key: cord-0748724-stllkzpb
authors: Bordi, Licia; Parisi, Gabriella; Sberna, Giuseppe; Amendola, Alessandra; Mariani, Bruno; Meoni, Guidi; Orazi, Daniela; Bartoletti, Pierluigi; Lombardozzi, Lorella; Barca, Alessandra; Capobianchi, Maria Rosaria; D'Alba, Fabrizio; Vaia, Francesco
title: Effective screening strategy against SARS-CoV-2 on self-collected saliva samples in primary school setting: a pilot project
date: 2021-05-21
journal: J Infect
DOI: 10.1016/j.jinf.2021.05.013
sha: 45b72fd67c8df0c7564b52df03fe9991502beaa6
doc_id: 748724
cord_uid: stllkzpb

nan

Recent articles published in this Journal highlighted the potential of using antigen-detecting rapid diagnostic tests (Ag-RDTs) on saliva samples for massive screening of asymptomatic subjects and epidemiological surveillance [1, 2] . Saliva has entered the shortlist of clinical samples to which the current laboratory tests can be applied, due to increasing evidences of comparable sensitivity and specificity with respect to nasopharyngeal swabs (NPS) [3] [4] [5] [6] . We previously described the performance of an automated chemiluminescence-based antigen assay applied to saliva samples in identifying individuals with high viral loads, underscoring the need for confirmatory molecular testing for SARS-CoV-2 antigen-positive cases in a setting of low prevalence [7] . Based on these results, we carried out a pilot project for SARS-CoV 2 screening on saliva in primary schools, aimed at evaluating the feasibility of the proposed algorithm, detecting any critical issues to be overcome before expanding the experience to a territorial scale, virtually to the entire region. The testing algorithm included a two-step approach: a chemiluminescence-based Lumipulse G Sars-CoV-2 Ag assay (Fujirebio) followed by molecular confirmation of positive samples using Simplexa Covid-19 direct assay (Diasorin). Both tests were currently the only ones CE-IVD marked for this specific sample matrix, and had been preliminarily evaluated [3, 7] . The pilot study was coordinated by the Regional Health Authority, within the context of surveillance and prevention activities implemented for school re-opening after summer vacations. The study involved five primary schools in Rome, hosting 2,522 students overall; 1,905 students participated (75.5%)

[median age: 9, ranging from 2 to 15; 970 males (50.9%) and 935 females (49.1%)]; sample collection was performed in 9 scheduled days during the period October 6th -November 2th, 2020.

Three-4 days before sampling, the school administrative offices acquired the informed consent from the parents of the children, as well as all data necessary to comply with the test recording procedures on the regional COVID-information platform. A barcode was generated by this procedure, that was applied on both the saliva collecting device and on the corresponding informed consent signed sheet. Saliva samples were collected at the school sites using Salivette® (Sarsted) devices, composed of two concentric tubes and a cotton sponge able to absorb saliva. The sponge should be kept in the mouth until it is well soaked (2-4 min) and then put back in the inner container, that is then sealed. Students had been asked to abstain from food or drinks or cleaning the teeth for at least 30 minutes preceding saliva collection. Student assistance in sample collection, transportation to the Microbiology Laboratory of the Saint Camillus Hospital, as well as pre-testing clerical work were performed by skilled health care worker teams named USCAR (Special Rehabilitation Care Continuity Units). Samples were registered on the local Laboratory Information System (LIS) and processed as follows:

1. Salivette®: centrifugation at 1,000xg for 2 minutes. In a low prevalence setting, the availability of an antigen test and of a molecular test that can be performed on the same saliva sample to confirm positive results, without requiring the subject to be recalled for sampling repetition, was a determining factor in the choice of the strategy adopted in this pilot study. The screening test adopted for the programme is a laboratory test and, therefore, required transport and processing in the laboratory, thus implying longer times than a point of care test (POCT). However, this did not represent a major obstacle to achieve same day diagnostic definition, due to the timely organization and information flow. On the other hand, the disadvantage of longer process was overcome by the greater accuracy of a laboratory test compared to a POCT [2, 9, 10] and the ability to quickly perform the confirmation test with a system compatible with "urgent" execution.

Overall, the adopted strategy did not evidence critical elements, and the workflow control mechanisms resulted to be appropriate, as they made it possible to timely monitor the process in all phases, from sample collection to the delivery of final results. Our results suggest that the model can be replicated and expanded in a modular way also to different settings that have similar logistics. 

Rapid Salivary Test suitable for a mass screening program to detect SARS-CoV-2: A diagnostic accuracy study

Evaluation of the rapid antigen test Panbio COVID-19 in saliva and nasal swabs in a population-based point-of-care study

Frequency and Duration of SARS-CoV-2 Shedding in Oral Fluid Samples Assessed by a Modified Commercial Rapid Molecular Assay

Comparison of Saliva and Nasopharyngeal Swab Nucleic Acid Amplification Testing for Detection of SARS-CoV-2: A Systematic Review and Meta-analysis

The Sensitivity and Costs of Testing for SARS-CoV-2 Infection With Saliva Versus Nasopharyngeal Swabs: A Systematic Review and Meta-analysis

Saliva as a gold-standard sample for SARS-CoV-2 detection. The Lancet Respiratory Medicine 2021

Capobianchi MR on behalf of the INMI COVID-19 study group. Saliva is a valid alternative to nasopharyngeal swab in chemiluminescencebased assay for detection of SARS-CoV-2 antigen

Technical Report: Options for the use of rapid antigen tests for COVID-19 in the EU/EEA and the UK. ECDC: Stockholm

Immunochromatographic test for the detection of SARS-CoV-2 in saliva

Salivary SARS-CoV-2 antigen rapid detection: A prospective cohort study