Assessment of SARS-CoV-2 infectivity by a Rapid Antigen Detection Test

Abstract

The identification and isolation of highly infectious SARS-CoV-2-infected individuals is an important public health strategy. Rapid antigen detection tests (RADT) are promising candidates for large-scale screenings due to timely results and feasibility for on-site testing. Nonetheless, the diagnostic performance of RADT in detecting infectious individuals is yet to be fully determined. Two combined oro- and nasopharyngeal swabs were collected from individuals at a routine SARS-CoV-2 diagnostic center. Side-by-side evaluations of RT-qPCR and RADT as well as live virus cultures of positive samples were performed to determine the sensitivity of the Standard Q COVID-19 Ag Test (SD Biosensor/Roche) in detecting SARS-CoV-2-infected individuals with cultivable virus. A total of 2,028 samples were tested and 118 virus cultures inoculated. SARS-CoV-2 infection was detected in 210 samples by RT-qPCR, representing a positive rate of 10.36%. The Standard Q COVID-19 Ag Test yielded a positive result in 92 (4.54%) samples resulting in an overall sensitivity and specificity of 42.86% and 99.89%. For adjusted Ct values <20, <25, and <30 the RADT reached sensitivities of 100%, 98.15%, and 88.64%, respectively. All 29 culture positive samples were detected by RADT. While overall sensitivity was low, Standard Q COVID-19 RADT reliably detected patients with high RNA loads. Additionally, negative RADT results fully corresponded with the lack of viral cultivability in Vero E6 cells. These results indicate that RADT can be a valuable tool for the detection of individuals that are likely to transmit SARS-CoV-2. RADT testing could therefore guide public health testing strategies to combat the COVID-19 pandemic.

ESCMID COVID-19 guidelines: diagnostic testing for SARS-CoV-2

“… In patients with severe or critical COVID-19, we recommend the use of laboratory-based NAAT versus rapid antigen detection testing for diagnosis of COVID-19. Strong against Very low [ 6 , 7 , 23 , 30 , [35] , [36] , [37] , [38] , [39] , [40] , [41] , [42] , [43] , [44] , [45] , [46] , [47] , [48] , [49] , [50] , [51] , [52] , [53] , [54] , [55] , [56] , [57] , [58] , [59] , [60] , [61] , [62] , [63] , [64] , [65] , [66] , [67] , [68] , [69] , [70] , [71] , [72] , [73] , [74] , [75] , [76] , [77] , [78] , [79] , [80] , [81] , [82] , [83] , [84] , [85] , [86] ...…”

“… In patients with signs and symptoms compatible with COVID-19, we suggest the use of laboratory based NAAT in nasopharyngeal samples versus rapid antigen detection testing in nasopharyngeal samples for diagnosis of COVID-19. Weak against Very low [ 6 , 7 , 23 , 24 , [26] , [27] , [28] , [29] , [32] , [33] , [34] , [35] , [36] , 38 , 39 , [41] , [42] , [43] , [45] , [46] , [47] , [48] , [49] , [50] , [51] , [52] , [55] , [56] , [57] , [58] , [59] , [60] , [61] , [62] , [63] , [64] , 69 , 72 , 73 , [75] , [76] , [77] , 80 , 81 , 85 , 86 , 89 ] 13 In patients with signs and symptoms compatible with COVID-19, should rapid antigen detection testing be used, compared with standard NAAT (commercial and/or in house) for diagnosis of COVID-19 in saliva samples ? In patients with signs and symptoms compatible with COVID-19, we suggest the use of laboratory-based NAAT in saliva samples versus rapid antigen detection testing in saliva samples for diagnosis of COVID...…”

“… In patients ≥ 12 years old with signs and symptoms compatible with COVID-19, we suggest the use of laboratory-based NAAT versus rapid antigen detection testing for diagnosis of COVID-19. Weak against Very low [ 6 , 23 , 26 , 29 , 30 , 32 , 36 , [45] , [46] , [47] , [54] , [55] , [56] , 68 , 71 , 76 , 84 , 88 ] 19 In patients with signs and symptoms compatible with COVID-19 at risk for severe illness , should rapid antigen detection testing be used, compared with standard NAAT (commercial and/or in house) for diagnosis of COVID-19? In patients with signs and symptoms compatible with COVID-19 at risk for severe illness, we recommend the use of laboratory-based NAAT versus rapid antigen detection testing for diagnosis of COVID-19.…”

“… In asymptomatic patients ≥12 years old without risk factors for severe COVID-19, we suggest the use of laboratory-based NAAT versus rapid antigen testing for diagnosis of COVID-19. Weak against Very low [ 6 , 23 , 26 , 27 , 31 , 45 , 46 , 48 , [54] , [55] , [56] , [57] , 60 , 74 , 75 , 82 ] 3 In asymptomatic people of any age with any risk factor(s) for severe COVID-19 (including age <3 or ≥65 years) should rapid antigen tests be used, as compared to laboratory-based NAAT to diagnose COVID-19? In asymptomatic people of any age with any risk factor(s) for severe COVID-19 (including age <3 months old or ≥65 years old), we suggest the use of laboratory based NAAT versus antigen testing for diagnosis of COVID-19.…”

“… In asymptomatic people of any age with any risk factor(s) for severe COVID-19 (including age <3 months old or ≥65 years old), we suggest the use of laboratory based NAAT versus antigen testing for diagnosis of COVID-19. Weak against Very low [ 6 , 23 , 26 , 27 , 30 , 31 , 33 , 40 , 45 , 46 , 48 , 51 , [54] , [55] , [56] , [57] , 60 , 62 , 67 , 74 , 75 , [77] , [78] , [79] , 82 , 83 ] 4 In asymptomatic people should rapid antigen test be used as compared to laboratory-based NAAT in nasopharyngeal samples to diagnose COVID-19? In asymptomatic people, we suggest the use of laboratory-based NAAT in nasopharyngeal samples versus rapid antigen testing in nasopharyngeal samples for diagnosis of COVID-19.…”