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Correlation of Serum and Fingerstick Blood Collection for Monitoring Sars-Cov-2 Spike and Nucleocapsid Antibodies
Journal of Pediatric Gastroenterology and Nutrition ; 75(Supplement 1):S151-S153, 2022.
Article in English | EMBASE | ID: covidwho-2058337
ABSTRACT

Background:

The rapid spread and recurrent infections of SARS-CoV-2 has led to increased use and availability of at-home antigen testing, but widespread testing of antibodies against spike and nucleocapsid to monitor vaccine-induced immunity and exposure to the virus is lacking. Most serological tests require a serum sample from a venous blood draw, increasing risk of exposure to COVID-19 and limiting availability and scalability of testing for many patients. This is especially the case for individuals who are immunocompromised, such as those with inflammatory bowel diseases (IBD), which are frequently on medications that might alter their immune response and impact vulnerability to SARS-CoV-2. Use of easily acquired and stably stored dried fingerstick blood serves a promising specimen source for at-home, remote testing for SARS-CoV-2 antibodies. Aim(s) Validate the use of fingerstick blood (dried and then eluted) versus serum as a specimen for the measurement of quantitative spike and nucleocapsid antibodies to SARS-CoV-2 in a diverse cohort of healthy and immunocompromised patients. Method(s) Patients were consented and enrolled into the Pediatric Gastrointestinal Tissue, Stool, Saliva and Blood Registry prior to having an endoscopic procedure. Five mL of blood was obtained by venipuncture and 10 muL of fingerstick blood was collected and dried on a Neoteryx Mitra device. Blood was eluted from the Neoteryx Mitra samples in 200 muL of dilution buffer (1% BSA, 0.05% Tween-20, 140 mM NaCl, 50 mM Tris (pH 8.0), 0.025% sodium azide) and placed on an orbital shaker at a speed of 500 RPM for 3 h. Paired serum and fingerstick blood eluate specimens were run on the quantitative Roche Elecsys SARS-CoV-2 spike antibody assay and the qualitative Roche Elecsys SARS-CoV-2 nucleocapsid antibody assay. Linear regression were performed on each assay with exclusion of values that were above the upper limit of detection of the assay. Result(s) We observed an excellent correlation in both SARS-CoV-2 antibody assays when comparing fingerstick blood eluates and serum. The linear regression for the nucleocapsid antibody assay had a slope of 15.5, intercept of 4.05, and R2 of 0.92, indicating that a Neoteryx value of 1.00 COI (cut-off index) equates to a serum value of 19.6 COI. The linear regression for the spike assay had a slope of 13.6, intercept of 953, and R2 of 0.95, indicating that a value of 1,000 U/mL from a fingerstick sample equates to a serum value of 14,544 U/mL. Conclusion(s) These data demonstrate that fingerstick blood collected on Neoteryx Mitra devices can be used as a specimen source in Roche Elecsys SARS-CoV-2 antibody assays to calculate the serum levels of spike and nucleocapsid antibodies. This can serve as a platform to remotely and reliably monitor the durability of antibody responses to natural infection with and immunization against SARS-CoV-2 in patients. Chart comparisons of nucleocapsid (top) and spike (bottom) protein antibody levels detected via remote fingerstick collection (Neoteryx, x-axis) and venous blood serum (y-axis).
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Collection: Databases of international organizations Database: EMBASE Language: English Journal: Journal of Pediatric Gastroenterology and Nutrition Year: 2022 Document Type: Article

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Collection: Databases of international organizations Database: EMBASE Language: English Journal: Journal of Pediatric Gastroenterology and Nutrition Year: 2022 Document Type: Article