Sample pooling is efficient in PCR testing of SARS-CoV-2; a study in 7,400 healthcare professionals

Estévez, Agustín; Catalán, Pilar; Alonso, Roberto; Marín, Mercedes; Bouza, Emilio; Muñoz, Patricia; Alcalá, Luís

SARS-CoV-2 pandemic shows the importance of having efficient virus diagnosis, especially in groups of particular relevance such as healthcare professionals, without involving a large economic expense. This is a prevalence study carried out in 7,400 healthcare professionals in a 1,350-bed hospital in Madrid, Spain. Pools of 10 samples were performed, using the Xpert® Xpress SARS-CoV-2 test for the diagnosis from clinical samples of nasopharyngeal exudate. A previous study was performed to evaluate the effect of the dilution in terms of sensitivity. The estimated sensitivity was over 95%. 740 pools were performed, with a final result of 218 healthcare professionals being positive. Using the pooling system, the reagent cost reduction to the institution was 75.3%. It can be concluded that the described sample pooling system is a useful and efficient tool in the diagnosis of SARS-CoV-2 in certain groups, assuming a cost reduction without reducing the sensitivity.