Estimating seroprevalence of SARS-CoV-2 infection after highly contagious Omicron outbreak: A cross sectional study in a university setting (preprint)

Abstract Objective: This study aimed to investigate the seroprevalence of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) antibodies among individuals aged 18 years and older Design: Prospective cohort study. Settings: Population-based study was conducted within the Arizona State University (ASU) community. Participants: The study recruited 1,397 adult participants that volunteered over a period of three days (March 1-March 3 of 2022). Primary outcome measures: Seroprevalence was conducted in the community to assess the presence of SARS-CoV-2-specific antibodies resulting from previous exposure to SARS-CoV-2 and/or vaccination. Results: The seroprevalence of anti-receptor binding domain (RBD) antibodies was found to be 96.3% using a semi-quantitative chemiluminescent immunoassay and 98% using an electrochemiluminescent immunoassay. For anti-nucleocapsid (NC) antibodies, the seroprevalence was 39.1% by an ELISA assay and 41.4% by an electrochemiluminescent immunoassay. Individuals that experienced breakthrough infections exhibited the highest levels of anti-RBD antibodies. Additionally, saliva samples showed promise as a potential diagnostic biofluid for measuring antibody levels, as they exhibited a strong correlation with the data obtained from serum samples. Conclusion: Accurate estimation of population-based serosurveillance for SARS-CoV-2 will monitor the trend of infection in the community and delineate the geographical spread of the infection. Cumulative incidence of SARS-CoV-2 infection during and after outbreaks is crucial for informing the development of effective risk mitigation protocols within the community. Protocols may include measures such as encouraging booster shots, extending mask mandates, or transitioning to online classes. Serosurveys repeated at regular intervals can also guide containment measures in communities and prompt respond to future outbreaks. Strengths and limitations of this study: * We simultaneously investigated active infection and seroprevalence for the university population. * Our study was strengthened by having the participants self-report data independently validated with diagnostic tests. * Saliva samples could be a potential diagnostic biofluid for measuring antibody levels. * Our study was performed within the university setting therefore it only reflects the COVID-19 situation within that community. * The number of breakthrough infections and the longitudinal samples were small, thus requiring confirmation.

Serosurvey of SARS-COV-2 at a large public university (preprint)

Arizona State University (ASU) is one the largest universities in the United States, with more than 79,000 students attending in-person classes. We conducted a seroprevalence study from September 13-17, 2021 to estimate the number of people in our community with SARS-CoV-2-specific antibodies due to previous exposure to SARS-CoV-2 and/or vaccination. Participants provided their age, gender, race, status (student or employee), and general COVID-19 health-related information like previous exposure and vaccination status. The seroprevalence of the anti-receptor binding domain (RBD) antibody was 90% by a lateral flow assay and 88% by a semi-quantitative chemiluminescent immunoassay. The seroprevalence for anti-nucleocapsid (NC) was 20%. In addition, individuals with previous natural COVID infection plus vaccination had higher anti-RBD antibody levels compared to those who had vaccination only or infection only. Individuals who had a breakthrough infection had the highest anti-RBD antibody levels. Accurate estimates of the cumulative incidence of SARS-CoV-2 infection can inform the development of university risk mitigation protocols such as encouraging booster shots, extending mask mandates, or reverting to online classes. It could help us to have clear guidance to take action at the first sign of the next surge as well, especially since there is a surge of COVID subvariant infections.

The Serological Sciences Network (SeroNet) for COVID-19: Depth and Breadth of Serology Assays and Plans for Assay Harmonization (preprint)

Background: In October 2020, the National Cancer Institute (NCI) Serological Sciences Network (SeroNet) was established to study the immune response to COVID-19, and to develop, validate, improve, and implement serological testing and associated technologies. SeroNet is comprised of 25 participating research institutions partnering with the Frederick National Laboratory for Cancer Research (FNLCR) and the SeroNet Coordinating Center. Since its inception, SeroNet has supported collaborative development and sharing of COVID-19 serological assay procedures and has set forth plans for assay harmonization. Methods: To facilitate collaboration and procedure sharing, a detailed survey was sent to collate comprehensive assay details and performance metrics on COVID-19 serological assays within SeroNet. In addition, FNLCR established a protocol to calibrate SeroNet serological assays to reference standards, such as the U.S. SARS-CoV-2 serology standard reference material and First WHO International Standard (IS) for anti-SARS-CoV-2 immunoglobulin (20/136), to facilitate harmonization of assay reporting units and cross-comparison of study data. Results: SeroNet institutions reported development of a total of 27 ELISA methods, 13 multiplex assays, 9 neutralization assays, and use of 12 different commercial serological methods. FNLCR developed a standardized protocol for SeroNet institutions to calibrate these diverse serological assays to reference standards. Conclusions: SeroNet institutions have established a diverse array of COVID-19 serological assays to study the immune response to SARS-CoV-2 virus and vaccines. Calibration of SeroNet serological assays to harmonize results reporting will facilitate future pooled data analyses and study cross-comparisons.

Emergence of a SARS-CoV-2 E484K variant of interest in Arizona (preprint)

SARS-CoV-2 is locked in a high-stakes arms race between the dynamics of rising population immunity and escape mutations. The E484K mutation in the spike protein reduces neutralization by post-vaccination sera and monoclonal antibody therapeutics. We detected the emergence of an E484K harboring variant B.1.243.1 from a common circulating variant (B.1.243) in the United States. In contrast to other instances when the E484K mutation was acquired independently in the parental lineage, genomic surveillance indicates that the B.1.243.1 variant of interest is in the process of being established in Arizona and beginning to cross state borders to New Mexico and Texas. Genomic, epidemiologic and phylogenetic evidence indicates that the B.1.243.1 variant of interest is poised to emerge. These findings demonstrate the critical need to continue tracking SARS-CoV-2 in real-time to inform public health strategies, diagnostics, medical countermeasures and vaccines.