Quantitative serology for SARS-CoV-2 using self-collected saliva and finger-stick blood

Convenient and widespread serology testing may alter the trajectory of the COVID-19 pandemic. This study seeks to leverage high-throughput, multiplexed serologic assays, which have been adopted as benchmarks for vaccine efficacy, to support large-scale surveys of SARS-CoV-2 immunity using finger-stick blood and/or saliva. Specifically, we optimized MSD’s serology assays, which were analytically validated for serum, to test self-collected finger-stick blood and saliva samples. We show that these assays can be used with FDA-registered specimen collection devices to obtain quantitative measurements for self-collected samples. Antibody levels were measured using an electrochemiluminescent (ECL) multiplex immunoassay, which has been used to measure humoral responses to several COVID-19 vaccines, including those funded by the U.S. Government’s Operation Warp Speed. First, we show that salivary antibodies are stable without refrigeration or preservatives for at least five days. Using matched samples, we show that testing of saliva and finger-stick blood equivalently identified individuals with humoral responses to CoV-2 antigens. Moreover, we piloted a simple saliva collection kit that can be used to safely send samples through the mail. This work demonstrates that robust methods for self-collection of finger-stick blood and saliva, in combination with quantitative, automated immunoassays, provide the technical capabilities needed to support large-scale serology testing.

Finger stick blood test to assess post vaccination SARS-CoV-2 neutralizing antibody response against variants

There is clinical need for a quantifiable point-of-care (PoC) SARS-CoV-2 neutralizing antibody (nAb) test that is adaptable with the pandemics changing landscape. Here, we present a rapid and semi-quantitative nAb test that uses finger stick or venous blood to assess the nAb response of vaccinated population against wild-type, alpha, beta, gamma, and delta variant receptor binding domains. It captures a clinically relevant range of nAb levels, and effectively differentiates pre-vaccination, post 1st dose and post 2nd dose vaccination samples within 10 minutes. The data observed against alpha, beta, gamma, and delta variants agrees with published results evaluated in established serology tests. Finally, our test revealed a substantial reduction in nAb level for beta, gamma, and delta variants between early BNT162b2 vaccination group (within 3 months) and later vaccination group (post 3 months). This test is highly suited for PoC settings and provides an insightful nAb response in a post-vaccinated population.

Multiplexed micronutrient, inflammation, and malarial antigenemia assessment using a plasma fractionation device

Collecting, processing, and storing blood samples for future analysis of biomarkers can be challenging when performed in resource limited environments. The preparation of dried blood spots (DBS) from heel or finger stick collection of whole blood is a widely used and established method. DBS pose less risk of infection from blood borne pathogens, do not require immediate specimen processing and tolerate a wider range of storage temperatures, and are easier to ship. As such, DBS are commonly used in large-scale surveys to assess infectious disease status and/or micronutrient status in vulnerable populations. Recently, we reported that DBS can be used with a multiplexed immunoassay, the Q-plex Human Micronutrient 7-plex Array (MN 7-plex). This tool can simultaneously quantify seven protein biomarkers related to micronutrient deficiencies (iodine, iron and vitamin A), inflammation and malarial antigenemia using plasma or serum. Serum ferritin, a key iron biomarker, cannot be measured from DBS due to red blood cell (RBC) ferritin confounding the results. In this study, we demonstrate the performance of a simple and rapid blood fractionation tool that passively separates serum from cellular components via diffusion through a membrane into a plasma collection disc (PCD) to produce plasma spots. We evaluated the concordance of MN 7-plex analyte concentrations from matched panels of eighty-eight samples of PCD, DBS, and wet plasma prepared from anticoagulated venous whole blood. The results show high correlation between eluates from PCD and DBS and wet plasma for each analyte. Serum ferritin measures from the PCD eluates were highly correlated to wet plasma samples. This suggests that surveillance for iron deficiency may be improved over the current methods restricted to only measuring sTfR in DBS as when used in combination with the MN 7-plex, all seven biomarkers can be simultaneously measured using PCDs.

Distinct SARS-CoV-2 antibody reactivity patterns elicited by natural infection and mRNA vaccination

We analyzed data from two ongoing COVID-19 longitudinal serological surveys in Orange County, CA., between April 2020 and March 2021. A total of 8476 finger stick blood specimens were collected before and after a vaccination campaign. IgG levels were determined using a multiplex antigen microarray containing antigens from SARS-CoV-2, SARS, MERS, Common CoV, and Influenza. Twenty-six percent of specimens from unvaccinated Orange County residents in December 2020 were SARS-CoV-2 seropositive; out of 852 seropositive individuals 77 had symptoms and 9 sought medical care. The antibody response was predominantly against nucleocapsid (NP), full length, and S2 domain of spike. Anti-receptor binding domain (RBD) reactivity was low and not cross-reactive against SARS S1 or SARS RBD. A vaccination campaign at the University of California Irvine Medical Center (UCIMC) started on December, 2020 and 6724 healthcare workers were vaccinated within 3 weeks. Seroprevalence increased from 13% pre-vaccination to 79% post-vaccination in January, 93% in February, and 99% in March. mRNA vaccination induced higher antibody levels than natural exposure, especially against the RBD domain and cross-reactivity against SARS RBD and S1 was observed. Nucleocapsid protein antibodies can be used to distinguish vaccinees to classify pre-exposure to SARS-CoV-2 Previously infected individuals developed higher antibody titers to the vaccine than non pre-exposed individuals. Hospitalized patients in intensive care with severe disease reach significantly higher antibody levels than mild cases, but lower antibody levels compared to the vaccine. These results indicate that mRNA vaccination rapidly induces a much stronger and broader antibody response than SARS-CoV-2 infection.

1028. Performance and Patient Acceptability Evaluation of the Chembio DPP® HIV-Syphilis Assay in an Emergency Department

Background Emergency departments (EDs) serve as sentinel settings for diagnosing sexually transmitted infections (STIs), including HIV and syphilis. We aimed to assess performance and patient acceptability of a point-of-care (POC) test, the Chembio Dual Path Platform (DPP®) HIV-Syphilis Assay, in an urban ED in Baltimore. Methods 170 patients were enrolled via convenience sampling from Oct 2019 – March 2020 and Jan 2021 – June 2021. Patients eligible were < 70 yrs, men who have sex with men, pregnant without care, had STI concerns, or history of drug use. Subjects received standard of care (SOC) HIV and syphilis testing under institutional laboratory algorithms. Subjects were then tested with the finger-stick POC test and completed a survey, both before and after the POC test to assess subjects’ attitudes about the POC test. Results Comparing the SOC and POC results, 165/170 (97.1%) were test concordant. 3 syphilis POC results were false negative, but reported successful treatment over 10 years prior to enrollment (treponemal antibody remains after treatment). 1 HIV result was false negative and 1 was false positive. Overall the sensitivity and specificity of the HIV POC test were 96.8% (95%CI: 83.3%, 99.9%) and 99.3% (95% CI: 96.1%, 100%), and for syphilis were 85.7% (95%Cl: 63.7%, 97.0%) or 100% (95%CI: 81.5%, 100%), if excluding 3 persons having been successfully treated, and 100% (95% CI: 97.6%, 100%) respectively. The pre-test survey found 67% and 77% of participants were comfortable with a finger-stick test and agreed the POC test result would be as good as the SOC test result, which increased to 96% and 86% in the post-test, respectively, (p< 0.05). At post-test, 86% reported they would feel confident to perform this test at home and 81% would use it at least once per year if it were available. 97% reported they were more likely to seek treatment if receiving a positive result during their ED visit and 91% reported it would reduce their stress/anxiety if receiving a negative test result in the ED. Conclusion Our findings demonstrated satisfactory performance and high patient acceptability of the Chembio DPP® HIV-Syphilis Assay. Given the test is FDA approved, implementation studies are needed to determine whether adoption of this POC test will benefit patients and be consistent with ED workflows. Disclosures Richard E. Rothman, PhD, MD, Chem bio (Grant/Research Support)

Implications of Remote Monitoring Technology in Optimizing Traditional Self-Monitoring of Blood Glucose in Adults with T2DM in primary care

Background: Self-monitoring of blood glucose (SMBG) has been shown to reduce hemoglobin A1C (HbA1C). Accordingly, guidelines recommend SMBG up to 4-10 times daily for adults with type 2 diabetes (T2DM) on insulin. For persons not on insulin, recommendations are equivocal. Newer technology-enabled blood glucose monitoring (BGM) devices can facilitate remote monitoring of glycemic data. New evidence generated by remote BGM may help to guide best practices for frequency and timing of finger-stick blood glucose (FSBG) monitoring in uncontrolled T2DM patients managed in primary care settings. Objective: To evaluate the impact of SMBG utility and frequency on glycemic outcomes using a novel BGM system which auto-transfers near real-time FSBG data to a cloud-based dashboard using cellular networks.Design: Secondary analysis of the intervention arm of a comparative non-randomized trial with propensity-matched chart controls.Participants: Adults with T2DM and HbA1C >9% receiving care in five primary care practices in a healthcare system. Interventions: Participation in a 3-month diabetes boot camp (DBC) using telemedicine and a novel BGM to support comprehensive diabetes care management. Main Measures: The primary independent variable was frequency of FSBG. Secondary outcomes included frequency of FSBG by insulin status, distribution of FSBG checks by time of day, and hypoglycemia rates.

Novel methods of continuous glucose monitoring and telehealth in the improvement of diabetes care: a narrative review.

Standard markers of glycaemic control, such as glycated haemoglobin (HbA1c) and self-measurement of blood glucose (SMBG), have proven insufficient. HbAc1 is an averaged measurement that does not give information about glucose variability. SMBG provides limited, intermittent blood glucose (BG) values over the day and is associated with poor compliance because of invasiveness of the method and social discomfort. In contrast to glucometers, continuous glucose monitoring (CGM) devices do not require finger-stick blood samples, but instead measure BG via percutaneous or subcutaneous sensors. The immediate benefits of CGM include prevention of hypoglycaemia or hyperglycaemia, and automated analysis of long-term glycaemic data enables reliable treatment adjustments. This review describes the principles of CGM and how CGM data have changed diabetes treatment standards by introducing new glycaemic control parameters. It also compares different CGM devices and examines how the convenience of sharing CGM data in telehealth applies to the current coronavirus-19 pandemic.

THE RELIABILITY OF GINGIVAL CREVICULAR BLOOD AS A DIAGNOSTIC TOOL FOR DIABETES BY USING GLUCOSE SELF-MONITORING DEVICE IN PATIENTS WITH PERIODONTAL DISEASE WITH AND WITHOUT DIABETES

Objective: To assess the reliability of gingival crevicular blood as a diagnostic tool for diabetes in patients with periodontal disease with and without diabetes. Study Design: Cross sectional study. Place and Duration of Study: Department of Periodontics, Jinnah Medical and Dental College, Karachi, Pakistan, from Jul 2017 to Jul 2018. Methodology: Forty patients with diabetes and 60 patients without diabetes with mild to moderate gingivitis or periodontitis in either the upper or lower anterior region were included. Gingival crevicular blood (GCB) was collected and was assessed by glucometer. The same patient underwent finger stick blood (FSB) and intravenous blood glucose level (IV). Plaque Index (PI), Periodontal Pocket Depth (PPD) and Gingival index were also recorded. Results: A positive correlation (r) was detected between glucose levels of Gingival crevicular blood with finger stick blood with the value of coefficient correlation ‘r’=0.849. The mean values of Gingival index in patients without diabetes is 1.53 ± 0.97mm, patients with newly diagnosed diabetes is 1.87 ± 0.920mm and without diabetes is 2.13± 0.94mm. Conclusion: Blood glucose level can be assessed with the help of Gingival crevicular blood as this technique was found easy and non-invasive to the patient and it can help in diagnosing diabetes during regular periodontal treatment.

SARS-CoV-2 virus masking of RBD epitopes; unmasking and cross-reactivity induced by mRNA vaccines

We analyzed data from two ongoing COVID-19 longitudinal serological surveys in Orange County, CA., between April 2020 and March 2021. A total of 8,476 finger stick blood specimens were collected before and after an aggressive mRNA vaccination campaign. IgG levels were determined using a multiplex antigen microarray containing 10 SARS-CoV-2 antigens, 4 SARS, 3 MERS, 12 Common CoV, and 8 Influenza antigens. Twenty-six percent of 3,347 specimens from unvaccinated Orange County residents in December 2020 were SARS-CoV-2 seropositive. The Ab response was predominantly against nucleocapsid (NP), full length spike and the spike S2 domain. Anti-receptor binding domain (RBD) reactivity was low and there was no cross-reactivity against SARS S1 or SARS RBD. An aggressive mRNA vaccination campaign at the UCI Medical Center started on December 16, 2020 and 6,724 healthcare workers were vaccinated within 3 weeks. Seroprevalence increased from 13% in December to 79% in January, 93% in February and 99% in March. mRNA vaccination induced much higher Ab levels especially against the RBD domain and significant cross-reactivity against SARS RBD and S1 was also observed. Nucleocapsid protein Abs can be used to distinguish individuals in a population of vaccinees to classify those who have been previously infected and those who have not, because nucleocapsid is not in the vaccine. Previously infected individuals developed higher Ab titers to the vaccine than those who have not been previously exposed. These results indicate that mRNA vaccination rapidly induces a much stronger and broader Ab response than SARS-CoV-2 infection.

Direct comparison of venipuncture serum draws versus whole blood finger-stick specimens by anti-COVID-19 IgG/IgM rapid lateral flow immunoassay and ELISA.

During the COVID-19 pandemic, manufacturers have developed several diagnostic test kits that include lateral flow immunoassays (LFIA) also known as rapid cassette testing. Rapid cassette testing provides qualitative test results indicating the presence or absence of IgG and IgM antibodies to determine COVID-19 (SARS-CoV-2) infection among individuals. Venipuncture blood draws have been the traditional and widely proposed sample collection method but is costly and not applicable to point-of-care testing (POC) and in remote settings. Whole blood finger-stick blood collections traditionally used by diabetics for glucose level testing is an ideal scenario, but raises concerns regarding the outcome of test results in regards to specificity and sensitivity. In this study we directly compare simultaneous collections of venipuncture serum (SST) blood draws and whole blood finger-sticks (n = 75) to detect human Anti-COVID-19 IgG and IgM antibodies using an EUA-approved lateral flow immunoassay, showing equal to enhanced performance characteristics for this specimen type.