Evaluation and Comparison of the Hologic Aptima SARS-CoV-2 Assay and the CDC 2019-nCoV Real-Time Reverse Transcription-PCR Diagnostic Panel Using a Four-Sample Pooling Approach
Stephanie L. Mitchell, Samantha E. Ventura
Abstract
To expand testing capacity during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, numerous molecular assays have been granted emergency-use authorization (EUA) for testing individual patient samples but not for sample pooling. Although pooling multiple patient samples may expand the testing capacity while reducing the burden of supply of test reagents, consumables, and kits, pooling inherently results in a dilution that may reduce sensitivity. The lack of detection of weakly positive samples may have significant consequences in efforts to curb SARS-CoV-2 transmission. At this time, only two pooling assays have received EUA (1). Quest Diagnostics applied four-sample pooling, stating 100% sensitivity (2). While it is unclear how many weakly positive samples were included, based on linear regression analysis, they state that samples with cycle threshold (CT) values of >37 are expected to be missed (2). The second EUA, by Poplar Healthcare, leveraged the Hologic Aptima SARS-CoV-2 assay with seven-sample pooling, stating 100% sensitivity (3). However, the highest CT value tested was only 34.6. Griesemer et al. evaluated five- and nine-sample pooling approaches using the CDC 2019 novel coronavirus (2019-nCoV) real-time reverse transcription-PCR (RT-PCR) diagnostic panel, emphasizing weakly positive samples (CT = 33 to 39) (4). They reported that 4 of the 24 nine-sample pools were missed, but all were detected in a five-sample pool.