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Evaluation of real-life use of Point-Of-Care Rapid Antigen TEsting for SARS-CoV-2 in schools for outbreak control (EPOCRATES)
Ana C. Blanchard; Marc Desforges; Annie-Claude Labbe; Cat Tuong Nguyen; Yves Petit; Dominic Besner; Kate Zinszer; Olivier Seguin; Zineb Laghdir; Kelsey Adams; Marie-Eve Benoit; Genevieve Leduc; Jean Longtin; Ioannis Ragoussis; David L. Buckeridge; Caroline Quach.
  • Ana C. Blanchard; CHU Sainte-Justine, University of Montreal
  • Marc Desforges; CHU Ste-Justine
  • Annie-Claude Labbe; Hopital Maisonneuve-Rosemont
  • Cat Tuong Nguyen; Direction regionale de sante publique de Montreal
  • Yves Petit; Pensionnat du Saint-Nom-de-Marie
  • Dominic Besner; Ecole secondaire Calixa-Lavallee
  • Kate Zinszer; University of Montreal
  • Olivier Seguin; Direction regionale de sante publique de Montreal
  • Zineb Laghdir; CHU Sainte-Justine
  • Kelsey Adams; CHU Sainte-Justine
  • Marie-Eve Benoit; CHU Sainte-Justine
  • Genevieve Leduc; CHU Sainte-Justine
  • Jean Longtin; Centre hospitalier universitaire (CHU) de Quebec
  • Ioannis Ragoussis; McGill University
  • David L. Buckeridge; McGill University
  • Caroline Quach; University of Montreal
Preprint in English | medRxiv | ID: ppmedrxiv-21264960
ABSTRACT
We evaluated the use of rapid antigen detection tests (RADT) for the diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in school settings to determine RADTs performance characteristics compared to PCR. MethodsWe did a real-world, prospective observational cohort study where recruited high-school students and staff from two high-schools in Montreal (Canada) were followed from January 25th to June 10th, 2021. Twenty-five percent of asymptomatic participants were tested weekly by RADT (nasal) and PCR (gargle). Class contacts of a case were tested. Symptomatic participants were tested by RADT (nasal) and PCR (nasal and gargle). The number of cases/outbreak and number of outbreaks were compared to other high schools in the same area. ResultsOverall, 2,099 students and 286 school staff members consented to participate. The overall RADTs specificity varied from 99.8 to 100%, with a lower sensitivity, varying from 28.6% in asymptomatic to 83.3% in symptomatic participants. The number of outbreaks was not different in the 2 participating schools compared to other high schools in the same area, but included a greater proportion of asymptomatic cases. Returning students to school after a 7-day quarantine, with a negative PCR on D6-7 after exposure, did not lead to subsequent outbreaks, as shown by serial testing. Of cases for whom the source was known, 37 of 57 (72.5%) were secondary to household transmission, 13 (25%) to intra-school transmission and one to community contacts between students in the same school. ConclusionRADT did not perform well as a screening tool in asymptomatic individuals. Reinforcing policies for symptom screening when entering schools and testing symptomatic individuals with RADT on the spot may avoid subsequent significant exposures in class. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSRapid antigen detection tests (RADT) have been used for years to diagnose respiratory pathogens, such as influenza and respiratory syncytial virus. These tests detect the presence of a specific viral antigen and are usually performed on nasopharyngeal or nasal specimens. RADT are relatively inexpensive and can be used at the point-of-care. Their performance characteristics vary, but they usually have high specificity and moderate sensitivity compared with PCR. For SARS-CoV-2, RADTs specificity has been quite high (99.5%), but with sensitivity ranging from 28.9% to 98.3%. Added value of this studyThis study determined the sensitivity and specificity of RADT against PCR for the diagnosis of SARS-CoV-2 in a real-life setting in high school students. The test performed well, in terms of specificity, but had a sensitivity that was as low as 28.6% in asymptomatic individuals to 83.3% in symptomatic individuals. The longitudinal aspect of the study also allowed to determine the impact of RADT on school outbreaks. Implication of all available evidenceRADT does not perform well as a screening tool for asymptomatic individuals. Reinforcing policies for symptom screening when entering schools and testing symptomatic individuals with RADT on the spot may avoid subsequent significant exposures in class.
Full text: Available Collection: Preprints Database: medRxiv Document Type: Preprint Language: English Year: 2021

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Full text: Available Collection: Preprints Database: medRxiv Document Type: Preprint Language: English Year: 2021
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