Study procedures
palate, drooling
Patients collected themselves the saliva for PCR analysis under supervision and according to a video sequence explained step by step by the health professional. Briefly they swabbed their upper and lower gingival space, plus cheeks on both sides, plus under the tongue to end with the hard and soft palate, and this for at least 20 seconds. They finished by drooling twice liquid saliva in the provided 3 ml tube containing universal transport medium, putting the swab in the tube and closing its cap. No coughing or sniffing prior to sample collection was required. Water was avoided 10 minutes prior to collection. Other drinks, food, and nasal sprays were avoided 20 minutes before sample collection. The saliva sampling procedure was chosen after multiple attempts in a pilot study in known negative and positive in- and outpatients.Then, the health professional collected two nasopharyngeal swabs, one for PCR and one for RDT analyses. Test and control lines were read by the person having collected the swab after 15 to 20 minutes and judged as positive intense, positive weak, or negative. Results were immediately entered into REDCap database. Remaining samples (saliva and the other NP swab) were sent to the molecular diagnostics laboratory for RT-PCR analysis. The patient was considered as positive for SARS-CoV-2 if any of the PCR results or the RDT result on nasopharynx was positive. Due to the nature of the intervention, blinding (to each-other PCR and RDT results) was limited to the molecular diagnosis laboratory. Once identifying information was no longer required for the basic functioning of the trial (i.e. the requirement to identify patient for result return), all eCRFs were strictly anonymised.