Using trained dogs and organic semi-conducting sensors to identify asymptomatic and mild SARS-CoV-2 infections: an observational study.

BACKGROUND: A rapid, accurate, non-invasive diagnostic screen is needed to identify people with SARS-CoV-2 infection. We investigated whether organic semi-conducting (OSC) sensors and trained dogs could distinguish between people infected with asymptomatic or mild symptoms, and uninfected individuals, and the impact of screening at ports-of-entry. METHODS: Odour samples were collected from adults, and SARS-CoV-2 infection status confirmed using RT-PCR. OSC sensors captured the volatile organic compound (VOC) profile of odour samples. Trained dogs were tested in a double-blind trial to determine their ability to detect differences in VOCs between infected and uninfected individuals, with sensitivity and specificity as the primary outcome. Mathematical modelling was used to investigate the impact of bio-detection dogs for screening. RESULTS: About, 3921 adults were enrolled in the study and odour samples collected from 1097 SARS-CoV-2 infected and 2031 uninfected individuals. OSC sensors were able to distinguish between SARS-CoV-2 infected individuals and uninfected, with sensitivity from 98% (95% CI 95-100) to 100% and specificity from 99% (95% CI 97-100) to 100%. Six dogs were able to distinguish between samples with sensitivity ranging from 82% (95% CI 76-87) to 94% (95% CI 89-98) and specificity ranging from 76% (95% CI 70-82) to 92% (95% CI 88-96). Mathematical modelling suggests that dog screening plus a confirmatory PCR test could detect up to 89% of SARS-CoV-2 infections, averting up to 2.2 times as much transmission compared to isolation of symptomatic individuals only. CONCLUSIONS: People infected with SARS-CoV-2, with asymptomatic or mild symptoms, have a distinct odour that can be identified by sensors and trained dogs with a high degree of accuracy. Odour-based diagnostics using sensors and/or dogs may prove a rapid and effective tool for screening large numbers of people.Trial Registration NCT04509713 (clinicaltrials.gov).

Short durations of corticosteroids for hospitalised COVID-19 patients are associated with a high readmission rate.

OBJECTIVE: Our objective was to describe the characteristics of patients admitted, discharged and readmitted, due to COVID-19, to a central London acute-care hospital during the second peak, in particular in relation to corticosteroids use. METHODS: We reviewed patients admitted from the community to University College Hospital (UCH) with COVID-19 as their primary diagnosis between 1st-31st December 2020. Re-attendance and readmission data were collected for patients who re-presented within 10 days following discharge. Data were retrospectively collected. RESULTS: 196 patients were admitted from the community with a diagnosis of COVID-19 and discharged alive in December 2020. Corticosteroids were prescribed in hospital for a median of 5 days (IQR 3-8). 20 patients (10.2%) were readmitted within 10 days. 11/20 received corticosteroids in the first admission of which 10 had received 1-3 days of corticosteroids. Readmission rate in those receiving 1-3 days of corticosteroids was 25%. CONCLUSIONS: Most international guidelines have recommended providing up to 10 days of corticosteroids for severe COVID-19 but stopping on discharge. Our findings show shorter courses of corticosteroids during admission are associated with an increased risk of being readmitted and support continuing the course of corticosteroids after hospital discharge monitored in the virtual ward setting.