Sensitivity of RSV detection by PCR in respiratory samples is not reduced by a 24 h delay from sampling to testing...

Respiratory Syncytial Virus (RSV) is a common cause of severe respiratory tract disease in infants, the elderly and immunocompromised patients. However, there is uncertainty as to how sample handling practices affect performance of tests to detect RSV. The aim of this study was to determine whether RSV RNA remains reliably detectable in nasopharyngeal/oropharyngeal (NP/OP) samples, saliva, and sputum samples over time.Respiratory samples were collected as part of a prospective observational study of acute lower respiratory tract disease (aLRTD) hospitalisations in adults in Bristol (UK). Samples that tested positive by PCR on receipt (0 h), were re-tested at 24 h having been stored at room temperature. We found that all but one of the samples PCR-positive for RSV at 0 h remained positive at 24 h, across all sample types and RSV strains. Ct values for NP/OP and saliva samples were significantly lower at 24 h than at 0 h, suggesting potential low-level viral replication in the samples. These results suggest that RSV tests can provide consistent results after a delay of up to 24 h following sample collection.