Comparison of Rapid Antigen Tests' Performance Between Delta and Omicron Variants of SARS-CoV-2

Soni, Apurv; Herbert, Carly; Filippaios, Andreas; Broach, John; Colubri, Andrés; Fahey, Nisha; Woods, Kelsey; Nanavati, Janvi; Wright, Colton; Orwig, Taylor; Gilliam, Karen; Kheterpal, Vik; Suvarna, Thejas; Nowak, Christopher; Schrader, Summer; Lin, Honghuang; O’Connor, Laurel; Pretz, Caitlin; Ayturk, Didem; Orvek, Elizabeth; Flahive, Julie; Lazár, Peter; Shi, Qiming; Achenbach, Chad J.; Murphy, Robert L.; Robinson, Matthew L.; Gibson, Laura; Stamegna, Pamela; Hafer, Nathaniel; Luzuriaga, Katherine; Barton, Bruce; Heetderks, William; Manabe, Yukari C.; McManus, David D.

doi:10.7326/m22-0760

Cited by 37 publications

(20 citation statements)

References 21 publications

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“…This potentially reflects either intrinsic changes in the SARS-CoV-2 virus or changes in testing proficiency and behaviour around testing over time but is in contrast to other reports of lower sensitivity with Omicron, [17,18] while others have reported similar performance with Omicron vs. Delta. [19] Conversely, although specificity remained >99%, it declined over time with successive variants. Symptomatic individuals had higher viral loads in the LFD evaluations.…”

Section: Discussionmentioning

confidence: 99%

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Performance of antigen lateral flow devices in the United Kingdom during the Alpha, Delta, and Omicron waves of the SARS-CoV-2 pandemic

Eyre

Futschik²,

Tunkel³

et al. 2022

Preprint

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Background Antigen lateral flow devices (LFDs) have been widely used to control SARS-CoV-2. Changes in LFD sensitivity and detection of infectious individuals during the pandemic with successive variants, vaccination, and changes in LFD use are incompletely understood. Methods Paired LFD and PCR tests were collected from asymptomatic and symptomatic participants, across multiple settings in the UK between 04-November-2020 and 21-March-2022. Multivariable logistic regression was used to analyse LFD sensitivity and specificity, adjusting for viral load, LFD manufacturer, setting, age, sex, assistance, symptoms, vaccination, and variant. National contact tracing data were used to estimate the proportion of transmitting index cases (with ≥1 PCR/LFD-positive contact) potentially detectable by LFDs over time, accounting for viral load, variant, and symptom status. Findings 4131/75,382 (5.5%) participants were PCR-positive. Sensitivity vs. PCR was 63.2% (95%CI 61.7-64.6%) and specificity 99.71% (99.66-99.74%). Increased viral load was independently associated with being LFD-positive. There was no evidence LFD sensitivity differed between Delta vs. Alpha/pre-Alpha infections, but Omicron infections were more likely to be LFD positive. Sensitivity was higher in symptomatic participants, 68.7% (66.9-70.4%) than in asymptomatic participants, 52.8% (50.1-55.4%). 79.4% (68.6-81.3%) of index cases resulting in probable onward transmission with were estimated to have been detectable using LFDs, this proportion was relatively stable over time/variants, but lower in asymptomatic vs. symptomatic cases. Interpretation LFDs remained able to detect most SARS-CoV-2 infections throughout vaccine roll-out and different variants. LFDs can potentially detect most infections that transmit to others and reduce risks. However, performance is lower in asymptomatic compared to symptomatic individuals. Funding UK Government.

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Section: Discussionmentioning

confidence: 99%

“…Delta. [19] Conversely, although specificity remained >99%, it declined over time with successive variants.…”

Section: Discussionmentioning

confidence: 99%

Performance of antigen lateral flow devices in the United Kingdom during the Alpha, Delta, and Omicron waves of the SARS-CoV-2 pandemic

Eyre

Futschik²,

Tunkel³

et al. 2022

Preprint

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“…This study was conducted during the circulation of the Delta and Omicron SARS-CoV-2 variants, and future variants may warrant further investigation, especially as milder, less symptomatic variants emerge. 16,17 Additionally, specimens were self-collected for RT-PCR and Ag-RDTs were self-performed. However, data has consistently shown substantial agreement between self-collected and clinician-collected anterior nasal swabs for SARS-CoV-2 testing.…”

Section: Discussionmentioning

confidence: 99%

Performance of Rapid Antigen Tests to Detect Symptomatic and Asymptomatic SARS-CoV-2 Infection

Soni

Herbert

Lin

et al. 2022

Preprint

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Background: Performance of Rapid Antigen Tests for SARS-CoV-2 (Ag-RDT) varies over the course of an infection, and their performance is not well established among asymptomatic individuals. Objective: Evaluate performance of Ag-RDT for detection of SARS-CoV-2 in relation to onset of infection for symptomatic and asymptomatic participants. Design, Setting, and Participants: Prospective cohort study conducted from October 2021 to February 2022 among participants > 2 years-old from across the US who enrolled using a smartphone app. During each testing encounter, participants self-collected one nasal swab and performed Ag-RDT at home; at-least fifteen minutes later, a second nasal swab was self-collected and shipped for SARS-CoV-2 RT-PCR at a central lab. Both nasal swabs were collected 7 times at 48-hour intervals (over approximately 14 days) followed by an extra nasal swab collection with home Ag-RDT test 48-hours after their last PCR sample. Each participant was assigned to one of the three emergency use authorized (EUA) Ag-RDT tests used in this study. This analysis was limited to participants who were asymptomatic and tested negative by antigen and molecular test on their first day of study participation. Exposure: SARS-CoV-2 positivity was determined by testing a single home-collected anterior nasal sample with three FDA EUA molecular tests, where 2 out 3 positive test results were needed to determine a SARS-CoV-2 positive result. Onset of infection was defined as day on which the molecular PCR comparator result was positive for the first time. Main Outcomes and Measures: Sensitivity of Ag-RDT was measured based on testing once (same-day), twice (at 48-hours) and thrice (at 96 hours). Analysis was repeated for different Days Post Index PCR Positivity (DPIPP) and stratified based on symptom-status on a given DPIPP. Results: A total of 7,361 participants enrolled in the study and 5,609 were eligible for this analysis. Among 154 eligible participants who tested positive for SARS-CoV-2 infection based on RT-PCR, 97 were asymptomatic and 57 had symptoms at onset of infection (DPIPP 0). Serial testing with Ag-RDT twice over 48-hours resulted in an aggregated sensitivity of 93.4% (95% CI: 89.1-96.1%) among symptomatic participants on DPIPP 0-6. Among the 97 people who were asymptomatic at the onset of infection, 19 were singleton RT-PCR positive, i.e., their positive test was preceded and followed by a negative RT-PCR test within 48-hours. Excluding these singleton positives, aggregated sensitivity on DPIPP 0-6 for two-time serial-testing among asymptomatic participants was lower 62.7% (54.7-70.0%) but improved to 79.0% (71.0-85.3%) with serial testing three times at 48-hour interval. Discussion: Performance of Ag-RDT within first week of infection was optimized when asymptomatic participants tested three-times at 48-hour intervals and when symptomatic participants tested two-times separated by 48-hours.

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“…RAT positivity is generally associated with culturable virus, which itself is often a proxy for infectiousness ( 5 – 7 ). In addition, to investigate concerns that RATs may have inferior performance for Omicron versus Delta infections, a study compared same-day positivity between the variants, finding similar sensitivity of RAT and PCR tests ( 8 ). Last, RATs have the advantage of relative affordability, fast turnaround time, and at-home self-administration compared with PCR tests, making them the only viable exit test option for much of the population ( 9 , 10 ).…”

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confidence: 99%

Daily Rapid Antigen Exit Testing to Tailor University COVID-19 Isolation Policy

Earnest¹,

Chen²,

Chaguza³

et al. 2022

Emerg. Infect. Dis.

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We evaluated daily rapid antigen test (RAT) data from 323 COVID-19–positive university students in Connecticut, USA, during an Omicron-dominant period. Day 5 positivity was 47% for twice-weekly screeners and 26%–28% for less-frequent screeners, approximately halving each subsequent day. Testing negative > 10 days before diagnosis (event time ratio (ETR) 0.85 [95% CI 0.75–0.96]) and prior infection >90 days (ETR 0.50 [95% CI 0.33–0.76]) were significantly associated with shorter RAT positivity duration. Symptoms before or at diagnosis (ETR 1.13 [95% CI 1.02–1.25]) and receipt of 3 vaccine doses (ETR 1.20 [95% CI 1.04–1.39]) were significantly associated with prolonged positivity. Exit RATs enabled 53%–74% of students to leave isolation early when they began isolation at the time of the first positive test, but 15%–22% remained positive beyond the recommended isolation period. Factors associated with RAT positivity duration should be further explored to determine relationships with infection duration.

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Comparison of Rapid Antigen Tests' Performance Between Delta and Omicron Variants of SARS-CoV-2

Abstract: Use of rapid tests for diagnosis of COVID-19 is now commonplace, but questions remain regarding their performance characteristics compared with those of polymerase chain reaction testing. The role of sequential rapid testing in improving sensitivity is of great interest.

Cited by 37 publications

References 21 publications

Performance of antigen lateral flow devices in the United Kingdom during the Alpha, Delta, and Omicron waves of the SARS-CoV-2 pandemic

Performance of antigen lateral flow devices in the United Kingdom during the Alpha, Delta, and Omicron waves of the SARS-CoV-2 pandemic

Performance of Rapid Antigen Tests to Detect Symptomatic and Asymptomatic SARS-CoV-2 Infection

Daily Rapid Antigen Exit Testing to Tailor University COVID-19 Isolation Policy

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