Skip to content
Publicly Available Published by De Gruyter March 15, 2022

Fujirebio Lumipulse SARS-CoV-2 antigen immunoassay: pooled analysis of diagnostic accuracy

Giuseppe Lippi ORCID logo, Brandon M. Henry, Khosrow Adeli and Mario Plebani ORCID logo
From the journal Diagnosis

Abstract

We provide here a pooled analysis of accuracy of Fujirebio Lumipulse SARS-CoV-2 Antigen chemiluminescent immunoassay for diagnosing acute SARS-CoV-2 infections. An electronic search was conducted in Scopus and Medline with the keywords “Lumipulse” AND “antigen” AND “SARS-CoV-2” or “COVID-19”, up to January 21, 2022, for identifying clinical investigations (minimum sample size ≥100) where diagnostic accuracy of Lumipulse G SARS-CoV-2 Ag was tested against reference molecular techniques. All studies which allowed to construct a 2 × 2 table were included in a pooled analysis. A final number of 21 studies, totalling 17,648 nasopharyngeal and 8538 saliva specimens, were finally included. The pooled diagnostic sensitivity and specificity in nasopharyngeal swabs were 0.80 (95%CI, 0.78–0.81) and 0.98 (95%CI, 0.97–0.98), respectively, whilst the area under the curve and agreement were 0.980 (95%CI, 0.973–0.986) and 94.9%, respectively. In the twelve studies which used the fixed 1.34 pg/mL currently recommended manufacturer’s threshold, the diagnostic accuracy remained unvaried. In saliva samples, the pooled diagnostic sensitivity and specificity were 0.75 (95%CI, 0.71–0.75) and 1.00 (95%CI, 0.99–1.00), respectively, whilst the area under the curve and were 0.976 (95%CI, 0.969–0.984) and 98.4%, respectively. In the five studies which used the fixed 0.67 pg/mL currently recommended manufacturer’s threshold, the diagnostic accuracy remained unvaried. In conclusion, Lumipulse G SARS-CoV-2 Ag assay demonstrates good diagnostic sensitivity and specificity, thus representing a valuable complementary and integrative option to molecular testing for SARS-CoV-2 in the current pandemic.

Introduction

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the virus responsible for Coronavirus Disease 2019 (COVID-19), was originally identified in Wuhan (China) in November 2019 and is now the cause of the most devastating pandemic since the Spanish flu occurred more than one century ago [1]. Although the official number of SARS-CoV-2 infections and COVID-19 deaths that have been officially recorded so far is around 350 and 5.6 million, respectively, several lines of evidence suggest that these figures may only represent the tip of the iceberg, with the real numbers likely to be 2- to 4-fold higher [2]. In this dramatic situation, where viral spread seems to have been reinforced by emergence of highly mutated and more transmissible SARS-CoV-2 lineages, such as the Omicron (B.1.1.529) variant [3], the traditional laboratory efficiency is dramatically challenged, and frequently disrupted, by the enormous number of tests that need to be carried out for diagnosing COVID-19 and contact tracing, as highlighted by a worldwide survey promoted by the American Association of Clinical Chemistry (AACC) [4].

Although many alternative approaches have been attempted (e.g., serology, mass spectrometry and imaging, among others), the identification (and possible quantification) of viral RNA by means of nucleic acid amplification techniques (NAATs) remains the gold standard for diagnosing acute SARS-CoV-2 infections [5]. This approach, based on amplification of specific targets within the SARS-CoV-2 genome, identifies infected people with high accuracy and reproducibility, though most routine molecular detection techniques are plagued by inherent drawbacks such as relatively long turnaround time, low throughput and need for dedicated instrumentation and skilled personnel [6]. To this end, the development and commercialisation of a vast array of manual, point of care (POC) and laboratory-based immunoassays represent a feasible solution to overcome the current shortage of human and technical resources needed for performing several millions of molecular tests daily all around the world [7]. The SARS-CoV-2 nucleocapsid (N) protein is the leading viral antigen used for developing immunoassays for diagnosing COVID-19 [8], since it is subjected to modest evolutionary pressure (i.e., its genetic structure appears more stable) as compared to the spike (S) protein, which is instead under higher evolutionary pressure. Targeting the N protein thus carries a lower risk of introducing mutations that may limit or completely prevent monoclonal antibodies binding in assays and, theoretically, may also be a better antigenic target since is seemingly shed in higher amount [9].

Although the use of rapid diagnostic tests for detecting SARS-CoV-2 antigens (Ag-RDTs) has some obvious advantages such as facility, rapidity, as well as possibility to be carried out without dedicated laboratory instrumentations and specific personnel, their diagnostic accuracy varies widely, and is especially plagued by relatively low sensitivity, i.e., around 60% in both the adult (0.68; 95%CI, 0.59–0.76) [10] and paediatric (0.64; 95%CI, 0.57–0.70) [11] populations. To this end, development and introduction of laboratory-based sensitive SARS-CoV-2 antigen immunoassays into routine practice should be seen as a tangible solution for relieving part of the pressure caused by the immense volume of SARS-CoV-2 diagnostic tests that is currently placed on clinical laboratories.

The Fujirebio Lumipulse G SARS-CoV-2 Ag (Fujirebio Holdings Inc., Tokyo, Japan) is a chemiluminescent enzyme immunoassay (CLEIA) to be used on the Lumipulse G systems for detection and quantitative measurement of SARS-CoV-2 N protein in human nasopharyngeal swabs (using both a squeeze and regular test tubes) or saliva. According to manufacturer’s specifications, the sample volume is 100 µL, the turnaround time is around 30 min, the throughput is 60 tests/h on Lumipulse G600II and 120 tests/h on Lumipulse G1200, the analytical sensitivity (limit of detection; LoD) is 0.19 pg/mL (corresponding to 2.95 TCID50/mL), the functional sensitivity (limit of quantitation; LoQ) is 0.60 pg/mL, the measuring range is between 0.60 and 5,000 pg/mL and the linearity between 0.36 and 6,057 pg/mL [12]. The diagnostic cut-offs currently recommended by the manufacturer are 1.34 and 0.67 pg/mL in nasopharyngeal and saliva specimens, respectively. This article is hence aimed at providing a pooled analysis of the accuracy of this fully-automated immunoassay for diagnosing acute SARS-CoV-2 infections.

Materials and methods

An electronic search was conducted using the scientific platforms Scopus and Medline (PubMed interface) with the keywords “Lumipulse” AND “antigen” AND “SARS-CoV-2” or “COVID-19” in all [Article Title] AND [Abstract] AND [keywords], without time or language limits (i.e., up to January 21, 2022), for identifying all clinical investigations where the diagnostic accuracy of Lumipulse G SARS-CoV-2 Ag has been tested against reference molecular diagnostic techniques. Two authors (G.L. and B.M.H.) screened all documents by title, abstract and full text (when available), picking up all studies where the rates of true positive (TP), false positive (FP), true negative (TN) and false negative (FN) cases were presented or could be extrapolated or approximated from other data or figures reported in the study for constructing a 2 × 2 table, with minimum sample size threshold set at ≥100. The references of these articles were systematically hand-searched for detecting other potentially pertinent investigations. The information reported in each study was analysed for estimating the pooled diagnostic sensitivity, specificity, and accuracy (summary receiver operating characteristic curve [SROC]; agreement; kappa statistics) with 95% confidence interval (95%CI). Two separate analyses were performed, pooling data obtained in nasopharyngeal swabs or saliva. We applied a random effects model for pooling data, whilst we calculated the heterogeneity with χ2 test and I2 statistic. The statistical analysis was conducted using Meta-DiSc 1.4 (Unit of Clinical Biostatistics team of the Ramón y Cajal Hospital, Madrid, Spain) [13]. The study was performed in agreement with the Declaration of Helsinki and within the terms of local legislation.

Results

Our electronic search in the two scientific databases based on the aforementioned criteria initially identified 27 articles after excluding duplicates. Six articles were excluded because they either did not present specific data regarding the diagnostic accuracy of Lumipulse G SARS-CoV-2 Ag (n=3), did not carry out clinical evaluation of test performance (n=1), were correspondence (n=1), or had insufficient sample size (n=1, only 27 patients) [14]. A final number of 21 studies, totalling 17,648 nasopharyngeal and 8538 saliva specimens were finally included in the pooled analysis [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36]. Nasopharyngeal swab was the only specimen collected in 15 studies, saliva was the only sample matrix collected in three studies, whilst both specimen types were collected in four studies. One study [22] reported data on two separate patient cohorts (an internal validation group and a real-life population). Three studies which used nasopharyngeal swabs [35, 36] and two which used saliva specimens [23], [24], [25] were published by the same team of authors, though we could not recognise whether parts of the study population or even the entire sample was used in the subsequent analyses.

Table 1 and 2 summarise the principal characteristics of all selected studies using nasopharyngeal (n=17,648) or saliva (n=8,538) specimens. Regarding the geographical setting, there was a disproportionate number of studies conducted in Japan (10/19 using nasopharyngeal swabs and 5/7 using saliva, respectively) and Italy (7/19 using nasopharyngeal swabs and 2/7 using saliva, respectively). A broad heterogeneity of reference molecular techniques were used for detecting and measuring SARS-CoV-2 RNA, as well as the range of viral load (when specified). The diagnostic threshold of Lumipulse G SARS-CoV-2 Ag varied consistently across the different investigations; in studies using nasopharyngeal swabs the 1.34 pg/mL cut-off was used in 12 instances and a double cut-off (<1.0 pg/mL: negative; >10 pg/mL: positive) in 4 cases, whilst in studies using saliva the 0.67 pg/mL cut-off was used in five instances and a double cut-off (<0.67 pg/mL: negative; >4.0 pg/mL: positive) in the remaining two cases.

Table 1:

Summary of studies which investigated the cumulative diagnostic performance of Fujirebio Lumipulse G SARS-CoV-2 Ag in nasopharyngeal samples.

Study Country Cut-off Sample size Molecular assay (gene targets) Range of viral load
Andreani et al. 2021 [16] France 1.34 pg/mL 210 Multiple assays – In-house from French National Reference centre (RdRp) and Abbott Alinity M SARS-CoV-2 assay (N and RdRP) 13–40 Ct
Aoki et al. 2021 [17] Japan 1.34 pg/mL 548 In-house – National Institute of Infectious Diseases (NIID) method (N) 0–1 × 106 copies/test
Baccani et al. 2021 [19] Italy 1.34 pg/mL 201 Seegene Allplex SARS-CoV-2 assay (E, N and RdPr) 16–40 Ct
Basso et al. 2021 [20] Italy 1.34 pg/mL 151 Applied Biosystems TaqPath COVID-19 RT-PCR kit (Orf1ab, N and S) 20–38 Ct
Caputo et al. 2021 [21] Italy 1.0 pg/mL 4,266 ThermoFisher TaqPath COVID-19 RT PCR CE IVD kit (ORF1ab, N, S) ∼2–11 log10 copies/test
Gili et al. 2021 [22] Italy 1.34 pg/mL 226 (validation) Seegene Allplex SARS-CoV-2 assay (E, N and RdPr) Unspecified (median 29 Ct)
Gili et al. 2021 [22] Italy 1.34 pg/mL 1728 (screening) Seegene Allplex SARS-CoV-2 assay (E, N and RdPr) Unspecified (median 22 Ct)
Hirotsu et al. 2021 [23] Japan <1.0 pg/mL NEG and >10 pg/mL POS 1,029 In-house – National Institute of Infectious Diseases (NIID) method (N) 14–39 Ct
Hirotsu et al. 2020 [24] Japan <1.0 pg/mL NEG and >10 pg/mL POS 313 In-house – National Institute of Infectious Diseases (NIID) method (N) 0–1 × 107 copies/test
Hirotsu et al., 2021 [25] Japan <1.0 pg/mL NEG and >10 pg/mL POS 529 In-house – National Institute of Infectious Diseases (NIID) method (N) Unspecified
Ishii et al. 2021 [26] Japan <1.0 pg/mL NEG and >10 pg/mL POS 485 In-house – National Institute of Infectious Diseases (NIID) method (N) 14–35 Ct
Kobayashi et al. 2021 [27] Japan <0.67 pg/mL NEG and >4.00 pg/mL POS 4,920 Shimadzu Ampdirect 2019 novel coronavirus Detection Kit (N) Unspecified
Kobayashi et al. 2021 [28] Japan 1.34 pg/mL 300 Shimadzu Ampdirect 2019 novel coronavirus Detection Kit (N) 0–110 × 104 copies/µL
Matsuzaki et al. 2021 [29] Japan 1.34 pg/mL 128 In-house – Japan National Institute of Infectious Diseases (NIID) method (N) 24–35 Ct
Mencacci et al. 2021 [30] Italy 10 pg/mL 671 Seegene Allplex SARS-CoV-2 assay (E, N and RdPr) 16–41 Ct
Menchinelli et al. 2021 [31] Italy 1.34 pg/mL 594 In-house (E) 11–40 Ct
Nomoto et al. 2021 [32] Japan 1.34 pg/mL 100 In-house – Japan National Institute of Infectious Diseases (NIID) method (N) 1 × 10−3–1 × 106 copies/test
Osterman et al. 2021 [33] Germany 1.34 pg/mL 410 Multiple assays – Seegene Allplex, Roche Cobas and Cepheid GeneXpert system (unspecified gene targets) 0.8 × 102–1.6 × 109 Geq/mL
Sberna et al. 2021 [34] Italy 1.34 pg/mL 513 Multiple platforms – Seegene Allplex SARS-CoV-2 assay (E, N and RdPr), Diatech Easy SARS-CoV-2 WE kit (N and RdRp) 12–40 Ct
Yokota et al. 2021 [35] Japan 0.67 pg/mL 326 In-house – National Institute of Infectious Diseases (NIID) method (N) 13–33 Ct

  1. Ct, cycle threshold; POS, positive; NEG, negative.

Table 2:

Summary of studies which investigated the diagnostic performance of Fujirebio Lumipulse G SARS-CoV-2 Ag Immunoassay in saliva.

Study Country Cut-off Sample size Molecular assay (gene targets) Range of viral load
Amendola et al. 2021 [15] Italy 0.67 pg/mL 169 DiaSorin Simplexa COVID-19 Direct assay (ORF1ab and S) 14–45 Ct
Asai et al. 2021 [18] Japan 0.67 pg/mL 305 In-house – US CDC (N) 15–35 Ct
Basso et al. 2021 [20] Italy 0.67 pg/mL 164 Applied Biosystems TaqPath COVID-19 RT-PCR kit (Orf1ab, N and S) 20–38 Ct
Ishii et al. 2021 [26] Japan <0.67 pg/mL NEG and >4.00 pg/mL POS 132 In-house – National Institute of Infectious Diseases (NIID) method (N) 14–35 Ct
Kobayashi et al. 2021 [28] Japan <0.67 pg/mL NEG and >4.00 pg/mL POS 5,386 Shimadzu Ampdirect 2019 novel coronavirus Detection Kit (N) Unspecified
Yokota et al. 2021 [35] Japan 0.67 pg/mL 326 In-house – National Institute of Infectious Diseases (NIID) method (N) 19–34 Ct
Yokota et al. 2021 [36] Japan 0.67 pg/mL 2,056 In-house – National Institute of Infectious Diseases (NIID) method (N) 14–38 Ct

  1. Ct, cycle threshold; POS, positive; NEG, negative.

The outcome of the pooled analysis of accuracy of Lumipulse G SARS-CoV-2 Ag for diagnosing acute SARS-CoV-2 infection in nasopharyngeal swabs is summarised in Figure 1. The diagnostic sensitivity and specificity were 0.80 (95%CI, 0.78–0.81) and 0.98 (95%CI, 0.97–0.98), respectively, whilst the area under the curve (AUC), agreement and kappa statistics were 0.980 (95%CI, 0.973–0.986), 94.9% and 0.80 (95%CI, 0.79 to 0.82), respectively, which reflects a nearly perfect agreement [37]. Results remained identical even when two of the three studies by the same team of authors with lower sample size were excluded [24, 25]. In the 12 studies that used the fixed 1.34 pg/mL diagnostic threshold currently recommended by the manufacturer, the diagnostic sensitivity and specificity remained almost unvaried at 0.82 (95%CI, 0.80–0.84) and 0.94 (95%CI, 0.93–0.95), respectively, whilst the AUC, agreement and kappa statistics were 0.963 (95%CI, 0.955–0.971), 91.2% and 0.76 (95%CI, 0.74–0.78), respectively, thus indicating substantial agreement [37].

Figure 1: 
Cumulative diagnostic sensitivity, specificity and accuracy (summary receiver operating characteristic curve [SROC]) with 95% confidence interval (95%CI) of Fujirebio Lumipulse G SARS-CoV-2 Ag immunoassay for diagnosing SARS-CoV-2 infection in nasopharyngeal samples.

Figure 1:

Cumulative diagnostic sensitivity, specificity and accuracy (summary receiver operating characteristic curve [SROC]) with 95% confidence interval (95%CI) of Fujirebio Lumipulse G SARS-CoV-2 Ag immunoassay for diagnosing SARS-CoV-2 infection in nasopharyngeal samples.

The outcome of the pooled analysis of accuracy of Lumipulse G SARS-CoV-2 Ag for diagnosing acute SARS-CoV-2 infection in saliva is summarised in Figure 2. The diagnostic sensitivity and specificity were 0.75 (95%CI, 0.71–0.75) and 1.00 (95%CI, 0.99–1.00), respectively, whilst the AUC, agreement and kappa statistics were 0.976 (95%CI, 0.969–0.984), 98.4% and 0.82 (95%CI, 0.79–0.85), respectively, which reflects almost perfect agreement [37]. Results remained identical even when one [35] of the two studies by the same team of authors with lower sample sizes was excluded. In the five studies that used a fixed 0.67 pg/mL cut-off in alignment with current manufacturer recommendations, the diagnostic sensitivity and specificity decreased to 0.66 (95%CI, 0.61–0.72), 0.99 (95%CI, 0.99–0.99), respectively, whilst the AUC, agreement and kappa statistics were and 0.944 (95%CI, 0.916–0.972), 95.6% and 0.73 (95%CI, 0.69–0.78), respectively, thus reflecting substantial agreement [36].

Figure 2: 
Cumulative diagnostic sensitivity, specificity and accuracy (summary receiver operating characteristic curve [SROC]) with 95% confidence interval (95%CI) of Fujirebio Lumipulse G SARS-CoV-2 Ag immunoassay for diagnosing SARS-CoV-2 infection in saliva.

Figure 2:

Cumulative diagnostic sensitivity, specificity and accuracy (summary receiver operating characteristic curve [SROC]) with 95% confidence interval (95%CI) of Fujirebio Lumipulse G SARS-CoV-2 Ag immunoassay for diagnosing SARS-CoV-2 infection in saliva.

Discussion

The almost unremittent spread of SARS-CoV-2, either due to naïve or breakthrough infections sustained by mutated lineages that are capable of escaping both natural and vaccine-elicited immunity [38], is now imposing an unprecedented burden on the modern systems of health care, society and economy [39]. Laboratory medicine is no exception to this rule, since the response capacity of many worldwide laboratory facilities is currently overwhelmed by an immense volume of tests, causing a backlog for many specimens which may hence remain untested for days [4041].

Although Ag-RDTs may represent a valuable resource [42], their routine clinical usage is mostly challenged by low diagnostic sensitivity, around 60%, which would leave many patients with acute SARS-CoV-2 infection underdiagnosed, and potentially trigger large outbreaks. This paves the way to introduce the use of more accurate and efficient laboratory-based immunoassays, such as Lumipulse G SARS-CoV-2 Ag. Overall, this immunoassay displayed a diagnostic sensitivity in nasopharyngeal samples that is nearly 20% higher than that exhibited on average by Ag-RDTs (i.e., 80 vs. ∼60%), coupled with an extremely high specificity (i.e., 98%) and 94.9% concordance with reference molecular diagnostic techniques. Notably, such accuracy was replicated in saliva, whereby the sensitivity was slightly lower at 75%, but the specificity and concordance with reference molecular diagnostic techniques were even higher (i.e., 100 and 98.4%, respectively). Although a head-to-head comparison would be misleading due to many heterogeneities in the study designs, it is notable that the accuracy of Lumipulse G SARS-CoV-2 seems higher than that found in other studies with different chemiluminescent immunoassays, such as Roche Elecsys SARS-CoV-2 antigen (0.68 sensitivity, 0.99 specificity and 89.5% accuracy, respectively) [43], DiaSorin LIAISON SARS-CoV-2 Ag (0.31 sensitivity, 1.00 specificity and 50% accuracy) [44] or Ortho VITROS SARS-CoV-2 Ag Test CLIA Kit (0.73 sensitivity, 1.00 specificity and 99.8% accuracy) [45].

Unfortunately, we could not perform a pooled analysis in samples with high viral load since this information was unavailable in more than half of the studies, and when present, the data could not be aggregated due to the use of different molecular techniques and gene targets, broad thresholds for identifying samples with high viral load (i.e., from 22 to 30 Ct values), as well as heterogeneous measuring units (i.e., Ct values, copies/test, copies/µL, Geq/mL). Nonetheless, it is rather predictable that the accuracy of Lumipulse G SARS-CoV-2 would be magnified in samples with high viral load. To this end, using the manufacturer’s recommended cut-offs of 1.34 and 0.67 pg/mL in nasopharyngeal swabs and saliva, respectively, Basso et al. reported that sensitivity, specificity and accuracy of this test in samples with Ct values <26 were as high as 1.00 (95%CI, 0.87–1.00), 0.94 (95%CI; 0.86–98) and 95.3% (95%CI, 89.3–98.5%) in nasopharyngeal samples and 0.94 (95%CI, 0.71–1.00), 0.97 (95%CI, 0.92–0.99) and 96.7% (95%CI, 91.7–99.1%) in saliva, respectively [46]. The antigen drift of the nucleocapsid (N) protein and the impact its mutations on antigen tests performance over time is another important aspect that needs to be accurately evaluated, considering that SARS-CoV-2 has greatly mutated so far, and will continue to do so in the foreseeable future [3]. For example, the three Omicron (B.1.1.529) lineages BA.1 (including BA.1.1), BA.2 and BA.3 contain between 4 and 5 mutations in the genetic sequence encoding for the N protein (P13L, Δ31–33, R203K, G204R, S413R) [46], and some of these changes may actually impair the affinity of the anti-SARS-CoV-2 N antibodies used in some immunoassays, as recently shown by Osterman et al. [47]. No study testing the Lumipulse G SARS-CoV-2 Ag assay has been conducted during the recent surge of the Omicron variant (i.e., the most recently published concluded the enrolment before October 2021, when the Delta variant was still locally dominating [34]) and thereby further investigations would be needed to clarify this important matter.

In conclusion, the Fujirebio Lumipulse G SARS-CoV-2 Ag assay demonstrates good diagnostic sensitivity and specificity, thus representing a valuable complementary and integrative option to molecular testing for SARS-CoV-2 in the current pandemic. The high analytical sensitivity of this immunoassay, combined with its automation and hence potential for high-throughput testing, allows accurate identification of acute SARS-CoV-2 infections in clinical practice, not only in samples with high viral load. Moreover, the diagnostic accuracy found in salivary samples would also allow for a non-invasive, simple and suitable alternative to nasopharyngeal swabs.


Corresponding author: Giuseppe Lippi, IFCC Task Force on COVID-19, Milan, Italy; and Section of Clinical Biochemistry, University of Verona, Piazzale L.A. Scuro, 10, 37134 Verona, Italy, Phone: +0039 045 8122970, Fax: +0039 045 8124308, E-mail:
Khosrow Adeli and Mario Plebani share senior authorship in this work.

  1. Research funding: The authors received no funding for this work.

  2. Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.

  3. Competing interests: Authors state no conflict of interest.

  4. Informed consent: Not applicable.

  5. Ethical approval: Not applicable.

References

1. Sampath, S, Khedr, A, Qamar, S, Tekin, A, Singh, R, Green, R, et al.. Pandemics throughout the history. Cureus 2021;13:e18136. https://doi.org/10.7759/cureus.18136.Search in Google Scholar PubMed PubMed Central

2. Adam, D. The pandemic’s true death toll: millions more than official counts. Nature 2022;601:312–5. https://doi.org/10.1038/d41586-022-00104-8.Search in Google Scholar PubMed

3. Lippi, G, Mattiuzzi, C, Henry, BM. Updated picture of SARS-CoV-2 variants and mutations. Diagnosis (Berl). 2021;9:11–7. https://doi.org/10.1515/dx-2021-0149.Search in Google Scholar PubMed

4. American Association of Clinical Chemistry. Coronavirus testing survey. Available at: https://www.aacc.org/science-and-research/covid-19-resources/aacc-covid-19-testing-survey [Last accessed 22 Jan 2022].Search in Google Scholar

5. Lippi, G, Horvath, AR, Adeli, K. Editorial and executive summary: IFCC interim guidelines on clinical laboratory testing during the COVID-19 pandemic. Clin Chem Lab Med 2020;58:1965–9. https://doi.org/10.1515/cclm-2020-1415.Search in Google Scholar PubMed

6. Bohn, MK, Mancini, N, Loh, TP, Wang, CB, Grimmler, M, Gramegna, M, et al.. IFCC interim guidelines on molecular testing of SARS-CoV-2 infection. Clin Chem Lab Med 2020;58:1993–2000. https://doi.org/10.1515/cclm-2020-1412.Search in Google Scholar PubMed

7. Bohn, MK, Lippi, G, Horvath, AR, Erasmus, R, Grimmler, M, Gramegna, M, et al.. IFCC interim guidelines on rapid point-of-care antigen testing for SARS-CoV-2 detection in asymptomatic and symptomatic individuals. Clin Chem Lab Med 2021;59:1507–15. https://doi.org/10.1515/cclm-2021-0455.Search in Google Scholar PubMed

8. Khan, WH, Khan, N, Mishra, A, Gupta, S, Bansode, V, Mehta, D, et al.. Dimerization of SARS-CoV-2 nucleocapsid protein affects sensitivity of ELISA based diagnostics of COVID-19. Int J Biol Macromol 2022;200:428–37. https://doi.org/10.1016/j.ijbiomac.2022.01.094.Search in Google Scholar PubMed PubMed Central

9. Lippi, G, Adeli, K, Plebani, M. Commercial immunoassays for detection of anti-SARS-CoV-2 spike and RBD antibodies: urgent call for validation against new and highly mutated variants. Clin Chem Lab Med 2022;60:338–42. https://doi.org/10.1515/cclm-2021-1287.Search in Google Scholar PubMed

10. Lee, J, Song, JU, Shim, SR. Comparing the diagnostic accuracy of rapid antigen detection tests to real time polymerase chain reaction in the diagnosis of SARS-CoV-2 infection: a systematic review and meta-analysis. J Clin Virol 2021;144:104985. https://doi.org/10.1016/j.jcv.2021.104985.Search in Google Scholar PubMed PubMed Central

11. Fujita-Rohwerder, N, Beckmann, L, Zens, Y, Verma, A. Diagnostic accuracy of rapid point-of-care tests for diagnosis of current SARS-CoV-2 infections in children: a systematic review and meta-analysis. BMJ Evid Based Med 2022:111828. bmjebm-2021. https://doi.org/10.1136/bmjebm-2021-111828 [Epub ahead of print].Search in Google Scholar PubMed PubMed Central

12. Fujirebio. Lumipulse® G SARS-CoV-2 Ag. Available at: https://www.fujirebio.com/en/products-solutions/lumipulse-g-sars-cov2-ag [Last accessed 22 Jan 2022].Search in Google Scholar

13. Zamora, J, Abraira, V, Muriel, A, Khan, KS, Coomarasamy, A. Meta-DiSc: a software for meta-analysis of test accuracy data. BMC Med Res Methodol 2006;6:31. https://doi.org/10.1186/1471-2288-6-31.Search in Google Scholar PubMed PubMed Central

14. Hirotsu, Y, Maejima, M, Shibusawa, M, Amemiya, K, Nagakubo, Y, Hosaka, K, et al.. Analysis of a persistent viral shedding patient infected with SARS-CoV-2 by RT-qPCR, FilmArray Respiratory Panel v2.1, and antigen detection. J Infect Chemother 2021;27:406–9. https://doi.org/10.1016/j.jiac.2020.10.026.Search in Google Scholar PubMed PubMed Central

15. Amendola, A, Sberna, G, Lalle, E, Colavita, F, Castilletti, C, Menchinelli, G, et al.. Saliva is a valid alternative to nasopharyngeal swab in chemiluminescence-based assay for detection of SARS-CoV-2 antigen. J Clin Med 2021;10:1471. https://doi.org/10.3390/jcm10071471.Search in Google Scholar PubMed PubMed Central

16. Andreani, J, Lupo, J, Germi, R, Laugier, C, Roccon, M, Larrat, S, et al.. Evaluation of six commercial SARS-CoV-2 rapid antigen tests in nasopharyngeal swabs: better knowledge for better patient management? J Clin Virol 2021;143:104947. https://doi.org/10.1016/j.jcv.2021.104947.Search in Google Scholar PubMed PubMed Central

17. Aoki, K, Nagasawa, T, Ishii, Y, Yagi, S, Okuma, S, Kashiwagi, K, et al.. Clinical validation of quantitative SARS-CoV-2 antigen assays to estimate SARS-CoV-2 viral loads in nasopharyngeal swabs. J Infect Chemother 2021;27:613–6. https://doi.org/10.1016/j.jiac.2020.11.021.Search in Google Scholar PubMed PubMed Central

18. Asai, N, Sakanashi, D, Ohashi, W, Nakamura, A, Kawamoto, Y, Miyazaki, N, et al.. Efficacy and validity of automated quantitative chemiluminescent enzyme immunoassay for SARS-CoV-2 antigen test from saliva specimen in the diagnosis of COVID-19. J Infect Chemother 2021;27:1039–42. https://doi.org/10.1016/j.jiac.2021.03.021.Search in Google Scholar PubMed PubMed Central

19. Baccani, I, Morecchiato, F, Chilleri, C, Cervini, C, Gori, E, Matarrese, D, et al.. Evaluation of three immunoassays for the rapid detection of SARS-CoV-2 antigens. Diagn Microbiol Infect Dis 2021;101:115434. https://doi.org/10.1016/j.diagmicrobio.2021.115434.Search in Google Scholar PubMed PubMed Central

20. Basso, D, Aita, A, Padoan, A, Cosma, C, Navaglia, F, Moz, S, et al.. Salivary SARS-CoV-2 antigen rapid detection: a prospective cohort study. Clin Chim Acta 2021;517:54–9. https://doi.org/10.1016/j.cca.2021.02.014.Search in Google Scholar PubMed PubMed Central

21. Caputo, V, Bax, C, Colantoni, L, Peconi, C, Termine, A, Fabrizio, C, et al.. Comparative analysis of antigen and molecular tests for the detection of Sars-CoV-2 and related variants: a study on 4266 samples. Int J Infect Dis 2021;108:187–9. https://doi.org/10.1016/j.ijid.2021.04.048.Search in Google Scholar PubMed PubMed Central

22. Gili, A, Paggi, R, Russo, C, Cenci, E, Pietrella, D, Graziani, A, et al.. Evaluation of Lumipulse® G SARS-CoV-2 antigen assay automated test for detecting SARS-CoV-2 nucleocapsid protein (NP) in nasopharyngeal swabs for community and population screening. Int J Infect Dis 2021;105:391–6. https://doi.org/10.1016/j.ijid.2021.02.098.Search in Google Scholar PubMed PubMed Central

23. Hirotsu, Y, Maejima, M, Shibusawa, M, Amemiya, K, Nagakubo, Y, Hosaka, K, et al.. Prospective study of 1308 nasopharyngeal swabs from 1033 patients using the LUMIPULSE SARS-CoV-2 antigen test: comparison with RT-qPCR. Int J Infect Dis 2021;105:7–14. https://doi.org/10.1016/j.ijid.2021.02.005.Search in Google Scholar PubMed PubMed Central

24. Hirotsu, Y, Maejima, M, Shibusawa, M, Nagakubo, Y, Hosaka, K, Amemiya, K, et al.. Comparison of automated SARS-CoV-2 antigen test for COVID-19 infection with quantitative RT-PCR using 313 nasopharyngeal swabs, including from seven serially followed patients. Int J Infect Dis 2020;99:397–402. https://doi.org/10.1016/j.ijid.2020.08.029.Search in Google Scholar PubMed PubMed Central

25. Hirotsu, Y, Sugiura, H, Maejima, M, Hayakawa, M, Mochizuki, H, Tsutsui, T, et al.. Comparison of Roche and Lumipulse quantitative SARS-CoV-2 antigen test performance using automated systems for the diagnosis of COVID-19. Int J Infect Dis 2021;108:263–9. https://doi.org/10.1016/j.ijid.2021.05.067.Search in Google Scholar PubMed PubMed Central

26. Ishii, T, Sasaki, M, Yamada, K, Kato, D, Osuka, H, Aoki, K, et al.. Immunochromatography and chemiluminescent enzyme immunoassay for COVID-19 diagnosis. J Infect Chemother 2021;27:915–8. https://doi.org/10.1016/j.jiac.2021.02.025.Search in Google Scholar PubMed PubMed Central

27. Kobayashi, R, Murai, R, Asanuma, K, Fujiya, Y, Takahashi, S. Evaluating a novel, highly sensitive, and quantitative reagent for detecting SARS-CoV-2 antigen. J Infect Chemother 2021;27:800–7. https://doi.org/10.1016/j.jiac.2021.01.007.Search in Google Scholar PubMed PubMed Central

28. Kobayashi, R, Murai, R, Moriai, M, Nirasawa, S, Yonezawa, H, Kondoh, T, et al.. Evaluation of false positives in the SARS-CoV-2 quantitative antigen test. J Infect Chemother 2021;27:1477–81. https://doi.org/10.1016/j.jiac.2021.06.019.Search in Google Scholar PubMed PubMed Central

29. Matsuzaki, N, Orihara, Y, Kodana, M, Kitagawa, Y, Matsuoka, M, Kawamura, R, et al.. Evaluation of a chemiluminescent enzyme immunoassay-based high-throughput SARS-CoV-2 antigen assay for the diagnosis of COVID-19: the VITROS® SARS-CoV-2 Antigen Test. J Med Virol 2021;93:6778–81. https://doi.org/10.1002/jmv.27153.Search in Google Scholar PubMed PubMed Central

30. Mencacci, A, Gili, A, Gidari, A, Schiaroli, E, Russo, C, Cenci, E, et al.. Role of nucleocapsid protein antigen detection for safe end of isolation of SARS-CoV-2 infected patients with long persistence of viral RNA in respiratory samples. J Clin Med 2021;10:4037. https://doi.org/10.3390/jcm10184037.Search in Google Scholar PubMed PubMed Central

31. Menchinelli, G, Bordi, L, Liotti, FM, Palucci, I, Capobianchi, MR, Sberna, G, et al.. Lumipulse G SARS-CoV-2 Ag assay evaluation using clinical samples from different testing groups. Clin Chem Lab Med 2021;59:1468–76. https://doi.org/10.1515/cclm-2021-0182.Search in Google Scholar PubMed

32. Nomoto, H, Yamamoto, K, Yamada, G, Suzuki, M, Kinoshita, N, Takasaki, J, et al.. Time-course evaluation of the quantitative antigen test for severe acute respiratory syndrome coronavirus 2: the potential contribution to alleviating isolation of COVID-19 patients. J Infect Chemother 2021;27:1669–73. https://doi.org/10.1016/j.jiac.2021.08.015.Search in Google Scholar PubMed PubMed Central

33. Osterman, A, Iglhaut, M, Lehner, A, Späth, P, Stern, M, Autenrieth, H, et al.. Comparison of four commercial, automated antigen tests to detect SARS-CoV-2 variants of concern. Med Microbiol Immunol 2021;210:263–75. https://doi.org/10.1007/s00430-021-00719-0.Search in Google Scholar

34. Sberna, G, Basile, F, Guarino, ML, Capobianchi, MR, Bordi, L, Parisi, G. Comparison of AllplexTM SARS-CoV-2 Assay, Easy SARS-CoV-2 WE and Lumipulse quantitative SARS-CoV-2 antigen test performance using automated systems for the diagnosis of COVID-19. Int J Infect Dis 2021;113:113–5. https://doi.org/10.1016/j.ijid.2021.09.069.Search in Google Scholar

35. Yokota, I, Sakurazawa, T, Sugita, J, Iwasaki, S, Yasuda, K, Yamashita, N, et al.. Performance of qualitative and quantitative antigen tests for SARS-CoV-2 using saliva. Infect Dis Rep 2021;13:742–7. https://doi.org/10.3390/idr13030069.Search in Google Scholar

36. Yokota, I, Shane, PY, Okada, K, Unoki, Y, Yang, Y, Iwasaki, S, et al.. A novel strategy for SARS-CoV-2 mass screening with quantitative antigen testing of saliva: a diagnostic accuracy study. Lancet Microbe 2021;2:e397–e404. https://doi.org/10.1016/s2666-5247(21)00092-6.Search in Google Scholar

37. Landis, JR, Koch, GG. The measurement of observer agreement for categorical data. Biometrics 1977;33:159–74. https://doi.org/10.2307/2529310.Search in Google Scholar

38. Lippi, G, Mattiuzzi, C, Henry, BM. Neutralizing potency of COVID-19 vaccines against the SARS-CoV-2 Omicron (B.1.1.529) variant. J Med Virol 2022;94:1799–802. https://doi.org/10.1002/jmv.27575.Search in Google Scholar PubMed PubMed Central

39. Smith Jervelund, S, Eikemo, TA. The double burden of COVID-19. Scand J Publ Health 2021;49:1–4. https://doi.org/10.1177/1403494820984702.Search in Google Scholar PubMed

40. Zehnbauer, B. Diagnostics in the time of coronavirus Disease 2019 (COVID-19): challenges and opportunities. J Mol Diagn 2021;23:1–2. https://doi.org/10.1016/j.jmoldx.2020.10.012.Search in Google Scholar PubMed PubMed Central

41. Nuzzo, JB. The United States’ SARS-CoV-2 testing challenges underscore the need to improve surveillance ahead of the next health security crisis. Clin Chem 2021;68:30–2. https://doi.org/10.1093/clinchem/hvab200.Search in Google Scholar PubMed

42. Drain, PK. Rapid diagnostic testing for SARS-CoV-2. N Engl J Med 2022;386:264–72. https://doi.org/10.1056/nejmcp2117115.Search in Google Scholar

43. Lippi, G, Henry, BM, Adeli, K. Diagnostic performance of the fully automated Roche Elecsys SARS-CoV-2 antigen electrochemiluminescence immunoassay: a pooled analysis. Clin Chem Lab Med 2022;60:655–61. https://doi.org/10.1515/cclm-2022-0053.Search in Google Scholar PubMed

44. Salvagno, GL, Gianfilippi, G, Fiorio, G, Pighi, L, De Nitto, S, Henry, BM, et al.. Clinical assessment of the DiaSorin LIAISON SARS-CoV-2 Ag chemiluminescence immunoassay. EJIFCC 2021;32:216–23.10.2139/ssrn.3834210Search in Google Scholar

45. Paul, D, Gupta, A, Rooge, S, Gupta, E. Performance evaluation of automated chemiluminescence immunoassay based antigen detection – moving towards more reliable ways to predict SARS-CoV-2 infection. J Virol Methods 2021;298:114299. https://doi.org/10.1016/j.jviromet.2021.114299.Search in Google Scholar PubMed PubMed Central

46. Desingu, PA, Nagarajan, K, Dhama, K. Emergence of Omicron third lineage BA.3 and its importance. J Med Virol 2022;94:1808–10. https://doi.org/10.1002/jmv.27601.Search in Google Scholar PubMed PubMed Central

47. Osterman, A, Badell, I, Basara, E, Stern, M, Kriesel, F, Eletreby, M, et al.. Impaired detection of omicron by SARS-CoV-2 rapid antigen tests. Med Microbiol Immunol 2022. https://doi.org/10.1007/s00430-022-00730-z [Epub ahead of print].Search in Google Scholar PubMed PubMed Central

Received: 2022-02-21
Accepted: 2022-02-28
Published Online: 2022-03-15

© 2022 Walter de Gruyter GmbH, Berlin/Boston