VIGILANCIA DE SARS-COV-2 EN INDIVIDUOS ASINTOMÁTICOS O PRE-SINTOMÁTICOS EMPLEANDO LA ESTRATEGIA DE AGRUPAMIENTO DE MUESTRAS: EXPERIENCIA EN UN ESCENARIO REAL DE PANDEMIA EN ÁREAS DE CÓRDOBA CON BAJA CIRCULACIÓN VIRAL

CASTELLARO A, VELEZ P, GIAJ MERLERA G, DUEÑAS J, CONDAT F, GALLARDO J, MAKHOUL A,CINALLI C, CAVAGLIERI L, DI COLA P, SICILIA P, LOPEZ L, BOCCO JL, BARBAS G, PISANO B, RÉ V, BELAUS A, CASTRO G

CABA

Congreso; XIII Congreso Argentino de Virología.; 2021

Sociedad Argentina de Virologia

Background The current COVID-19 pandemic has overloaded the diagnostic capacity of laboratories by the gold standard method rRT-PCR. This disease has a high spread rate and almost a quarter of infected individuals never develop symptoms. In this scenario, active surveillance is crucial to stop the virus propagation. Methods Between July 2020 and April 2021, 11580 oropharyngeal swab samples collected in closed and semi-closed institutions were processed for SARS-CoV-2 detection in pools, implementing this strategy for the first time in Córdoba, Argentina. Five-sample pools were constituted before nucleic acid extraction and amplification by rRT-PCR. Comparative analysis of cycle threshold (Ct) values from positive pools and individual samples along with a costbenefit report of the whole performance of the results was performed.Results From 2314 5-sample pools tested, 158 were classified as positive (6.8%), 2024 as negative (87.5%), and 132 were categorized as indeterminate (5.7%). The Ct value shift due to sample dilution showed an increase in Ct of 2.6±1.53 cycles for N gene and 2.6±1.78 for ORF1ab gene. Overall, 290 pools were disassembled and 1450 swabs were analyzed individually. This strategy allowed correctly identifying 99.8% of the samples as positive (7.6%) or negative 2(92.2%), avoiding the execution of 7,806 rRT-PCR reactions which represents a cost saving of 67.5%. Conclusion This study demonstrates the feasibility of pooling samples to increase the number of tests performed, helping to maximize molecular diagnostic resources and reducing the work overload of specialized personnel during active surveillance of the COVID-19 pandemic.