Session Type: ePosters
Session Title: ePosters
Authors(s): P. Posteraro (1), F.M. Errico (1), A. De Carolis (1), G. Menchinelli (2), M. Sanguinetti (2), B. Posteraro (2)
Authors Affiliations(s): (1) Ospedale San Carlo GVM, Laboratorio di Analisi Chimico-Cliniche e Microbiologiche, Italy, (2) bDipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Università Cattolica del Sacro Cuore, Italy
Background:
Rapid antigen detection assays are less laborious and require shorter time-to-result than RT-PCR assays. However, these assays are prone to yield false positive results, requiring that positive antigen test results must be confirmed by RT-PCR. We assessed the results of individuals who tested positive with the AFIAS COVID-19 Ag (Avant Medical, Geffen, The Netherlands) assay, an automated fluorescence immunoassay that detects SARS-CoV-2 nucleoprotein antigen in nasopharyngeal swabs within 12 minutes from sample collection.
Methods:Positive antigen results (expressed as values ≥1 cut-off index [COI]) were evaluated in comparison with those obtained by RT-PCR (expressed as RNA detected or undetected, respectively) on nasopharyngeal swabs of 171 individuals who were resampled the same day to confirm antigen positivity. Results were stratified by groups of emergency department (ER; n=76) or pre-hospitalized (n=69) patients from or healthcare workers (HCWs; n=26) at the San Carlo GVM hospital in Rome (Italy) during two months of COVID-19 testing.
Results:Testing of 2230 samples with the AFIAS COVID-19 Ag assay resulted in 2059 (92.3%) negative samples and 171 (7.7%) positive samples (Figure 1). Compared with RT-PCR results, 49 (71.0%) of 69 pre-hospitalized patients, 12 (46.2%) of 26 HCWs and 6 (7.9%) of 76 ER patients, accounting for 39.2% (67/171) of individuals in total, were falsely detected as positive by the AFIAS COVID-19 Ag assay. Of note, rates of false positive results differed significantly among individuals’ groups (P <0.001 for comparisons of ER patients versus pre-hospitalized patients or versus HCWs; and P = 0.02 for the comparison of pre-hospitalized patients versus HCWs). Consistently, AFIAS COVID-19 Ag assay agreed with RT-PCR for 104 (60.8%; 95% CI, 53.1%–68.2%) of 171 results (COI values, ≥1 to ≤100) and, excluding nine samples (COI values, ≥1 to ≤4), for 95 (99.0%; 95% CI, 94.3%–100.0%) of 96 results (COI values, >4 to ≤100) (Figure 1).
Conclusions:Our findings suggest that careful application of AFIAS COVID-19 Ag or similar assays to specific clinical settings may significantly increase the probability that a positive SARS-CoV-2 antigen result represents a true SARS-CoV-2 infected patient, thereby curbing repeating RT-PCR results for confirmation.
Keyword(s): rapid antigen test, diagnostic testing, SARS-CoV-2Session Type: ePosters
Session Title: ePosters
Authors(s): P. Posteraro (1), F.M. Errico (1), A. De Carolis (1), G. Menchinelli (2), M. Sanguinetti (2), B. Posteraro (2)
Authors Affiliations(s): (1) Ospedale San Carlo GVM, Laboratorio di Analisi Chimico-Cliniche e Microbiologiche, Italy, (2) bDipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Università Cattolica del Sacro Cuore, Italy
Background:
Rapid antigen detection assays are less laborious and require shorter time-to-result than RT-PCR assays. However, these assays are prone to yield false positive results, requiring that positive antigen test results must be confirmed by RT-PCR. We assessed the results of individuals who tested positive with the AFIAS COVID-19 Ag (Avant Medical, Geffen, The Netherlands) assay, an automated fluorescence immunoassay that detects SARS-CoV-2 nucleoprotein antigen in nasopharyngeal swabs within 12 minutes from sample collection.
Methods:Positive antigen results (expressed as values ≥1 cut-off index [COI]) were evaluated in comparison with those obtained by RT-PCR (expressed as RNA detected or undetected, respectively) on nasopharyngeal swabs of 171 individuals who were resampled the same day to confirm antigen positivity. Results were stratified by groups of emergency department (ER; n=76) or pre-hospitalized (n=69) patients from or healthcare workers (HCWs; n=26) at the San Carlo GVM hospital in Rome (Italy) during two months of COVID-19 testing.
Results:Testing of 2230 samples with the AFIAS COVID-19 Ag assay resulted in 2059 (92.3%) negative samples and 171 (7.7%) positive samples (Figure 1). Compared with RT-PCR results, 49 (71.0%) of 69 pre-hospitalized patients, 12 (46.2%) of 26 HCWs and 6 (7.9%) of 76 ER patients, accounting for 39.2% (67/171) of individuals in total, were falsely detected as positive by the AFIAS COVID-19 Ag assay. Of note, rates of false positive results differed significantly among individuals’ groups (P <0.001 for comparisons of ER patients versus pre-hospitalized patients or versus HCWs; and P = 0.02 for the comparison of pre-hospitalized patients versus HCWs). Consistently, AFIAS COVID-19 Ag assay agreed with RT-PCR for 104 (60.8%; 95% CI, 53.1%–68.2%) of 171 results (COI values, ≥1 to ≤100) and, excluding nine samples (COI values, ≥1 to ≤4), for 95 (99.0%; 95% CI, 94.3%–100.0%) of 96 results (COI values, >4 to ≤100) (Figure 1).
Conclusions:Our findings suggest that careful application of AFIAS COVID-19 Ag or similar assays to specific clinical settings may significantly increase the probability that a positive SARS-CoV-2 antigen result represents a true SARS-CoV-2 infected patient, thereby curbing repeating RT-PCR results for confirmation.
Keyword(s): rapid antigen test, diagnostic testing, SARS-CoV-2
Session Type: ePosters
Session Title: ePosters
Authors(s): P. Posteraro (1), F.M. Errico (1), A. De Carolis (1), G. Menchinelli (2), M. Sanguinetti (2), B. Posteraro (2)
Authors Affiliations(s): (1) Ospedale San Carlo GVM, Laboratorio di Analisi Chimico-Cliniche e Microbiologiche, Italy, (2) bDipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Università Cattolica del Sacro Cuore, Italy
Background:
Rapid antigen detection assays are less laborious and require shorter time-to-result than RT-PCR assays. However, these assays are prone to yield false positive results, requiring that positive antigen test results must be confirmed by RT-PCR. We assessed the results of individuals who tested positive with the AFIAS COVID-19 Ag (Avant Medical, Geffen, The Netherlands) assay, an automated fluorescence immunoassay that detects SARS-CoV-2 nucleoprotein antigen in nasopharyngeal swabs within 12 minutes from sample collection.
Methods:Positive antigen results (expressed as values ≥1 cut-off index [COI]) were evaluated in comparison with those obtained by RT-PCR (expressed as RNA detected or undetected, respectively) on nasopharyngeal swabs of 171 individuals who were resampled the same day to confirm antigen positivity. Results were stratified by groups of emergency department (ER; n=76) or pre-hospitalized (n=69) patients from or healthcare workers (HCWs; n=26) at the San Carlo GVM hospital in Rome (Italy) during two months of COVID-19 testing.
Results:Testing of 2230 samples with the AFIAS COVID-19 Ag assay resulted in 2059 (92.3%) negative samples and 171 (7.7%) positive samples (Figure 1). Compared with RT-PCR results, 49 (71.0%) of 69 pre-hospitalized patients, 12 (46.2%) of 26 HCWs and 6 (7.9%) of 76 ER patients, accounting for 39.2% (67/171) of individuals in total, were falsely detected as positive by the AFIAS COVID-19 Ag assay. Of note, rates of false positive results differed significantly among individuals’ groups (P <0.001 for comparisons of ER patients versus pre-hospitalized patients or versus HCWs; and P = 0.02 for the comparison of pre-hospitalized patients versus HCWs). Consistently, AFIAS COVID-19 Ag assay agreed with RT-PCR for 104 (60.8%; 95% CI, 53.1%–68.2%) of 171 results (COI values, ≥1 to ≤100) and, excluding nine samples (COI values, ≥1 to ≤4), for 95 (99.0%; 95% CI, 94.3%–100.0%) of 96 results (COI values, >4 to ≤100) (Figure 1).
Conclusions:Our findings suggest that careful application of AFIAS COVID-19 Ag or similar assays to specific clinical settings may significantly increase the probability that a positive SARS-CoV-2 antigen result represents a true SARS-CoV-2 infected patient, thereby curbing repeating RT-PCR results for confirmation.
Keyword(s): rapid antigen test, diagnostic testing, SARS-CoV-2Session Type: ePosters
Session Title: ePosters
Authors(s): P. Posteraro (1), F.M. Errico (1), A. De Carolis (1), G. Menchinelli (2), M. Sanguinetti (2), B. Posteraro (2)
Authors Affiliations(s): (1) Ospedale San Carlo GVM, Laboratorio di Analisi Chimico-Cliniche e Microbiologiche, Italy, (2) bDipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Università Cattolica del Sacro Cuore, Italy
Background:
Rapid antigen detection assays are less laborious and require shorter time-to-result than RT-PCR assays. However, these assays are prone to yield false positive results, requiring that positive antigen test results must be confirmed by RT-PCR. We assessed the results of individuals who tested positive with the AFIAS COVID-19 Ag (Avant Medical, Geffen, The Netherlands) assay, an automated fluorescence immunoassay that detects SARS-CoV-2 nucleoprotein antigen in nasopharyngeal swabs within 12 minutes from sample collection.
Methods:Positive antigen results (expressed as values ≥1 cut-off index [COI]) were evaluated in comparison with those obtained by RT-PCR (expressed as RNA detected or undetected, respectively) on nasopharyngeal swabs of 171 individuals who were resampled the same day to confirm antigen positivity. Results were stratified by groups of emergency department (ER; n=76) or pre-hospitalized (n=69) patients from or healthcare workers (HCWs; n=26) at the San Carlo GVM hospital in Rome (Italy) during two months of COVID-19 testing.
Results:Testing of 2230 samples with the AFIAS COVID-19 Ag assay resulted in 2059 (92.3%) negative samples and 171 (7.7%) positive samples (Figure 1). Compared with RT-PCR results, 49 (71.0%) of 69 pre-hospitalized patients, 12 (46.2%) of 26 HCWs and 6 (7.9%) of 76 ER patients, accounting for 39.2% (67/171) of individuals in total, were falsely detected as positive by the AFIAS COVID-19 Ag assay. Of note, rates of false positive results differed significantly among individuals’ groups (P <0.001 for comparisons of ER patients versus pre-hospitalized patients or versus HCWs; and P = 0.02 for the comparison of pre-hospitalized patients versus HCWs). Consistently, AFIAS COVID-19 Ag assay agreed with RT-PCR for 104 (60.8%; 95% CI, 53.1%–68.2%) of 171 results (COI values, ≥1 to ≤100) and, excluding nine samples (COI values, ≥1 to ≤4), for 95 (99.0%; 95% CI, 94.3%–100.0%) of 96 results (COI values, >4 to ≤100) (Figure 1).
Conclusions:Our findings suggest that careful application of AFIAS COVID-19 Ag or similar assays to specific clinical settings may significantly increase the probability that a positive SARS-CoV-2 antigen result represents a true SARS-CoV-2 infected patient, thereby curbing repeating RT-PCR results for confirmation.
Keyword(s): rapid antigen test, diagnostic testing, SARS-CoV-2