Evaluation of the New Molecular Alere™i RSV Test for Rapid Detection of Respiratory Syncytial Virus (RSV) in Routine Conditions

Background: RSV is an important respiratory pathogen in children, but also in elderly adults with underlying cardiopulmonary diseases, in young adults, and in the immunocompromised. The epidemic period of RSV infection in Belgium stretches from early October to late February, with a peak in December and January. In our institution, the diagnosis of RSV is made with the immunochromatographic BinaxNOW® RSV assay during epidemic period and with the SimulFluor® direct immunofluorescence during the rest of the year. However, these methods lack sensitivity (estimated at 52%-79% and 65%-86% respectively).

Objectives: We aimed to compare performance and convenience of the new molecular Alere™i RSV to our usual methods in routine conditions.

Methods: Consecutive clinical samples were collected during 15 days within the epidemic period and tested with BinaxNOW®, SimulFluor® and Alere™i according to the manufacturer’s instructions. In absence of PCR in our lab, we used a composite gold standard, with help of the National Influenza Reference Center (NRC) in order to confirm discordant results.

Results: 36 paediatric and 13 adult samples were tested during the study period (January 9 to 24, 2017). 12 out of 49 samples were found positive with the composite gold standard (N=11 in children <1y.o.; N=1 in a 83y.o. adult). We observed 6 discrepant results, positive with Alere™i and negative with both BinaxNOW® and SimulFluor®. Out of these 6 samples sent to the NRC, 2 were positive for RSV-B in PCR, 3 were negative, and 1 was positive for Entero/Rhinovirus. BinaxNOW® and SimulFluor® showed similar results, with sensitivity of 83.3% and specificity of 100% (NPV: 94.9%). Alere™i sensitivity and specificity were 100% and 89.2% respectively, with a PPV of 75.0%.

Conclusions: Alere™i lacks specificity compared to BinaxNOW® and SimulFluor®, but is a very sensitive and easy-to-use tool for rapid detection of RSV in less than 13 minutes. Further experience is needed on larger series.