A range of new in vitro diagnostic (IVD) devices have been launched onto the US market in the last two months for Covid-19. As expected, sales of these devices have experienced extraordinary growth as demand for Covid-19 testing reagents continues to outstrip supply.

Many of the first IVD devices to be granted emergency use authorisation by the US Food and Drug Administration (FDA) were RT-PCR–based assays used to diagnose the disease. These include SARS-CoV-2 specific testing kits and laboratory-developed tests, which are mostly composed of generic PCR reagents.

Two of the RT-PCR testing kits, the Xpert Xpress SARS-CoV-2 by Cepheid Inc and the Abbott ID NOW Covid-19 test by Abbott Laboratories, have shorter than average turnaround times of 30 minutes and five minutes respectively. The rapid testing and near-patient capabilities of the devices have been highlighted as key selling features by both manufacturers.

On 12 May, a study conducted by New York University (NYU) was posted on the non-peer-reviewed, preprint repository bioRxiv, indicating that the Abbott ID NOW Covid-19 test is less effective than the Cepheid Xpert Xpress SARS-CoV-2 device. The authors of the study found that the Abbot ID NOW Covid-19 device missed between 33.3% and 48.4% of positive samples detected by the Cepheid Xpert.

Abbott Laboratories responded to the report saying that the NYU investigators did not use the device as intended and that their results are not consistent with several other studies. Abbott Laboratories is now advising customers that its ID NOW device should be used with dry nasal swabs instead of viral transport media.

On 15 May, the FDA released an alert regarding the Abbott ID NOW test for Covid-19 and its potential to provide inaccurate negative results. This alert was issued in response to 15 adverse event reports the FDA received for the Abbott ID NOW device.

In response to these findings, Abbott Laboratories agreed to carry out post-market studies on the ID NOW device, which will include a minimum of 150 positive Covid-19 patients in various different clinical settings.

Attempts are also being made by the FDA to investigate whether false negatives could be due to the types of swabs or viral transport media being used.

On 21 May, Abbott Laboratories then released interim data from a clinical study that has enrolled 256 patients to date and includes five urgent care centers in New Jersey, Tennessee, Louisiana, Texas and South Carolina. The interim analyses demonstrated a sensitivity performance of 94.7% and a specificity performance of 98.6% of the ID NOW Covid-19 devices.

Two other clinical studies sponsored by Abbott Laboratories demonstrated performance sensitivities of 83.3%–91.3% and specificities of 96.5%–100%.

While the Abbott-sponsored studies support the continued use of the ID NOW Covid-19 test, the conflicting clinical data and questions that have been raised about the device mean that some physicians may be hesitant to employ the ID NOW Covid-19 test if there is an alternative IVD device available.