Validating saliva as a biological sample for cost-effective, rapid and routine screening for SARS-CoV-2 (preprint)

Purpose: Compared to nasopharyngeal/oropharyngeal swabs, non-invasive saliva samples have enormous potential for scalability and routine population screening of SARS-CoV-2. In this study, we are investigating the efficacy of saliva samples relative to nasopharyngeal/oropharyngeal swabs for use as a direct source for the RT-PCR based SARS-CoV-2 detection. Methods: Paired nasopharyngeal/oropharyngeal swabs and saliva samples were collected from suspected positive SARS-CoV-2 patients and tested using RT-PCR. Generalised linear models were used to investigate factors that explain result agreement. Further, we used simulations to evaluate the effectiveness of saliva-based screening in restricting the spread of infection in a large campus such as an educational institution. Results: We observed 75.4% overall result agreement. Prospective positive samples stored for three or more days showed a drastic reduction in the probability of result agreement. We observed 83% result agreement and 74.5% test sensitivity in samples processed and tested within two days of collection. Our simulations suggest that a test with 75% sensitivity, but high daily capacity can be very effective in limiting the size of infection clusters in a workspace. Guided by these results, we successfully implemented a saliva-based screening in the Bangalore Life Sciences Cluster (BLiSC) campus. Conclusion: These results suggest that saliva may be a viable sample source for SARS-CoV-2 surveillance if samples are processed immediately. We strongly recommend the implementation of saliva-based screening strategies for large workplaces and in schools, as well as for population-level screening and routine surveillance as we learn to live with the SARS-CoV-2 virus.

COVID-19 symptoms reduce with targeted hydration of the nose, larynx and trachea (preprint)

Dirty air and poor access to healthcare threatens the lives of billions of people in low-income regions of the world. We investigated whether upper-airway hydration might alter two-phase flow in the airways on normal tidal breathing and be a useful, safe, easily distributed non-drug intervention for limiting risks of COVID-19. In observational human volunteer studies involving 464 human subjects in Marburg, Germany (357 normal subjects), Boston, US (20 healthy subjects), and Bangalore, India (87 subjects recently tested positive for COVID-19), we find that respiratory droplet generation increases by up to 4 orders of magnitude with up to 1% total body mass dehydration (n=20), and in dehydration-associated states of advanced age (n=357), elevated BMI-age (n=148), and SARS-CoV-2 infection (n=87). Hydration of the nose, larynx and trachea in a protocol of exercise-induced dehydration by the nasal inhalation of calcium-rich hypertonic salt droplets of mean diameter 8-12 µm diminished respiratory droplet numbers and increased oxygenation relative to a non-treatment control (P<0.05). In a randomized double-blinded nasal-saline control study, thrice-a-day delivery of the calcium-rich hypertonic salts (active) over three days suppressed respiratory droplet generation by 51% +/- 11% and increased oxygen saturation by 48.08% ± 9.61% (P<0.001) in COVID-19 positive subjects (n=20), while no changes in exhaled aerosol (P=0.235) or oxygen saturation (P=0.533) were observed in the nasal-saline control group (n=20). In the active group 47% of patients discharged with no self-reported symptoms while all of the subjects in the nasal saline group discharged with lingering symptoms. Hydration of the upper airways appears promising as a non-drug approach for reducing risks of lower respiratory-tract infections such as COVID-19.