Perceived Stress Scale (PSS). The perceptions of the participants towards stigmatisation of their profession during the COVID-19 pandemic were also assessed through a Likert's scale. The magnitude of anxiety, depression, and stress were analysed using a mean ± SD, correlation and percentages in respective statistics. A p value of <0.05 was considered significant. RESULTS: This study found that 32.9% of the healthcare workers frequently faced COVID-19 cases during the ongoing pandemic. As many as 35.6% were unusually anxious. A mean anxiety score of 8.43 ± 4.6 was noted, with significantly higher scores for women and those workers with inadequate training (p < 0.001 and 0.028). Moreover, a mean depression score of 7.6 ± 4.7 (p < 0.002) was recorded for the healthcare workers with inadequate training. About 27.9% of the participants were depressed. The mean stress score of the study cohort was 6.86 ± 2.5. From the cohort, 24.5% and 72.8% experienced mild and moderate stress, respectively. This study found that inadequate training for infection control was associated with a higher proportion of anxiety and depression [OR 1.86 (95% CI: 1.5-2.3; p < 0.043) and OR 2.21 (95% CI: 1.7-2.8; p < 0.018), respectively. CONCLUSION: This study found a high prevalence of anxiety, depression, and moderate stress among healthcare workers, regardless of their job specifications. The associated risk factors for anxiety and depression included inadequate training for infection control, and pre-existing stress-provoking medical conditions.

Performance evaluation of novel fluorescent-based lateral flow immunoassay (LFIA) for rapid detection and quantification of total anti-SARS-CoV-2 S-RBD binding antibodies in infected individuals.

BACKGROUND: A vast majority of the commercially available lateral flow immunoassay (LFIA) is used to detect SARS-CoV-2 antibodies qualitatively. Recently, a novel fluorescence-based lateral flow immunoassay (LFIA) test was developed for quantitative measurement of the total binding antibody units (BAUs) (BAU/mL) against SARS-CoV-2 spike protein receptor-binding domain (S-RBD). AIM: This study aimed to evaluate the performance of the fluorescence LFIA FinecareTM 2019-nCoV S-RBD test along with its reader (Model No.: FS-113). METHODS: Plasma from 150 reverse trancriptase-PCR (RT-PCR)-confirmed positive individuals and 100 prepandemic samples were tested by FincareTM to access sensitivity and specificity. For qualitative and quantitative validation of the FinCareTM measurements, BAU/mL results of FinCareTM were compared with results of 2 reference assays: the surrogate virus-neutralizing test (sVNT, GenScript Biotech, USA) and the VIDAS®3 automated assay (BioMérieux, France). RESULTS: FinecareTM showed 92% sensitivity and 100% specificity compared with PCR. Cohen's Kappa statistic denoted moderate and excellent agreement with sVNT and VIDAS®3, with values being 0.557 (95% CI: 0.32-0.78) and 0.731 (95% CI: 0.51-0.95), respectively. A strong correlation was observed between FinecareTM/sVNT (r = 0.7, p < 0.0001) and FinecareTM/VIDAS®3 (r = 0.8, p < 0.0001). CONCLUSION: FinecareTM is a reliable assay and can be used as a surrogate to assess binding and neutralizing antibody response after infection or vaccination, particularly in none or small laboratory settings.

Low Risk of Serological Cross-Reactivity between the Dengue Virus and SARS-CoV-2-IgG Antibodies Using Advanced Detection Assays.

Several studies have reported serological cross-reactivity of the immune responses between SARS-CoV-2 and DENV. Most of the available studies are based on the point-of-care rapid testing kits. However, some rapid test kits have low specificity and can generate false positives. Hence, we aimed to investigate the potential serological cross-reactivity between SARS-CoV-2 and DENV-IgG antibodies using advanced assays including chemiluminescence immunoassay (CLIA) and enzyme-linked immunosorbent assay (ELISA) test. A total of 90 DENV-IgG-ELISA-positive and 90 DENV-IgG-ELISA-negative prepandemic sera were tested for anti-SARS-CoV-2-IgG using the automated CL-900i CLIA assay. Furthermore, a total of 91 SARS-CoV-2-IgG-CLIA-positive and 91 SARS-CoV-2-IgG-CLIA-negative postpandemic sera were tested for anti-DENV-IgG using the NovaLisa ELISA kit. The DENV-IgG-positive sera resulted in five positives and 85 negatives for SARS-CoV-2-IgG. Similarly, the DENV-IgG-negative sera also resulted in 5 positives and 85 negatives for SARS-CoV-2-IgG. No statistically significant difference in specificity between the DENV-IgG-positive and DENV-IgG-negative sera was found (p value = 1.00). The SARS-CoV-2-IgG-positive sera displayed 43 positives, 47 negatives, and 1 equivocal for DENV-IgG, whereas the SARS-CoV-2-IgG-negative sera resulted in 50 positives, 40 negatives, and 1 equivocal for DENV-IgG. No statistically significant difference in the proportion that is DENV-IgG positive between the SARS-CoV-2-IgG-positive and SARS-CoV-2-IgG-negative sera (p value = 0.58). In conclusion, there is a low risk of serological cross-reactivity between the DENV and SARS-CoV-2-IgG antibodies when using advanced detection assays.

Performance evaluation of novel fluorescent-based lateral immune flow assay (LIFA) for rapid detection and quantitation of total anti-SARS-CoV-2 S-RBD binding antibodies in infected individuals (preprint)

Background: The vast majority of the commercially available LFIA is used to detect SARS-CoV-2 antibodies qualitatively. Recently, a novel fluorescence-based LIFA test was developed for quantitative measurement of the total binding antibody units (BAU/mL) against the receptor-binding domain of the SARS-CoV-2 spike protein (S-RBD). Aim: To evaluate the performance of the fluorescence LIFA FinecareTM 2019-nCoV S-RBD test along with its reader (Model No.: FS-113). Methods: Plasma from 150 RT-PCR confirmed-positive individuals and 100 pre-pandemic samples were tested by FinCareTm to access sensitivity and specificity. For qualitative and quantitative validation of the FinCarTm measurements, the BAU/mL results of FinCareTm were compared with results of two reference assays: the surrogate virus-neutralizing test (sVNT, GenScript, USA), and the VIDAS3 automated assay (BioMerieux, France). Results: FinecareTM showed 92% sensitivity and 100% specificity compared to PCR. Cohen's Kappa statistic denoted moderate and excellent agreement with sVNT and VIDAS3, ranging from 0.557 (95% CI: 0.32-0.78) to 0.731 (95% CI: 0.51-0.95), respectively. A strong correlation was observed between FinecareTM/sVNT (r=0.7, p<0.0001) and FinecareTM/VIDAS3 (r=0.8, p<0.0001). Conclusion: FinecareTM is a reliable assay and can be used as a surrogate to assess binding and neutralizing antibody response post-infection or vaccination, particularly in none or small laboratory settings.

Comparison of antibody immune responses between BNT162b2 and mRNA-1273 SARS-CoV-2 vaccines in naïve and previously infected individuals.

BACKGROUND: Two mRNA vaccines, Pfizer-BNT162b2 and Moderna-mRNA-1273, obtained the Emergency Use Listing by WHO for preventing COVID-19. However, little is known about the difference in antibody responses induced by these two mRNA vaccines in naïve and previously infected (PI) individuals. METHOD: We investigated the levels of anti-S-RBD (total, IgG and IgA) levels in naïve and PI individuals, 1-13 (median = 6) weeks following the second dose of either vaccine. Results in the naïve-vaccinated group, the mRNA-1273 vaccine induced significantly higher levels of anti-S-RBD total antibodies (3.5-fold; P < 0.001), IgG (2-fold, P < 0.01) and IgA (2.1-fold, P < 0.001) as compared with the BNT162b2 vaccine. In addition, both vaccines produced significantly higher anti-S-RBD total antibody levels in the PI-group compared with naïve-vaccinated group. The PI group elicited a higher level of anti-S-RBD IgG than the naïve-BNT162b2 (P = 0.05), but not more than the naïve-mRNA-1273 (P = 0.9) group. Interestingly, the PI vaccinated group elicited a comparable level of IgA ratio to the naïve-mRNA-1273 group but significantly higher than the naïve-BNT162b2 group (1.6-fold, P < 0.001). CONCLUSION: Our results showed that the PI-vaccinated group produces a higher level of antibodies than the naïve vaccinated group, particularly for those vaccinated with BNT162b2.

Characterization of Infant Cardiopulmonary Resuscitation Delivery with Range Sensor Feedback on Performance

Cardiac arrest (CA) in infants is an issue worldwide, which causes significant morbidity and mortality rates. Cardiopulmonary resuscitation (CPR) is a technique performed in case of CA to save victims’ lives. However, CPR is often not performed effectively, even when delivered by qualified rescuers. Therefore, international guidelines have proposed applying a CPR feedback device to achieve high-quality application of CPR to enhance survival rates. Currently, no feedback device is available to guide learners through infant CPR performance in contrast to a number of adult CPR feedback devices. This study presents a real-time feedback system to improve infant CPR performance by medical staff and laypersons using a commercial CPR infant manikin. The proposed system uses an IR sensor to compare CPR performance obtained with no feedback and with a real-time feedback system. Performance was validated by analysis of the CPR parameters actually delivered against the recommended target parameters. Results show that the real-time feedback system significantly improves the quality of chest compression parameters. The two-thumb compression technique is the achievable and appropriate mechanism applied to infant subjects for delivering high-quality CPR. Under the social distancing constraints imposed by the SARS-CoV-2 pandemic, the results from the training device were sent to a CPR training center and provided each participant with CPR proficiency.

Effect of multiple freeze-thaw cycles on the detection of anti-SARS-CoV-2 IgG antibodies.

Several studies have investigated the effect of repeated freeze-thaw (F/T) cycles on RNA detection for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). However, no data are available regarding the effect of repeated F/T cycles on SARS-CoV-2 antibody detection in serum. We investigated the effect of multiple F/T cycles on anti-SARS-CoV-2 IgG detection using an ELISA test targeting the nucleocapsid antibodies. Ten positive and 1 negative SARS-CoV-2 IgG sera from 11 participants, in replicates of 5, were subjected to a total of 16 F/T cycles and stored at 4 °C until tested by ELISA. Statistical analysis was performed to test for F/T cycle effect. None of the 10 positive sera became negative after 16 F/T cycles. There was no significant difference in the OD average reading between the first and last F/T cycles, except for one serum with a minimal decline in the OD. The random effect linear regression of log (OD) on the number of cycles showed no significant trend, with a slope consistent with zero (B=-0.0001; 95 % CI -0.0008; 0.0006; P-value=0.781). These results suggest that multiple F/T cycles had no effect on the ability of the ELISA assay to detect SARS-CoV-2 IgG antibodies.

Can commercial automated immunoassays be utilized to predict neutralizing antibodies after SARS-CoV-2 infection? A comparative study between three different assays.

Background: High-throughput assays that can infer neutralizing activity against SARS-CoV-2 are of great importance for assessing the immunity induced by natural infection and COVID-19 vaccines. We aimed to evaluate the performance and degree of correlation of three fully automated anti-SARS-CoV-2 immunoassays with neutralization activity using a surrogate virus-neutralizing test (sVNT) from GenScript, targeting the receptor-binding domain. Methods: 110 sera collected from PCR-confirmed asymptomatic COVID-19 individuals were tested for neutralizing antibodies (nAbs) using the sVNT. Positive samples were tested on three automated immunoassays targeting different viral antigens: Mindray CL-900i®, Abbott Architect, and Ortho VITROS®. The diagnostic sensitivity, specificity, agreement, and correlation with the sVNT were assessed. Receiver operating characteristic (ROC) curve analysis was performed to determine optimal thresholds for predicting the presence of neutralizing activity by each assay. Results: All three assays showed 100% specificities. The highest sensitivity was 99.0%, demonstrated by VITROS®, followed by 94.3%, for CL-900i®, and 81.0%, for Architect. Both VITROS® and CL-900i® had the strongest correlation with the sVNT (ρ = 0.718 and ρ = 0.712, respectively), while Architect showed a moderate correlation (ρ = 0.618). ROC curve analysis indicated that the manufacturer's recommended cutoff values are adequate for predicting the presence of nAbs and providing a strong correlation with the sVNT. Conclusion: VITROS® and CL-900i® serological assays, which detect antibodies against SARS-CoV-2 spike protein, could serve as reliable assays to predict neutralization activity after infection or vaccination.

Is Microthrombosis the Main Pathology in Coronavirus Disease 2019 Severity?-A Systematic Review of the Postmortem Pathologic Findings.

This systematic review attempts to retrieve and report the findings of postmortem studies including the histopathologic data of deceased coronavirus disease 2019 patients and to review the manifestations of coronavirus disease 2019-associated thrombotic pathologies reported in the recent literature. DATA SOURCES: PubMed, Excerpta Medica Database, and Cochrane library between December 1, 2019, and August 26, 2020. STUDY SELECTION: Investigators screened 360 unique references, retrieved published autopsy series, and report on the postmortem histopathologic information on patients who had died of coronavirus disease 2019. DATA EXTRACTION: Investigators independently abstracted all available data including study design, participant demographics, key histopathologic findings, disease severity markers, duration of hospital stay, and cause of death. DATA SYNTHESIS: From the 65 eligible studies, 691 total completed autopsies were included in evidence synthesis. Histopathologic evaluation of the lungs revealed presence of diffuse alveolar damage in 323 of 443 patients and pulmonary microthrombi in 242 of 326 patients. Deep venous thrombosis and pulmonary embolism were found in 41% and ~15%, respectively, of the cadavers examined for thromboembolic events. d-dimer levels were generally higher in patients with severe clinical course of coronavirus disease 2019. Plasma levels of ferritin, lactate dehydrogenase, interleukin-6, and C-reactive protein were higher in nonsurvivors when compared with survivors. Overall, microthrombi and extensive angiogenesis of lung vasculature were the most common pathologic findings in the lungs and microthrombi in most of the assessed organ-tissue. CONCLUSIONS: Diffuse alveolar damage was the most predominant feature in the lungs of coronavirus disease 2019 patients who underwent postmortem assessment. Widespread pulmonary microthrombosis and extensive pulmonary angiogenesis, in addition to frequent pulmonary and extrapulmonary microthrombotic and thromboembolic findings in patients with coronavirus disease 2019, appear to be consistent with the disease-specific hypercoagulability. Further discovery efforts in assessing the link between coronavirus disease 2019, hypercoagulable state, and immunothrombosis are warranted. In the interim, increased attention to anticoagulant treatment approaches in coronavirus disease 2019 patients is needed.

No evidence of significant cross-reactivity between the dengue virus (DENV) and SARS-CoV-2 IgG antibodies (preprint)

BackgroundSeveral studies reported serological cross-reaction between DENV and SARS-CoV-2 IgG antibodies using rapid point of care (POC) assays. Limited data are available about cross-reactivity when testing is done using advanced chemiluminescence immunoassay (CLIA) and ELISA assays. ObjectiveThis study aims to investigate potential serological cross-reactivity between SARS-CoV-2-IgG and DENV-IgG using CLIA and ELISA assays. Study-designA total of 90 DENV-IgG-ELISA positive and 90 negative pre-pandemic sera were tested for anti-SARS-CoV-2-IgG using the automated CL-900i CLIA assay. Furthermore, a total of 91 SARS-CoV-2-IgG-CLIA positive and 91 negative post-pandemic sera were tested for anti-DENV-IgG using the Novalis ELISA assay. ResultsThe DENV-IgG positive sera had 5 positives and 85 negatives for SARS-CoV-2-IgG. The DENV-IgG negative sera also had 5 positives and 85 negatives for SARS-CoV-2-IgG. No statistically significant difference in specificity between the DENV-IgG positive and DENV-IgG negative sera was found (p-value=1.00). The SARS-CoV-2-IgG positive sera had 43 positives, 47 negatives, and 1 equivocal for DENV-IgG. The SARS-CoV-2-IgG negative sera had 50 positives, 40 negatives, and 1 equivocal for DENV-IgG. No statistically significant difference in the proportion that is DENV-IgG positive between the SARS-CoV-2-IgG positive and SARS-CoV-2-IgG negative sera (p-value=0.58). ConclusionsNo evidence for cross-reactivity between the DENV and SARS-CoV-2 IgG antibodies was found.

Effect of multiple freeze-thaw cycles on detection of anti-SARS-CoV-2 IgG antibodies (preprint)

Several studies have investigated the effect of repeated freeze-thaw (F/T) cycles on RNA detection for SARS-CoV-2. However, no data is available regarding the effect of repeated F/T cycles on SARS-CoV-2 antibody detection in serum. We investigated the effect of multiple F/T cycles on anti-SARS-CoV-2 IgG detection using an ELISA test targeting the nucleocapsid antibodies. Ten positive and one negative SARS-CoV-2 IgG sera from 11 participants, in replicates of five were subjected to a total of 16 F/T cycles and stored at 4 degrees celsius until tested by ELISA. Statistical analysis was done to test for F/T cycle effect. Non-of the 10 positive sera turned into negative after 16 F/T cycles. There was no significant difference in the OD average reading between the first and last F/T cycles, except for one serum with a minimal decline in the OD. The random-effect linear regression of log (OD) on the number of cycles showed no significant trend with a slope consistent with zero (B=-0.0001; 95% CI -0.0008; 0.0006; p-value=0.781). These results suggest that multiple F/T cycles had no effect on the ability of the ELISA assay to detect the SARS-CoV-2 IgG antibodies.

Estimating the public response to mitigation measures and self-perceived behaviours towards the COVID-19 pandemic.

OBJECTIVES: Since March 2020, a rapid increase has been observed in the prevalence of the COVID-19 pandemic, which has essentially resulted from increased disease transmission and intensified testing and reporting. The international guidelines for the prevention and treatment of the COVID-19 pandemic have been frequently updated. Such guidelines assist the governmental regulatory bodies in taking optimal measures and safeguarding their citizens against the pandemic. We conducted a short survey with a Saudi cohort to understand the awareness about COVID-19 and estimate the responses for mitigation strategies. METHODS: An electronic survey was conducted, and the first 388 responses were analysed for publishing an initial report. The questionnaire comprised 27 items and was divided into three sections, namely demographic, awareness, and response to mitigation strategies and participants' self-perceived behaviours regarding COVID-19. The perceptions of the participants were compared with their responses to mitigation measures. RESULTS: In our study, 89.7% understood the meaning of pandemic, while 82.2% correctly identified that the elderly belonged to a high-risk group for the COVID-19 infection. As many as 96.1% agreed that staying at home was one of the mitigation strategies. Nearly 35% preferred self-medication. Higher educational level (OR: 2.09, 95% CI: 1.02-4.29) and longer working hours were found to be significantly associated with a positive response to mitigation measures with p < 0.04 and p < 0.02, respectively. CONCLUSIONS: We report better understanding and appropriate response to mitigation measures towards the COVID-19 pandemic among the general population in KSA. Nevertheless, the tendency towards self-medication was reported by one-third of the responders.