[Internal validity of a rapid test for COVID-19 antigens in a nursing home]./ Validez interna de una prueba rápida de detección de antígenos COVID-19 en una residencia de mayores.

INTRODUCTION: RT-qPCR is the reference test for the detection of SARS-CoV-2 infection, however, rapid antigen detection tests (RADT) are now available. In this work, the internal validity of the RADT was evaluated in the context of an outbreak in a nursing home. METHODS: Nasopharyngeal exudate samples were analyzed by RADT and RT-qPCR from 61 residents of a nursing home. The sensitivity and specificity of RADT with respect to RT-qPCR was calculated. RESULTS: Specificity was 100% (95% CI 54.1-100.0), while sensitivity in asymptomatic people was 70.3% (95% CI 53.0-84.1) and in symptomatic people 83.3% (95% CI 51.6-97.9). CONCLUSIONS: The RADTs are sufficiently sensitive and specific to be used as screening tests in nursing homes, especially in situations of outbreaks or suspected outbreaks due to the presence of symptoms.