APHL 2021 Poster Abstracts
COVID-19
Performance Evaluation of the Abbott BinaxNOW Rapid Antigen Test in a High-throughput , Drive-through Community Testing Site in Massachusetts
K . Tran , Massachusetts State Public Health Laboratory , Jamaica Plain , MA
Background : Rapid diagnostic tests ( RDTs ) for SARS-CoV-2 antigens ( Ag ) that can be performed at point-of-care ( POC ) can supplement molecular testing and help mitigate the COVID-19 pandemic . Deployment of an Ag RDT requires an understanding of its operational and performance characteristics under real-world conditions and in relevant subpopulations . We evaluated the Abbott BinaxNOW™ COVID-19 Ag Card in a high-throughput , drive-through , free community testing site in Massachusetts ( MA ) using anterior nasal ( AN ) swab RT-PCR for clinical testing .
Methods : Individuals presenting for molecular testing in two of seven lanes were offered the opportunity to also receive BinaxNOW testing . Dual AN swabs were collected from symptomatic and asymptomatic children (< 18 years ) and adults . BinaxNOW testing was performed in a testing pod with temperature / humidity monitoring . One individual performed testing and official result reporting for each test , but most tests had a second independent reading to assess inter-operator agreement . Positive BinaxNOW results were scored as faint , medium , or strong . Positive BinaxNOW results were reported to patients by phone and they were instructed to isolate pending RT-PCR results . The paired RT-PCR result was the reference for sensitivity and specificity calculations .
Results : Of 2,482 participants , 1,380 adults and 928 children had paired RT-PCR / BinaxNOW results and complete symptom data . 974 / 1380 ( 71 %) adults and 829 / 928 ( 89 %) children were asymptomatic . BinaxNOW had 96.5 % ( 95 % confidence interval [ CI ] 90.0- 99.3 ) sensitivity and 100 % ( 98.6-100.0 ) specificity in adults within seven days of symptoms , and 84.6 % ( 65.1-95.6 ) sensitivity and 100 % ( 94.5-100.0 ) specificity in children within seven days of symptoms . Sensitivity and specificity in asymptomatic adults were 70.2 % ( 56.6-81.6 ) and 99.6 % ( 98.9-99.9 ), respectively , and in asymptomatic children were 65.4 % ( 55.6-74.4 ) and 99.0 % ( 98.0- 99.6 ), respectively . By cycle threshold ( Ct ) value cutoff , sensitivity in all subgroups combined ( n = 292 RT-PCR-positive individuals ) was 99.3 % with Ct < 25 , 95.8 % with < 30 , and 81.2 % with < 35 . Twelve false-positive BinaxNOW results ( out of 2,308 tests ) were observed ; in all 12 , the test bands were faint but otherwise normal and were noted by both readers . One invalid BinaxNOW result was identified . Inter-operator agreement ( positive versus negative BinaxNOW result ) was 100 % ( n = 2230 / 2230 double reads ). Each operator was able to process 20 RDTs per hour . In a separate set of 30 specimens ( from individuals with symptoms < 7 days ) run at temperatures below the manufacturer ’ s recommended range ( 46-58.5 ° F ), sensitivity was 66.7 % and specificity 95.2 %.
Presenter : Kristine Tran , Massachusetts State Public Health Laboratory , Kristine . Tran @ mass . gov
Performance Evaluation of the Access Bio CareStart Rapid Antigen Test in a High-throughput , Drive-through Community Testing Site in Massachusetts
K . Tran , Massachusetts State Public Health Laboratory , Jamaica Plain , MA
Background : To facilitate deployment of point-of-care ( POC ) testing for SARS-CoV-2 , we evaluated the Access Bio CareStart COVID-19 Antigen ( Ag ) test in a high-throughput , drive-through , free community testing site using anterior nasal ( AN ) swab RT-PCR for clinical testing .
Methods : Consenting symptomatic and asymptomatic children (< 18 years ) and adults received dual AN swabs . CareStart testing was performed with temperature / humidity monitoring . All tests had two independent reads to assess inter-operator agreement . Patients with positive CareStart results were called and instructed to isolate pending RT-PCR results . The paired RT-PCR result was the reference for sensitivity and specificity calculations .
Results : Of 1603 participants , 1245 adults and 253 children had paired RT-PCR / CareStart results and complete symptom data . 83 % of adults and 87 % of children were asymptomatic . CareStart sensitivity / specificity were 84.8 % ( 95 % confidence interval [ CI ] 71.1- 93.7 )/ 97.2 % ( 92.0-99.4 ) and 85.7 % ( 42.1-99.6 )/ 89.5 % ( 66.9-98.7 ) in adults and children , respectively , within 5 days of symptoms . Sensitivity / specificity were 50.0 % ( 41.0-59.0 )/ 99.1 % ( 98.3-99.6 ) and 51.4 % ( 34.4-68.1 )/ 97.8 % ( 94.5-99.4 ) in asymptomatic adults and children , respectively . Sensitivity in all 234 RT-PCR-positive individuals was 96.3 % with cycle threshold ( Ct ) < 25 , 79.6 % with < 30 , and 61.4 % with < 35 . All 21 false positive CareStart tests had faint but normal bands . Inter-operator agreement was 99.5 %. Operational challenges included identification of faint test bands and inconsistent swab elution volumes .
Conclusions : CareStart had high sensitivity in individuals with high viral loads and moderate sensitivity in symptomatic individuals overall . Specificity was unexpectedly lower in symptomatic versus asymptomatic individuals . Excellent inter-operator agreement was observed , but operational challenges indicate that operator training is warranted .
Presenter : Kristine Tran , Massachusetts State Public Health Laboratory , Kristine . Tran @ mass . gov
Utilization of A Novel PCR-MALDI-TOF MS Assay for Highthroughput , Multiplex Detection of Five SARS-CoV-2 Variants
I . Machado , Z . Stewart , E . Decurtis , L . Yourkin , A . Kirar , D . Trollinger , S . Groshong , J . Finigan , S . Frankel , R . Khare and Y . Wang , National Jewish Health , Denver , CO
Background : There is growing concern about the increasing prevalence of SARS-CoV-2 variants in the population because of their potential for increased infectiousness , increased pathogenicity , and their potential for vaccine or therapeutic evasion . Highthroughput screening can be used to identify variant rapidly for both clinical and epidemiologic purposes . To achieve this goal , we developed a novel assay to screen five well-characterized SARS- CoV-2 variants of concern ( VOC ): B . 1.1.7 ( Alpha *), B . 1.351 ( Beta *), P . 1 ( Gamma *), B . 1.427 and B . 1.429 ( CAL . 20C ) and cluster 5 by detecting 14 key mutations ( N501Y , 69 / 70 deletion , P681H , I692V , K417N , K417T , E484K , Y144 deletion , L452R , S13I , Q677H , Q677P , A701V and W152C ).
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LAB MATTERS Summer 2021 |
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