Comparison of Abbott ID NOW, a novel isothermal amplification based COVID-19 diagnostic method with RTPCR

The emergent crisis of the COVID-19 pandemic has posed enormous challenges for clinical laboratories to speed up diagnostics. The current reference standard for the diagnosis of COVID-19 is real time reverse transcriptase PCR on various platforms. However, even with automation, the turnaround time is huge enough to keep up with ever increasing numbers of patients. With increasing surge of COVID cases we need rapid diagnostic tests with good sensitivity and specificity.

Comparison between Abbott ID NOW COVID-19 and real time reverse transcriptase PCR as a reference method.

Specimens from seventy-two individuals were obtained over a period of two months which were processed for ID NOW and RTPCR at a dedicated COVID-19 centre of AIIMS. Dry nasal swabs were used for ID NOW while nasopharyngeal swabs along with throat swab were used for RTPCR. Among the participants, 15 were healthcare workers. Mild COVID was seen in 36 participants, moderate in 19 and severe in 9. Eight participants had non COVID illness.

From the given samples, we observed that ID NOW has a sensitivity of 93.22% (55/59) specificity 100% (13/13), PPV 100% (55/55) and NPV 76.47% (13/17).

ID NOW is a convenient, rapid molecular test which makes it suitable for both in laboratory use and as a point of care test. It can be a rapid rule-in test for COVID-19. Negative results, however, have to be interpreted as per the context.