Participants and sample sourcing
INFECTIOUS DISEASES, THORACIC, ONCOLOGY
The samples were collected from: the III Infectious Diseases Unit, L. Sacco Hospital, ASST Fatebenefratelli-Sacco, Milan, Italy; the Division of Thoracic Surgery of the European Institute of Oncology (IEO), Milan, Italy; COVID-19 screening stations across the North of Italy.Participants were divided into two groups as shown in Table Groups and sample size of training and test–retest phases.
Cases, N. 146 patients COVID-19 positive, who had tested positive by RT-PCR for SARS-CoV-2 within 24 h prior collection, regardless of COVID-19 symptoms.Controls, N. 571 patients COVID-19 negative, who had tested negative by RT-PCR for SARS-CoV-2 within 24 h prior collection.The number of samples was calculated based on the number of training and test–retest sessions required according to the training technique we developed, so that dogs could be presented with several samples while ensuring a case: control ratio of 1:5. Samples collected were used multiple times only during training.