Rapid Diagnostic Test for RSV Evaluated

Respiratory syncytial virus (RSV) is a common ubiquitous pathogen responsible for mild upper respiratory tract infection in most children and healthy adults. In infants, RSV is mainly associated with acute lower respiratory infections.

In elderly and immunocompromised patients, RSV has been known to cause severe respiratory failure, extended hospitalizations, higher mortality, with symptoms similar to those associated with seasonal influenza. Respiratory syncytial virus is responsible for severe respiratory infections and higher costs in medical care.

Scientists at Normandy University carried out two studies, one which focused on fresh nasopharyngeal swabs sent to the virology laboratory of Caen University Hospital for virological diagnosis and the second was conducted over a 20 weeks winter period from November 13, 2013 (week 46) to March 31, 2014 (week 13) for point-of-care testing (POCT), in the pediatric emergency department (ED) of the same hospital.

In the first study all the respiratory samples were tested using SOFIA RSV, Direct Immunofluorescence Assay (Quidel, San Diego, CA, USA), that detects eight viral targets (direct fluorescent antibody, DFA): influenza virus type A, B (FluA, FluB), human RSV (hRSV), human metapneumovirus (hMPV), human adenovirus (hAdV), and human parainfluenza viruses 1, 2, 3 (hPIVs). In the second study two SOFIA RSV analyzers were set up and nurses performed the rapid diagnostic tests on fresh respiratory specimens, After a sample extraction, an aliquot was pipetted onto the test cassette. An incubation of 15 minutes and one-minute reading phase were performed as per mandatory protocol within the SOFIA RSV analyzer. Rapid positive and negative results were provided after 15 minutes.

The team found that that among 401 samples in the first study, 123 (30.7%) tested RSV positive using the molecular method, 101 (25.2%) using SOFIA RSV, 80 (19.9%) using RSV DFA, and 53 (13.2%) using cell culture. The sensitivities of SOFIA RSV in infants (aged less than 24 months) performed in the laboratory and in the pediatric ED were respectively 95% and 74.8% to polymerase chain reaction (PCR). In the first study, the sensitivity among children (from 2 to 15 years old) and adults (above 15 years old) dropped to 45% and 59%, respectively. In the second study there were some differences in bed-management of SOFIA RSV positive compared to SOFIA RSV negative infants.

The authors concluded that SOFIA RSV tests performed in the laboratory and in the pediatric ED show high and satisfactory sensitivities among young children less than 24 months, which supports its robustness and reliability. SOFIA RSV tests will be very useful when new specific treatments become available, for example antiviral or immunomodulators, to reduce viral load and clinical severity scores. The study was published on June 26, 2017, in the journal BMC Infectious Diseases.