Then and NOW: A Prospective Population-Level Validation of the Abbott ID NOW SARS-CoV-2 Device Implemented in Multiple Settings for Testing Asymptomatic and Symptomatic Individuals

Abstract

ABSTRACTIMPORTANCESince December, 2020, the ID NOW was implemented for use in 4 different populations across Alberta: in mobile units as part of community outbreak response, COVID-19 community collection sites, emergency shelters and addiction treatment facilities (ES), and hospitals.OBJECTIVEDiagnostic evaluation of the ID NOW in various real world settings among symptomatic and asymptomatic individualsDESIGNDepending on the implemented site, the ID NOW was tested on patients with symptoms suggestive of COVID-19, asymptomatic close contacts or asymptomatic individuals as part of outbreak point prevalence screening. From Jan – April, a select number of sites also switched from using oropharyngeal swabs to combined oropharyngeal + nasal (O+N) swabs. For every individual tested, two swabs were collected: one for ID NOW testing and the other for either reverse-transcriptase polymerase chain reaction (RT-PCR) confirmation of negative ID NOW results or for variant testing of positive ID NOW results.RESULTSA total of 129,112 paired samples were analyzed (16,061 RT-PCR positive). 81,697 samples were from 42 COVID-19 community collection sites, 16,924 from 69 rural hospitals, 1,927 from 9 ES, 23,802 samples from 6 mobile units that responded to 356 community outbreaks, and 4,762 from 3 community collection sites and 1 ES using O+N swabs for ID NOW testing. ID NOW sensitivity was highest among symptomatic individuals presenting to community collection sites [92.5%, 95% confidence interval (CI) 92.0-93.0%, n=10,633 RT-PCR positive] and lowest for asymptomatic individuals associated with community outbreaks (73.9%, 95% CI 69.8-77.7%, n=494 RT-PCR positive). Specificity was greater than 99% in all populations tested, but positive predictive value (PPV) was lower among asymptomatic populations (82.4–91.3%) compared to symptomatic populations (96.0-96.9%). There was no statistically significant differences in sensitivity with respect to age, gender, NP vs OP swab for RT-PCR confirmation, variants of concern, or with combined oropharyngeal and nasal swabs using COVID-19 ID NOW testing.CONCLUSIONSSensitivity of ID NOW SARS-CoV-2 testing is highest when used on symptomatic community populations not seeking medical care. Sensitivity and PPV drops by approximately 10% when tested on asymptomatic populations. Using combined oropharyngeal and nasal swabs did not improve ID NOW performance.