Prevalence and Factors Associated With Antigen Test Positivity Following SARS-CoV-2 Infection Among Health Care Workers in Los Angeles

Adamson, Paul C; Currier, Judith S.; Uslan, Daniel Z.; Garner, Omai B.

doi:10.1093/ofid/ofac462

Cited by 2 publications

(1 citation statement)

References 15 publications

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“…Previous studies have demonstrated RAT positivity rates of 31%-58% after at least 5 days of isolation [3], suggesting a strategy based on a negative RAT and symptom resolution to reduce the number of individuals leaving isolation while still infectious as well as reducing the number of people who remain unnecessarily in isolation [6,7]. A study of a health care worker's return-to-work antigen testing program found that antigen test positivity was 60.5% at day 5 and 47.4% positive at day 7 [8]. A second study of college athletes found that after 7 days of isolation, 27% continued to test positive on rapid antigen tests; it concluded that a 5-day isolation period may be insufficient [9].…”

Section: Introductionmentioning

confidence: 99%

Use of Rapid Antigen Tests to End Isolation in a University Setting: Observational Study

Zigo¹,

Wilkinson²,

Landry³

et al. 2023

JMIR Form Res

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Background COVID-19 isolation recommendations have evolved over the course of the pandemic. Initially, the US Centers for Disease Control and Prevention required 10 days of isolation after a positive test result. In December 2021, this was reduced to a minimum of 5 days with symptom improvement, followed by 5 days of mask wearing. As a result, several institutions of higher education, including the George Washington University, required persons testing positive for COVID-19 to either submit a negative rapid antigen test (RAT) with symptom resolution to leave isolation after 5 days or to maintain a 10-day isolation period in the absence of a negative RAT and the presence of continued symptoms. RATs are tools that can be used both to shorten isolation periods and to ensure that persons testing positive for COVID-19 remain in isolation if infectious. Objective The purpose of this analysis is to report on the experience of implementing RAT policies, examine the number of days that isolation was reduced via RAT testing, determine the factors that predicted uploading a RAT, and determine RAT positivity percentages to illustrate the utility of using RATs to end isolation. Methods In this study, 880 individuals in COVID-19 isolation at a university in Washington, DC, uploaded 887 RATs between February 21 and April 14, 2022. Daily positivity percentages were calculated, and multiple logistic regression analyses examined the odds of uploading a RAT by campus residential living status (ie, on or off campus), student or employee designation, age, and days in isolation. Results A total of 76% (669/880) of individuals in isolation uploaded a RAT during the study period. Overall, 38.6% (342/887) of uploaded RATs were positive. Uploaded RATs were positive 45.6% (118/259) of the time on day 5; 45.4% (55/121) on day 6; 47.1% (99/210) on day 7; and 11.1% (7/63) on day 10 or beyond. Adjusted logistic regression modeling indicated cases living on campus had increased odds of uploading a RAT (odds ratio [OR] 2.54, 95% CI 1.64-3.92), whereas primary student affiliation (OR 0.29, 95% CI 0.12-0.69) and days in isolation (OR 0.45, 95% CI 0.39-0.52) had decreased odds of uploading a RAT. Of the 545 cases with a negative RAT, 477 were cleared prior to day 10 of their isolation due to lack of symptoms and timely submission, resulting in a total of 1547 days of lost productivity saved compared to all being in isolation for 10 days. Conclusions RATs are beneficial, as they can support a decision to release individuals from isolation when they have recovered and maintain isolation for people who may still be infectious. Future isolation policies should be guided by similar protocols and research to reduce the spread of COVID-19 and minimize lost productivity and disruption to individuals’ lives.

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Section: Introductionmentioning

confidence: 99%

Use of Rapid Antigen Tests to End Isolation in a University Setting: Observational Study

Zigo¹,

Wilkinson²,

Landry³

et al. 2023

JMIR Form Res

View full text Add to dashboard Cite

show abstract

Performance of rapid antigen tests to detect SARS-CoV-2 variant diversity and correlation with viral culture positivity: implication for diagnostic development and future public health strategies

Goux,

Green,

Wilson

et al. 2024

mBio

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Antigen-based rapid diagnostic tests (Ag-RDTs) provide timely results, are simple to use, and are less expensive than molecular assays. Recent studies suggest that antigen-based testing aligns with virus culture-based results (a proxy of contagiousness at the peak viral phase of illness); however, the performance of Ag-RDTs for newer SARS-CoV-2 variants is unclear. In this study, we (i) assessed the performance of Ag-RDTs and diagnostic antibodies to detect a range of SARS-CoV-2 variants and (ii) determined whether Ag-RDT results correlated with culture positivity. We noted only minor differences in the limit of detection by variant for all assays, and we demonstrated consistent antibody affinity to the N protein among the different variants. We observed moderate to high sensitivity (46.8%–83.9%) for Ag-RDTs when compared to PCR positivity (100%), and all variants were assessed on each assay. Ag-RDT sensitivity and PCR Ct showed an inverse correlation with the detection of viable virus. Collectively, our results demonstrate that commercially available Ag-RDTs offer variable sensitivity compared to PCR, show similar diagnostic validity across variants, and may predict the risk of transmissibility. These findings may be used to support more tailored SARS-CoV-2 isolation strategies, particularly if other studies clarify the direct association between Ag-RDT positivity and transmission risk. The apparent trade-off between sensitivity in the detection of any PCR-positive infection and concordance with infectious virus positivity may also inform new RDT diagnostic development strategies for SARS-CoV-2 and other epidemic respiratory pathogens. IMPORTANCE Despite the availability of vaccines, COVID-19 continues to be a major health concern, and antigen-based rapid diagnostic tests (Ag-RDTs) are commonly used as point-of-care or at-home diagnostic tests. In this study, we evaluated the performance of two commercially available Ag-RDTs and a research Ag-RDT to detect multiple SARS-CoV-2 variants using upper respiratory tract swab samples from clinical COVID-19 cases. Furthermore, we determined whether Ag-RDT results correlated with culture positivity, a potential proxy of viral transmissibility. Our results have important implications to inform future testing and response strategies during periods of high COVID-19 transmission with new variants.

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Prevalence and Factors Associated With Antigen Test Positivity Following SARS-CoV-2 Infection Among Health Care Workers in Los Angeles

Cited by 2 publications

References 15 publications

Use of Rapid Antigen Tests to End Isolation in a University Setting: Observational Study

Use of Rapid Antigen Tests to End Isolation in a University Setting: Observational Study

Performance of rapid antigen tests to detect SARS-CoV-2 variant diversity and correlation with viral culture positivity: implication for diagnostic development and future public health strategies

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