SARS-CoV-2 Serology Testing in an Asymptomatic, At-Risk Population: Methods, Results, Pitfalls.

The primary aim of this study was to determine the seroprevalence of SARS-CoV-2 antibodies in a population of pediatric healthcare workers (HCWs). This study was conducted 14 May-13 July 2020. Study participants included pediatric HCWs at a pediatric hospital with either direct patient contact or close proximity to patient-care areas. SARS-CoV-2 antibodies were assessed via the Wytcote Superbio SARS-CoV-2 IgM/IgG Antibody Fast Detection Kit and the Abbott Architect SARS-CoV-2 IgG assay. Participants underwent RT-PCR testing upon entry to the study and following rapid IgM+/IgG+ results; respiratory panel PCR (RP-PCR) was performed following IgM+ results. A total of 57 of 289 (19.7%) of participants demonstrated positive serology as assessed by the Wytcote rapid kit (12 on Day 1 and 45 throughout the study). However, only one of these participants demonstrated IgG+ serology via the Abbott assay. Two participants tested SARS-CoV-2+ via RT-PCR testing. One individual was adenovirus+ and enterovirus/rhinovirus+. In our study population, we observed a seroprevalence of SARS-CoV-2 antibodies of 0.35%. The lack of concordance between antibody tests suggests that the Wytcote rapid test kit may not be of use as a screening tool. However, the feasibility of the overall process indicates that a similar methodology may have potential for future epidemiologic surveillance.

Provider Antibody Serology Study of Virus in the Emergency Room (PASSOVER) Study: Special Population COVID-19 Seroprevalence.

INTRODUCTION: Limited data on the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among healthcare workers (HCW) are publicly available. In this study we sought to determine the seroprevalence of SARS-CoV-2 in a population of HCWs in a pediatric emergency department (ED). METHODS: We conducted this observational cohort study from April 14-May 13, 2020 in a pediatric ED in Orange County, CA. Asymptomatic HCW ≥18 years of age were included in the study. Blood samples were obtained by fingerstick at the start of each shift. The inter-sampling interval was ≤96 hours. The primary outcome was positive seroprevalence of SARS-CoV-2 as determined with an antibody fast detection kit (Colloidal Gold, Superbio, Timisoara, Romania) for the SARS-CoV-2 immunoglobulin M/immunoglobulin G (IgM/IgG) antibody. RESULTS: A total of 143 HCWs participated in the study. Overall SARS-CoV-2 seroprevalence was 10.5% (n = 15). Positive seroprevalence was classified as IgG only (4.9%), IgM+IgG (3.5%), or IgM only (2.1%). SARS-CoV-2 was detected by reverse transcription polymerase chain reaction RT-PCR in 0.7% of the overall study population (n = 1). Samples obtained on Day 1 indicated seropositivity in 4.2% of the study population (n = 6). Subsequent seroconversion occurred in 6.3% of participants (n = 9). The rate of seroconversion was linear with a rate of approximately one new case every two days, starting at Day 9 of the study. CONCLUSION: We observed a linear rate of seroconversion to SARS-CoV-2-positive status among asymptomatic HCWs who underwent daily symptom surveys and temperature screens in an environment with universal source control. Rapid antibody testing may be useful for screening for SARS-CoV-2 seropositivity in high-risk populations, such as HCWs in the ED.

Rapid antibody testing for SARS-CoV-2 vaccine response in pediatric healthcare workers.

BACKGROUND: The durability of the immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination remains unknown. The objective of this study was to evaluate a rapid SARS-CoV-2 IgM/IgG antibody detection kit as a qualitative screen for the humoral response to vaccination. METHODS: Study participants (n = 125) included pediatric healthcare workers (HCWs) who had received two doses of BNT162b2 or mRNA-1273. Participants were tested on study entry (March 12, 2021 to April 9, 2021). The mean number of days post second dose was 22 (range 17-36). Participants were tested for IgM/IgG antibodies to the SARS-CoV-2 spike protein with the RightSign COVID-19 IgG/IgM Rapid Test Cassette. ELISA/competitive inhibition ELISA (CI-ELISA) were subsequently run to assess for the neutralization effect and SARS-CoV-2 anti-nucleocapsid IgM/IgG antibodies. RESULTS: Overall, 98.4% of participants were IgG-positive and 0.8% were IgM-positive on rapid RightSign testing. Of those with IgG-positive results, 100% were anti-spike protein IgG-positive on CI-ELISA; none of those who tested IgG-negative via the rapid test were IgG-positive on CI-ELISA. All HCWs who tested RightSign positive demonstrated neutralizing capability on CI-ELISA. Overall, 1.6% demonstrated anti-nucleocapsid IgM antibodies and 5.6% demonstrated anti-nucleocapsid IgG antibodies. CONCLUSIONS: The strong agreement between the rapid RightSign IgG results and confirmatory CI-ELISA testing suggests that this test may be used to assess for positive, and neutralizing, antibody responses to SARS-CoV-2 mRNA vaccination.

Pediatric Deep Brain Stimulation Using Awake Recording and Stimulation for Target Selection in an Inpatient Neuromodulation Monitoring Unit.

Deep brain stimulation (DBS) for secondary (acquired, combined) dystonia does not reach the high degree of efficacy achieved in primary (genetic, isolated) dystonia. We hypothesize that this may be due to variability in the underlying injury, so that different children may require placement of electrodes in different regions of basal ganglia and thalamus. We describe a new targeting procedure in which temporary depth electrodes are placed at multiple possible targets in basal ganglia and thalamus, and probing for efficacy is performed using test stimulation and recording while children remain for one week in an inpatient Neuromodulation Monitoring Unit (NMU). Nine Children with severe secondary dystonia underwent the NMU targeting procedure. In all cases, 4 electrodes were implanted. We compared the results to 6 children who had previously had 4 electrodes implanted using standard intraoperative microelectrode targeting techniques. Results showed a significant benefit, with 80% of children with NMU targeting achieving greater than 5-point improvement on the Burke⁻Fahn⁻Marsden Dystonia Rating Scale (BFMDRS), compared with 50% of children using intraoperative targeting. NMU targeting improved BFMDRS by an average of 17.1 whereas intraoperative targeting improved by an average of 10.3. These preliminary results support the use of test stimulation and recording in a Neuromodulation Monitoring Unit (NMU) as a new technique with the potential to improve outcomes following DBS in children with secondary (acquired) dystonia. A larger sample size will be needed to confirm these results.