Clinical validation of quantitative SARS-CoV-2 antigen assays to estimate SARS-CoV-2 viral loads in nasopharyngeal swabs

Aoki, Kotaro; Nagasawa, Tatsuya; Ishii, Yoshikazu; Yagi, Shusuke; Okuma, Sadatsugu; Kashiwagi, Katsuhito; Maeda, Tadashi; Miyazaki, Taito; Yoshizawa, Sadako; Tateda, Kazuhiro

doi:10.1016/j.jiac.2020.11.021

Cited by 40 publications

(23 citation statements)

References 12 publications

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“…In the current study, anterior nasal samples provided a lower antigen test sensitivity than our previous study evaluating nasopharyngeal samples (3). The sensitivity of antigen tests is largely influenced by the viral load in collected samples (9)(10)(11)(12). The QuickNavi-COVID19 Ag test could detect SARS-CoV-2 in almost all samples with Ct values < 30, and in 18.8% of samples with Ct values > 30 (3).…”

Section: Discussioncontrasting

confidence: 55%

Diagnostic Performance and Characteristics of Anterior Nasal Collection for the SARS-CoV-2 Antigen Test: A Prospective Study in Japan

Takeuchi

Akashi

Kato

et al. 2021

Preprint

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We conducted a prospective study in Japan to evaluate the diagnostic performance of the antigen test QuickNavi-COVID19 Ag using anterior nasal samples and to compare the degrees of coughs or sneezes induction and the severity of pain between anterior nasal collection and nasopharyngeal collection. A total of 862 participants were included in the analysis. In comparison to the findings of reverse transcription PCR using nasopharyngeal samples, the antigen test using anterior nasal samples showed 72.5% sensitivity (95% confidence interval [CI]: 58.3%-84.1%) and 100% specificity (95% CI: 99.3%-100%). Anterior nasal collection was associated with a significantly lower degree of coughs or sneezes induction and the severity of pain in comparison to nasopharyngeal collection (p < 0.001). The antigen test using anterior nasal samples showed moderate sensitivity but was less painful and induced fewer coughs or sneezes.

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Section: Discussioncontrasting

confidence: 55%

Diagnostic Performance and Characteristics of Anterior Nasal Collection for the SARS-CoV-2 Antigen Test: A Prospective Study in Japan

Takeuchi

Akashi

Kato

et al. 2021

Preprint

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“…Previous reports on the Lumipulse G SARS-CoV-2 Ag assay in NPS samples showed a concordance with RT-qPCR of 91·4% in 313 samples 15 and 98·2% in 548 samples. 16 By contrast, Kobayashi and colleagues 17 reported a lower concordance of 66·0% in 100 NPS samples, although samples with discrepant results were collected considerably later in the course of infection than those with concordant results. To our knowledge, our study is the first to evaluate saliva samples with CLEIA.…”

Section: Discussionmentioning

confidence: 94%

“… 14 In June, 2020, a quantitative antigen test that uses a chemiluminescent enzyme immunoassay (CLEIA) was developed, which can detect SARS-CoV-2 proteins in NPS or saliva samples within 35 min, called Lumipulse G SARS-CoV-2 Ag (Fujirebio, Tokyo, Japan). 15 , 16 , 17 In the present study, we prospectively compared the utility of this CLEIA test against RT-qPCR when applied on self-collected saliva, including performance in asymptomatic people, and we propose a two-step strategy for mass screening of SARS-CoV-2.…”

Section: Introductionmentioning

confidence: 99%

A novel strategy for SARS-CoV-2 mass screening with quantitative antigen testing of saliva: a diagnostic accuracy study

Yokota¹,

Shane²,

Okada³

et al. 2021

The Lancet Microbe

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Background Quantitative RT-PCR (RT-qPCR) of nasopharyngeal swab (NPS) samples for SARS-CoV-2 detection requires medical personnel and is time consuming, and thus is poorly suited to mass screening. In June, 2020, a chemiluminescent enzyme immunoassay (CLEIA; Lumipulse G SARS-CoV-2 Ag kit, Fujirebio, Tokyo, Japan) was developed that can detect SARS-CoV-2 nucleoproteins in NPS or saliva samples within 35 min. In this study, we assessed the utility of CLEIA in mass SARS-CoV-2 screening. MethodsWe did a diagnostic accuracy study to develop a mass-screening strategy for salivary detection of SARS-CoV-2 by CLEIA, enrolling hospitalised patients with clinically confirmed COVID-19, close contacts identified at community health centres, and asymptomatic international arrivals at two airports, all based in Japan. All test participants were enrolled consecutively. We assessed the diagnostic accuracy of CLEIA compared with RT-qPCR, estimated according to concordance (Kendall's coefficient of concordance, W), and sensitivity (probability of CLEIA positivity given RT-qPCR positivity) and specificity (probability of CLEIA negativity given RT-qPCR negativity) for different antigen concentration cutoffs (0•19 pg/mL, 0•67 pg/mL, and 4•00 pg/mL; with samples considered positive if the antigen concentration was equal to or more than the cutoff and negative if it was less than the cutoff). We also assessed a two-step testing strategy post hoc with CLEIA as an initial test, using separate antigen cutoff values for test negativity and positivity from the predefined cutoff values. The proportion of intermediate results requiring secondary RT-qPCR was then quantified assuming prevalence values of RT-qPCR positivity in the overall tested population of 10%, 30%, and 50%. Findings Self-collected saliva was obtained from 2056 participants between June 12 and Aug 6, 2020. Results of CLEIA and RT-qPCR were concordant in 2020 (98•2%) samples (Kendall's W=0•99). Test sensitivity was 85•4% (76 of 89 positive samples; 90% credible interval [CrI] 78•0-90•3) at the cutoff of 0•19 pg/mL; 76•4% (68 of 89; 68•2-82•8) at the cutoff of 0•67 pg/mL; and 52•8% (47 of 89; 44•1-61•3) at the cutoff of 4•0 pg/mL. Test specificity was 91•3% (1796 of 1967 negative samples; 90% CrI 90•2-92•3) at the cutoff of 0•19 pg/mL, 99•2% (1952 of 1967; 98•8-99•5) at the cutoff of 0•67 pg/mL, and 100•0% (1967 of 1967; 99•8-100•0) at the cutoff of 4•00 pg/mL. Using a two-step testing strategy with a CLEIA negativity cutoff of 0•19 pg/mL (to maximise sensitivity) and a CLEIA positivity cutoff of 4•00 pg/mL (to maximise specificity), the proportions of indeterminate results (ie, samples requiring secondary RT-qPCR) would be approximately 11% assuming a prevalence of RT-qPCR positivity of 10%, 16% assuming a prevalence of RT-qPCR positivity of 30%, and 21% assuming a prevalence of RT-qPCR positivity of 50%.Interpretation CLEIA testing of self-collected saliva is simple and provides results quickly, and is thus suitable for mass testing. To improve accuracy, we propose a two-step ...

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“…Since the first day of this study, 3 August 2020, the NAT, which was used as the screening test for COVID-19, was completely replaced by a quantitative antigen detection test (Lumipulse SARS-CoV-2 Ag; Fujirebio) at 4 of the 5 major airport quarantine stations, other than Fukuoka Airport, where the screening test was thoroughly shifted to the antigen detection test on 16 September 2020 [ 14 , 15 ]. If the result of the antigen detection test was inconclusive even after the replacement, NAT was performed for confirmation.…”

Section: Methodsmentioning

confidence: 99%

Epidemiology and Risk of Coronavirus Disease 2019 Among Travelers at Airport and Port Quarantine Stations Across Japan: A Nationwide Descriptive Analysis and an Individually Matched Case-Control Study

Tsuboi

Hachiya

Ohtsu

et al. 2021

Clinical Infectious Diseases

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Background The epidemiology and risk of COVID-19 among travelers at international borders remain unclear. Methods We conducted descriptive and individually matched case-control studies using a nationwide register for COVID-19 testing of travelers from August 3 to October 31, 2020 at airport/port quarantine stations across Japan. Cases defined as COVID-19-positive travelers on arrival were individually matched with four controls for arrival date and airport/port. We assessed associations between test positivity and traveler characteristics using conditional logistic regression. Results Overall, 157,507 travelers arriving from 146 countries/areas at 17 quarantine stations across Japan were tested for COVID-19. The test percent positivity during the study period was 0.35%. In the case-control study with 536 cases and 2,144 controls, we found evidence of lower test positivity in travelers aged 3–19 years, females, and travel corridor users (adjusted odds ratio [95% confidence interval]: 0.36 [0.22–0.60], 0.71 [0.56–0.89], and 0.48 [0.30–0.77], respectively), whereas higher positivity was associated with arrival from South-East Asia (1.88 [1.33–2.65]) or lower-middle- or low-income countries (2.46 [1.69–3.58] and 7.25 [2.22–23.66], respectively), any symptom (4.08 [1.43–11.65]), and nasopharyngeal compared to saliva sampling (2.75 [1.85–4.09]). A higher 14-day average incidence in the countries of stay was also associated with higher test positivity (1.64 [1.16–2.33] and 3.13 [1.88–5.23]). Conclusions These findings justify travel restrictions based on the epidemic situation in countries of stay, although underestimation of the epidemic in lower income countries should be considered. A strict travel corridor could also reduce COVID-19 importation risk.

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Clinical validation of quantitative SARS-CoV-2 antigen assays to estimate SARS-CoV-2 viral loads in nasopharyngeal swabs

Cited by 40 publications

References 12 publications

Diagnostic Performance and Characteristics of Anterior Nasal Collection for the SARS-CoV-2 Antigen Test: A Prospective Study in Japan

Diagnostic Performance and Characteristics of Anterior Nasal Collection for the SARS-CoV-2 Antigen Test: A Prospective Study in Japan

A novel strategy for SARS-CoV-2 mass screening with quantitative antigen testing of saliva: a diagnostic accuracy study

Epidemiology and Risk of Coronavirus Disease 2019 Among Travelers at Airport and Port Quarantine Stations Across Japan: A Nationwide Descriptive Analysis and an Individually Matched Case-Control Study

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