Improved performances of the second generation of the ID NOW influenza A&B 2® and comparison with the GeneXpert®.

Due to the congestion of emergency wards, a rapid and accurate method for flu diagnosis is required. However, the first evaluations of the ID NOW® influenza A&B performances were heterogeneous. We aimed to (i) assess the performance of the second generation of the ID NOW® influenza A&B 2 and (ii) compare the ID NOW® to the GeneXpert® use when performed within a central laboratory. (i) Analytical performances of ID NOW® were assessed using a collection of 112 clinical samples in comparison with a reference multiplex PCR (Seegene®); (ii) Invalid rate per operator and time to result were calculated for the GeneXpert® Xpress Flu/RSV and the ID NOW® influenza A&B 2® during 2017-2018 and 2018-2019 flu outbreaks respectively. ID NOW® reaches an overall sensitivity and specificity of 96.6% and 96.1% respectively. Most of the false-negative display a CT > 37. For both instruments, a single operator was involved in about a half of all invalid results. Excluding this operator involved in most invalid result, the invalid rate was about 1% for both instruments. Time to result from sampling was significantly shorter in the ID NOW® versus the GeneXpert® group (33 vs 97 min, P < 0.01). The second generation of the ID NOW® influenza A&B 2 displays high performances, comparable with conventional PCR method. In order to prevent invalid results, we highlight the need for adequate training of operators. Also, when implemented in a central laboratory, the location of the instrument could have a strong impact on the time-to-results.