Persistence of SARS-CoV-2 in saliva: Implications for late-stage diagnosis and infectious duration.

Saliva has been a COVID-19 diagnostic specimen of interest due to its simple collection, scalability, and yield. Yet COVID-19 testing and estimates of the infectious period remain largely based on nasopharyngeal and nasal swabs. We sought to evaluate whether saliva testing captured prolonged presence of SARS-CoV-2 and potential infectiousness later in the disease course. We conducted an observational study of symptomatic COVID-19 patients at University Hospital in Newark, NJ. Paired saliva and nasal specimens from 96 patients were analyzed, including longitudinal analysis of paired observations from 28 of these patients who had multiple time-points. Saliva detected significantly more cases of COVID-19 beyond 5 days (86.1% [99/115] saliva vs 48.7% [56/115] nasal, p-value < 0.001), 9 days (79.4% [50/63] saliva vs 36.5% [23/63] nasal, p-value < 0.001) and 14 days (71.4% [20/28] saliva vs 32.1% [9/28] nasal, p-value = 0.010) of symptoms. Additionally, saliva yielded lower cycle thresholds across all time periods, indicative of higher viral loads in saliva. In the longitudinal analysis, a log-rank analysis indicated that the survival curve for saliva was significantly different from the curve for nasal swabs (p<0.001) with a median survival time for saliva of 18 days compared to 13 days for nasal swabs. We additionally performed saliva viral cultures among a similar COVID-19 patient cohort and noted patients with positive saliva viral cultures between 7 to 28 days of symptoms. Findings from this study suggest that SARS-CoV-2 RNA persists longer and in higher abundance in saliva compared to nasal swabs, with potential of prolonged propagating virus. Testing saliva may thus increase yield for detecting potentially infectious virus even beyond the first five days of symptomatic COVID-19.

S100 Staining Adds to the Prognostic Significance of the Combination of Perineural Invasion and Lymphovascular Invasion in Colorectal Cancer.

Studies have suggested that perineural invasion (PNI) and lymphovascular invasion (LVI) serve as independent prognostic factors in colorectal cancer (CRC). Currently, little is known regarding the combination of PNI and LVI as prognostic factors, independent of stage. We hypothesized that this combination was a better prognostic marker than either PNI or LVI alone, and that S100 staining would detect PNI not seen with hematoxylin and eosin (H&E). Surgical pathology slides were retrospectively reviewed for 151 stages I to IV CRC patients who had surgery between January 1, 2008 and December 8, 2008 at 3 Hackensack Meridian Health hospitals in New Jersey. PNI and LVI were detected by H&E staining and a subset of 127 patient samples were additionally examined for PNI by S100 staining. Correlation between staining characteristics and patient outcomes was assessed using the Pearson χ tests and the Fisher exact tests. Survival was analyzed using Kaplan-Meier methods. Of the 151 cases reviewed, 30.5% were positive for PNI and 35.1% were positive for LVI by H&E. The use of S100 staining for PNI enabled its detection in 27 additional cases. Median time from patient diagnosis to death was significantly shorter for patients who were positive for both PNI and LVI (P<0.001). PNI and LVI were individual markers for poor survival in CRC patients and their combined presence had an even worse outcome. Failure to detect PNI on H&E can be overcome by S100 staining.