Saliva as a Reliable Sample for COVID-19 Diagnosis in Paediatric Patients (preprint)

Saliva has been described a less invasive and easy to handle sample, compared to nasopharyngeal swabs (NPS), in the diagnosis of COVID-19 in adults. Although the advantages of using saliva is still more evident in paediatric patients, little is now about its sensitivity in this group. The aim of this study was to compare the performance of saliva to that of NPS in the detection of SARS-CoV-2 in paediatric patients with mild symptoms. This study evaluated saliva samples from children with suspected COVID-19 who attended public healthcare services of Araraquara, Sao Paulo, Brazil. Children were asked to spit into a sterile container for collection of about 1ml of saliva after the NPS collection. SARS-COV-2 detection was performed by using the Altona RealStar(R) SARS-CoV-2 RT-PCR Kit 1.0. The sample consisted of 50 patients, in which 27 were girls (54%) and 23 were boys (46%). Ten were positive for SARS-CoV-2 in at least one sample collected. The mean age was 10.24 {+/-} 3.52 years old and saliva was collected after 4.76 {+/-} 1.31 days from the symptoms. Saliva and NPS have showed the same performance in the SARS-CoV-2 detection (k = 0.865, P < 0.001). In conclusion, saliva is a reliable alternative sample for COVID-19 diagnosis in paediatric population.

Discontinuation of isolation for persons with COVID-19: Is 10 days really safe? (preprint)

BackgroundThe detection of SARS-CoV-2 RNA by real-time polymerase chain reaction (PCR) in respiratory samples from COVID-19 patients is not a direct indication of the presence of viable viruses. The isolation of SARS-CoV-2 in cell culture system however, can acts as surrogate marker of infectiousness. Cell culture based studies performed mostly with hospitalized and moderate/severe COVID-19 claims that no replication competent virus is found after 9 days of the symptoms onset in respiratory samples. Therefore, it is now recommended 10 days isolation before patient discharge. MethodsWe cell-cultured 29 SARS-COV-2 RT-PCR positive respiratory samples at the 10th day after the illness in Vero E6 cells. After two passages, cytopathic effect and cycle threshold (CT) lower than the obtained in the original sample were used to determine positivity. FindingsWe found viable particles in (7/29) 24% of samples tested. The positivity in cell culture was strongly associated (p<0.0001) to the low cycle thresholds in clinical samples (Ct <21). ConclusionThis data adds important knowledge to the current protocols for de-isolation of patients with non-hospitalized mild COVID-19.