Evaluation of a self-administered antigen test in a university setting  Virology Journal

Evaluation of a self-administered antigen test in a university setting Virology Journal

This investigation was a collaboration between the participating college, the Georgia Department of Public Health (GDPH), and the US Centers for Disease Control and Prevention (CDC). The protocol for this investigation has been reviewed by their Institutional Review Boards and determined to be non-investigative and conducted in accordance with applicable federal law and CDC policy as defined at 45 CFR46.102(I)(2).

setting and participants

The investigation was conducted between February 22nd and April 20th, 2021 at a primarily residential college in Georgia, USA. The level of COVID-19 transmission in the surrounding county was moderate at the start of the investigation and low at the end [7]. At the start of the investigation period when vaccine eligibility was limited, 14.6% of the county’s total population had received at least one dose of the COVID-19 vaccine and 9.1% were considered fully vaccinated [7]. On March 25, vaccine eligibility was expanded to everyone 16 and older. By the end of the investigation, 28.7% of county residents had received at least one dose of the COVID-19 vaccine, and 22.2% of county residents were considered fully vaccinated [7]. The college’s vaccination rate at the start of the investigation was 19.8% for employees and 5.4% for students. Mass vaccination events were held on campus in the weeks of March 22 and April 19; By the end of the investigation, vaccination rates among staff and students were 75.6% and 62.2%, respectively.

Most students (90%) who attend the college live in residence halls on a controlled campus. The school has put in place several COVID-19 prevention strategies, including mask mandates, physical distancing in classrooms, improved cleaning of facilities, limiting access to campus, and encouraging students to form small, mutually exclusive social “bubbles” of 5 students. College-attended students (N = 1982), staff/faculty members (N = 643), and associates (eg, spouses of staff) associated with the college were eligible for investigation. Anyone who was in quarantine due to exposure to SARS-CoV-2 or who had symptoms of COVID-19 was not eligible for testing. In the two weeks prior to the investigation, seven cases of COVID-19 were reported on campus (prevalence rate: 133.3/100,000).

Self antigen screening test twice a week

The Quidel QuickVue At-Home COVID-19 Test (hereinafter referred to as the Self-Administered Antigen Test) is a collateral flow assay based on the qualitative detection of SARS-CoV-2 nucleocapsid protein. Results are read visually on the test strip after ten minutes. At the time this investigation began, this test was subject to FDA review for an emergency use authorization (EUA) for self-administration and was granted EUA approval in March 2021. [8].

Participants were provided with self-administered antigen tests and manufacturer’s instructions and directed to be tested twice weekly for seven consecutive weeks. During the third week, nasal swabs for paired rRT-PCR testing were collected on the same day as the antigen test (Fig. 1).

Chart 1

Chronology of the investigation of the self-administered sequential COVID-19 antigen test

Participants were asked to submit their self-administered antigen test results and a photo of their test strip through the college’s electronic symptom screening reporting system. Participants who tested positive by self-antigen testing were advised to receive a confirmatory test on the same day by RT-PCR and to self-isolate.

SARS-CoV-2 IgG antibody test

To assess the number of SARS-CoV-2 infections the twice-weekly self-administered antigen test was not tested for, we examined SARS-CoV-2 seroconversion, with paired baseline (week 1) and endline (week 9) serological testing ( Diagram 1). The college provided participants with COVID-19 vaccination records and positive SARS-CoV-2 test results within the 90 days prior to and during the investigation.

Nurses collected blood samples from consenting participants in K2-EDTA tubes. Plasma was separated from whole blood by centrifugation within 24 hours of collection. Plasma samples were aliquoted into refrigerated Nalgene vials, heat-treated at 56 °C (132.8 °F) for 10 min, and frozen at −80 °C. A single plasma aliquot with VITROS-specific antibody against SARS-CoV-2 was tested in an in vitro diagnostic test on the VITROS 3600 Automated Immunodiagnostic System (Ortho Clinical Diagnostics), which measures total SARS-CoV-2 antibody against SARS-CoV – 2 spike protein. The automatically calculated ratio of test sample signal to cutoff value (S/C) < 1.0 was interpreted as non-reactive, and S/C of 1.0 was interpreted as reactivity for anti-SARS-CoV-2 total antibody.

To determine infection versus vaccine-induced antibody responses among vaccinated participants, plasma samples were analyzed using a V-plex SARS-CoV-2 2 IgG panel (Mesoscale Diagnostics). [MSD]) as directed by the manufacturer. This multiplex assay detects antibodies against SARS-CoV-2 nucleocapsid (N), spike (S), and spike receptor-binding domain (RBD). Samples that were positive for nucleocapsid antibodies, in addition to S and/or RBD, were classified as having an infection-induced antibody response; Only endline samples positive for S and/or RBD were classified as having a vaccination-induced antibody response only (that is, no evidence of infection).

Paired rRT-PCR assay

During the third week of investigation, participants were asked to submit a nasal swab sample for rRT-PCR testing and to have a self-administered antigen test on the same day. Participants were instructed to collect a two-sided anterior nasal swab for rRT-PCR testing. These swabs were stored in tubes with viral transport media in coolers with cold packs and transported daily to the Georgia Public Health Laboratory and stored at 4 °C until testing. Within 48 hours of collection, the DNA sample was isolated using the Perkin Elmer Chemagic Viral DNA/RNA Assay on a Perkin Elmer Chemagic 360 instrument (Perkin-Elmer) and analyzed using the CDC Influenza SARS-2 (Flu SC2) Multiplex Assay according to the manufacturer’s instructions. to use [9]. The remaining frozen samples were positive for SARS-CoV-2 by either test and were subjected to viral culture. Samples were cultured by limiting dilution in Vero E6/TMPRSS2 cells and observed daily for cytopathic effects in 96-well plates, described previously. [10]. The supernatants were harvested from cells that showed cytopathic effects and tested by rRT-PCR using the Flu SC2 Multiplex Assay to confirm the presence of SARS CoV-2. A sample was culture positive if the first viral lane had a cycle threshold (Ct) value at least two Ct values ​​lower than the clinical sample.

Acceptance and use surveys

Participants underwent surveys during the second and eighth weeks of investigation to assess the characteristics and acceptability of a twice-weekly self-administered antigen test via an online survey platform (Qualtrics). Participation in the second survey was low and results were not reported. Survey questions are included in Supplementary File 1.

statistical analysis

Analyzes were performed using SAS (version 9.4; SAS Institute) and validated by an independent analyst. Frequencies of descriptive variables were calculated among groups of participants. The sensitivity, specificity, positive predictive value, and negative predictive value of the self-conjugated antigen test were calculated as compared to the rRT-PCR test and seroconversion. Percentages of test conditions and acceptability of test methods were calculated from the surveys.

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