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

INTRODUCTION Since December, 2020, the ID NOW was implemented for use in 4 different populations across Alberta: in mobile units as part of community outbreak response, COVID19 community collection sites, emergency shelters and addiction treatment facilities (ES), and hospitals. OBJECTIVE Diagnostic evaluation of the ID NOW in various real world settings among symptomatic and asymptomatic individuals METHODS Depending 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 to 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 (RTPCR) confirmation of negative ID NOW results or for variant testing of positive ID NOW results. RESULTS A total of 129,112 paired samples were analyzed (16,061 RTPCR 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 RTPCR positive] and lowest for asymptomatic individuals associated with community outbreaks (73.9%, 95% CI 69.8 to 77.7%, n=494 RTPCR positive). Specificity was greater than 99% in all populations tested, but positive predictive value (PPV) was lower among asymptomatic populations (82.4 to 91.3%) compared to symptomatic populations (96.0 to 96.9%). There was no statistically significant differences in sensitivity with respect to age, gender, NP vs OP swab for RTPCR confirmation, variants of concern, or with combined oropharyngeal and nasal swabs using COVID-19 ID NOW testing. CONCLUSIONS Sensitivity of ID NOW SARS CoV2 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.

Evaluation of the ID NOW Among Symptomatic Individuals During the Omicron Wave

“…However, we previously observed no differences in sensitivity based on common patient, collecting and testing characteristics, including age, gender, and swab type. 2 Our current study also did not demonstrate any difference in performance with these characteristics, though the sample size was not large enough to make any concrete conclusions. Another limitation is the inability to exclusively study Omicron by itself.…”

“…In the face of Omicron, our study demonstrated increased ID NOW sensitivity compared to prior variant waves. 2 The ID NOW sensitivity in assessment centres before Omicron (as of November 24, 2021) was 92.5% (95% CI 92.0-93.0%). Our current data during the Omicron wave has demonstrated a higher ID NOW sensitivity of 96.0% (95% CI 94.5-97.3%).…”

“…However, its performance was still higher for Omicron than what we previously observed, but not statistically significant (likely due to the lower sample size in our Omicron study). 2 There may be various factors to account for the decreased ID NOW sensitivity observed among hospitals compared to assessment centres.…”

“…Due to the same testing sites, procedures, and methodology, the results during Omicron can be accurately compared to our results from before Omicron. 2 Due to the routine surveillance testing of many positive ID NOW or RT-PCR samples for variants of concern, which included E gene RT-PCR from a consistent RT-PCR testing platform (APL LDT), we were able to roughly assess the specificity of the ID NOW and examine the relationship of E gene Ct values between true positive and false negative ID NOW results in the face of Omicron.…”

“…The clinical sensitivity and specificity of the ID NOW among symptomatic individuals in hospital was 89.5% (95% CI 88.3-90.6%) and 99.3% (95% CI 99.2-99.4%), respectively (n=16,924 with 2,932 RT-PCR positive). 2 Currently, there is a paucity of data on the ID NOW performance in the setting of the Omicron variant. Abbott has reported that mutations found in the Omicron variant does not affect the performance based on in silico data.…”